document resume - eric resume. ce 039 362. ... preventive maintenance service on. changing engine...

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CE 039 362

Batchelor, Leslie A.; Abercrombie, Richard, Ed.Heavy Duty Mechanics Apprenticeship Training, ModuleOne. Volume II.British Columbia Dept. of Education, Victoria.ISBN-0-7718-8234-3[80]266p.; For volume I, see CE 039 361.Publication Services Branch, Ministry of Education,878 Viewfield Road, Victoria, BC V9A 4V1 (Set of twovolumes--$15.00).Guides - Classroom Use Materials (For Learner)(051)

EDRS PRICE MF01 Plus Postage. PC Not Available from EDRS.DESCRIPTORS *Apprenticeships; *Auto Mechanics; Electric

Batteries; Electric Circuits; *Electricity; ElectricMotors; Electronic Equipment; *Engines; EquipmentMaintenance; Equipment Utilization; ForeignCountries; Hand Tools; Inservice Education; JobSkills; Machine Tools; Magnets; *Mechanics (Process);On the Job Training; Postsecondary Education; Safety;School Shops; *Trade and Industrial Education

IDENTIFIERS British Columbia; *Heavy Equipment Mechanics;Ignition Systems

ABSTRACTThis training manual, the second of two volumes,

comprises the final three blocks in a nine-block in-service trainingcourse for apprentices working in heavy duty mechanics. Addressed inthe individual blocks included in this volume are engines, basicelectricity, and winches. Each block contains a section on partstheory that gives the purpose, topics, operations, and applicationsof the parts and systems being discussed; a set of questions on partstheory; a section on scheduled maintenance and service repair; a setof questions on service; and a list of validated tasks to becompleted during the course of daily on-the-job routines. The manualis illustrated with photographs and drawings. (MN)

***********************************************************************Reproductions supplied by EDRS are the best that can be made

from the original document.*****.*****************************************************************

Heavy Duty MechanicsApprenticeship Training,

Module One

o S IMPARTMENT or coucarioNNATIONAL INSTITUTE OF toucAnoty

, An.IP.A 41 .. 1.44 i k, ,NI ORMA10N

, tNetta lea

. . 4 ,.. ... ,T 0.% .1 . ,t . .I.

VOLUME II

Province ot British Columbia"PERMISSION TO REPRODUCE THIS

MATERIAL IN MICROFICHE ONLY

HAS SEEN GRANTED BY

TO THE EC JCATIONAL RESOURCES

INFORMATION CENTER (ERIC)"

Developed by Program Research and Development.Ministry of Education

In Cooperation with theApprenticeship Training Programs Branch.

Ministry ot Labour

2

Canadian Cataloguing in Publication DataMain entry under title:

Heavy duty mechanics apprenticeship training.

Prepared for publication by Leslie A. Batchelor ;Richard Abercrombie, editor.

ISBN 0-7718-823h-3

1. Machinery - Maintenance and repair - Handbooks,manuals, etc. I. British Columbia. Ministry ofEducation. Program Research and Development. II.

British Columbia. Apprenticeship Training ProgramsBranch. III. Batchelor, Leslie A. IV. Abercrombie,Richard.

This manual was prepared for publication by:Leslie A. Batchelor.

Heavy Duty Mechanics Instructor.Cariboo College.

Richard Abercrombie. Editor.

3

ACKNOWLEDGMENTS

We wish to thank the following members of the Heavy Duty Mechanics TradeAdvisory Committee to the Ministry of Labour who were instrumental ininitiating the writing of this manual:

Ken Brown. Coast Tractor and Equipment Ltd.Art Latto. Kaiser Resources Ltd.Doug LaVae. Finning Tractor and Equipment Co. Ltd.Dennis Waunch. International Union of Operating EngineersA Thygesen. Pulp. Paper and Woodworkers of CanadaDon Staples. B.0 Forest Products Ltd.Jim Cameron. Utah Mines Ltd.Dave Baston. AoprenticeshiD Counsellor. Ministry of LabourVic Amirault. Program Development Officer. Ministry of Labour

We wisn to also extend our thanks to othe' members of the Heavy DutyMechanics Trade Advisory Counc.1 for the support they gave to this manual

0 0,,r,stry or f *Avon PrownCe of BMW) Columbia CanaCa140 pan of this publication may be reproduced in anyform without permisston rn writino from the publisher

4

INTRODUCTION

This is an in-service training manual for ap-prentices working in heavy duty mechanicsshops who wish to complete Module One,Heavy Duty Mechanics ApprenticeshipTraining in-service. It covers the samematerial that is taught in the 14 week trainingprogram for Module One at the vocationalschools. Although you don't have an In-structor to assist you like apprentices atschool. you will receive assistance from youremployer and the journeyman you work with.

The manual is divided into nine blocks: (1)Shop Equipment and Practices, (2) Starting.Stopping. Moving Equipment, (3) Hydraulics.(4) Brakes. (5) Power Trains. (6) Frames.Suspension. Running Gear and Working At-tachments, (7) Engines, (8) Electricity. and (9)Winches, Hoists and Cables. The material inblocks 1, 2, 6 and 9 is deal: with in a fairlythorough manner as these subjects won't becovered again in your training courses. Theother blocks. blocks 3, 4. 5. 7 and 8, are intro-ductions that give a basic gro:nding in theirsubjects. The topics in these blocks will becovered in greater detail in later courses. Themain idea behind the depth that sublects arestudied in this manual is to ty to relatecourse material to the work you will actuallybe doing in the shop at this level of your ap-prenticeship. This is the reason, for example,that detailed information is given on frames,suFdensions and running gear. whereas onlybasic informaticn is given on electricity it isassumed that you will be doing a lot of workon suspension and running gear. but little onelectrical systems.

Each of the blocks is laid out in the followingpattern: the block begins with a section onparts theory that gives the purpose, types.operations (how they work) and applications(where they are used) of the parts andsystems being discussed. A set of questier sfollows the parts theory. the answers to which.are given at the end of the block. Next is asection on service that is divided into DailyRoutine Maintenance. Scheduled Main-tenance and Service repair. Daily RoutineMaintenance deals with watchful visualchecks and adjustments: Scheduled Main-tenance with scheduled lubrication andchecks: Service Repair with removal,disassembly, repair or replacement and in-stallations. The Service Repair sections in theblocks that are written at a basic level arelimited to the types of repair that you are

likely to be doing in your shop. Another set ofquestions follows the service section Theblocks end with a list of practical tasks thatshould be cnne during daily work at your job`.'our employer has a Task Check Chart, thathe will complete to vouch that you have doneall the tasks listed in the manual.

Following is some advice on how to approachthe course:

5

It is expected that the program will becompleted within a three month period:however. provision is made for up to athree month extension if required. Tryto space the blocks out over the timeyou set to do the course There is a lotof material here. and if you leave it allto the end. you won't get finished.Monitoring of your progress in thecourse is done by your employer andby contact with the ApprenticeshipBranch. Since this is an individualizedlearning package. Were is no onestanding over you telling you to do somuch today and so much tomorrow.The onus is on you to keep a regularprogress through the course. And itwon't be easy.

Don t skip out a section thinking thatyou already know it. There probablywilt be material in it that you are uncertain of. And besides. if you knowmost of the material already you'll beable to go through it quickly.

Stocks 1. 2, 3, 4 and 5 should be donefirst. The other blocks can be taken inany order, although it's probably bestto take them in the order in which theycome.

The questions are straightforward:'here are no trick ones. They can all beanswered from a close study of thetext. Try to do as many of the questionsas you can, without going back to thetext. If you can't get a question, thenopen the text and seek the answerrather than t..rning to the answers. Thisway you re-read the topic and get amore complete understanding of it thanit you just look up the answer.

The practical tasks should normally becompleted as you work on the materialin each block: however, this may not be

4

practical due to other work com-mitments in the shop.

N.B. Some tasks may have alreadybeen covered in your day to daywork.

Check with your employer to ensurethat all areas of practical training havebeen covered.

When you complete this manual andthe practical tasks you will be requiredto write an Apprenticeship Branchexamination.

6

1

TABLE OF CONTENTS

BLOCK 7 ENGINES

EnginesBasic Internal Combustion EngineCombustion TheoryCharacteristics of EnginesQuestions - Introduction to InternalCooling Systems

Types of Cooling SystemsCooling System ComponentsCoolant

Preventive Maintenance ServiceRadiator LeakageOther Leakage AreasServicing the Cooling FilterBelts

Questions - Cooling SystemLubrication System

Lubrication System ComponentsMotor Oils

Preventive Maintenance Service onChanging Engine Oil

Questions - Lubrication SystemAir Induction System

Types of Air Induction SystemsIntercoolersAir CleanersAir Filter Restriction IndicatorTubing Hose and Clamps

Preventive Maintenance on Air InductionAir Cleaner Service

Questions - Air Induction SystemsExhaust SystemsPreventive Maintenance on Exhaust SystemsQuestions - Exhaust SystemsFuel Systems

Gasoline Fuel SystemsLiquified Petroleum Gas Fuel SystemsDiesel Fuel Systems

Basic Components of Gasoline. Diesel and LPG FuelFuelsStoring Fuels

Preventive Maintenance Service of Fuel SystemsQuestions - Fuel and Fuel SystemsAnswers - Internal Combustion EngineAnswers - Cooling SystemAnswers - Lubrication SystemAnswers - Air Induction SystemAnswers - Exhaust SystemAnswers - Fuel and Fuel SystemsTasks - Engines

717.27.27.4

Combustion Engine 7.97.107.107.117.17

on Cooling Systems 7.207.207.217.237.247.287.317.317.36

Lubrication Systems 7.387.397.437.447 447.467.487.507.51

Systems 7.537:547.567.577.587.607.617:617.627.64

Systems 7.657:717.737.787'827.847.857.867.877'887.897.90

BLOCK 8 BASIC ELECTRICITY

Basic Electricity 8:1Functions of Electricity in Heavy Duty Vehicles 81Electron Theory 8.1Basic Factors of Electricity 8.2Basic Electrical Circuit 8.4

7

Electrical Term DefinitionsBasic Electrical SymbolsTypes of Electrical CircuitsMagnetismElectromagnetismElectromagnetic InductionElectrical Test Equipment

Care and Safe Practices with Electrica: Testing EquipmentQuestions - Electricity TheoryLead Acid Storage BatteriesBattery ConstructionBattery ElectrolyteBattery Operating Cycles .

The Battery and the Charging CircuitTypes of BatteriesCapacity Ratings of BatteriesVariation in Battery Efficiency or Terminal VoltagePoints on Battery Use and ReplacementPreventive Maintenance on BatteriesBattery QuestionsBattery Testing

Hydrometer TestLoad TesterThree Minute Fast Charge Test.Summary of Testing Conventional BatteriesTesting Maintenance-Free Batteries

Questions - Battery TestingCharging Batteries

Charging Conventional BatteriesCharging Maintenance-Fre- BatteriesJumper Cables

Questions - Battery ChargingBasic Starting Circuit

The Starting MotorSwitches for Starting MotorsStarting Motor DrivesRemoving and Installing Starters

Questions - Starter MotorsCharging Circuits

DC CircuitsAC CircuitsPreventive Maintenance Service of

Questions - Charging CircuitsIgnition System

Ignition Circuit OperationWiring in the Primary CircuitIgnition Coil and CondenserIgnition DistributorCentrifugal Advance MechanismSecondary WiringBallast ResistorSpark PlugsCam Angle (Dwell) and Basic TimingPreventive Maintenance of Ignition Systems.Removing and Installing Spark PlugsAdjusting the Contact Point Gap or Cam DwellUse of Timing LightWiring HarnessFuses

8.48.68.78:108118.148.168.178.188.208.208.218.218.228.228.248.248.258'258.298.318.318.338.358.368'378.398.408.408:448.458.468.478.488.508.538.578.588:598.608.61

Charging Systems 8.648.658.668.668.688.688.698.718.728:738.738.758.768.768.778.788.788.79

8

Points on Fuses 8/9Questions Ignition Circuit 8.80Answers -- Electricity Theory 8.82Answers Batteries 8.83Answers Battery Testing 8-84Answers Battery Charging 8.85Answers Starter Motors 8.86Answers Charging System 8'87Answers Ignition Circuit ..8.88Tasks Electricity 8.89

BLOCK 9 WINCHES

WinchesTractor Mounted Winches.Types of Single-Drum Tractor- Mounted WinchesWinch Brakes

91.91939.7

Power Shift Clutches 9.10Winch Options 9.12Questions Tractor Mounted Winches 9.12Preventive Maintenance Service of Tractor Mounted Winches ....... .. ...913

Scheduled Maintenance Checks 913Winch Adjustments 9.19

Removal and Installation of Tractor Mounted Winches.... .. ..... .... ...... 9.20Questions Maintenance and Repair of Tractor Mounted Winches. . . 9 20Hoist Winches for Cranes. Excavators and Yarders 9 22Cable Operation. 9.25Basic Winch Assembly 9.26Drum Operation 9.28Winch Power Train 9.29Drums and Drum Lagging 9'31Hoist Winch Clutches Brakes and Controls .....9 33

Basic Hoist Winch Brake 9.33Basic Hoist Winch Clutch 9.33Expanding Air Tube. Multi-Disc Clutches 9.34Air Tube Clutches 9.34Magnetic Clutches 9 34Cab Controls for Clutches aid Brakes 9 35

Hoist Winches on Hydraulic Cranes 9.35Questions Hoist Winches 9.37Removal and Installation of Crane.Excavator and Yarder Hoist Winches 9 38Scheduled Maintenance Checks, Adjustments and Lubrication

on Hoist Winches 9 38Adjustments on Contracting Band Clutch 9.38Clutch Band Lines 918Example Adjustment of Contracting Band Brake 9 39Lubrication for Hoist Winches 9.40

Questions Maintenance of Hoist Winches .9.43Wire Rope 9 44Measuring a Wire Rope .... 9 47Cores 9'48Wires 9.48Strands 9 48Wire Rope Inspection 9.51

Points on Inspecting Wire Rope 9.51External Rope Damage or Abuse .... 9.52Diameter Measurement and Broken Wire Count .9.54Inspect Drums and Sheaves 9.55

9

Lubricating Wire Rope 9.55Cutting Wire Rope 9:56Clamps and Sheaves 9.57Removing and Installing Wire Rope 9.60Attaching U-Bolts 9.62Attaching Double Saddle Clips 9.64Reeving Wire Rope 9.64Questions Wire Rope 9.68Answers Tractor Mounted Winches 9/0Answers Maintenance and Repair of Tractor Mounted Winches 9'70Answers Hoist Winches 9/1Answers Maintenance of Hoist Winches 9.71

Answers Wire Rope 912Tasks Winches, Hoists and Cables 9'73

BLOCK

Engines

11

r

ENGINES 7:1

BASIC INTERNAL COMBUSTION ENGINE

An internal combustion engine IS basically acontainer in which a mixture of air and fuel isburned. This mixture rapidly expands while 81burns, creating a force that pushes against apiston. With the force of expanding gas actingon 81. the piston has the potential to performwork. Thus an internal combustion engineconverts the heat energy of fuel intomechanical work energy A simple internalcombustion engine is shown in Figure 7-1

FUEL-AIRMIXTURE

COMPRESSION

COMBUSTION

RECIPROCATINGMOTION

ROTARYMOTION

(7.1)

Courtesy of John Deere Ltd

An engine performs the following series ofevents

t Fails the cylinder with a combustible mix-ture of fuel and air (intake)

2 Compresses this mixture into a smallerspace (compression)

3. Ignites the mixture and causes d to ex-pand, producing power (powel)

4 Removes the burned gases from the cylin-der (exhaust)

One complete series of these events is calleda cycle. To produce sustained power theengine must repeat this cycle over and overagain.

An engine uses two forms of motion to trans-mit energy (Figure 7-2)

reciprocating motion' up-and-down orback-and-forth motion

rotary motion circular motion around apoint

X 1923

CYLINDER

X 13:4

RECIPROCATINGNOTION

(7-2)ROTARYMOTION

Courtesy of Jona Deere Ltd

PISTON

CONNECTING ROD

CRANKSHAFT

(7-3) BASIC PARTS OF THE ENGINECourtesy of John Deere Ltd

Using four basic parts an engine convertsreciprocating motion into rotary motion(Figure 7-3). The piston and cylinder aremated parts. closely fitted so the piston glideseasily in the cylinder with a minimum ofclearance at the sides There is sufficientspace above the piston for the combustionchamber, and the top of the cylinder is closedby a cylinder head. The c nnecting rod trans-mits the motion the piston to thecrankshaft. A simple cranl shaft has a sectionoffset from the centerline of the shaft so that itcranks whey. the shaft is turned. The stroke ofthe piston (how tar it travels in the cylinder) isset by the throw of the crankshaft (how far it isoffset).

12

7:2 ENGINES

Thus. the swing of the connecting rod and theoffset of the crankshaft convert the verticalmotion of the piston to rotary motion at thecrankshaft (Figure 7.4). This change in motionis basically the same as that created whenpedalling a bicycle. the up and down motionof your leg is changed to rotary motion at thesprocket and wheels.

OftOm`-.44

ka0OFFSET

CRANKSHAFT

%Alb

(7_4) HOW RECIPROCATING MOTION ISTRANSk TIED TO THE CRANKSHAFT

AS ROTARY MOTIONCourtesy of John Deere Ltd

COMBUSTION THEORY

Three basic elements aro needed to produceheat energy in an engine:

airfuel

combustion

When fuel is mixed with air and ignited. themixture will burn It's the oxygen in the air thatallows the fuel to burn, fuel can't burn withoutoxygen. The characteristics of air and fuelthat affect combustion are discussed below.

Air

1. Air can be compressed. One cubic foot ofair can be packed into one cubic inch orless (Figure 7-5). Since air does compress.a large volume of it can be packed into acylinder to surround the fuel and help itburn

2"

0 0 0 0 00 0 0 0 00 0 0 0 00 0 0 0 00 0 0 0 0

ATMOSPHERIC AIR

(7.5)

--COMPRESSED AIR


2. Air heals when it's compressed (Figure 7-6) The air molecules rub against eachother and produce heat. The heat aidscombustion because It vaporizes the fueland fuel burns best In a vaporized state.

000000O 00000000000O 00000O 00000O 00000O 00000

ATMOSPHERIC AIR COMPRESSED AIR

(7-6) AIR HEATS WHEN COMPRESSEDCounesy of John Deere Ltd

Fuel and Combustion

1. Fuel mixes readily with air. The moderngasoline engine works beet when about15 parts of air are mixed with one part offuel (Figure 7-7).

X 19:6

13

O 00000AO 0000

0

(SS:i AIR

A FUEL

(7-7)

FUEL-AIR RATIO FORGASOLINE ENGINE

Counesy of John Deere Ltd

ENGINES 7:3

Fuel-Air Ratio For Gasoline Engine

These parts are measured by weight, notby volume. Since air is very light 90.000gallons would be needed to make up :heweight necessary to mix with 10 gallons offuel.

2. Fuels are volatile. That is. they vaporize atlow temperatures. The ability of a fuel tovaporize allows each particle of fuel tocontact enough air to burn lully.

3. A fuel's physical state affects the speed atwhich it will burn. i.e.. the more air thatcan get at the fuel. the faster it will burn(Figure 7-8).

Courtesy of John Deere Lid

(7-8)

SOLID fuELI.': IN CONTAINER

Burns lazily because aironly contacts the

surface fuel

V:gfOriMigSOLID FuEl.

SPREAD OUT

Burns more auicklybecause more aircontacts the fuel

In an engine only vaporized fuel is burned.

4. Fuel must burn quickly to give the ex-plosive force necessary for full enginepower. yet it can't burn too explosively orIt could blow up the engine. The rate ofburning can be controlled by regulating.

the volatility of the fuelthe proportion of fuel in the fuel airmixture

the pressure and the heat of the air

Supplying, Compressing and Igniting Fuel AirMixtures

In gasoline engines. fuel and air are mixedoutside the cylinders in the carburetor andmanifold. the mixture is drawn into the cylin-der by the partial vacuum created during thepiston's intake stroke. In diesel engines. thereis no pre-mixing of air and luel outside thecylinder. Air only is taken into the cylinderthrough the intake manilold.

VAPORIZED NEL

Burns very quicklybecause air can completely

surround the particlesof fuel

After entering the cylinder the air fuel mixturein a gasoline engine. and only the air in adiesel engine, are compressed. The amountthat are compressed is called the com-pression ratio. An 8 to 1 compression ratio istypical for gasoline engines while a 16 to 1ratio is common for diesels (Figure 7-9).

GASOLINE DIESEL8 TO 1 RATIO 16 TO 1 RATIO

(7.9) COMPRESSION RATIOS COMPAREDCourtesy of John Deere Ltd

14

7:4 ENGINES

The fuel in the compressed fuel air mixture ina gasoline engine is ignited by a spark plug.In a diesel engine. as the piston nears the topof its compression stroke. fuel is injected orsprayed into the cylinder and mixes with thecomCressed air The fuel is then ignited by theheat (approximately 538 C) of the denceiycompressed air.

Figure 7 to 10 summarizes fuel combustion ingasoline and Mosel engines.

FUEL-AIRMIXTURE

GASOLINE (7-10)

1 Fuel-Air AreMixed in Carburetor

2 Mixture Enters Cylinderand Is Compressed

3 Spark IgnitesThe Mixture

DIESEL

AIR

1 Air Only Enters Cylinder2 Air Is Compressed3 Fuel Is Sprayed In4 FuelAir Ignites

From Heat of Compression

Courtesy of Jonn Deere Ltd

Note that the higher compression ratio makesa diesel more efficient than a gasoline engineThe higher ratio allows for a greater ex-pansion of gases in the cylinder after com-bustion and this results in a more powerfulstroke A consequence of the higher com-pression ratio is that diesel engines have tobe built of sturdier. more expensive parts thangasoline engines to withstand the greatercombustion forces A diesel's pistons. pins.rods and cranks are beefed up. and it hasmore main bearings to support the crankshaft.

CHARACTERISTICS OF ENGINES

Engines can be characterized or classifiedaccording to:

number of cylindersarrangement of cylinders

arrangement of valvesnumber of strokes per cycletype of coolingtype of fuel burned

These engine characteristics are discussedbelow

NUMBER OF CYLINDERS

The previous discussion of basic engine prin-ciples focused on a single cylinder engine.Single cylinder engines are used on smallequipment such as lawnmowers. Otherengines have multiple cylinders: 2. 3. 4. 5, 6, 8,12 and 16 An even number of cylinders ismost common. Multiple cylinder engines givea smoother more conlinuous power flow thansingle cylinder engines.

Multiple cylinder engines have one commoncrankshaft with all the pistons and connectingrods connected to it (Figure 7-11).

15

e

ENGINES 7:5

I III I I II

JAIA610111)

1-6

3-4

FLYWHEEL

(7-11) CRANKSHAFT FOR A SIX-CYLINDER ENGINECourtesy or John Deere Ltd

The crankshaft is shaped so that the pistonswill all complete one cycle intake. com-press:on power and exhaust wit:iin one. or insome engines two. crankshaft revolutions.Weights on the crankshaft balance the forcesfrom the rapidly moving parts within theengine. A heavy flywheel connected to therear of the crankshaft also balances or evensout the power impulses from the pistons.

:d.

ARRANGEMENT OF CYLINDERS

Multi-cylinder engines are made in one ofthree configurations (Figure 7-12):

V

opposed

V-TYPE

(7-12)

/6

OPPOSED

Courtesy ot John Deere Lld

7:6 ENGINES

The in-line cylinder arrangement has all thecylinders in a straight line above thecrakshaft; the V has two banks of cylindersarranged in a V above the crankshaft: the op-posed has Iwo rows of horizontal cylinder. oneon either side of the crankshaft The in-lineand V are the two most common cylinderarrangements found on heavy duty machines

The cylinders in an engine are usually num-bered In-line engine cylinders are numbered1. 2, 3.4, etc , starting at the end of the enginefurthest from the flywheel. The cylinder num-bering for V and opposed cylinderarrangements varies with the manufsctuier.

VALVE ARRANGEMENT

Another common way to classify engines is bythe arrangement of the intake and exhaustvalves, The valves can be located in diffe,ritPositions in the cylinder head or the cylinderblock. Figure 7-13 shows four types of valvearrangments.

CYLINDER HEAD

I-HEAD

Y : 4

BLOCK

H HEADt2 CYCLE) (7-13)

Two Stroke Cycle Engine

In the two stroke cycle engine. the completecycle of events intake, compression. powerand exhaust takes place during two pistonstrokes. Every time the piston moves down it'sa power stroke. every time it moves up it's acompression stroke The intake and exhausttake place during part of the compression andpower strokes Figure 7-14 illustrates thecycle of events on a two stoke diesel engine.

(7-14)

CYLINDER HEAD

BLOCK

0

11

F-HEAD


The 1 -Head and H-Head are combined underthe name of overhead valves and are the mostcommon valve arrangements used today.

NUMBER OF STROKES PER CYCLE

Most engines have either a two or a fourstroke cycle. The two strolte cycle engine hastwo strokes of the piston. one up and onedown. during each cycle. These two strokesoccur during the one revolution of thecrankshaft and are repeated over and overagain.

The four stroke cycle engine has four strokesof the piston. two up and two down, duringeach cycle. The four strokes occur during tworevolutions of the crankshaft. Most enginestoday have a four stroke cycle.

ilITAKE AND EXHAUST

17

COMPRESSION

POWER

Courtesy of JOhn Deere Lld

ENGINES 7:7

Occasionally. in this type of diesel engine. ablower (also called a scavenge blower) forcesair into the cylinder for the expulsion ofexhaust gases and the supply of fresh air forcombustion In place of intake valves thecylinder wall contains a row of ports whichare above the piston when it is at the bottomof its stroke These ports admit air from theblower into the cylinder when they are un-covered (during intake)

The flow of air toward the exhaust valvespushes the exhaust gases out of the cylindersand leaves them full of clean air when thepiston again rises to cover the ports (duringcompression) At the same time. the exhaustvalves close and the fresh air is compressedin the closed cylinder.

As the piston nears the top of :ts compressionstroke. fuel is sprayed into the combustionarea The heat of compression ignites the fueland the resulting pressure forces the pistondown on its power stroke. The piston then un-covers the intake ports. the exhaust valvesopen. and the cycle begins once more.

This entire cycle is completed in onerevolution of the crankshaft or two stokes ofthe piston. The number of pistons the enginehas makes no difference, ail pistons in thistwo cycle engine will fire during onerevolution of the crankshaft

AIR

F elis.

Four Stroke Cycla Engine

fri four stroke cycle engines. the same fouroperations occur -- intake. compression.power, and exhaust however. lour strokes ofthe piston. two up and two down. are neededto complete the cycle As a result. thecrankshaft will rotate two turns before onecycle is completed.

Figure 7-15 shows the strokes of a lour strokecycle gasoline engine.

The intake stroke starts with the piston nearthe top and ends with it near tree bOttcen of itsstroke. The intake valve is opened and as thepiston moves down a low pressure is createdwithin the cylinder. Atmospheric pressurethen forces the air-fuel mixture in a gasolineengine. or air only in a diesel engine into thecylinder.

The compression stroke begins with thepiston at the bottom of the cylinder. Next thepiston rises, compressing the fuel-air mixture.Since the intake and exhaust valves areclosed. there is no escape and the mixture iscompressed to a fraction of its originalvolume.

(7-15) FOUR STROKE CYCLE ENGINE(Gasoline Shown)

i_

INTAKE COMPRESSION POWER EXHAUST

Fool Air Mixture Mixture Is Compressed Compressed Mixture Is Piston On Up-StrokeIS ()town Into By Up-Stroke Of Poston Ignited By Spook PIN Forces Horned (dosesCy Imdel From Cor Both Intoko and Exhoust and Expanding Goes From Cylinder ThroughIngetor Through volues ore Closed. Porto Prston To Bottom Open Exhaust Vo lueOpen Info lie VOW 06 Cylinder VoguesSy 0own-Stroke Of Remain Closet!.Piston CouitosY of John Deem lid

18

7:8 ENGINES

The power stroke begins when the pistonnears the top of its stroke and the fuel -air mix-ture is ignited As the mixture burns and ex-pands. it forces the piston down on its powersloke The valves remain closed so that allthe force is exerted on the piston

The exhaust stroke begins when the pistonreaches the end of its power stroke Theexhaust valve is opened and the piston rises.pushing ow the burned gases When thepiston reaches the top, the exhaust valve isclosed and the piston IS ready for a new fourstroke cycle of intake. compression powerand exhaust When the piston competes thecycle the crankshaft will have gone aroundtwice

Two Cycle versus Four Cycle Engines

It mignt be reasoned that the two cycle enginecan produce twice as much power as a fourcycle engine However. this IS not quite trueIn the !wo cycle engine, some power may beused to drive the blower that forces the fuel-air charge into the cylinder under pressure.Also. the burned gases are not completelycleared from the cylinder. resulting in lesspower per power stroke Another loss in theeffective power stroke occurs because theexhaust valves open earlier in a two cycleengine

The actual gain in power of a two cycleengine over a four cycle engine of the samedisplacement is about 75%

TYPES OF ENGINE COOLING

Engines can also be classified according totheir cooling system There are two types ofcooling water cooled and air cooled Aircooled systems are generally used on smallengines although one manufacturer of dieselengines. Ouetz uses air cooling on itsengineS Water or liquid cooled is the mostcommon metnod of engine cooling Coolingsystems are detailed later

TYPE OF FUEL BURNED

The three most common types of engine fuelare

gasoline

dieselLiquid Petroleum Gas (usuallypropane) (LPG)

The three fuel systems are discussed in detailfurther on in this section The chart in Figure7-16 compares the performance of gasoline.LPG. and diesel engines

The comparisons assume that each fuel isavailable at a reasonable price. Performanceis based on general applications which aresuited to the engine and fuel type It es alsoassumed that the engines are all in good con-dition

(7-16)

COMPARING THE ENGINES

Gasoline LPG Diesel

Fuel Economy Fair Good Best

Hours BeforeMaintenance Fair Good Good

Weight perHorsepower Low Low High

Cold WeatherStarting Good Fair Fair

Acceleration Good Good Fair

ContinuousDi'ty Fair Fair Good

Lubricating OnContamination Moderate LOwest Low

CompressionRatio Low Higher Highest

19

CoutteSy 01 Juhn Deere Lid

ENGINES 7:9

QUESTIONS INTRODUCTION TOINTERNAL COMBUSTION ENGINE

1. An internal combustion engine convertsthe energy of fuel into

energy that does work.

2. What are the three basic elementsneeded to produce heat energy in anengine?

3 What happens to the air in a cylinderwhen it is compressed?

4. In what physical state is fuel burnt in anengine?

5. True or False? It is the nitrogen in airthat causes fuel to burn.

6 An engine changes reciprocating motioninto _ motion to transmitenergy.

7. For an engine to Lperate. whichsequence of events must occur?

(a) intake. exhaust. compression andpower

(b) compression. intake. power andexhaust

(c) exhaust. power. compression andintake

(d) intake. compression. power andexhaust

8 One complete series pi the events on th'last question is called a

(a) stroke

(b) circle(c) cycle

(d) stroke-cycle

9 When both intake and exhaust valves arelocated in the cylinder head. the engineis said to De a

(a) F-Head

(b) I-Head

(c) L-Head

(d) 14-Head

10 Briefly explain the basic difference be-tween a two stroke cycle engine and afour stroke cycle engine.

11. Engines can either be cooledor cooled.

s.

12. What are the three most common typesof fuel burned in internal combustionengines?

13. What is the basic difference on the com-bustion processes of diesel and gasolineengines?

14 Why is the compression ratio higher in adiesel engine?

20

7:10 ENGINES

The remainder of this block on Engines willdiscuss the five basic engine supportsystems: cooling. lubrication. air induction.exhaust and fuel.

COOLING SYSTEMS

The cooling system has two functions.

1. To prevent overheating of the engine.Overheating could burn up engine parts ina short time. Some heat is needed forcombustion. but a working enginegenerates too much heat. The coolingsystem must carry off this excess heat.

2 To regulate engine temperature.

Regulating the temperature allows theengine to be maintained at the best heatlevel for good combustion during eachstage of operation During starting. nocooling is necessary since the enginemust be warmed up as fast as possibleLater. during peak operations. the enginemust be cooled.

TYPES OF COOLING SYSTEMS

Two types of cooling systems are used onmodern engines-

1Thermostat2Crossover Tube3Coolant Outlet Hoses4Radiator6Deaeration Line6Thermostat 14-busing7Over Flow tube8Water Pump9Coolant Inlet Hose

10Engine Oil Cooler11Pressure Renef Valve12Water Filter (If Used)13Drain Cock

Air cooling air passes around the engine todissipate heat.

Liquid Cooling water circulates around theengine to dissipate heat.

.-.ir Cooling is used primarily on small enginesor aircraft as it is difficult to route air to all theheat points of larger engines. Metal baffles.ducts. and blowers are used to aid indistributing air to engine parts.

Liquid Cooling normally uses water as acoolant. In cold weather. anti-freeze solutionsare added to the water to prevent freezing.

The circulation of the coolant through thecooling system can be followed in Figure 7-17.A water pump (8), mounted on tha engine.draws coolant from the radiator oottom.through the coolant inlet hose (9). The coolantis then forced through the oil cooler (tG), andinto the cylinder block. 1 he coolant then cir-culate, around the cylinder bores and up intothe cylinder head water jacket. through thethermostat housings (6). up through coolantoutlet noses (3) and back to the radiator (4).Air flow through the radiator cools the waterand dissipates heat into the air. The waterthen recirculates into the engine to pick upmore heat.

RADIATOR MOUNTING AND HOSES(COOLING SYSTEM)

2 1 3

(7-17)1\3 12

21

Courtesy of Terex Division ofGeneral Motors Corporation

ENGINES

COOLING SYSTEM COMPONENTS

Blocks, Heads and Manifolds

The engine cyl,nder block and head contain anumber of connecting passages to allowcoolant to flow completely around all of thecylinders. combustion chambers and valves.Together these passages make up the waterjacket (Figure 7-18)

WATERJACKETS

CYLINDER liEAD

VALVE

CYLINDER

PISTON

(7-18) IN-LINE BLOCK

CYLINDERBLOCK


The water jacket holds only a small amount ofcoolant This small amount allows for rapidwarm up while the thermostat is closed whenfirst starting the engine. but is still enough toprovide efficient cooling to all the vital areaswhen the thermostat is open and the enginewarm

Note the holes in the cylinder block and cylin-der head in Figure 7-19 Not all. but many. ofthese holes are water passages

As well as the internal connecting passages ofthe water jacket. some engines use externalconnecting passages called water manifolds.They are bolted onto the outside of the engineby a flange mount and have a gasket betweenthe two mating surtaces. Water manifolds areused, for example. between cylinder headswhen an engine has multiple cylinder heads.or between the oil cooler and engine block.

0

c % AOel;twiA6Afr,.W .1vArAr.

41.

7:11

(7-19) fIEMOvING THE CYLINDER HEADCounesy of John Deere Ltd

RadiatorThe radiator is the heat exchanger for thecooling system (Figure 7-20). It consists of atop tank. a bottom tank and a finned core sec-tion. The bottom tank is equipped with a drainat its lowest point. The tanks may be solderedto the core section like the one shown below.or the tanks and side pieces may be bolted tothe core sections. Radiators used for largeengines and machines generally have bolted-on tanks.

TOP TANK

Coultesy of J i Case

CORE

BOTTOMTANK

(7-20)TYPICAL RADIATOR

22

7:12 ENGINES

Two types of radiator cores are illustrated inFigure 7-21. a tube and fin core and a cellularcore Variations on the tube and fin core arethe most commonly used in radiators today.

AIR

WATERPASSAGE TUBE

(7-21) TUBE and FIN-TYPERADIATOR CORES

Courtesy of John Deere LtdWATER

PASSAGE

AIR

(7-21) CELLULAR-TYPERADIATOR CORE


Radiators work on the principles of con-vection (circulation of the coolant) andradiation (sending heal in waves into the air).Flow created by the water pump and by ther-mal syphon action carries heated coolantfrom the engine to the radiator. The heatedcoolant enters the radiator by the upperradiator connection hose. As the coolantflows down through the core. heat from the

RADIATOI

coolant is transferred to the fins From the finsthe heat is radiated out into the air currentsthat pass through the core and is carriedaway

Water Puma

The water pump is said to be the heart of thecooling system: it must circulate the waterthroughout the cooling system (Figure 7-22).

The pump is located at the front of the engineand is generally driven directly or indirectly byV belts attached to the crankshaft pulley. Thepump shaft is mounted on lubricated andsealed anti-friction bearings. The impeller. thepart of the pump that propels the coolant. ispressed on the inner end of the shaft. The sizeand design e the impeller will depend on thecoolant flow requirements of a particularengine.

Most cooling systems use a centrifugal pumpSimilar to the one in Figure 7-23.

COVER

SPRING RETAINER

ELBOW t BALL BEARING

HOUSING

IMPELLER

X :: 1, 0

SEAL

is+

FAN PULLEY

FAN HUB

GASKET

(7-23) WATER PUMP DISASSEMBLED

Courtesy 01 John Deere Ltd

WATERPUMP BLOCK

(7-22) WATER PUMP Courtesy of John Deere Ltd

23

Ylr

ENGINES 7:13

Thermostats

The thermostat provides automatic control ofengine temperature to get the best per-formance from an engine The thermostat isbasically a temperature sensing device and avalve. The temperature of the coolant acts onthe heat sensory unit which opens and closesthe valve creating a flow of coolant that main-tains the desired engine temperature. Only asmall part of the engine's cooling capacity isrequired under light lc Js, even during warmweather. During warm-up the thermostatremains closed; by means of a bypass thewater pump circulates coolant through onlythe engine water jacket. The engine quicklywarms up to its operating temperature beforethe thermostat opens. When the thermostatopens. hot coolant flows from the engine tothe radiator and back to the engine (Figure 7-24).

TO RADIATOR

BYPASS

it CoolantCold

THERMOSTATCLOSED

COOLANTTHERMOSTAT HOT

OPEN

(7-24) COOLING SYSTEM THERMOSTAT


The thermostat is located between the coolantoutlet of the cylinder head and the top tank ofthe radiator The exact location will vary from

.engine to engine. Large engines sometimesuse two thermostats to reduce the restrictionof water flow that can be caused by one ther-mostat.

The two most common types of thermostatsare

1. Wax pellet type wax pellet expandswith increased temperature to open thevalve.

2. Bellows type gas inside a bellows ex-pands when heated Causing the valve toopen.

Thermostats are made in a variety of tem-perature ranges to meet various working con-ditions. A high temperature thermostat hassome advantages. High-temperature ther-mostats. which open at 82.0 (180 F) or more.improve engine operation and reduce crank-case sludging and corrosive wear of engineparts. An engine operating above 82'C (180 F)is hot enough to:

improve combustion

burn impurities out of the oil in thecrankcase

thin the oil to provide good lubrication

Caution; Do not use low-boiling-pointalcohol or methanol anti-freezewith high-temperature thermostats.

Overheating may so damage a thermostat thatthe valve won't function properly. Rust canalso interfere with thermostat operation. If athermostat is not running properly the enginewill run too hot or too cold. The followingpractices should be observed with ther-mostats:

Always keep a thermostat in goodworking condition.Never operate the engine without athermostat.

Always use the thermostat (design)specified for the make and model of theengine being used.)

Fans, Belts and Drives

The purpose of the engine fan is to create adraft of air through the radiator. When theengine runs. the fan pulls or pushes air acrossthe radiator core to cool the liquid in theradiator. The ideal location of the fan is ap-proximately 2'rt inches from the radiator core.The size and number of blades on the fan willvary depending on the cooling requirementsof the machine.

Fans on smaller engines are bolted to a flangeon the water pump shaft. Larger engines havethe tan mounted on a separate fan hub; thisfan is generally driven by a belt(s) from theengine crankshaft. as seen in Figure 7-25.

24

7:14 ENGINES

FAN HUB

(7.25)

Conres. of Generm Movers Corpotanon

./

ADJUSTING BOLT tr!-- -

BELTS

Fans can be either suction or blower fans.depending upon the design of the coolingsystem Suction fans (Figure 7-26) pull airthrough the radiator and push it over theengine The suction design permits the use ofa smaller fan and rldiator than is requited forblower fans Sue .n tans are used whenmachine mot' aids air movement throughthe radiator such as on a truck

SUCTIONFAN

(7-26)

Counesy ofJohn Deere Ltd

Blower fans (Figure 7-26) pull air across theengine, then push it through the radiator. Theyare used in slow-moving machines and onequipment where harmful materials might bedrawn into the radiator by a suction fan.

BLOWERFAN

(7 -26)

Counesy of John Deere Ltd

CRANKSHAFT

The Ian can be fixed drive or thermostatically-operated drive The fixed drive fan turns con-tinuously as the crankshaft turns. the ther-mostatic drive fan is temperature controlledand operates oily when it is required Thethermostat drive has the advantage of notwasting engine horsepower to turn the fanwhen it isn't needed.

Some machines have a shrouding around thefan (Figures 7-27 and 7-28). Shrouding in-creases fan efficiency by controlling or direc-ting air flow through the radiator. Fan shroudsfit close to the fan blades to prevent recir-culation of air at the blade tips. A blower fanIS usually set 1/3 into the shroud and a suctionfan is usually set 2/3 into the shroud.

ti

r'

Fan Shroud.

25

FAN SHROUD

6.

jt

yt

(7-27)

Counesy of Caterpillar Tractor Co

ENGINES 7:15

RADIATOR

Courtesy of Font MOlOr Company

-NLOWER HOSE

Belts that drive fans are called V belts be-cause of their V shape A belt's ability totransmit power from the crankshaft dependson.

1 The tension holding the belt to the pulleyBelt tenon is a very important servicepoint and will be covered later.

2 Friction between the belt and pulleysBelts should run dry. Oil on belts causesthem to slip. and so any oil teaks in thearea of the belts must be quickly repaired

3 Arc of contact or wrap between the beltand pulleys Wrap is built into a belt andpulley when manufactured Figure 7-29illustrates how a V-belt runs in a sheaveboth at rest and under load.

\---vt----

(7-29) UNDER LOAD


Because there is a definite fit to a belt andpulley. replace belts Only with the typerecommended in the service manual.

Small engines (on automobiles and lighttrucks) generally use one belt and this beltperforms three lobs drives the water pump,the fan. and the alternator Larger gasolineand diesel engines use multiple belts In mat-ched sets that may drive just the fan or theymay drive all three: the fan. water pump ?r"lalternator.

Hoses and Clamps

Flexible hoses connect the radiator to theengine. Flexible hose is used rather than rigidpipe because the hose stands up better undervibration. Radiator hose slide fits over theradiator and engine connections and issecured with a compression clamp (Figure 7-30). CAP

(7-30)

RADIATOR ROSEUPPER 8260

CLAMP

VIA DUI MA HOSE LOWER

RADIATOR ASSEMBLY MS

Courtesy of Ford Motor COmdany

7:16 ENGINES

Various types of hose are mat e'

1 Straight hoses will collapse if bent. andso is only used between two in-line fit-tings. Available in various I.D sizes and inthree or four foot lengths to be cut asdesired.

2 Universal flex-hose has spiral wiremoulded into the hose to prevent it fromcollapsing when installed where a curvedhose is required It too comes in variousI 0 sizes and in three or four foot lengthsto be cut as desired.

3 Mouldit hoses are manufactured to thecorrect size. length and angle to fit aspecific location.

As durable as hoses are. they still have weakpoints Radiator hoses can be damaged by hotair or over heated water and 7.,snera:ly willdeteriorate over long period: , ..1 age. Twocommon types of hose damage are

1 Hardening or cracking which destroyshose flexibility. causing leakage andallowing small pieces of rubber from thehose's inner liner to clog the radiator.

2. Softening and swelling which deterioratesthe hose lining and can cause the hose torupture or break

Radiator Shutters

Shutters help to maintain optimum enginetemperature by controlling air flow throughthe radiator

The system consists of (Figure 7-31)-

t the shutter

2 shutter control bar

3 air cylinder

4 shutterstat (temperature control valve)

SHUTTERSTAT--..

/SHUTTER

27

AIRCYLINDE-

(7-31) AIR - OPERATED RADIATOR SHUTTERASSEMBLY GAS ENGINE

Courtesy of Ford Motor CompanyQ101 5 -A

Shutter action depends upon engine tem-peratures as sensed by the shutterstat. Theshutterstat is located so that it responds tocoolant temperature. Until coolant tem-perature rises to approximately 185 F (85 C).the shutters remain closed. When the shut-terstat operating temperature is reached. ther-mostatic action shuts off air supply to the aircylinder and simultaneously exhausts airpressure from the cylinder. Shutter spring ac-tion then opens the shutters. Note that theshutters don't partially open; they are eitherfully open or fully closed.

Coolant Filter

Some engines use a filter in the coolingsystem The coolant filter (Figure 7.32) softensthe water and removes dirt As a result. thecooling system dissipates heat better and itsworking parts wear longer

ENGINES

(7-32) COOLANT FILTERCourtesy 01 John Deem Ltd

The coolant filter has a replaceable element. Italso has a sump at the bottom of the filterwhere dirt settles. The sump drain plug shouldbe opened periodically to dispose of thesediment.

Instead of replaceable element coolant filters.some manufacturers use spin-on filters thatare thrown a. ray after the engine has gone acertain num er of miles For servicing theirvehicle these manufacturers supply a set ofspin-on-throw-away filters for oil. fuel andcoolant They reason that the coolant filter isless likely to be overlooked (which does hap-pen with replaceable element filters) if it is in-cluded with the other filters

Chemicals in the filler element and resistorplates soften the water by removingcorrosives The softer water helps to keep theradiator and water Jackets free of scaleAnother chemical in the filter dissolves intothe water to alkalize it just enough to preventacid corrosion of the metal parts. Rustinhibitors are also placed in the elementwhich dissolve into the water and form a rust-protective film on the metal surfaces of thecooling system

The filter shown in Figure 7-32 is a bypasstype If it clogs. all water will bypass the filterand go straight to the engine.

7:17

Different types of coolant filters are availableOne factor that has a bearing on filter type isthe kind o. :nti-freeze used in the coolingsystem. r, Ite:s *61 anti-freezes must be com-patibici.

COOLANT

Coolant Rewire Items

A suitable coolant solution must meet thefollowing i.a.;..: tequirements:

provide for adequate heat transfer

provide a corrosion-resistant en-vironment within the cooling system

prevent formation of scale or sludgedeposits in the cooling system

be compatible with the cooling systemhose and seal materials

provide adequate freeze protectionduring cold weather operation.

When freeze protection is not required asolution of suitable water plus corrosioninhibitors (assuming no coolant filter) willsatisfy these requirements When freezeprotection is required a solution of suitablewater plus permanent anti-freeze (which con-tains corrosion inhibitors) will be a satisfac-tory coolant.

The Need For Corrosion Inhibitors

Any water. whether of drinking quality or not.will produce corrosion in the cooling systemAlso. scale deposits may form on the internalsurfaces of the cooling system due to themineral content of the water. Therefore. waterused as a cooiant, mast be properly treatedwith inhibitors to protect the metallic surfacesof the cooling system against corrosion andscale deposits.

Figure 7-33 illustrates the harm done bymineral deposits. cast iron with mineraldeposit withholds its heat rather than readilytransferring it to the coolant.

28

ENGINES

HEAT TRANSFER CAPACITY

41\_I/16-

MINERAL DEPOSIT

114

CASTIRON

I CAST IRON PLUS 1116- MINERAL DEPOSIT4 1 /4 CAST IRON IN HEAT TRANSFERARIUTY

(7-33)Courtesy of Detroit Diesel Division ofGeneral Motors Corporation

All inhibitors become depleted through nor-mal operation, and additional inhibitors (oranti-freeze) must be added to the coolant atprescribed intervals to maintain originalstrengths. Also. after a scheduled amoun. ofhours or miles the coolant should be com-pletely drained and replenished. Alwaysfollow the manufacturer's recommendationson inhibitor and anti-freeze usage.

Anti-freeze

When freeze protection is required. a per-manent anti-freeze must be used An inhibitorsystem is included in this type of anti-freeze.and no additional inhibitors are required if. oninitial fill a minimum anti-freeze concentrationof 30% by volume is used Solutions of lessthan 30% concentration do not provide suf-ficient corrosion protection. Conversely, con-centrations over 67% adversely affect freezeprotection and heat transfer rates.

There are two kinds of anti-freeze: ethyleneglycol base anti-freeze and methoxy propanolbase anti-freeze Ethylene glycol is most com-mon The methoxy propanol base anti-freezeis incompatible with the seals used in somecooling systems and should not be usedunless recommended by the manufacturer.

The inhibitors in permanent anti-freeze shouldbe replenished at approximately 500 hours or20.000 mile intervals. Commercially availableinhibitors may be used to restore inhibitorstrengths in anit-freeze solutions. However.most manufacturer's will recommend

changing the coolant and adoing a new anti-freeze-water solution at certain hour ormileage intervals.

As was mentioned earlier. coolant filterswhich are found on some machines havecorrosive inhibiting chemicals in their filteringmaterial. Additional inhibitors are not neededand shouldn't be added. Cooling systemswhich have a filter and need permanent anti-freeze (which has corrosion inhibitors) willuse a special type of filtering element.

29

PA

ENGINES 7:19

Summary of Coolant Recommendations

1. Always use a properly inhibited coolantand maintari the inhibitor strength.

2. Do not use soluble oil as an inhibitor.

3. Always follow the manufacturer's recom-mendations on inhibitor and anti-freezeusage and handling.

4. If freeze protection is required, alwaysuse a permanent anti-freeze.

5. To keep up inhibitcr strength in anti-freeze add a recommended non-chromate inhibitor or drain the systemand change the anti-freeze.

6. Do not use a chromate inhibitor with per-manent anti-freeze.

7. Do not use methoxy propanol base anti-freeze unless recommended by themanufacturer.

8. Do not mix ethylene glycol base anti-freeze with methoxy propanol base anti-freeze in the cooling system.

9. Do not use an anti-freeze containingsealer additives.

10. Use extreme care when removing theradiator pressure control cap.

30

.

4

7:20 ENGINES

PREVENTIVE MAINTENANCE SERVICE ONCOOLING SYSTEMS

The cooling system should be -isually in-spected during the daily walk around check.and (luring scheduled maintenance on thesystem. Minor problems should be im-mediately repaired. and major ones should bereported Inspection checks on the coolingsystem can be found in the service manualand should include the following.

1 Check the coolant level and add water iflow.

(a) System without reserve tanks.remove the radiator cap and checkthe coolant level. Caution: If thesystem is hot. it contains pressure.Removing the radiator cap when thecoolant is hot could cause injury.Wait until the coolant cools down.and then slowly remove the cap.Hissing after a slight turn of the capwill indicate the system is still underpressure and too hot tr. open.

(b) Cooling system with reserve tanks:check the coolant level by checkingthe level of the see-through plasticreserve tank or by removing the cap.

2. Inspect for ieaks. Leaks can occur in theradiator, on the outside of the enginewaterjacket. in hoses and at hose con-nections. Internal water leaks can also oc-cur. but they won't be dealt with here.Leakage is the most rommon problem in acooling system and can increase duringwinter due to metal shrinkage. Airpressure leakage testers can be helpful inlocating external leaks. Leaks are easiestfound when the system is cold.

Minor teaks can be repaired with a sealingcompound. However, only practical ex-perience enables a serviceman to tell if aleak can be corrected with a sealingsolution. Follow instructions when usingsealing solutions: some react chemicallywith anti-freeze and rust inhibitors andmay seriously affect coolant performance.

Radiator Leakage

Most radiator leakage is due to cracking ofsoldered joints caused by engine vibration.frame vibration, and cooling system pressure.

Carefully examine radiator for leaks beforeand after cleaning. Some leakage points mayhave gone undetected because they were

plugged with rust. White. rusty. or coloredstains indicate previous rldiator leakage. Ifwater cr an alcohol-based anti-freeze is usedthese spots may be dry because suchcoolants evaporate quickly. If the stains aredamp it's because an ethylene glycol anti-freeze was used and it doesn't evaporate.

Always seal a radiator leak before installriganti-freeze coolant. Depending on size andnumber. radiator leaks can be repaired with asealing compound. by soldering. or they mayhave to be tended to by a radiator repair shop.Note that sealing compounds are not recom-mended by some manufacturers because:

1. they aren't a permanent repair.

2. they can ultimately cause plugging of theradiator.

Other Radiator Checks

1. Check radiator baffles (Figure 7-34).Missing or damaged baffils can allowenough air recirculation to causeoverheating.

BAFFLES

31

(7-34)Courtesy of Cater Pular Tractor Co

ENGINES 7:21

2. Check for radiator plugging. The majorcause of reduced air flow is the ac-cumulation of foreign material in theradiator core air passages (Figure 7-35). Inland clearing. sanitary land fill and otherjobs where trash is present, leaves, weedsand other debris are drawn into theradiator core. As the core becomesplugged. the effective cooling area isreduced and heat transfer rapidlydecreases.

Courtesy of Catercatiar Tractor Co,z...

-.....

(7-35) DIRT CAKED IN CORE FINS

PLUGGED RADIATOR CORE

Keep the radiator clean and free of dirtand trash A quick visual observationusually won't detect core plugging. Aclose inspection is necessary. Check theradiator core area outside the an circle.The core is usually free of plugging withinthe fan circle. but a close look oftenreveals extensive plugging in the outercore areas. An air flow meter can be usedto measure the flow of air through theradiator and thus pinpoint plugged areas

The radiator core can be cleaned withwater or air pressure (Figure 7-36).

If

74ii1 RPlianift

In

.

...Ma.

(7-36) CLEANING THE RADIATOR CORECourtesy of Caterpritar Tractor Co

External Waterjacket Leakage

Inspect the engine cylinder block while theengine is running both before and after it getshot. Leakage of the engine block isaggravated by pressure in the cooling systemand temperature changes of the metal. Smallleaks may appear only as rust. corrosion. orstains due to evaporation.

Other Leakage Areas

Watch for leaks at these trouble spots'

1. Core-Hole or Frost Plugs: Remove the oldplug then clean the plug seat and coat itwith a sealing compound. Drive a newplug into place with the proper tool

2. Gaskets: Tighten the joint or install a newgasket. Use a sealing compound whenrequired.

3. Stud Bolts and Cap Screws Apply sealingcompound to threads.

4. Check for leaks in hose lengths and athose clamps. Also check for hosedeterioration (Figure 7-37).

Cooling systems are constantly expandingand contracting as the engine starts. runsand shuts down. Owing to such variationsin temperature. clamps can loosen andthe hose material can deteriorate.

32

(7-37) DAMAGED HOSESCourtesy of John Deere Lid

ENGINES

Hoses and clamps should be examined atleast twice a year. Check the outside ofhoses for

(a) hardening. cracking

(b) softening. swelling

Cracked or swollen hoses should bereplaced immediately. Also check the in-side of hoses for

(a) corrosion of any reinforcing springs.

(b) material failure. Hoses candeteriorate en the inside and still ap-pear all right on the outside (Figure7-38).

To be ^ale repua.se hoses often enough so thatthey are always pliable and able to passcoolant without leakage. When replacinghoses:

1. Use the best quality hose available.

2. If universal flex hose is used. allowenough hose for movement. but not sorruch that buckling or wrinkling occurs.

3. Straight hoe must only be Lsed whenconnections are in-line.

4 lViLuided hoses must be of the correctshape and length.

5. Clean the pipe connections and apply athin layer of non-hardening sealingcompound when installing hoses (Figure7-39).

Sedog

Compound

(7-39) SEAL THE CONNECTIONS


Locate the hose clamps properly over the con-nections as shown in Figure 7-40 to provide asecure fastening. An improperly installedhose (1) will be blown off by the pressurizedcooling system or (2) will allow air to be drawninto the inlet side of the pump. causingaeration of the coolant which is very harmfulto the engine.

X 1761

(7.38) INTERIOR OF DAMAGED HOSE

Courtesy of John Deere Ltd(7-40)

TIGHTEN HOSE CLAMPS SECURELYCourtesy of Jahn Deere Lld

33

ENGINES 7:23

CHANGING THE COOLING FILTER

Cooling filters should be changed at the timeintervals stated in the service manuals. Atypical maintenance procedure is givenbelow.

Cooling Filter Service

1 Check the condition of the electro-chemical plates. 4 and 6 in Figure 7-41. af-ter every 500 hours of operation. if theplates are rusted. pitted or corroded. theyshould be cleaned with steel wool. andthen rinsed in cleaning solvent and driedwith filtered, compressed air. When theplates are badly deteriorated. install newones.

1 Cover Bolt2 Cover3 Cover Gasket4 Upper Plate5 Element

I Cent 4414tewte

Co** Cuket4 9**9 Mt*I 0.44494

Lowtr 4744Spine'mot S.4471.

6 Lower Plate7 Spring8 Filler Body9 Plug

t7-41) WATER FILTER COMPONENTSCourtesy of Genera! Motors Corporaiion

2. The sump at the bottom of the housing (8)should be drained and cleaned out every500 hours.

3. Change the filter element (5) every 500hours (see Manual for Procedures).

After the filter has been reassembled and in-stalled. check the following points:

1. Make sure the inlet and outlet shut-offvalves are open

2. Check all hoses. fittings and connectionsfor leaks.

3. Check the coolant level in the radiatorand replenish as neccesary to com-pensate for losses during cooler ser-vicing.

These points are extremely important, Forexample. you can imagine what would happenif the valves were not opened.Sometimes the filter may be serviced whenthe complete cooling system is drained andflushed. When installing new coolant remem-ber the following: never add rust inhibitor to acooling system that has a water filter. Thefilter contains a corrosion inhibitor

Testing Anti-freezeThe strength of anti-freeze solution must besufficient to prevent freezing at the lowesttemperature expected. A number of testersare made to check the strength of anti-freezebut a hydrometer is the most common one(Figure 7-42). The hydrometer works on theprinciple of a float in a sight glass rising to alevel that indicates the strength of the anti-freeze.

RUBBER-4.BALL

FLOAT

REFERENCESCALE

11 a

(7-42)Courtesy ofFord Motor Company

To use the hydrometer. insert the hydrometer.,rubber hose into the coolant at the top of theradiator. Squeeze the rubber ball of thehydrometer to draw up the coolant info thesight glass. The float will rise to a ocrtainlevel. Compare this level to a reference scaleto determine the strength of the anti-freezesolution.

34

7:24 ENGINES

BELTS

Belts have to be checked for their condition.alignment and tension

Belt Condition

Belts are not meant to ride on the ' Atom ofthe groove When they do, they heat checkand crack (Figure 7-43) or grow hard andpolished A heal damaged belt indicates thateither its badly worn. forcing it to ride too lowIn the sheave. or that the sheave is dished out(Figure 7-44).

HEAT CHECKED

'JO

17-431 BELT RUINED BY TOO MUCH HEATCourtesy of John Deere Ltd

In addition to heat. grease and oil can alsoruin drive belts II oil or grease is allowed tosoak into a belt. d can soften. swell andgenerally deteriorate very rapidly. Note that08: resistant belts are available for certainengine locations that are unavoidably greasyor oily. When oil or grease IS round on a belt.wipe it off with a clean cloth dampened with adetergent solution. Then dry the belt with aclean dry cloth.

CAUTION: Never try to clean a belt while itis operating.

While inspecting the belts. the condition ofthe pulleys or sheaves should be checked.Examine pulleys for chips. cracks. bentsidewalls. rust. corrosion or other damage(Figure 7-44). Damaged sheaves cause rap*belt wear and should be repaired or replacedimmediately

1

CHIPPED

BENT

(7-44) DAMAGED SHEAVESCounesy of John Deere Ltd

Other points on belt condition:

-- A tear on the outside cover could becaused by something interfering withthe belt. Ticking sounds when the beltis running may indicate interference.

A belt that has operated while rolledover in the sheave groove is probablydamaged. Replace it.

Store belts in a cool. dry place. Ifstored on a machine. relieve tension onthe belts.

Belt Alignment

Misalignment soon causes a good belt to sail.Misalignment usually occurs when the mcun-ting for the component that the belt is drivingcomes loose or has been improperly installedBelt alignment can be checked by lining up acord or straight edge on the aide of the twopulleys. as shown in Figure 7-45 Make atleast two checks. 180 apart

CORD OR STRAIGHTEDGE

35

tCORRECT ALIGNMENT

INCORRECT ALIGNMENT A.25118

17-45) PULLEY ALIGNMENTCourtesy 01 General Motors Corporation

ENGINES

Belt Tension and Adjustment

To carry their full load. drive belts must gripthe entire area of contact with the pulley Im-properly adjusted bells can damage thepulleys Loose belts undergo unnecessarywear: they can slip. tear. burn or grab andsnap. Belts that are too tight. can also causeproblems They can damage the engine byover-loading the crankshaft. crankshaftbearings. and accessories or accessorybearings. Also. excessrde tension on a beltwill stretch and weaken it.

To get maximum life and performance from abell it must be run at the correct tension. Belttension can be checked by:

1. A belt tension gauge. Markings on thegauge will indicate correct or incorrecttension (Figure 7-46).

V-BELT TENSIONGAUGE

T.9964

(7-46) Courtesy 01 General Motors Corporation

2. Deflecting the belt (Figure 7-47):

Colidesy of Cummins Engine Company

7:26

The chart in Figure 7-48 shows theamount of deflection different size beltsshould have If a belt deflects 1/8 of aninch too much or too little, readjust it.

17-48)

Table 2: Fan Belt Tension

Belt WidthInch (mm)

Deflection Per ft.of Span Inch (mm)

1/2 (12.700) 13/32 (10.3187)11/16 (17.4625) 13/32 (10.3187)3/4 (19.0500) 7/16 (11.1125)7/8 (22.2250) 1/2 (12.7000)1 (25.4000) 9/16 (14.2875)

Courtesy of Cummins Engine Co

The gauge is the most accurate method tocheck belt tensicn but the deflectionmethod is very reliable too.

Figures 7-49. 7-50 and 7-51 show threetypes of belt adjusting methods usingeither slotted or elongated holes. Ad-justing a belt requires moving one of thepulleys away from the other if the belt istoo loose. or vice versa, closer to the otherif the belt is too tight.

X 1440 'e

36

(7-49) ADJUSTING BOLT IS INA SLOTTED BRACKET

(Gasoline Engine)


7:26 ENGINES

C ci

ADIUSTING BOLT*

LOCK NUT;

ao

`-'

ADJUSTING BOLT

(7-50)

ADJUSTING BOLT(Diesel Engtne)

/7 Courtesy of General Motors CorporationI f

BR CKET

l'

' V

..: .::al P4-F

MOUNT1NteROLTS

sik

SUPPORTSSEMBLY

- ' .r't

16,-

A.74416

(7-51)

ADJUSTING BOLT INELONGATED HOLE

(Diesel Engine)

Courtesy of General Motors Corporation

37

ENGINES

Some belt-pulley systems use a thirdpulley called an idler which is moved toadjust the belt tension (Figure 7-52).

IDLER PULLEYON

SLACK SIDE DRIVEOF

DRIVE(PREFERRED)

(7 -52)

IDLER PULLEYON

TIGHT SIDE DRIVE

OFDRIVE

(ACCEPTABLE)

IDLERLOCATED

DRIVENNEARDRIVE

SHEAVE

DRIVE DRIVEN


IDLERLOCATED

DRIVEN NEARDRIVENSHEAVE

An Idler pulley can be used on both a con-tinuous and an intermittent drive fan Forcontinuous drive the idler IS adjusted in aset position For intermittent drive the idleris moved in to apply tension and start thefan. and out to slacken the tension andstop it The idler on the intermittent fan isoperated by a temperature controlled aircylinder.

Good Practices When Installing andAdjusting Belts

1. When replacing dual or triple runningdrive belts. replace the complete set ofbelts at the same time. Uneven operationwould result from running a new belt withworn ones. Install them in the sets sup-plied by the manufacturer. Never combinebelts from different sets.

2. Never pry a V-belt or force it into thesheave groove. You can damage both thebelt and the drive component. Loosen thelightener before installing the belt- (Figure7-53).

WRONG!NEVER FORCE

'BELT ON SHEAVE'

'`.40-k

.r

7:27

A 110,040.4stA

(7-53)NEVER FORCE A V-BELT ONTO A SHEAVE

Courtesy 01 John Deere LId

3. Never attempt to check or adjust beltswhile they are running.

4. V-belts stretch most during their first 24hours of operation. Check the tension of anew belt after it has run for a few shifts.

5. Never attempt to correct belt slippage byusing a belt dressing. If belts slip evenwhen properly tensioned. check foroverload. worn sheave.' grooves. oil orgrease on belts. or seized bearings.

6. Note that more fan belts fail from beingtoo loose than from being too tight.However. don't overtighten belts: you'lldamage the drive component's bearings.

7:28 ENGINES

QUESTIONS COOLING SYSTEM

1 What are the two basic purposes of thecooling system?

2. True or False? In a liquid cooled systemthe coolant flows into the bottom of theradiator and out through the top.

3 What is the purpose of having the waterJackets hold only a small amount ofcoolant?

4 The radiator is a _for the cooling system.

5 Radiators work on the principle of

(a)

(b)

(c)

(d)

currents

convention

convection

circulation

6 What is the function of the water pump?

7 Engine temperature is automatically con-trolled by the use of a

8 True or False? Thermostats that operateat 180'F or more improve engineoperation and reduce both crankcasesludging and corrosive wear of engineparts.

9. On what type of machines are blowerfans used rather than suction fans? Whatis the reason?

10. Shrouding is used around a fan to:

(a) simply protect the fan blades.(b) to increase fan efficiency(c) quieten fan operation

(d) make it look neater

11. True or False? All belts ht the same justthe lengths are different.

12. Radiator shutters are:

(a) closed by spring pressure andopened by air

(b),..., closed by spring pressure andopened by spring pressure

(c) closed by air pressure and openedby air pressure

(d) closed by air pressure and openedby spring pressure

13. What is the purpose of the water filler?

14. True or False? Any water. whether ofdrinking quality or not. will produce acorrosive environment in the coolingsystem. Thus the need for

15 On an engine equipped with a coolantfilter and using anti-freeze, whatprecaution must be taken whenchanging the filter?

16. What is the most common problem with acooling system?

17. Leaks are easiest found when the systemis

18. Give two reasons why some manufac-turers do not recommend sealing com-pounds to fix radiator leakage.

19. What is the major cause of air flowrestriction in a radiator and how can it beimproved?

20. What is the obvious sign of a hose that isdeteriorated?

21. List the three things belts should bechecked for during a P.M. of the coolingsystem.

22 List the three important checks thatshould be made after installing a newwater filter element.

23 The strength of the anti-freeze solution ischecked with a:

(a)

(b)

(c)

(d)

water meterammeter

hydrometer

any of the above

24. True or False? A V-belt is designed toride on the sides and bottom of thepulley.

25. A good maintenance practice for V-beltson a vehicle that is to be stored for aperiod of time is to:

(a'

(b)

(c)

(d)

39

adjust it for the correct tensionrelieve all belt tensionremove the belt entirelycover the belt to protect it

ENGINES 7:29

26. When replacing dual or triple drive beltsthe recommended practice is to:

(a) replace all as a set

(b) replace only the worn one(s)(c) remove the worn one(s) and run the

other(s) until they need replacing

27 Referring to the fan belt tension chart,find out how much a 3/4 inch belt with aspan of 11/2 feet should deflect.

40

7:30 ENGINES

LUBRICATION SYSTEM

The lubrication system is another one of thelive support systems common to all engines

The lubrication system does the followingjots for the engine (Figure 7-54).

1 Reduces fr.ctirn between moving parts.

2. Absorbs and dissipates heat.

3 Seals the piston rings and cylinder walls.

4 Cleans and flushes moving parts

5. Helps deaden the noise of the engine.

1 OIL FILMREDUCESFRICTIONAND WEAR

The basic lubrication system used on today'sengines is called a full pressure system. Fullpressure means that oil is delivered underpressure created by the oil pump to all thevital lubrication areas of the engine Figure 7-55 shows a full pressure system and some ofthe areas that it must serve.

2 OIL COOLSMOVING PARTS

3 OIL HELPS THERINGS TO SEAL

DEADENS NOISE

X:Sae

CAMSHAFTBEARINGS

(7-54)

WHAT AN ENGINEOIL MUST DO

Courtesy 0 John Deere Lid

4 OIL CLEANSES THE PARTS

TAPPET PISTONLEVER SHAFT PIN BEARING

CRANKSHAFTMAIN BEARINGS

MAINCIL

GALLERY

OIL PUMPAND FILTERS

41

(7-55)

Courtesy 01 JOhn Deere Ltd

ENGINES 7:31

LUBRICATION SYSTEM COMPONENTS

1. Oil pump and relief valve.

2 Oil Sump usually referred to as EngineOil Pan.

3. Filter(s)

4. Oil Cooler.

5. Pressure Differential Valves for coolersand filters.

6. Breathers and vents.

Oil Pump

The oil pump is a positive displacement gearpump which can be mounted internally in thesump or externally on the engine block. Oilpumps are driven either by the crankshaft orthe camshaft or by the timing gear train. Thepump must distribute oil under pressurethroughout the lubrication system Oilpressure varies in different engines usuallyfrom 20 P.S.I. to 65 PSI.. although some willgo even higher. To protect the pump frompressures higher than it is designed for, amaximum pressure relief valve is located in ornear the pump. A further protection to thepump is a pick-up screen on the intake linethat prevents large pieces of contaminantfrom getting into the pump.

Oil Filters

Oil contamination reduces engine life morethan any other factor. To help combat it oilfilters are built into all modern enginelubrication systems. The two basic types of oilfilters are surface filters and depth filters(Figure 7-56). In surface filters oil flowsstraight through the filtering material,whereas in depth filters the oil takes anirregular path.

(7-56)

SURFACE FILTER DEPTH FILTER


Surface Filters have a single surface that cat-ches and removes dirt particles larger thanthe holes in the filter. Dirt is strained orsheared from the oil and stopped outside thefilter as oil passes through the holes in astraight path. Many of the large particles willfall :0 the bottom of the reservoir or filter con-tamer, but eventually enough particles willwedge in the holes of the filter i.. , revent fur-ther filtration. At this point the filter must becleaned or replaced. The pleated paper filterin Figure 7-57 is a surface filter.

X 1184

42

Ihr6:4///1,11N)

11111111I

(7-57) PLEATED PAPER FILTER

Courtesy 0 John Dee Ltd

I

7:32 ENGINES

Depth Fillers in contrast to surface fillers. usea large volume of filter material to make theoil move in many different directions before itfinally gets into the lubrication system Thefilter made of cotton waste in Figure 7-58 is anexample of a depth filter

x 7774

(7-58)DEPTH FILTER COTTON WASTE TYPE

Courtesy 01 .141n Deere Ltd

FILTERING SYSTEMS

There are two basic types of filtrationsystems* bypass and full-flOw Some largerdiesel engines use a combination of the twosystems

Bypass Filtration System

In the bypass filtration system there are twoseparate oil flows. one to the bearings andone to the filter (Figure 7-59)

In this system. five to ten percent of the oildelivered by the pump is routed or bypassedto the filter instead of to the bearings. Alterfiltering. the oil is returned to the crankcase.This system is sometimes called a partial :.,.)wbecause only part of the supply oil is filteredat one time.

The volume of oil bypassed through the filteris initially controlled by a restriction in thefilter outlet However, as the :low passagesbecome clogged, the volume of oil throughthe filter is reduced and thus so is the volumeof filtered oil returning to the crankcase. Ob-viously then. the filter and the oil must bechanged regularly to provide properly filteredoil to the system

43

IL

FILTER

FILTEREDOIL

OIL TOBEARINGS

PRESSUREREGULATING

VALVE

UNFILTEREDOIL

OILPUMP

1_01!PAN

BYPASS OIL FILTER(7-59) Courtesy of John Deere Lid

A main advantage of the bypass filtrationsystem is that because of the direct feed fromthe pump to the bearings there is a constantoil pressure at the bearings, regardless of thecondition of the filter.Full-Flow Filtration System

In the full-flow filtration system there is onlyone oil flow that travels from the pump to thefilter and then to the bearings (Figure 7-60).As in the bypass system. a pressure gaugeand pressure regulating valve are used.

FILTER------BYPASSVALVE

FILTEREDOIL TO

BEARINGS

PRESSUREREGULATING

VALVE

UNFILTEREDOIL

OILPUMP

i OILPAN

FULLFLOW OIL FILTER

(7-60)t . ; 4 '


, v

ENGINES 7:33

Filter Bypass Valves (Pressure DifferentialValves)

Note the filter relief or bypass valve in theabove diagram Every filter in a lull-flowlubrication system must have a bypass valveWhen the filter is new. there is very littlepressure drop through rt. However. if the fillergets clogged. the resulting additionalpressure will open the relief valve and allowunfiltered oil to bypass the filter and go direct-ly to the bearings. What would happen if abypass valve was not provided? When thefilter became completely clogged. pressurewould build up on its inlet side. This pressurewould cause the regulating valve to opencompletely, allowing all of the oil to returndirectly to the crankcase. The result: a burn-ed-up engine

The bypass valve. then. is a safety device toensure that the oil. filtered or dirty. will get tothe bearings. The valve is usually set to openbefore the filter becomes completely clogged.Figure 7-61 shows the filter bypass valve intwo locations, inside the filter and in the filtermounting pad.

0.,Inlet

r-111

OilOutlet

BY-PASS VALVE INSIDEFILTER HOUSING

Oil Outlet Spring

Oat Iniet

Sps.m

VolvoPoppet

VolvoPoppet

(7-61)

BY-PASS VALVE IN

MOUNTING FAO OF FILTER


Many spinon filter elements have the bypassbuilt into the element. When replacing a filter.be sure to use only the recommended filterbecause another type may not have the built-in bypass valve.

Bypiss valves are often used with oil coolersfor the same reason that they are used withfilters. If the oil cooler becomes clogged, oilflows through the valve and back into thelubrication system

Combination FullFlow and Bypass System

A combination of full-flow and bypasslubrication systems is found in many largediesel engines. The full-flow filter does theprimary filtering and the bypass filter thesecondary filtering. As lull-flow filtered oil isdistributed to all the vital lubrication areas. asmall amount flows through the bypass filterfrom where it drains back to the sump. Anexampie of a full-flow bypass system is shownin Figure 7-62. Note the filter bypass valve, oras Its sometimes called. the pressure dif-ferential valve.

44

7:34 ENGINES

Olt MIER

EGA1N TOCAM POCKETS

Olt ROMMAIN

GALLERY

OILOftAiN

TOOtOWER

/E\elfPASS

BITER

Gm DRAIN,FROM OtOwER

(7-62)

TYPICAL LUBRICATING SYSTEM

Courtesy of Mtnostry of Education

Oil Coolers

10 PSIDIFF PRESSURE

Ott COMERsy PASS VANE

DRAIN TOOP. PAN

Many lubrication systems use an oil cooler tocool hot oil. and thus help dissipate heatcreated by the engine. Most coolers useengine coolant to cool the off The oil coolermay be mounted internally in the crankcase orexternally on the outside of the engine block.Most engines use an externally mounted oilcooler. like the one in Figure 7-63.

When the cooler is mounted externally bothcoolant and lubricating oil are pumpedthrough it (Figure 7-64).

OIL OUT

COOLANTOUT

4111",

(7.64) OPERATION OF ENGINEOIL COOLER


OIL IN

-WATERINLET

SO PSIOlt PRESSURE

REGULATOR VALVE

18.2iOIFF PRESSUREFILTER OYPASS

VALVE

105 PSISAFETY VALVEIN Olt PUMP

INtEr SCREEN

COOLANT u4k,COOLANT

VALVER #041, NOUS :NG i

..mor

wowCOoLANT

Itt

45

(7.63)

WATER4RETURN

11.22E

UiL COOLER MOUNTEDOUTSIDE ENGINE


ENGINES

Coolant flows through the tubes in the coolerand oil circulates around the tubes. Heat fromthe oil is transferred to the coolant which thentravels to the radiator and is itsell cooled

Another common type of cooler works op-posite to the one above. Instead of coolantflowing through tubes. oil is pumped througha small radiator-like core and coolant is cir-culated around it.

A bypass valve is used with some oil coolersto assure 011 circulation if the cooler shouldbecome clogged. Note the location of the oilcooler bypass valve in the diagram of thecombined full-flow bypass lubrication system.Trace the oil flow that would occur on a coldstart when thick oil could cause both the filterand the cooler bypass valves to open (Figure7-62)

Breathers and Vents

In every internal combu.stion engine some un-burned gases pass by the piston rings. If thesegases, called blow-by, are not vented they willtend to build-up pressure In the oil pan. bothcontaminating the oil and forcing the frontand rear pan seals to leak. Breathers andvents remove the blow-by gases and thepressure.

Two basic methods are used to allow theengine to breathe:

1. open crankcase ventilation using a roaddraft tube or cover vents.

2. positive crankcase ventilation.

Open crankcase ventilation removes blow-bygas through the road draft tube attached tothe side of the engine (Figure 7-65).

Movement of the vehicle forward at speeds of20 mph or faster creates a low pressure at thebottom end of the tube. Fresh air is taken inthrough the fresh air breather at the top of theengine. combines with the gases in the crank-case. and then exits through the road tube.The mixture of gas and air flows out the tubebecause the pressure of this mixture is higherthan the pressure at the road end of the tube(gases at higher pressure always move in thedirection of lower pressure). Most dieselengines use the open ventilation system.having either a tube going from the top of theengine down the side or vents on the valvecovers.

7:35

(7-65)Courtesy of General Motors Corporation

Open ventilation is not used on gasolineengines today because gasoline blow-by con-tains harmful hydrocarbon fumes that con-tribute greatly to air pollution. Instead.positive crankcase ventilation is used.

(7-66)Courtesy of General Motors Corporation

In this system a hose passes from the crank-case. through a ventilation valve to the intakemanifold. Fresh air enters the breather cap onthe valve cover. mixes with the blow-by gases.and is drawn up by manifold vacuum throughthe ventilation valve and into the intakemanifold. Thus the blow-by gases finally endup in the combustion chamber again. The ven-tilation valve. usually called a PCV valve. is a

46

7:36 ENGINES

spring loaded metering valve which regulatesthe amount of flow from the crankcase to theintake manifold

Besides contributing to cleaner air in the en-vironment another advantage of the positiveventilation system is that tf a gases areremoved even when the engine is idling. Theopen system requires vehicle movement (20mph) to create the low pressure and the draftnecessary to remove the gases

MOTOR OILS

Motor oils are often taken for granted. Itisn t generally appreciated that they mustlubricate despite high oxidizing conditions.extreme temperatures. and large amounts ofcontaminants High-output engines coupledwith reduced crankcase capacities and ex-tended dram intervals have all compoundedthe severe conditions under which the oilmust perform

MOTOR OIL FUNCTIONS(Courtesy of Imperial Oil Limited)

I Wear Prevention

Wear takes place due to metal-to-metalcontact of moving parts. as well as fromacidic corrosion. from rusting and fromthe abrasive action of contaminantscarried in the oil. To prevent metal-to-metal contact. motor oil musk maintainsufficient viscosity to provide a full fluidfilm between moving parts under alloperating temperatures. The viscositymust not be so thick. however. A to makestarting the engine difficult

2 Engine Cooling

Motor Oil is largely responsible for pistoncooling. The cooling is done bytransferring heat directly from the pistonthrough the oil film to the cylinder wallsand then out to the cooling system. and bycarrying heat from the underside of thepiston. crown and skirt to the crankcase.Oils must therefore have good heat con-ductivity. but at the same time the oil musthave adequate thermal stability to resistdecomposition when in contact with thesehot surfaces.

3 Engine Cleaning

Over a period of time oil starts todeteriorate and oxidize The oxidationcauses the formation of harmful con-taminants acids. varnish. carbon. sludge.

Motor oil must minimize the formation ofthese contaminants in the first place. butwhen they inevitably do form. the oil mustkeep the contaminants in suspension sothat they don't settle inside the engine.

Oil must also act as a cleansing agent.carrying to the oil filter abrasive con-taminants that form in the engine.

4. Cylinder Sealant

Cylinder pressures of 145 p.s.i. at cre.:11(ingspeeds are not unusual. while combustionpressures may reach 900 p.s.i. Piston ringsalone cannot seal off this pressure; theyneed the help of the oil film between therings and the cylinder wall.

5 Control Engine Octane Requirement

Motor Oil must minimize the formation ofoil deposits in the combustion chamber.These deposits decrease the volume ofthe chamber thereby increasing the com-pression ratio and thus the octanerequirement of the gasoline. The depositsare also a source of hot spots that canglow and cause pre-ignition.

6. Control Rust

Engine components such as valve stems.hydraulic valve lifters. piston rings andcylinder walls are subjected to severerusting conditions Extended periods ofengine idling or short trip stop and godriving allow water to accumulate in theoil Also. condensation of water on engineparts can occur overnight when theengine isn't running. An essential functionof the motor oil is to provide a protectivefilm on engine parts to prevent rustingwhen it's not being used.

7. Control Corrosion

Products of combustion in.:!ude corrosivematerials. such as acids. which ac-cumulate in the engine crankcase. Unlesstne engine oil can control the to idency ofthese products to corrode bearings andother finely finished surfaces. corrosivewear will reduce engine life.

MOTOR OIL COMPOSITION

Motor oils are manufactured from base stocksand fortified with additives to provide the per-formance level required.

47

o

s

ENGINES 7:37

Motor Oil Additives CLASSIFYING MOTOR OILS

1. AntiOxidant prevents oil oxidation.sludge and acid formation.

2 Corrosion Inhibitors prevent bearingcorrosion.

3 Detergent/Dispersal cleans engineparts and disperses sludge and other solidcontaminants. These detergents actsimilarity to soaps to remove deposits andthen to retain the deposits as finelydispersed particles in the oil. Detergentsmay become depleted and after prolongedcontinued service they may not be able tokeep the contaminants in suspension.

4. Rust Inhibitors prevent rusting ofengine parts. particularly hydraulic valvelifters.

5. Pour Point Depressant provides free-flowing qualities at low temperatures.

6. Viscosity Index Improver viscosity in-dex can be defined as a measurement ofthe change in the viscosity as the tem-perature changes. The improver additivereduces the rate at which the oil thins outwith increasing temperature.

7. Anti-wear Agent prevents galling andscoring of heavily loaded engine parts.particularly the valve train. A widely usedmaterial is a zinc-sulphur-phosphorousadditive often referred to as -MOP-.

S. Reserve Alkalinity new engine oils arebasic in composition to neutralize acidsformed by the combustion processes

9. Foam Suppressor does not preventfoam from forming. but renders the foamunstable so that it settles quickly.

Whi's there may seem to be a great many ad-ditives used in motor oils. the concentrationsare often very low. Anti-oxidants andcorrosion inhibitors, for example. are used atconcentrations as low as 0.1%. High additiveoils may have as much as 12% detergentpresent. The quantity of additive, it should bepointed out, is not necessarily an indication ofthe quality or the strength of an oil.

S.A.E. Classification

The most important single property of alubricating oil is viscosity. Viscosity. as statedearlier. is a measurement of the resistance ofa liquid to flow. The viscosity of an oil isdetermined at specific temperatures; O'F and100'F and 210'F are the most widely used.The viscosities of different oils can be com-pared only at the same temperature. TheSociety of Automotive Engineers (S A.E ) iden-tify oils by their viscosity ranges. Motor oilscan have S.A.E. numbers of:

5 W10 W The higher the number the20 W greater the viscosity (the30 W thicker) the oil.40 W50 W

Engine Service Classification

As well as an S.A.E. classification. motor oilsare also classified according to the serviceconditions under which they will be used. In1970 a new crankcase oil performanceclassification called -Engine ServiceClassification" was established to replace theAPI Service Classification formerly used. itspecifically lists the tests and performancerequirements for each of the classifications,and in addition. is open-ended to allow for theaddition of new performance levels as theyare developed.

The Engine Service Classification is dividedinto two categories. The -5" category refersmainly to gasoline engine low temperaturerequirements while the "C" category refersmainly to diesel engine high temperaturerequirements (Figure 7.67). Many applicationswill call fOr a dual rated oil such as SD/CDwhich requires both extremely low and hightemperature performance levels.

48

ENGINES

Engine Service Classification

LETTERDESIGNATION

SERVICE DESCRIPTION

SA Non-additive oils. Not recom-mended for crankcase ser-vice

SB Ugh, Duty Gasoline Non-detergent Not normallyrecommended for crankcaseservice.

SC 1967 and earlier gasolineengine service in passengercars and (rucks

SD 1971 and earlier gasolineengine service in passengercars and trucks

SE Current and earlier gasolineengine service in passengercars and trucks

CA MIL12104A Light duty dieselengine service

CB Supplement 1Moderale duly diesel engineservice

CC MIL-L-2104B Moderate dulydiesel and gasoline engineservice

CD Caterpillar Series 3 Severeduty diesel engine service.

Refer to Block 4. Power Trains. for informationon handling and storing oil.

(7-67)

Courtesy of The Society of Automotive Engineers :5 A E )

PREVENTIVE MAINTENANCE SERVICE ONLUBRICATION SYSTEMS

As part of the daily walk around check beforestart uo to* tube system should be inspectedfor leaks. damage or deterioration. Whenminor leaks are spotted. tighten fittings orbolts: if this doesn't stop the leak report thecondition to a supervisor Oil leaks should beattended to immediately. To be able to seeleaks better. keep a machine clean by regularsteam cleaning or high pressure washing.

Oil level checks are a vital part of routinemaintenance on a vehicle Correct oil levels

should be maintained at all times. Followthese practices when checking oil levels andwhen topping up the oil.

1. Park the vehicle on level ground.

2 Practise cleanliness. Use a clean rag towipe the area around the dipstick and towipe oil off the stick.

3. Check the oil level before starting theengine. An engine should be stopped forat least five minutes before the oil levelis checked. Some manufacturer's call fora running as well as a stopped check.The dipstick on these machines will bemarked on both sides. on -Engine Stop-ped- and the other -Engine Running-.

Figure 7-68 gives an example of amanufacturer's directions for an oil levelcheck on a crawler dozer. Note that thecheck must be done when the engine isrunning.

EVERY 10 SERVICE HOURSDIESEL ENGINE CRANKCASE

=- ..,I

.,

4. .

Check oil level with engine at low idle and oilhot Maintain oil level between FULL andADD marks on ENGINE RUNNING side ofgauge (7-68)

Courtesy of Cat erpitiar TraCtOr Co

4. Check for evidence of water or fine metalparticles in the oil. When such con-taminants are found. further checkingroll be necessary to determine wherethey are coming from.

5. Keep records of quantities of oil addedbetween changes: a sharp increase oftop-up oil usually indicates a rapidlydeveloping problem.

6. Contaminated oil can seriously reduceengine life. When top-up oil is requiredbe certain that the oil container has nowater or dirt in it. Human error in not

ENGINES 7:39

keeping oil dean is one of the most com-mon way . that contaminants enter anengine

7 Use only oil recommended in the servicemanual

8 Do not mix engine oils

9 Do not overfill the crankcase

10 Never operate an engine if the oil quan-tity is below the low-ievel mark

CHANGING ENGINE OIL

Over a period of time oil gets dirty and wearsout making it unfit for use. On the other hand.lust because crankcase oil is black. doesn'tnecessarily mean the oil has to be changedSince it s difficult to tell by just looking at oilwhen it should be changed. the best policy isto follow the manufacturer's recom-mendations on oil and filter changes.

In addition to scheduled oil changes manycompanies are now carrying out oil analysisprograms The term oil analysis reiers to alaboratory analysis of used oil which deter-mines the types and amounts of wear metalspresent in the oil By charting on a regularoasis the amount of certain metals in oil. thecondition of the parts that the oil lubricatescan be watched When a concentration higherthan has been the pattern of a certain metalbegins to appear. it indicates that the partfrom which the metal has worn off is startingto wear more rapidly. The laboratory can warnthe customer to take protective action prior tothe unit failing Laboratories have con-siderable experience in detecting wear pat-terns from used oil and can fairly accuratelystate the condition If internal componentsproviding that sampling is done on a regularbasis

In an oil analysis program. oil samples mustbe taken from each lubrication system on themachine. e g engine oil. hydraulic oil. finaldrive oil. brake and transmission fiuid For oilanalysis to be successful Amples must betaken on a regular basis: between 125 and 250hours for engine oil and 250 to 500 hours forall other lubrication systems Oil samplesmust be taken when the oil is warm andthoroughly mixed There are various methodsof taking the samples a valve or petcock putstraight into a main oil line. a suction gun witha sample jar to take ail from dipstick and oil-fill holes. a thick rubber bulb including a one-way check valve a vac cap and a sample jar.

It musi be stressed that a good oil sample.one that is not cross-contaminated withanother oil system. is essential for an ac-curate laboratory analysis

50

vo=

7:40 ENGINES

SPE 3 VEAR/CONtM4INAT1ON (SAMPLE)

XYZ TRUCKING CO.

, deldtrie0/1\NIP

BOX 41608INDIANAPOLIS IND 46241

ACC; NO S

UNIT CONDITION AND RICVAUNDATIONS

UNII. 1330

;On DETROIT DIESEL,MODEL 8V -71

TYPEMfr GNI* URSA

Piston pin bushing metal; Resample at NORMAL interval.

2L piston metals; Ring /cylinder metals; Check blow-by (compression); Resample at NORMAL interval.

3r- Piston metals, Ring/cylinder metals; Inspect cylinder areas; Resample at NORMAL Interval.

r_ Piston sets's. Ring/cylinder metals, Inspect cylinder areas, Resample at NORMAL interval. FEEDBACK. Several broken rings4

and scored liners. Vtist pins---7--

J-- TESTS INDICATE UNIT IS IN SATISFACTORY CONDITION. Rasample at NORMAL interval.

6

I .

ES7

N0 0

DATII

t

KE

P.a..,

mgiALSPARTSPERMst.tsONBrwEsGittcoNtamimArION USE DATA

zm

0u -

aO.' 0

a...>,0.

-.u 8 0

m

,4

3,7)

:Iu

3:-4n

.3Z

x

Soso*140.A

S...COsIn Fuel

%%NO

W4I41ANS

ANS210°FWS

latOBier

NoSw.4.1,

An 05.4,

0 $4**,

;Z Mita.) RI 032. 5 003. < 008. 002. 000. 000. 006. 023. 001. OIO. 2300 0000M ,1111111;10"1:6

2 AIRRaE71) 003. 002. 009. 002. 000. 000. 007. 030. 001. 010. !4_. 30002 NM 30t05riig224 t 0, 003. 002. I009.,003. 000 000. 006. 001. 010. 2400 0000ERIE 1.0 EVEita 11:

IM:01"..T1 P-4(401,m-z...71.12.1110003 002. 006. 006. 0001. 000. 000. 007 002. 010. 2620 1,, ,I!!!!!!! rizgliP!,, a.

191;;Figg;;;;0 030. 001. 001. 006. 003. 001. 000. 000. 006. 030 010. 2390 taNTIIIII 1 C411:1119!!

6 .11 Ill RE 1.Gv okot OWL (04( ell t XP(101 Ne(a 1,01.4,f ovaied too.renples.

NOTE Or. 41.1. to 9. ',A, 401/1, 404 Dyed on to e. ..not.on wat tr.e Lamp. snd det4$ A...,1,$) 4. 4*. Al-' 14110Ia 4 *4000. 4 M.LTbtlo,

(7-69)

51

town A..,669( AA. ()N.,. Mb ft qv( 09*6

Courtesy of Lubrecon Consultants Inc

ENGINES 7:41

PROCEDURES FOR CHANGING OIL ANDOIL FILTERS

Procedures for changing oil and filters aremuch the came for all engines However. thenumber f.,f filters, the drain location and thecapac.(y of the system will vary from engine toengine Some good practices to follow are

1 Move the vehicle to a level area.

2. Run the engine long enough (15 minutes)to warm the oil. and then stop the engine.When the oil is warm contaminants willmix with the oil and will dram out with it.

3 Make sure you know the capacity of thesystem and have a container largeenough to hold all the drained oil.

4 If an oil sample is to be taken. do so atthis point (Within 15 minutes of shut-down )

5 Remove the plug carefully. Caution: Hotoil can burn.

6. Drain the filler(s) if they are equippedwith a drain. and then remove the filterelement. Take a few seconds to inspectthe old filter element (Figure 7-70).especially if oil sampling is not done.Evidence of metal ships will indicate thatthere are problems within the enginerequiring immediate attention.

7. Wash the filter housing(s) and install anew filter element. Replacing some oilfilters requires installing new gaskets orsealing rings. Be sure the sealing sur-faces on the engine and filter are clean.

8. Replace all drain plugs.

9 Referring to the Service manual for thecorrect type and amount of oil. fill thecrankcase with oil.

10. Remove crankcase breathers andthoroughly wash them with solvent orkerosene. Below are typical directionsfrail a service manual on how to clean abreather:

Clean breather element (Figure 7-71)in cleaning solvent and dry with com-pressed air. Wipe out breatherhousing. Soak element in oil: drain outexcess. Check gasket: replace ifdamaged.

\St,

494-

' err

.11.414

"- r-.1.

44444144

AV&

(7-70) INSPECTING PAPER ELEMENT PLEATS

COurtoSy of Cummins Engine Co

4

..-4.4414 -"OW"

(7-71) CRANKCASE BREATHER

_ 46

MESH ELEMENTCourtesy of Cummins Engine Co

11. Start the engine. run for ten minutes andcheck for leaks.

12. Check oil level with engine slopped andtop-up as required.

13. Keep a record of all oil and filter changesto be sure of regular engine service

14. New or rebuilt engines require oil andfilter changes after a specified break-inperiod. Performing this service on time isvery important since foreign materialsaccumulate in the oil at a faster rateduring initial operation than later whenthe engine is broken in.

52

Nat

7:42 ENGINES

Flushing The Lubrication System

A lubrication system is generally flushedwhen it becomes contaminated with coolant.fuel. or metal chips What flushing amounts tois changing the oil twice To flush the enginefollow the same procedure as changing theoil drain. change filters. refill Refill with thesame grade of engine oil as regularly used orwith a recommended flushing oil Run theengine until the oil is warm. and then com-pletely drain the system and discard thefilters

Renew ;he filters. including new seal ringsRefill the crankcase Run the engine andcht.,..K for leaks Shutdown the engine andcheck the oil level

For an engine that is contaminated with metalchips such as would occur after an internalfailure. the same flushing procedures wouldapply as above. but with these additionalflushing and precautionary measures.

I Remove the oil cooler and flush it.

2 Remove any external lines such as abypass filter line. flush and blow themclean with compressed air

3 II the engine has a turbo charger. remove.flush and blow clear the turbo tube lines

53

ENGINES 7:43

QUESTIONS LUBRICATION SYSTEM

1 Two of the functions of the lube systemin an engine are to reduce ___

between movingparts and absorb and dissipate _

2 True or False? Most engines today use afull-pressure lube system.

3 What protects the oil pumps from overpressurizing?

4 What are the two common types of 081filter systems

(a)

(b)

(c)

(d)

Full pressure and low pressureFull flow and bypassFull flow and medium flowPartial flow and bypass

5 Give an example of a surface filter-element.

6 On a bypass filter system when the oilhas passed through the filter it goes tothe-

(a)

(b)

(c)

,d)

bearings

valve covercamshaft

crankcase

7 On a full-flow filtration system the oil al-ter passing through the filter goes to the.

(a)

(b)

(c)

(d)

bearings

valve covercamshaft

crankcase

8 What occurs within a lull-flow oil filter ifthe filter becomes plugged?

9 What is the function of the pressure dif-ferential valve between an inlet andoutlet line of an oil cooler?

10 Why is crankcase ventilation so im-portant?

12 True or False? There is a simpleequation between additives and oilquality the more additives, the better theoil

13 The S A E number identifies oils by theirrange The higher the

number the ________ the oil

14 What are the two categories that engineoils are divided into for serviceclassification?

15 What is 081 classified as CC suitable for?

16. True or False? An engine should be stop-ped for at least five minutes before theoil level is checked.

17 What does the term oil analysis refer to?

18 What is considered to be an ideal sampl-ing interval for engine oil analysis?

(a) 10 to 50 hours

(b) 50 to 100 hours(c) 125 to 250 hours

(d) 250 to 500 hours

19. What information can a regular oilanalysis program give you?

20. Why should oil be warm when it isdrained for changing?

21 Under what three conditions would it benecessary to flush the engine's lubesystem?

54

7:44 ENGINES

AIR INDUCTION SYSTEM

The air Ind. ctton system must*

1 Supply an abundance of clean air for com.bustion The air must be at the rightdegree of coolness and the air intaken.ust not be too noisy

2 Supply a.r to aid in scavenging burnedgases from the cylinder.

Three types of systems are used to supply airto an engine:

1 Naturally aspirated. and naturallyaspirated and scavenge blown

2 Turbo charged.

3 Turb: charged and after cooled.

PRE-CLEANER

Th

The naturally aspirated system. often referredto as N.A . IS the simplest of the air inductionsystems. The term naturally aspirated is ex-p:ained as follows* asphalting refers to thedrawing in of air. A naturally aspirated engineI.; said to draw in air or breathe naturally Onthe piston's intake stroke. air via the aircleaner is drawn into the engine. No aids areused to help get the air in or out of the engine.air is drawn in because atmospheric pressureIS higher than the pressure in the cylinders.

In a naturally aspirated 08 N.A. engine (Figure7-72) air enters the cleaner and flows to thecarburetor where it mixes with gasoline. Fromthe carburetor the mixture travels through theintake manifold and enters the combustionchamber at the intake valve.

In a naturally aspirated engine. since there isno carburetor. air travels directly from thecleaner through the intake manifold and intothe combustion chamber where it is mixedwith injected fuel.

MUFFLER

CARBURETOR ON GASOLINEENGINE

VALVE

EXHAUSTVALVE

AIR CLEANEK

INTAKEMANIFOLD

(7-72)

NATURALLY ASPIRATED AIR SYSTEM

55

EXHAUSTMANIFOLD

CYLINDER


7

a

ENGINES 7:45

A naturally aspirated. scavenge blown airsystem is similar tv the basic N.A. system ex-cept that an air pump. driven by the engine isused to supplement the natural intake strokebreathing. This scavenged blown system isused on two stroke cycle diesel engines (e g..Detroit Diesels) when intake ports rather thanintake valves are used (Figure 7-73).

The air pump. called a Roots Blower. createsa positive pressure approximately 4 psi withina chamber that completely surrounds all thecylinders The chamber is called the air boxWhen the piston is at its lowest point the in-take ports are open and the exhaust valvesare also open Fresh pressurized air in the airbox rushes into the cylinder forcing theexhaust gases out through the open exhaustvalves. The pump ensures completescavenging of all the exhaust gases (thus thename scavenge blown), as well as ensuring aplentiful supply of fresh air for the next powerstroke

AIRBOX

EXHAUSTVALVE

PUMP

INTAKEPORT

INTAKE AND EXHAUST

One of the drawbacks of a naturally aspiratedair system is that the amount of air that theengine can take in is limited and therefore theengine's horsepower is limited A turbocharged system brings more air into theengine cylinder and thereby increases theengine's horsepower The turbo chargedsystem uses an exhaust driven turbine to drivean air compressor. By compressing the airmore of it can be packed into the combustionchamber. With more air (i.e., oxygen) in thecylinder. more fuel can be burned 9n thepower stroke and thus the increase in horse-power. Although a turbo charger is aprecision built device that can operate atspeeds up to 130,00 RPM, it is a relatively sim-ple. durable piece of machinery Figure 7-74shows the basic parts of a turbo charger.

COrArRESSION

(7-73) ONE-VALVE TWO-CYCLE ENGINEWITH BLOWER

FLOATINGBEARINGS

THRUST COLLAR

SHAFT

'3432 TURBINE

56

(7-74)

COMPRESSOR

POWER

Courtesy of John Deere LW


4

7:46 ENGINES

Exhaust gases on their way to the muffler passthrough the turbine housing and rotate theturbine wheel The turbine wheel in turn drivesthe compressor The compressor takes airthat has come in from the air cleaner. com-Presses it. and discharges it into the intakemanifold where it travels to the combustionchamber (Figures 7-75 and 7-76).

TURBOCHARGEREXHAUST

4:1:ZiAMBIENT AIR

AMBIENTAIR

tiNILET

EXHAUSTGASES

(7-75)ENGINE CYLINDER

COMPRESSORAIR DISCHARGE

TURBINEWHEEL

TURBINEEXHAUST GAS

loft, OUTLET

COMPRESSORWHEEL

OPERATION OF BASIC TURBO CHARGER

Courtesy of Jurrn Deere Lid

The increase in the pressure of the com-Pressed air delivered by the turbo charger IScalled boost pressure The beauty of a turbocharger is that boost pressure is at its highe6iwhen the engine needs tt most. Since thecompressor IS run by exhaust gases. boostpressure IS at maximum when the engine isoperating at full load Tne boost can reach 15p s i or higher The increase in boost pressureas the engine load increases is important Interms of getting the air onto the cylinderWhen an engine is running at 2500 RPM theintake valves are open less than .017 seconds.With the air under greater pressure. it takesless time for it to get Into the cylinder In ad-dition to turbo chargers. some engines areequipped with a cooler Installed between theturbo charger and the intake manifold. It IS

referred to as an after-cooler or intercoolerSuch an arrangement is called turbo chargedand alter cooled

(7-77)

EXHAUST GASINLET

(7-76) TURBO CHARGER

Courtesy of Detroit Diesel General Motors Corpora..on

INTERCOO LERS

When the turbo charger compresses theengine intake air. the air becomes heated(due to compression) and expands. When theheated air expands, it becomes less dense.The result is that part of the purpose of theturbo charger is defeated because less air isforced into the engine. To overcome this con-dition. some turbocharged engines are equip-ped with an Intercooler. An intercooler is-*thing more than a heat exchanger; theheated intake air flows over a series of tubesthrough Ix hick engine coolant 8s circulatedane tne air is coaled, as shown in Figure 7-77.

5A

6 7t 1 4 I U

AIR INDUCTION AND EXHAUST(SCHEMATIC)

Cotine of CafernMar itaCiOf Company

-.-

I" 8

1Coolant inlets to altercoolers 2Coolantoutlets from aftercoolers 3 Aftercoolers

4 -Aircleaner air inlet 5Air transfer pipes6Turbo charger compressor impeller

7Turbo charger turbine wheel8Exhaust outlet 0-- Exhaust mandold

57

ENGINES 7:47

The intercooler reduces the temperature ofthe compressed atr by 25 to 30'C. Thereduced temperature makes the air denserallowing more to be packed into the com-bustion chambers The result is.

1. More power: Sufficient air is provided toburn the fuel resulting in higher horse-power.

2. Greater economy The fuel is burned morecompletely. giving more power from agiven amount of fuel.

3. Quieter combustion' By lowering the tem-perature of the air for fuel-air mixing.there is a smoother pressure rise in theengine cylinder. Figure 7-78 shows atypical intercooler mounting

(7.78) TYPICAL INTERCOOLER MOUNTING

HOUSINGSHUTDOWN

SHUTDOWN4,,SOLENOID

INLETHOUSINGADAPTOR

INTERCOOLER

:4:;17:4.

rY

LINKAGE INLET TUBESHUTDOWN

- / 111111

'(":t1

OUTLET

+. HOSEAzp

ohm.

WATERMANIPOLD?ki,''t"-

t..F.F )-;.,"4>.

INLET

HOSE

TURBOCHARGER

SOB

HOSE

CLAMP

OILSUPPLY

LINE

Courtesy of Geffen! Motors CorPontion

58

7:48 ENGINES

AIR CLEANERS

Clean air is essential to satisfactory engineperformance and long engine life. The aircleaner must remove fine materials such asdust and blown sand as well as coarsermaterials such as chaff or lint. This residuecollects in a reservoir which must be largeenough that operation is maintained over areasonable period of time before cleaning andservicing is necessary. If an air cleaner is notcleaned buildup of dust and dirt in itspassages will eventually choke off the air sup-ply. causing incomplete combustion andheavy carbon deposits on valves and pistonsMultiple air cleaner installations aresometimes used where engines are operatedunder extremely dusty air conditions or wheretwo small air cleaners must be used in placeof a single large one.

The most common types of air cleaners are

1. Pre-cleaners

2. Dry element cleaners

3 Oil bath cleaners

PreCleaners

Pre-cleaners (Figure 7-79) are usually in-stalled at the end of a pipe extended upwardinto the air from the air cleaner inlet. In thislocation pre-cleaners are relatively free ofdust Pre-cleaners are simple devices whichremove large particles of dirt or other foreign

matter from the air before it enters the mainair cleaner. They relieve much of the load onthe air cleaner and allow longer intervals be-tween servicing. Most pre-cleaners have apre-screener which prevents lint. chaff. andleaves from entering the air intake.

COLLECTORBOWL

(7-79)PRE-CLEANER

R 40$ PRE-SCREENER

Pre-Cleaners and Re-Soreeners Keep LargeForeign Particles From Reaching the Air Cleaner


Dry Element Air Cleaners

Cylindrical Dry Element Cleaner (vane andtube type)

Atmospheric air enters the inlet opening of adry element air cleaner (Figure 7-80) where itimmediately travels through a ring of vanes ortubes which create a cyclonic twist to the air.The air twist throws most of the dust and dirtparticles outward and down into a removabledust cup. The air, now cleaner. passesthrough a paper filter which removes theremaining dust.

(7-80)

Dry Element TypeAir Cleaner

CouriesY 01 John Deere Lid

ENGINES 7:49

Panel Cartridge Dry Element Cleaner

Pane cartridge dry element cleaners (Figure7-81) have a twostage cleaning processsimilar to the cylindrical models Deflectorvanes create a twist in the incoming air whichthrows out most of the dust. The air thenspirals back through the cleaner's elementwhich removes the remaining dust.

FIRSTSTAGE

(7-81)PANEL CARTRIDGE AIR CLEANER


SECOND STAGE

Some panel cartridge air cleaners use anexhaust aspirator to remove the dust throughthe exhaust system (Figure 7-82)

(7-82)CARTRIDGE TYPE-AIR CLEANER-TWO STAGE


Other panel cartridge air cleaners replace thefirst stage of cleaning with a moistureeliminator Some vehicles such as on-highwaytrucks are subjected to water/salt spray andthe incoming air needs to have the moistureremoved from 0 before it reaches the dry filterelement Attached to the front of the cleaner.the eliminator traps and expells the moisturefrom the wet air and then sends the dry air tobe further cleaned by the paper fillers (Figure1-83)

MOISTUREELIMINATOR

(7-83)

Courtesy ofCummins Engine Co v--- DUST BIN

Oil Oath CleanersOil bath cleaners have a cleaning element in-side a housing that contains oil (Figure 7-84).Incoming air reverses when it strikes the sur-face of the oil causing most of the dirt to be-come trapped by the oil and settle in thesump. Tho air then passes upward through themain cleaner element where more dust andsuspended oil is removed. These second-stage filtered contaminants drain back intothe sump and also settle out of the oil. Cleanair leaves the cleaner at the air outlet. Light.medium and heavy duty cleaners areavailable. Note that the space above the mainelement in the air cleaner acts as a silencer tosubdue intake noise. Courtesy of John Deere LW

AIRINLET

MROUTLET

MAINELEMENT

OILCUP

%

AIRTUB 71

I EROIL CUP

(7-84)AIR FLOW THROUGH HEAVY-DUTY OIL

BATH AIR CLEANER60

7:50 ENGINES

FILTERINGELEMENT

CLEANAIR TOENGINE

OIL SPRAYDRAWN UP,

CLEANSPARTICLESFROM AIR

;41, Service filter element when red signal reachesSERVICE LEVEL, then reset indicator.

OIL CIO 4,4:

(7-85) AIR FILTER RESTRICTION INDICATORCourtesy 0 General Motors Corporation

1,"

(7-84) MEDIUM-DUTY OIL BATH AIR CLEANERcouslesy ol John Deeoe LIct

AIR FILTER RESTRICTION INDICATOR

The air filter restriction indicator (Figure 7.85),r;:f44:**is a warning device that tells when the air

filter is dirty and needs to be serviced. The in-dicator is constructed s the warning notice isgiven before any damage occurs to theengine as me rssult of a clogged filterelemen: The res:riction indicato: is located inthe air inlet manifold and is readily visiblewhen the engine compartment is oper, The in-dicator itself requires no service other thanresetting.

When the fillet element is clogged to such adegree that air flow is restricted, a red in-dicator ring appears in the transparent area ofthe body marked "service level". This is thesignal that the air cleaner must be serviced.After servicing the cleaner, the indicator isreset by depressing the buttor on top of it.The red ring will then move out of the trans-parent area of the indicator.

NOTE Some vehicles will have an airrestriction gauge rather than an in-dicator The restriction gauge (Figure7-86) is located on tne panel board inthe cab and performs the same func-tion as the indicator.

I

111111MIM111.

4

I

1-6413

(7-86) AIR FILTER RESTRICTION GAUGE(TYPICAL)

Cowiesy OI General Motors Corporal or

Si

ENGINES 7:51

TUBING, HOSE AND CLAMPS FORMR INDUCTION SYSTEMS

Air induction piping works in conjunction withthe air cleaner to carry clean air to the engine.It is importelt that all the piping joints areproperly sealed and free of leaks. An aircleaner is completely ineffective if leaks oc-cur in the piping between the air cleaner andthe engine.

Dirt is the basic cause of wear on pistons.rings. liners and valves. One of the most prob-able places for dirt to enter an engine isthrough an opening in air induction piping.Field experience has shown that most airleaks occur when wire reinforced hoses areused in the au induction system. The leaksare caused by wire wearing through the hosefabric and they are often barely visiLle to thenaked eye. Even a very small hole can allowlarge quantities of duty air to enter an engine.Therefore. wire reinforced hose is not recom-mended for air induction tubing.

Smooth-Welded Steel Tubing

Smooth-welded steel tubing (Figure 7-87)should be used instead of flexible hose ormetal tubing that has rough-weld steel tubingangle joints Smooth welded steel tubing hasa smooth surface that gives a good sealingcontact with rubber connecting hose.

(7-97) SMOOTH-WELDED STEEL TUBINGCounesy 0 Cummins Engine Co

Connecting Hose

Steel tubing is joined by connecting hose(Figure 7-88). The hose has a built-up hump atliS center to give It strength and durability.Note that ideally two pieces of tubing whenconnected by a hose should be 3/4 inch (19mm) apart.

(7-88) CONNECTING HOSECounesy of Cummins Engine Co

Molded Rubber Elbows

To make angular connections molded rubberelbows are used (Figure 7-89) Elbows areavailable in both 90° and 45° angles A 90°elbow with ribbed reinforcement is alsoavailable to prevent possible collapsing underhigh temperature conditions or high inletrestriction.

(7-89) MOLDED RUBBER ELBOWSCourtesy of Cummins Engine Co

Hose Clamps

"T" bolt type non crimping hose clamps(Figure 7-90) should be used on air inductionsystems When tightened. the clamp exertsequal pressure around the circumference ofthe hose. A lock nut prevents the clamp froms..pping. and thus assures a tight permanentseas

82

(7-90) TBOLT HOSE CLAMPCourtesy of Cummins Engine CO

4

7:52 ENGINES

Figure 7-91 illustrates the tubing, connectinghose and clamps used on a typical dual inletair induction system for a large engine

1 Inlet Cap 8 Clamp2 Extension 9 Tube3 Clamp Assembly tO. Air Cleaner Assembly4 Either Starting Aid 11 Band Brackets5 Tube 12 Front Supports6 Support 13 Rear Supports7 Elbow 14 Engine Inlets

(7-91)

A 3975

Courtesy of General Motors Corporation

ENGINES 7:53

PREVENTIVE MAINTENANCE ON AIRINDUCTION SYSTEMS

Good maintenance practices on air inductionsystems'

1. Keep the air cleaner-to-enine con-nections tight.

2. Keep the air cleaner properli assembledso all joints are oil and air tight.

3. Periodically make a careful examinationof the air induction system for leaks. Overa period of time enough dusty air can passthrough even a small crack to severelydamage the engine

4 When conditions are dusty frequently in-spect the cleaner.

5 Service oil bath cleaners often enough toprevent oil from becoming thick withsludge

6 Use the correct grade of oil. Keep the oilat the proper level in the cup. Do not over-fill

NOTE Oil from an overfilled cup can bedrawn into an engine. The over-flow oil can cause a dieselengine to run away (overspeed)and severely damage itself.

7 Always practice cleanliness whenworking on air systems. Some points ofcaution are:

(a) Be careful when working around anopen air intake with the engine run-ning. Rags. loose clothing or otherobjects can be drawn into the engineand severely damage it.

(b) Never leave an intake pipe open. Ar-ticles can be dropped into an openpope and cause serious damagewhen the engine is started. Don'tcover the opening with a rag but withsomething hard such as a piece ofplywood.

64

7:54 ENGINES

AIR CLEANER SERVICE

Refer to the service manual about cleaningprocedures for particular air cleaners. Typicalair cleaner service procedures are givenbe low.

Pre-Cleaner and Pre-Screenar Service

COLLECTORBOWL NN

O 0 00O 0

0PRE-SCREENER 0 0

O 00 000

(7-92)

Courtesy 01 John Deere LW

If too much dirt is allowed to collect in the pre-cleaner. it becomes clogged and a greaterload is placed on the main cleaner. Removethe pre-screener and blow or brush off any ac-cumulation of lint. chaff. or other foreign mat-ter (Figure 7-92) If the pre-cleaner has aremovable collector bowl. take it off andthoroughly clean it.

Dry Element Air Cleaner Service

Servicing dry element air cleaners involvesemptying the dust cup and either cleaning orreplacing the dry element (Figure 7-93) Theelement should be replaced if It Is damaged orif it has been in normal service for one year.

"ft

FILTERELEMENT

BAFFLE

AIMIA,Af

DUST CUP

RESTRICTIONI.NDICATOR

X 1974

(7-93) DRY ELEMENT TYPE AIR CLEANERCourtesy 0 John Deere Ltd

Clean the filter element at the following times:

1 Units with restriction indicators: clean theelement whenever the indicator signalshows a restriction.

2. Units without indicators: clean theelement at recommended intervals ormore often during dusty or unusualoperation

To clean the filter element shake it vigorouslyto remove most of the dust Use compressedair or a vacuum cleaner to remove anyremaining dirt (Figure 7-94).

R1:00

Patting The Element

65

R

Slowing' ;.lenient

(7-94) CLEANING THE DRY ELEMENTCourtesy of John Deere Lti

a

ENGINES

II the element is still dirty. it can be washed ina solution of luke warm water and commercialfilter-element cleaner or similar non-sudsingdetergent Washing dry elements has becomequite common because of the high cost of theelements They can be washed up to six timesThe washing can be done in a shop but morelikely the elements will be sent out to com-panies who provide this service. Spareelements should be kept on hand to use invehicles while others are being washed anddried. After an element is washed it should bechecked and stored as shown in Figure 7-95)

CHECKING ELEMENT

insert light inside clean anddry element Check element.Discard element if pin holes ortears are found

2 Wrap and store elements in aclertn dry place

(7-95)Coqu'ecy of Caterotat fraclor

Medium and Heavy Duty Oil Beth Air CleanerService

For a meaium-duty air cleaner. remove the oilcup. pour out the oil. remove the sediment andtnoroughly clean the cup (Figure 7-96). Whenrefilling the cup use the same oil as is used inthe engine Inspect the under-surface of thefixed element for a collection of lint. trash. orother foreign matter If any of these arepresent. the cleaner should be removed andcleaned.

7:55

(7-96)

HEAVY-DUTY AIR CLEANER OIL CUP AND TRAYCourtesy of John Deere Lid

To clean the element soak it in solvent toloosen accumulated dirt. Thoroughly flush theelement by rcnning solvent through it from theair inlet end. Allow excess solvent to drip outBlow out the element with compressed air

CAUTION: Never attempt to clean theelement with a steam cleaner.The force of the steam cannot bemaintained throughout theelement and will only force thedirt to the center of the element.

Wipe out the center tube with a clean lint-freecloth. Inspect the inside of the air cleaner-to-manifold pipe for accumulation of oil and dirt.If necessary. remove the pipe and clean it. Aheavy duty oil bath cleaner is cleaned in asimilar way to a medium duty one. In addition.though. some heavy duty cleaners have acollector screen(s) attached to the inlet tubewhich must be cleaned. Wash the screen insolvent and blow it out with compressed air.When a clean sere en is held up to the light. aneven pattern of ligot should be visible If thescreen doesn't pass this test repeat thecleaning operation or replace it.

NOTE. The fixed elements of heavy-duly aircleaners are self-cleaning However.it may be necessary to remove andclean these elements periodicallySee the operator's manual for com-plete in formation.

66

7:56 ENGINES

QUESTIONS AIR INDUCTION SYSTEMS

1 What are the three types of air ino...ctionsystems used to supply air to the engine?

2 Briefly explain how a scavenge blownengine differs from a natural aspiratedengine.

3. The Turbo charger is driven by

(a)

(b)

(c)

(d)

gears in the engineoil pressure

exhaust driven turbineintake driven compressor

4 How does a turbo charger get more airinto the combustion chambers than anaturally aspirated engine'?

5 Under what condition does a turbocharged engine receive its maximumboost pressure/

6 An after cooler (intercooler) is used o.1 aturbo charged engine to:

7

8

9

10

cool the exhaust gasescool the inlet air before it enters theengine

cool the inlet air before it enters theturbo charger

cool the exhaust manifold

What are the three most common typesof air cleaners'

True or False If an engine has a pre-cleaner it doesn't need a main aircleaner

What is the purpose of the circular ordeflector vanes in the dry element aircleaner?

In an oil bath air cleaner. what happensto the air when it strikes the surface ofthe oil/

What indication does an air restrictor in-dicator give when the air filter needs ser-vicing/

(a) a light comes on(b) a buzzer sounds(c) a red band is visible on the indicator

(d) It won't allow the engine to start

12 When Servicing an oil bath air cleaner.what is the danger of over filling thecup'?

13 List two safety practices to be observedwhen working on an air inductionsystem

14 How often should a dry air later elementbe cleaned/

15 Why should an oil bath air cleaner not besteam cleaned?

16 True or False/ A minor leak in air in-duction piping between the air cleanerand the engine probabli won't do toomuch damage.

17 What type of oil is used in an oil bath aircleaner.

16 In a medium-duty oil bath cleaner thecleaner should be removed and cleanedif(a)

(b)

(c)

67

the oil is lowthe oil appears to be dirtylint and other contaminants appearon the underside of the element

fi$

ENGINES

EXHAUST SYSTEMS

The function of the exhaust system is tocollect exhaust gases from the engine cylin-ders and disperse them. quietly The exhaustsystem consists of the following parts*

Exhaust Valves seal the burning gases withinthe cylinder until most of the energy has beenexpended. and then open so that the cylindercan clear before the next air or fuelair chargeis admitted

Exhaust Manifolds receive burned gases fromeach cylinder and carry them away from theengine (Figure 7-97) Some heat from theexnaust manifold is used in gasoline enginesto maintain the intake manifold at the propertemperature

(7-97)EXHAUST MANIFOLD IGASOLINE ENGINE!

counesv of John Deere Ltd

Turbo Chargers use exhaust gases to drivethe compresso- turbine

Mufflers carry away exhaust gases and heat.and muffle engine noise The exhaust ports inthe engine and the passages in the exhaustmanifold are large enough to allow completescavenging and expansion of the escapinggases If any burned gases were left in thecylinders following the exhaust stroke. theamount of air or fuel-air mixture that could betaken in on the next intake stroke would belimited Engine power would be reduced andfuel consumption it used

/1 II I -TMSTRAIGHT-THROUGH MUFFLER

(7-98)Courtesy of John Deere Ltd

7:57

REVERSE-FLOW MUFFLER


MUFFLERS

There are two common types of mufflers:

Straight-through

Reverse-flow

Straight-through mufflers consist of a per-forated inner pipe enclosed by an outer piperoughly three times larger in diameter. Thespace between the pipes is sometimes filledwith a sound-absorbing and heat-resistantmaterial (Figure 7.98).

Reverse-flow mufflers are hollow chambersusing short pieces of pipe and baffles to forcethe exhaust gases to travel a back-and-forthpath before being discharged (Figure 7-98)

Mufflers reduce engine noise. but at the sametime they must not restrict the flow of exhaustgases enough to cause back pressure in theexhaust system. Back pressure causes in-complete cylinder scavenging which in turncauses loss of power and increased fuel con-sumption Excessive back pressure can evendamage combustion chamber components.For each two ps i. of back pressure about fourengine horsepower are lost. The trade-off inmuffler design then is to keep back-pressureat a minimum while keeping the noise at anacceptable rwel. Note that special mufflersare made to minimize the additional noise onsystems that have engine brakes.

68

ak.

"tr

7:58 ENGINES

Muffler and piping size is related to enginecapacity Usually the muffler volume is equalto six to eight times engine displacement(engine displacement is the total volume ofair /fuel mixture an engine theoretically cantake into all cylinders in one cycle) Bends inexhaust piping should be gradual. not sharp.so that gas flow is not restricted. The generalrule for bends is that the radius of the bend befou: to I've times the diameter of the tubingFor example 3 inch tubing should have a 12inch radius bend (Figure 7-99)

(7-99) RAMPS OF BEND

Bends in exhai..-1 pipe are not usually made inshops: custom lengths and bends areavailable from manufacturem

Vehicles working in forested and industrialareas where fire may be a hazard have a fur-ther addition to their exhaust system aspark arrester A spark arrester is a screenover the exhaust ot oet to reduce the chancesof hot pieces of carbon or sparks beingdischarged.

PREVENTIVE 1TENANCE ONEXHAUST SYSTEMS

Exhaust systems should be inspectedperiodically for restrictions and leaks. Restric-tions such as kinked or crimped pipes resultin harmful back pressure. while exhaust leakscreate unwanted noise and a oanger ofposonous gas seeping up into the cabRestrictions are caused by pipes being struckLeaks are usually caused by

1 loose clamp assemblies

...elective connections between manifoldand exhaust pipe. and exhaust pipe andmuffler(s)

3 corroded pipes

4 punctured muffler.

69

Leaks can be detected by running your hand afew inches abwe the pipe while the engine isrunning. Damaged or corroded exhaustsystem components should be replacedvalho...t delay for both engine efficiency and

ve safety.

SOME POINTS ON EXHAUST SYSTEMREMOVAL AND INSTALLATION

1 Caution: One of the products of com-bustion is carbon monoxide This is adeadly. odorless. poisonous gas. Providegood ventilation anytime the engine isoperating

2. Be careful of hot pipes and muffler(s) ifthe engine has been running recently.When removing pipes and the muffler.support the whole assembly to prevent itfrom falling on you when the clamps andbolts are removed.

3. Exhaust components must have a 3/4 inchclearance with the frame or the cab. Com-ponents without proper clearance v..frequently the cause of annoying noisesand rattles. The 3/4 inch clearance is alsonecessary to prevent overheating of thecab paneling. If needed, a metal orasbestos heat shield can be installed onthe part of the pipe that passes a criticalarea To get proper clearance. leave allclamp assemblies and muffler strap boltsloose temporarily until the entire systemhas been inspected to determine if thereis adeqv Ite clearance between exhaustcomponents and frame members. Whilethe clamp and bolts are loose also checkto see that the weight of the exnaustsystem is properly distributed on all sup-porting brackets and hangers. If the loadis not properly balanced reposition pipesat connecting joints.

When the clearance and balance arecorrect. tighten all bolts and clamps.working from front to rear. Note when in-stalling the exhaust pipe to the manifold.always use new packing and new nuts orbolts Be sure to clean the manifold studthreads with a wire brush before installingthe new nuts

Alter everything is tightened start theengine and check the connections forleaks A horizontal muffler installation isshown in Figure 7-100 and a verticle muf-fler installation in Figure 7-101 Note how

4.

.45

ENGINES

the clamps and support brackets arepositioned to ba:ance the weight of thepipes and muffier(s)

7:59

Courtesy of General Motors Corporuon

(7-100)HORIZONTAL MUFFLER INSTALLATION

-5255

Ll ...._ALL CLAMPS t2 I? PT L0

Either a curved end or arain-cap shoul': be installed

on the end of the pipe

MUFFLER-5225

RN EXTENSIOU50209

RN PIPE-5245MUFF LER INLET WEAN

CLAMP-5A281 SA212

ENCORE PIPE OREf/-

914ACKET11291 \JJMI" 21t25E20/

MUFFLER OAST PIPELI4 5245

BRACKET -5A245

UOOLT -5A720CLAMP 6270WAS14,44111742uv7 -349e7 S2

CONNECTOR

MUFF LER-5225

Courtesy of Ford Motor Co

(7-101) Typical Heavy Trlc MAI Exhaust SystemL, LT-, LNT -9000 with V-903 Dual Vertical Mufflers Shown OthersSimilar

70

VINO

7:60 ENGINES

QUESTIONS EXHAUST SYSTEM

1 Besides carrying away exhaust gases andheat a muffler must'

(a) increase horsepower

(b) help control engine temperature

(c) muffle engine noise(d) all of the above

2 Back pressure causes.

(a) incomplete cylinder scavenging(b) loss of power (four horsepower for

every two P.5.1. back pressure)(c) increased fuel comsumption(d) a. b and c are all correct

3 Usually muffler volume is equal totimes engine displacement.

(a) 6 to 8(b) 4 to 6(c) 7 to 9td) 2 tr., 4

4 Why are gradual bends better than sharpbends in an exhaust system?

5 What is the danger of leaks in exhaustpiping'

6 From a safety point of view, what is themost important precaution to take whenrunning an engine indoors?

7 How can you check exhaust pipe con-nections for leaks,

71

ENGINES 7:61

FUEL SYSTEMS

The basic purpose of a fuel system is toply enough fuel to meet engine speed andload demands Gasoline, diesel and L.P gasengines all have a different type of fuelsystem.

GASOLINE FUEL SYSTEMS

The gasoline fuel system supplies a com-bustible mixture of fuel and air to power theengine The gasoline fuel system has threebasic parts (Figure 7-102):

fuel tank stores gasoline for the engine

fuel pump moves the fuel from the tankto the carburetor

carburetor atomizes the fuel and mixesfuel and air in the proper ratio

FUELAIRMIXTURE

CHOKEVALVE(OPEN)

VENTURI

THROTTLEVALVE

CL(PARTLY

OED)

AIR INLET

I "- )AT

NOZZLE

ktiake Valve

FMIX


FUEL PUMPAND FILTER

(7-102)

GASOLINE FUEL SYSTEM

The fuel pump draws the gasoline through afuel line from the tank and forces it in to thefloat oharbher of the carburetor where it isstopped. Ti' .1 carburetor is basically an airtube connected to a float chamber thatoperates by a difference in air pressure(Figure 7-103)

The pressure difference in the carburetor iscreated when air flows through a narrow neckcalled the venturi. In order to maintain its rateof flow air traveling through a tube at a givenrate will speed up as it goes through anarrowing in the tube (ie.. at the narrowingnot as much air can get through. Therefore.the air must travel faster By speeding up. thesame amount of air per second can travel

FUEL INLET

FUEL INTAKEVALVE

Combo/mienChamber

(7-103)

Poston

ENGINE


through the narrow neck. and the rate of flowis maintained) When the air speeds up itsmolecules spread out and consequently itspressure is reduced For example. airtraveling at 14 7 lbs per square inch can dropto 8 passr.g through the venturi Thisdrop mates a pressure difference betweenthe carbLretor float chamber and the car-buretor nozzle that opens onto the ventunThe pressure difference at the nozzle tipdraws fuel from the float chamber and deliversit to the nozzle In the form of tiny droplets Thedroplets mix with the air . d vaporize givingthe air-fuel mixture for combustion.

72

7:62 ENGINES

The fuel-air mixture must pass a throttle valvebefore it goes to the engine The throttle con-trols the amount of mixture going to the cylin-ders. and thereby controls engine speed

The other basic part of a carburetor is thechoke which is needed for starting an enginein cold weather The choke is located in theincoming air passage and partially or fullyclosing it causes a vacuum to form un-derneath it The vacuum causes the car-buretor to produce a mixture which has agreater percentage of fuel This richer mixtureIS necessary because when gasoline is cold itdoes not vaporize as readily as it does whenit s hot: so. more fuel is needed to supply anadequate amount of vapors Tne choke maybe automatically controlled. opening as theengine warms up. or it may be manually con-trolled by the operator.

Of course. actual carburetors are more com-plex: they will be studied in future training

Recommended reading: Chapter 18 and 19.Automotive Fuel Systems and AutomotiveCarburetors. in Automotive Mechanics,Seventh Edition.

LIQUIFIED PETROLEUM GASFUEL SYSTEMS

Facts About Liquified Petroleum Gas (LP3)

LPG 15

1 A by-product of gasoline refining

Vapor

LigeldFuel

CONVERTER

2 Also obtained from natural gas.

3 Made up of propane. butane or a mixtureof the two.

4 Vaporizes very easily Remains a liquidonly when under pressure

5 Liquified by compressing many gallons ofvapor to make one gallon of liquid.

6 Easy to handle and store as a liquid.Stored in strong. heavy tanks withpressure relief valves.

7 Expansive when heated (due to morevaporization).

8 Converted to vapor again on way to theengine.

The basic difference in the operations of anLPG fuel system and a gasoline fuel system isthat LPG is vaporized before it reaches thecarburetor whereas gasoline is vaporized inthe carburetor.

Parts Of A LPG Fuel System

The LPG fuel system has four basic parts(Figure 7-104%:

Pressurized Fuel Tank

Fuel StrainerConverter

-- Carburetor

Het Woe:From Engine

VapotAirMixture

FUELSTRAINER

FUEL TANK

LyReturn Nutty

CARBURETOR

Vepot

< AirInteke

(7-104) LPG FUEL SYSTEMCourtesy of John Deere Ltd

73

ENGINES 7:63

The pressurized fuel tank stores the liquid fuelunder pressure. A space for vapor is left at thetop of the tank. To withdraw LPG from thetank two methods are used liquid withdrawaland vapor withdrawal

Most modern systems use the liquid with-drawal method The fuel is drawn from thetank under pressure as a liquid and thenvaporized. The vapor withdrawal method isnormally used only for starting when theenvie is cold and hasn't enough heat to con-vert liquid fuel to vapor. Vapor is drawn off thetop of the tank to provide vaporized fuel forstart up. Once the engine is warm, the fuelsystem is switched to liquid withdrawal.

The fuel strainer cleans the liquid fuel. it nor-mally has a solenoid which permits flow onlywhen the engine ignition is turned on.

The converter changes the liquid fuel to vaporby warming it and lowering its pressure.

The carburetor mixes the fuel vapor with air inthe proper ratio for the engine.

Comparing LPG and Gasoline

t. Both propane and butane produce slightlyless heat per gallon than gasolineHowever. LPG has a higher octane ratingwhich means that the compression ratio ofLPG engines can be raised to offset theheat losses.

2. LPG burns slower than gasoline becauseit ignites at a higher temperature. For thisreason. the spark is often advanced far-ther on LPG engines.

3 More voltage at the stark plugs may beneeded for LPG engines than for gasoline.

4. LPG engines do not require as much heatat the intake manifold as gasoline modelsbecause LPG will vaporize at lower tem-peratures The result: less heat is wastedand more heat goes into engine power.

Advantages and Disadvantages of LPG

The advantages of LPG are:

Burns much cleaner than gasoline ordiesel fuel; its exhaust contains lesscarbon monoxide and other harmfulemissions. For this reason it is used inmachines such as fork lifts that operatein warehouses or other closed en-vironments.

Cheaper fuel especially where close tosource.

Less oil consumption due to lessengine wear.

Reduced maintenance costs, longerengine life between overhauls.

Smoother power from slower, moreeven burning of LPG fuel.

The disadvantages of LPG are:

Equipment costs are high. Bulk storageand carburetion equipment are costly.

Fewer accessible fueling points. Notmany LPG filling stations.

Harder to start engines on LPG in coldweather (0*F or below) because oil onthe cylinder walls remains undilutedand makes the engine harder to turn.

74

7:64 ENGINES

8

COMBUSTION]CHAMBER

INJECTION NOZZLES

1

INJECTIONPUMP

is HIGH PRESSURELOW PRESSURETANK PRESSURE r

t_

FUEL FILTERS

5

(7-105)DIESEL FUEL SYSTEM

(DISTRIBUTOR TYPE SHOWN)

DIESEL FUEL SYSTEMS

The prime lob of a diesel fuel system is to in-ject a precise amount of atomized andpressurized fuel into each engine cylinder atthe proper time

Combustion in the diesel engine occurs whenthis charge of fuel is mixed with the hot com-pressed air that ignites the fuel.

The major parts of the diesel fuel system are(Figure 7.105)*

Fuel tank stores fuel

Fuel Transfer Pump pushes fuelthrough filters to the injection pump.

Fuel filters cleans the fuel.

Injection Pump times, measures anddelivers fuel under pressure to thecylinders

a governor controls engine speed.

Injection Nozzles atomizes andsprays fuel into the cylinders.

FUEL TANK

%-0*--"--

FUELTRANSFER

PUMP

Courtesy 01 -Porn Deere Ltd

A 1"/

Fuel either flows by gravity pressure from thefuel lank to the transfer pump or it is drawnfrom the tank by the transfer pump From thetransfer pump fuel is pushed through filtersand clea.ed (It is very important that dieselfuel be absolutely clean so that the closely fit-ted parts in the injection systeo are notdamaged The fuel then travels to the in-jection pump where it is metered and highlypressurized and then delivered lo each of theinjection nozzles The injection nozzlesatomize the fuel and spray it into the com-bustion chambers

Function Of Fuel Injection

The Diesel Fuel Injection must.

Supply Fuel The fuel injection systemmust supply the exact amount of fuel toeach cylinder on each cycle.

2 Timed Fuel Celivery Fuel delivered tooearly or too late during the power strokecauses a loss of power Fuel must be in-jected into the cylinder at the instantmaximum power can be realized.

75

ft

ENGINES

3 Control Delivery Rate Smoothoperation from each cylinder depends onthe length of time it takes to inject thefuel Fuel must be injected at a rate thatcontrols combustion and cylinderpressure. The higher the engine speed the,,.ster the fuel ust be infected.

4 Atomize Fuel The fuel must bethoroughly mixed with the air for completecombustion. For this reason the fuel mustbe broken up into fine pa. tides.

5 Distribute Fuel The fuel must be spreadevenly in the cylinder to unite with all theavailable oxygen This makes the enginetun smoothly and develop maximumpower

There are a number of different fuel injectionsystems. but they all must perform these fivebasic :unctions Diesel fuel supply systemswill be dealt with in greater detail at a laterd ale

BASIC COMPONENTS OF GASOLINE,DIESEL AND LPG FUEL SYSTEMS

Following is a closer look al some of the fuelsupply components of the three fuel systemsthat you are most likely to be in contact withat this level of training.

Fuel Tanks

Fuel tanks for gasoline. LPG and Diesel allhave the same purpose to provide a safemethod for storing fuel. The location, size andtank material for the three systems, however.will vary

Gasoline and Diesel tanks generally have thefollowing features'

1 A drain plug or drain cock on the bottomof the tank which allows water orsediment to be periodically drained.

2 A shut-off valve on the outlet line

3 A idler cap that is twist sock or threaded

4 A vent mechanism It may be built into thefiller cap or be located separately Thevent allows air to enter the tank to replacethe space of the fuel that is drawn out.thus preventing restriction of the fuel llowor a vacuum in the tank

5 An outlet pine is raised slightly from thebottom of the tank to prevent dirt or watergetting into the fuel 1:ne. As an added

1:65

precaution against dirt. the fuel pick upline will have a coarse filter such as ascreen at the fuel entry point

6. Diesel fuel systems generally have areturn line as well. This line returns at theopposite end to the outlet so that any en-trapped air can escape.

7. Baffies to strengthen the tank and preventsloshing of the fuel.

8. A gauge or some means of checking thefuel level.

9. Dual tanks have connecting lines andpossibly a three-way valve to switch fromone tank to the other.

Gasoline fuel tanks in small vehicles areusually made of tight gauge metal pressedinto shape anL treated to prevent rusting. Fueltanks for larger vehicles, whether for gasolineor diesel. are made of much heavter gaugemetal. and are rolled and welded with stam-ped ends. These tanks are also treated in-ternally to prevent rusting

Fuel tanks come in many different sizes andshapes. The tank must be capable of storingenough feel to operate the engine for areasonable length e time. The shape of thetank is made to conform to the spaceavai!able on the machine. A tank can be tall.short, round. square, whatever shape that willfit into the allotted space.

76

.

7:66 ENGINES

LPG Tanks

An L.P gas fuel tank must be strong andheavy to withstand the pressure of its fuel.The fuel tank is never filled completely full ofliquid fuel (usually to 80%) because roommust be left for vapors and expansion. Thetanks require special equipment to fill themTwo types of tanks are shown in Figure 7-106.a vapor withdrawal tank and a liquid with-drawal tank

PRESSURE RELIEF VALVE

Er; FILL VALVE

VAPOR

FUEL

VAPOR LINE

PRESSURERELIEFVALVE 80 (';

FILLING VALVEVALVE

FILL

r

LOW-PRESSURE

PRESSURE REGULATOR

GAUGE

0

HIGH-PRESSUREREGULATOR

HOT WATER FROM ENGINE

RETURN WATER

ENGINEINTAKE MANIFOLD

ADJUSTINGVALVE

LPGAS SYSTEM USING VAPOR WITHDRAWAL

V4PORLINE

VALVE

VAPOR

RETURN LIQUID LINEVALVE VALVE

STRAINERVALVE

LOW-PRESSUREREGULATOR

CARBURETOR

ENGINEINTAKE

MANtFOLO

VAPORIZER

VAPOR

FUEL

HOT WATERFROM ENGINE

--111-=,/

HIGH-PRESSUREFUEL TANK REGULATOR

r_-11RETURNWATER

LP --GAS SYSTE" 'SING LIQUID WITHDRAWAL

(7-106)

LPG FUEL SYSTEM

77

CARBURETOR

Courtesy Jonn Deere Lid

mri

Co

ENGINES 7:67

Fuel Filters

Contamination of fuel can be a major cause ofwear to internal engine parts that eventuallyleads to engine failure Fuel filter must cleanthe fuel before it gets into the carburetor ingasoline and L P gas engines. or into the in-jection pump in a diesel engine

Types Of Filters

Filtration removes suspended matter from thefluid Some filters will also remove soluble Im-purities

Filtration can be done in three ways.

straining

absorption

magnetic separation

Straining is a mechanical way of filtering(Figure 7-107). A screen blocks and traps par-ticles larger than the openings. The screenmay be wire mesh for coarse filtering or paperor cloth for liner filtering.

I'll

I I

I I

1 111

1111I I

ABSORPTION

la

I11STRAINING

(7-107)Couruisy of John Deere Ltd

Absorption is a way of trapping solid particlesand some moisture by forcing these con-taminants to stick to the filter media cottonwaste. cellulose, woven yarn. or felt (Figure 7-107).

Magnetic Separation is a method of removingwater lrom fuel. A paper filter is treated withchemicals that cause any water in the fuel toseparate and drip into a water trap (The filteralso rerno%.es solid particles by one of theother methods of filtration )

Filters are rated according to the degree towhich they filter out particles Filtrationdegree is usually measured in microns. Onemicron is approximately .00004 inch or one 40millionth of an inch. To get an idea of howsmall a micron is it would take 25.000 micronslaid side to side to make up an inch. Thesmallest particles that can be seen with theunaided eye are about 40 microns. Sincesome of the finer fuel filters (diesel) are ratedat two microns. many of the particles theyfilter out are invisible.

Fuel filters in gasoline engines are usually in-corporated into the fuel pump. as below:

FUELSTRAINER

HAND PRIMERLEVER

Y " 6 (7-108)

FUEL BOWL

ROCKERARM


The filter acts as a water trap and provides aplace where sediment can settle out of thefuel. Sediment build up can be examinedthrough the glass bowl and should be cleanedwhen necessary. In addition to this filter manygasoline fuel systems use an in-line-filter be-tween the pump and the carburetor (Figure 7-t09).

WITHOUT VAPOR RL l'URN LINE

rFilter

Fuel PumpCarburetor

78

Fuel TankFiller

(7-109) Courtesy of Font Corpnrat!on

7:68 ENGINES

An in-line fuel filter usually has a pleatedpaper filtering element (porous bronze orceramic is also used) enclosed in a sealedplastic container In-line filte, cartridges arethrow-away items replaced after so manyhours of service (Figure 7-110).

17-110) TYPICAL IN-LINE FILTER CARTRIDGECourtesy of Frain Corporation

FUELOUT

SPRING

SOLENOIDCOIL

VALVEPLUNGER

FILTERELEMENT


79

Another location for a filter is at the inlet of theca-turetor The filter is threaded into the inletand has a tube connector at the other cid.This filter generally uses a screen as afiltering element.

L.P. gas systems use a fuel strained (Fig..re 7-111) located between the fuel tank and theconverter.

The fuel strainer has two functions:

1. Strains fuel to clean it.

2. Shuts off fuel when system is notoperating.

The strainer has stages including a screen. afelt filter, a chamois filter (to remove water),and another screen. A sediment bowl with adrain plug collects the foreign matter.

The shut-off is an electrical solenoid coilgenerally referred to as a filter lock. When theengine ignition is turned on, the solenoidmagnetizes the va;ve plunger ar.1 opens it,allowing fuel to flow. When the ignition isturned off or fails, the valve closesautomatically. Pressure of the fuel holds ittightly on its seat.

Diesel Fuel Filter

Although important to gasoline engines. fuelfiltration is even more important to dieseloperation because:

1. Diesel fuels tend to be impure.

2. Injection parts are precision made anddirty fuel will damage them.

Because filtration is so important to a dieselfuel system. the fuel will be filtered not oncebut several times. A typical system like theone in Figure 7-112 has three progressivestages of filters. a primary filter. a secondaryfilter and a final stage filter.

or Compressed._So Hot ThatFuel Ignites :

hen Intectediit

INJECTION NOZZLES

ENGINES 7:69

INJECTIONPUMP

(7-112) FUEL

iDIESEL FUEL SYSTEM TRANSFER

FUEL PiL1ERS PUMPCourtesy of John Deere Ltd

FUEL TANK

5---?

Primary filters are generally a combination ofa coarse filter that removes large particlesand a water trap: secondary filters are finerfilters that remove most small particles; finalstage filters are very fine (rated as low as twomicrons) and remove tiny. invisibLt particles.Fuel will Pass through all three filters beforereaching the injection pump. Note in the r;\diagram the drain screws at the bottom of V)each stage filter. OUTLET

Transfer Pumps

Gasoline and diesel fuel systems generallyrequire a fuel supply or trunsfer pump to movethe fuel from the tank to the engine. The mostcommon type of pump is the mechanicaldiaphragm pump which is found on gasolineand diesel engines. There are also. electric.gear and piston transfer pumps. Figure 7-113illustrates the operation of a typicalmechanical fuel pump

OUTLETVALVE

INLETVALVE

FUEL (3)INLET =,

DIAPHRAWA

SPRING 0PULLROD

80

(7-113)

+oENGINE

CAM

ROCKERARM


7:70 ENGINES

The pump operates as follows'

Power is applied to the pump rocker arm at (1)by an eccentric (an offset disc) on the enginecamshaft As the camshaft rotates. the ec-centric causes the rocker arm to rock backand forth The inner end of the rocker arm islinked to a flexible diaphragm located be-tween the upper and lower pump housing. Asthe rocker arm rocks. it pulls the diaphragmdown. and then releases it A spring locatedunder the diaphragm forces it back up. Thusthe diaphragm moves up am down as therocker arm rocks.

When the diaphragm is pulled down. avacuum or low pressure area is created abovethe diaphragm. This causes atmosphericpressure in the fuel tank to force fuel into thepump at (2) The inlet valve (3) opens to admitfuel into the center chamber (4).

When the diaphragm is released. the springforces it back up. cau sir g pressure in the areaabove the diaphragm. This pressure closesthe inlet valve and opens the outlet valve (5).forcing fur! from the pump through the outlet(6) to the carburetoi.

If the needle valve in the float bowl of the car-buretor closes the inlet so that no fuel can en-ter the carburetor. the fue! pump can nolonger deliver fuel. In this case. the rockerarm continues to rock but the diaphragmremains at its lower I: nit of travel so thespring cannot for- r th, . aphragm up. Normaloperation of the ro .esumes as soon e theneedie valve in the float bowl opens the 'metvalve. allowing the spring to force thediaphragm up

HIGH PRESSURE FUEL LINESAND FITTINGS

Some diesel fuel systems have a bank of pum-ping units in one housing and require highPressure lines to deliver the metered andpressurized fuel to she injectors. Special thickwalled tubing and fittings are required towithstand the extremely high pressures. Caremust be used not to bend or kink riese linesand not to cross thread the fittin!..,s whenremoving and installing them.

Preventive Maintonanco Sarvice 0 n FuelLines an:s' Fittings

1 Periodically inspect the fuel I nes forloose connections. leaks. or kr KS.

2. Keep the line connectors tight. but not tootight Tighten the connectors until snug,but don't strip the threads. To avoid ben-ding the lines, use only one hand with twowrenches for final tightening, as shown inFigure 7-114.

Asss#01111

A

1/.4.17e2i "'

Y

e

(7-114)TIGHTENING LINE CONNECTIONS TO AVOID

BENDING THE LINES(FINAL TIGHTENING SHOWN)


3. When replacing a fuel line. be sure to usean identical line in size. shape and Iencth.The inside diameter is very critical with in-jection lines.

FUELS

COMPRESSION AND FUELS

When discussing fuels. the term compressionratio often comes up. Corm:hes:4°n rally. asstated earlier. is the relation between tne totalvolume inside the engine cylinder when thepiston is at its greatest distance from thecylinder head. compared to the volume whenthe piston has traveled closest to the cylinderhead.

The type of fuel an engine uses is directlyrelated ) the engine's compression ratio.Each fuel has its limits on how much it can becompressed and still burtI properly

ENGINES 7:71

1 Kerosene or distillate. when used in aspark ignition engine, operates best atabout a 4 to 1 compression ratio

2 Gasoline operates at a 7 or 8 to 1 com-pression ratio.

3 L P gls has an 8 5 or 9 to 1 compressionratio

4 Diesel fuel operates usually at about a 16tc' 1 compression ratio. although somedie:PI engines can have 3 ratio as high as20 to 1.

Gasoline fuel has certain characteristics thatmake a gasoline engine run efficiently. Thesame can be said of diesel fuel and L.P. gas.As well, there are different grades or qualitiesof ;nese fuels. Below is a discussion of someof the basic characteristics and qualities ofgasoline. diesel and L.P. gas fuels.

GASOLINE

Octane Rating

To understand octane rating, you have toknow what engine knock is. The followingdiagram illustrates how knock occurs in agasoline engine.

1 Spark Begins Fuel-AirMixture Burning

Cenetcbsy of 1.1ho 04x..6 Ltd

Fuel knock is a serious problem because it ;shard on valves. pistons and bearings andcauses a loss of power Tests have found thateven a very light knock, one that probablywouldn't sound harmful. increases the wearon the top piston ring about four times.

The octane rating of a gasoline is a measureof the gasoline's antiock properties. Thehigher the octane rating, the less tendencythe fuel has to knock.

The names premium and regular are roughcomparative measures of octane ratings

1. regular 88 to 94 octane

2. premium approximately 100 octane

Premium. h;gh octane gasoline is made forube in gasoline engines that have a higherthan rormal compression ratio. Most gasolineengines today, however, are built to run onregular gas.

What ;s the result of using premium gasolineon an engine designed to use regular?Premium grade gasoline can be use 'Iutthere is usually no advantage sine t ostengines haven't a high enough compressionratio to utilize the benefits of the higher oc-tane rating. Premium in this case is a waste ofmoney. The best policy is to use an octanerated gasoline that matches the octanerequirements of the engire.

1 02 Plarrie Advances

Smoothly. Ltorn-pressing and HeatingEnd-Charge

(7-115)

82

1 11 1

3 EndCharge SuddenlySelf Ignites WithViolence. Producing AKnock, Knocking AndCompression RatioAre Direotty RelatedThe Higher The Com-pression The GreaterLikelihood TheGasoline Will Knock

s

7:72 ENGINES

Volatility

The gasoline property mr important inengine starting is volatihttendency toevaporate) If volatility is too low. insufficientvapor may be drawn into the cylinder to alloweasy starting in cold weather Warm-up willalso be slow On the other hand, a gasolinewith too high a volatility is apt to cause car-buretor icing or vapor lock under certain at-mospheric conditions

Oil companies change the volatility ofgasoline with the seasons. In summer theyproduce a gasoline with low volatility sincethe warm temperatures aid in vaporizing thegasoline In winter. on the other hand, theyproduce a high volatility gasoline so that itwill vaporize more readily in the colder tem-peratures For this reason if a summer supplyof gasolle is held over to winter, difficultiesin engine starting will probably resu.t.

Gasoline Additives

Additives are put into gasoline to improve itsperformance and storage life Some of themain ones are

i Antiknock components to increase theoctane rating

2 Alcohol anti - freezes to prevent any waterin the gasoline from freezing and toprevent ice-plug formation

3

4

5

7

Anti-icers to Prevent the carburetor throt-tle plate from icing

Detergents to clean the carburetor andkeep it free of nisi.

Anti-oxidenis to improve storage stabilityand ratard gum formation

Phc...zntiortis compounds to minimize sparkplug fouling and surface ignition

Metal deactivators to protect the gasolineagainst harmful metals that may get intothe gasohne

DIESEL FUEL

Diesel fuel is made by distilling crude oil Justas the octane rating is probably the most im-portal', characteristic of a gasoline. thecetane number the important quality01 a diesel fuel Celane number is a measureof the way the fuel .gnites in the combustionchamber In a diesel engine there is a slightdelay between the time the fuel is injected

and the time it begins to burn This delay iscalled the ignition delay period The delayperiod is important because if it is too longthe fuel, when it does start to burn. will burnexplosively causing engine knock Cetanenumber measures the ignition delay period.the higher the cetane number the shorter theperiod

The speed of an engine prescribes the cetanenumber that the engine requires. Dieselengines whose rated speeds are below 500RPM are classed as slow speeo engines, from500 to 1200 RPM as medium speed. and over1200 RF-M as high speed. Cetane numbers offuels readily available range from 40 to 60with values of 45 to 50 most common. Thesecelane values are satisfactory for medium andhigh speed engines, but low speed engmcsmay use fuels in the 25 to 40 octane numberrange

It is interesting to note that the octane ratingof gasoline and the celane rctrig of dieselfuel mea-gire opposite fuel qualities Figure 7-116). A high octane rating means that thegasoline has a low tendency to combust spon-taneously By c.mtrast. a high cetane numbermeans that the diesel fuel will combustquickly and spontaneously

GASOLINE DIESEL FUEL(MUST BURN EVENLY) (MUST BURN FAST)

VOCTANE NUMBER

VCETANE NUMBER

MEASURE OF FAST.MEASURE OF ABILITY SPONTANEOUS

TO RESIST DETONATION COMBUSTION

OPPOSITES

83

(7-116) OCTANE AND CE.rANE NUMBERSARE OPPOSITES


An important difference exists when using oc-tane and cetane numbers to Judge the qualityof the fuel. Theoretically the higher the octanerating the better the fuel. assuming of coursethat the engine can take advantage of thehigh octane fuel by increasing the com-pressing ratio or by super-charging the

4,

,yr

ENGINES

airifuel mixture The same is not true of thecetane number Too high a cetane numbermay lead to incomplete combustion andexhaust smoke if the ignition delay period istoo short to allow proper mixing of the fueland air within the combustion space

There are two classes of diesel fuels. No. 1-0au.d No 2-D These classes set standards forfuel characteristics such as cetane number,volatility. viscosity. pour and cloud point. car-bon residue. sulfur content and others Thenumbers 1 and 2 do not mean that No. 1 is ahigher grade than No 2: both are of goodquality but each has characteristics that aresuitable for different engines and operatingconditions Some manufacturer will recom-mend using either 1-0 or 2-0 depending onworking conditions For example, the table ondiesel fuel usage in Figure 7-117 is taken froma John Deere Ltd tractor operator's manual

Type of EngineService

Ambient Diesel FuelAir Grade

Temperature No

Light load low speed Above 80 F 2-Dconsiderable idling Below 80 F 1-D

Intermeoiate and heavy Above 40 F 2-0load' high speed. Below 40 F 1-Dminimum of idling

At altitudes above5 000 feet

rlesy of John Deere Ltd (7-117)

All 1.0

7:73

LPG

As stated earlier LPG can be all propane. allbutane. or a mixture of the two Today.however ' °G is usually all or mostly propaneLPG. gasoline. has an octane rating:propane and butane 96. The high oc-tane ratings ..PG make it suitable for highcompression engines LPG does not come indifferent grades or qualities

STORING FUELS

There are two main areas of concern whenstoring fuel:

protection of fuel quality

safety

STORING GASOLINE

Three conditions must be controlled to Mtn-lain satisfactory supplies of gasoline:

Control loss through evaporation.

Avoid gum deposits in gasoline.

Protect gasoline from water and dirt

Controlling Evaporation Loss

Figure 7-118 illustrates the effects of coloring.shading. and a pressure vacuum relief valveon gasoline evaporation.


PRESSURE.SUOMI;RELIEFVALVE

r:01

A Red Tank Exposed To Sun's HeatWhite Or Aluminum Tad &posed To Sun's Heat

C While Tank Protected By A ShadeD While Shaded Tank Equipped With A Pressure-Vacuum

Relief Valve17-118) SUMMER EVAPORATION LOSSES FROM 300-GALLON GASOLINE STORAGE TANKS

84

7:74 ENGINES

Although this test is conducted under summertemperatures. similar res-Its would occur Inwinter because winter fuel. as was describedearlier, is more volatile and evaporatesquicker

If an underground tank IS used the tem-perature of the stored fuel remains lowenough all through the year so thatevaporation losses are small

Avoiding Gum DepositsGasoline will oxidize and form gum deposits ifkept for king periods. (311 companies add aninhibitor that will protect the fuel le- sixmonths to a year under normal storage con-ditions. but the interval is greatly reduced ifthe gasoline is exptsed to sunlight and tohigh storage temperat.ires To limit gum for-mation avoid storing more gasoline that youcan use conveniently in a period of about 30days Gum deposit is less of a problem withunderground tanks since the fuel remainscooler

Protecting Gacntine From Water and DirtContaminationPractice strict habits of cleanliness when

VENY

adding fuel to a tank or taking it out No mat-ter how careful you are. though. water and dirtwill still enter the tank Condensation formson the inside of the lank and the moisturedrops to the bottom of the tank because waterIS heavier than gasoline. The more the tem-perature of the tank varies. the greater theamount of condensation. Thus the sameprecautions that are taken to keepevaporation down will also limit condensation.Water must be occasionally drained or pum-ped out of the tank

Like condensation dirt in the fuel will settle tothe bottom of the tank. This sediment must oc-casionally be drained or pumped out of thetank See the next section on storing dieselfuels for illustrations of pumping and drainingtanks

Safety

Fire prevention regulations regarding tankplacement are shown in Figure 7-119. Thedistance that the tank must be away from abuilding IS intended to protect the building incase of lire

ABOVE GROUNDTANK

4031AINIAllt`

BUILDING"' Jai

UNDERGROUNDTANK

(7-119)

SAFE I.00ATION OF GASOLINE STORAGETANKS IN RELATION TO BUILDINGS

Courinsv of John 0(.4br ,.! LW

iiie.,..L'4,l

85

Evaporation during storage. whether above orbelow ground. is not rapid enough with dieselfuel to be a concern More important withdiesel fuel is to

1 keep it free of dirt and water

2 prevent gum deposit

hours before fuel is drawn from them. Alsodon't let water collect on lop of drums (Figure7-120) because

Keep Fuel Free Of Dirt and Water

It is important that all fuels be kept free of dirtand water. but it is especially important withdiesel fuel The reason' the fuel injectionsystem on a diesel engine is fitted with partsthat are held within millionths of an inchclearance Very fine dirt particles soon ruinthe parts and cause an expensive repair job.Water. even extremely small amounts. causescorrosion which ruins the high-polished Sur-faces of the injector nozzles. Ad operator'smanuals for diesels emphasize the im-portance of clean fuel

Water is ahout the same weight as diesel fuelso it settles out very slowly For this reasonallow 24 hours for water and dirt to settle tothe bottom of the storage tank after it hasbeen refilled Use two storage tanks: wr enone is refilled. the other can be used to st.oplyfuel If you have only one storage tank. besure to fill your machine's fuel tank before thesupplier refills the storage tank Another goodpolicy is to fill engine Tanks at the end of eachday to reduce overnight condensation inthem

waler resting on the top tends to rust thedrum.

as fuel is drawn from the tank. water maybe drawn through the air vent directly intothe fuel supply.

NOZZLECAP

If drwris are used for storing fuel. be sure thatthey are mounted rigidly in place Any han-dling will ream the dirt particles and waterfrom the bottom of th?. tank with the fuelWhen portable drums are used for re:ueling inthe held. be sure they are in place at least 24

Dirt particles may come from several differentsources. Some particles may be present in thefuel when delivered. but dirt is far more likelyto come from carelessness or improperstorage Some rules for preventing dirt in thefuel supply are:

Don t use an open container to transferfuel from the storage tank to tne machinetank. it will greatly increase the chance ofdirt entering the fuel tank. To transfer fuel.equip aboveground tanks with a pump andhose (Figure 7-120) or a gravity hose(Figure 7 -121). Be sure to cap the end 0.the hose nozzle while the hose isn't inuse

7:76 ENGINES

2 Don't store diesel fuel in a galvanizedtank A galvanized tank is satisfactory forgasoline. but when diesel fuel is stored in8t. the fuel reacts with the galvanizedfinish causing powdery particles to form.These particles soon clog the fuel filterson a diesel engine. Use steel tanks toavoid this problem

3 Don't use a tank formerly used forgasoline to store diesel fuel. Fine rust anddirt particles that settled out of gasolineand accumulated on the bottom of thetank. mix readily with diesel fuel and mayremain suspended in it until drawn fromthe tank

4 Don't let the suction pipe to the fuel pumpextend to the bottom'of the storage tank.This permits the pump to pick up waterand sediment that has settled out of thefuel The end of the pipe should be threeor lour inches from the bottom If possible.slope the tank away from the pipe oroutlet valve

5 Always drain the storage tank beforerefilling and clean the tank twice a yearotherwise the dirt and water residue mayrise high enough to be drawn out with thefuel (Figure 7-122)

Preventing Gum Deposits

Diesel fuel. like gasoline. contains a guminhibitor which retards the formation of gumand varnish for about three months Keepingaboveground tanks shaded will help to limitgum deposits.

Diesel fuel may be stored longer thangasoline: while gasoline should not be storedlonger than 30 days. diesel fuel may be keptfor about three months.

Safety

Although diesel luel is safer than gasoline.the safety precautions that apply to gasolineshould also apply to diesel fuel

PITCHERPUMP

(7-123)USING HAND PUMP 10 CLEAN

DIRT AND WATER FROMUNDERGROUND STORAGE TANK .

P.

coorti, of John Deem Ltd

SEDIMENT, WATERAND FUEL

1 DRAIH SEDIMEHT, WATER ANDFUEL FROM TANK

(7-122)

WATER SEDIMENTCourtesy of John Deere Ltd

2 FLUSH TANK WITH CLEANDIESEL FUEL

87

ENGINES 7:77

STORING LPG

Since LPG is stored in pressurized tanks.there are no problems in maintaining thequality of the fuel. nor problems with the fuelevaporating. Also the fuel will not changechemically. during storage. Therefore. LPGcan be stored for as long as necessary.

Safety With LPG

1 Remember that LPG is always underpressure and the fuel supply componentsmust be leak proof

2 Never smoke or use any flame near thefuel

3 Fill holes and low spots in the vicinity ofthe storage Gas fumes that leak from thelank or escapes while filling the machineare heavier than air. The fumes will ac-cumulate in low spots and become a firehazard

Large storage tanks for LPG like thosegasoline ano diesel fuel have to be located ata safe distance from buildings and from otherfuel tanks. In Figure 7.124 note the postsprotecting the pump and hose connections.

20'

MINIMUMDISTANCE

FROM OTHERFUEL. STORAGE

POSTS

(Prated Tank mud PumpFrom Acestlental Bumpata)

\FUEI. PUMP

(7-124) SAFE LOCATION OF LP-GAS STORAGE TANKS IN RELATION TOBUILDINGS AND OTHER FUEL STORAGE

88

\U V.....if

COls nosy 01 J.11:1 Deere Ltd

7:78 ENGINES

PREVENTIVE MAINTENANCE SERVICE OFFUEL SYSTEMS

DAILY WALK AROUND CHECKS

The following checks on the fuel systemwould be made as part of the daily walkaround check and at any time that scheduledmaintenance is done on the fuel system

1 Look for leaks in fuel lines. in the tank. atconnections and generally throughout thesystem Also check for damaged or kinkedfuel lines.

2 Check for water or dirt accumulation inthe primary filter glass bowl (if equipped)and clean the bowl if contaminants arefound On primary filters that don't have aglass bowl. open the drain momentarily tocheck for water or dirt

3 Momentarily open the fuel tank drain tocheck for contamination

4 Remove the fuel tank filter cap ^lean thecap and the area around it

CHANGING FUEL FILTERS

Fuel filters are changed at intervals specifiedby the manufacturer The iNo main types oftitter elements are

1 cartridge filters installed in a case orhousing

2 spin dn. Irow away filters

tAinter traps with washable elements are alsoused on sow.- s _ ;stems

3elow are good practices when cha...4ingfilters These practices apply to ffIters for bothdiesel and gasoline fuel syste

1 Always be aware of potential fire hazardswhen working on fuel systems especially.vith gasoline anrt take the necessnryprecautions

i II me system nas a shut -Ott on the wettanlasi or fuel line close it beforeremoving the filter

3 Since clear linas aro of utmost im-portance when working fuel sys'4emsfpaitic Wady on Jiesels) thoroughly cleanthe entire area around a filter beforeremoving ii Also clean the inside of thenousing on cartridge briers. and makesure that thP gasket sealing surface onspin on filters is absolutely clean

4. Always install new gaskets.

5 On diesel fuel systems. fill new filter car-tridges or filter housings with fuel beforeinstalling them: this will lessen thechance of air oiling into the system andmaking the engine difficult to start. Dieselfuel systems must be completely free ofair to function properly

6 Bleed the fuel system of air. Bleeding isdescribed later in this section

8:3

7 After installing the filler. start the enginemakingabsolutely sure that there are noleaks

ENGINES 7:79

Figures 7-124, 7-125, 7-126 give examples oftypical fuel filter changing procedures takenfrom service manuals.

Water Trap With Washable Parts(Figure 7-124)

FUEL SYSTEM FILTERS Service When Fuel Pressure Gauge Registers OUTwith Engine Running.

Primary Fuel Filter

1)ALLELIEFAMP`

,paiww--

I Close fuel supply valve 2 Remove bowl and element

Throw Away Filter (FigureFinal Fuel Filter

cr,

7.125)

(7-124)

Courtesy ofCaterpillar Tractor Co

3 Wash element and bowl in cleankerosene

4 Install elemen and bowl

5 Open fuel valve and start engine

If Net pressure gaircie still registersOUT change final luel Met

'u

(7-125)

1 Coortrmy of(...arerplioar tr.octor rLo

fidagmog.

close fuoi supply valve and 2 Clean filter base gasket surfacerPrnove filter Lubricate new fillet gasket with

dean beset fuel

I

3 Install new filter Tighten tilleruntil gasket surface conta:tsbase then tighten additional 1.2turn

90

4 Open fuel 'valve andprime fuel system

5 Start engine rind checktoo leaks

7:80 ENGINES

Cartridge Filter (Figur& 7-126)

Remove drain plug from bottom of filtercase and dram contents

2 Loosen bolt at top of fuel filter Take outdirty element. clean filter case and installa new element.

(7-127) Priming Fuel System

. senod.1

I Move governor control to offposition Open vent valve.

(7476) INSTALLING 11EPLACSABLE FUELFILTER ELEMENTechotesv Cummins Engine Co

3 Fill filter case with clean fuel to aid infaster pick-up of fuel. Install a new gasketin filter head and assemble case andelement T'ghlen center bolt to specifiedtorque

Bleedirtra A Diesel System

Whenever hrixfs are aesconnected. a fuel pumpis changed or new filter(s) are installed, thefuel system 'III venerally have to be bled orpurged of air Bleeding is sometimes reterredto as priming

Some fuel systems are easier to bleed thanothers Cranking rle engine will purge the airon one system. whereas another system willrequire loosening the injector lines or filterbleeders and then cranking :he cog'- a. Athird type of system is eouipped with a handpump that must be activated to prime the fLelsystair Operating instructions for such apuv.'p are given in Figure 7-127

-*-tiO Mr

2 Unlock "riming pump plungerand operate pump until. .

3 -low of fuel flam drain line isfree of air bubbles Lock pumppiunger and close vent valveColinew ol Tractor Co

91

ENGINES 7:81

Once the pump has tied the system. start theengine The ungine may run rough for a littlewhile until all the air is gone

SERVICING THE FUEL STRAINER INA LPG FUEL SYSTF.11A

If the fuel strainer frosts up. its filter elementis probably clogged and needs cleaningBefore attempting to clean the strainer. makesure both withdrawal valves are closed, theengine is cold. and the lines and strainer areemptied of gas To clean the strainer. forstremove the dram plug and chaan out foreignmatter Follow service manual instruc...ons onblowing out the strainer and cleaning thestrainer parts

A failed solenoid in the strainer is inoica'oedwhen the ignition is turned on and gas fails toflow to the converter The prob'em is likely asticking valve plunger.

1:82 ENGINES

QUESTIONS FUEL AND FUEL SYSTEMS

1 List the three basic parts of a gasolinefuel system.

2 Besides metering the fuel a carburetor

(a) atmoizes the fuel

(b) mixes fuel and air in the proper ratio

(c) distributes this fuel-air mixture in tothe manifold

(d) all of the above

3. A carburetor works on the basic prin-ciple of:

(a)

(b)

(C)

(d)

difference in powerdifference in pressuredifference in speedall of the above

A choke valve is required en a carburetorto

(a) increase the power when the engineis hot

(h) increase the power when the engineis cold

(c) clean out the mixture during coldstarts

(d) give a richer mixture for cold starts

5 LF.:..5 is made up of -._.. or a mixture of the Iwo

6 LPG will only remain a liquid when it is

(a)

(b)

(c)

(d)

stored outsidestored in large containersstored under pressurestored in a heated area

7 What is the basic difference .1 theoperation o! an LPG fuel system and agasoline fuel system?

8. In an LPG fuel system the-changes the liquid gas to a vapor

9 Why is LPG commonly used in suchwarehouse machines as fork lifts'

10. How does a diesel engine's method ofdelivering ;uel to the engine differ fromthat used by a carbureted r solineengine?

11 The function of the injection pump in thediesel fuel system is to:

(a) time the injection and measure ormeter the fuel

(b) pressurize and deliver the fuel toeach cylinder

(c) both (a) and (b) are right.

12. What is the difference between an LPGfuel tank and a gasoline or diesel tank?

13 The degree of filtration of a filler ismeasured in.

(a)

(bi(c)

(d)

Protons

Electrons

Microns

Neutrons

14 When an in-line fuel filter is used in agasoline fuei system. u is usudiiy pidcedhetve, an the.

(a)

(b)

(C)

(d)

gas tank and fuel pumpscarburetor and manifoldfuel pump and air cleanerfuel pump and carburetor

15 The filter in a LPG fuel system serves twopurposes. it strains impurities from 'lefuel and:

(a) pre-heats the fuel

(b) coois the fuel(c) shuts off the fuel when the system is

not operating

(d) stores extra fuel

16 Gave two reasons filtering is so importantin a diesel fuel system

17. A mechanical diaphragm fuel pumpopei ales by an arm that ru is on a cam onthe engine's

(a)

(b)

(c)

(d)

crankshaft

camshaft

water pump shaftrocker shaft

18 True or False? When replacing fuel in-jection lines, any line size or length willdo provided the connections fit properly.

19 Care must be taken not to_______ _ fuel line connectors

43

. . '

ENGINES 7:83

20 How does compression rata relate to thefuel in engine uses?

21 Which of the lollowint, fuels is burned E.tthe hig ,est comprelslon ratio/

'a) gasol.ne

diesel

(c) LPG

27 What does octane rating refer to ingasoline/

23 How does low volatility gasoline effectcold starling/

24 What does the cetane number refer to indiesel fuel/

25 List the two main areas of concern whenstoring fuel

26 How does the color of a fuel tank effectthe loss of gasoline throughevaporation/

27 When gasoline and diesel fuel are storedf Dr long periods of time. they will oxidizeforming deposits. Gasoline should notbe stored for periods overDiesel fuel can be stored up to

28 How can gum deposits be minimized inabove ground diesel fuel tanks?

29 How long should you wait beforedrawing fuel from a newly filled dieseltank or drum/

(a)

(b)

(c)

(d)

5 to 10 minutes3 or 4 hoursovernight24 hours

30 What is the best policy to follow toreduce overnight condensation in amachine s fuel tank?

(a) store the rnachme In a warm place(b) drain the water trap at the beginning

and end of each shift(c) fill the tank at the end of each shift

or day(d) sill the tank before it runs out

31 True or False/ Galvanized tanks aresuitable for storing diesel fuel/

32 What advantage does LPG have overgasoline and diesel with respect tostoring?

33. How far should a pump intake pipe befrom the bottom of a fuel storage tank/Why/

34. Briefly list items that should be checkedduring a daily p.m. of the machine's fuelsystem.

35 To aid in starting a diesel engine after afuel filter change it is a good practice to:

(a) change the filter quickly(b) don't shut the engine off while

changing the filter(c) have the fuel tank full before

changing the filter(d) fill the new filter with fuel before in-

stalling it

36. Bleeding or priming a diesel fuel systemIS necessary to remove all the

in the fuel system after fuellines have been disconnected or a pumpOr filter changed.

37. An obvious sign of a clogged filter on anLPG fuel system is the:

(a)

(b)

(c)

(d)

engine is hard to startengine runs roughfuel strainer frosts upengine will miss at high speed

94

7:84 ENGINES

ANSWERS lNTERNAL COMBUSTIONENGINE

1 heat mechanical

2 (a) air

(b) fuel

(c) combustion

3 It's heated

4 In a vaporized state

5 False Oxygen causes the fuel to burn

6 rotary

7 id) intake. compression. power. andexhaust

8 to) cycle

9 it>) I -Head

l^ in a two stroke cycle engine. the cycle iscompleted during one revolution of thecrankshaft The piston makes twostrokes, one up and one down. In a fourstroke cycle engine, the cycle is com-pleted during two revolutions of thecrankshaft The piston makes fourstrokes. two up and two down.

11 water air

12 1 gasoline

2 diesel

3 LPG

13 In a gasoline engine fuel and air aremixed in the carburetor and then sent tothe combustion chamber where the mix-ture is compressed and ignited by aspark plug In a diesel engine air is com-pressed in the combustion chamber andthen injected with fuel. The heal of thecompressed air ignites the fuel.

14 To raise the temperature high enough toignite the fuel without a spark.

95

-9

1

ENGINES 7 :85

ANSWERS COOLING SYSTEM 22. 1. Make sure inlet and outlet valves are

1. Prevents overheating of the engine. opened.

Regulates temperatures at best level for 2 Check all hoses. fittings and con-engine operation. nections for leaks.

2. False. 3. Check. and top-up the coolant level.

.3. Allows for rapid warming at start-up. 23 (c) hydrometer.

4 .. heat exchager ... 24. False.

5. (c) Convection. 25. (b) relieve all belt tension.

6. To circulate the water throughout the 26. (a) replace all as a set.cooling system. 27. 7/16" for one foot. and so half of that

7. thermostat. again for one and a half feet.. .

8. True.

9. Blower fans are used on slow movingmachines because there L. a possibilityof harmful materials being drawn into theradiator with rei auction Ian.

10. (b) to increase fan efficieue:y.

11. False.

12. (d) closed by air pressure and openedby spring pressure.

13. Softens the water (i.e.. removes thecorrosives) and removes the dirt.

14. True. ... corrosive inhibitors.

15. A special element that is compatible withthe anti-freeze needs to be used in thefilter.

16. Leakage.

t7 ... cold

18. 1 They don't give a permanent repair.

2. They will ultimately cause pluggingof the radiator,

19. Accumulation of foreign material in thecore air passages. Regularly check andblow out the radiator with water or airpressure.

20. Cracked or swollen.

21. 1 Condition.

2. Alignment.

3. Tension.

7/16 + 31I2 = 101/2 or approximately16 16

10"=

5"816

96

It

7:86 ENGINES

ANSWERS LUBRICATION SYSTEM

1. .... friction ... heat.

2 True.

3. A maximum pressure-relief valve.

4. (b) flit flow end bypass.

5. Pleated paper filter.

6. (d) crankcase.

7. (a) bearings.

8. The filter's bypass valve opens.

9 If the cooler becomes clogged or there istoo much internal resistance within thecooler on a cold start-up. the pressuredifferential valve opens allowing oil tostill reach the bearings.

10. If the blow-by gases in the pan are notvented. they will build pressure andcause the front and rear crankshaft sealsto leak. Also. if not vented the blow-bygases would contaminate the oil.

11 Base stock oil fortified with additives toprovide the required performance level

12. False. Each type of oil with its additivesis right for the operating conditions it isdesigned for.

13. .. viscosity . .. thicker

14 "S" Gasoline engines.'C" Diesel engines

15 Moderate duty diesel and gasoline ser-vice.

16. Tree.

17. It refers to laboratory analysis of used oilto determine the types and amounts ofworr. metals In the oil.

18. (c) 125 to 250 hours.

19. The condition of the internal parts thatthe oil lubricates.

20 So that contaminants will mix with the oiland be drained out with it.

21 When it becomes contaminated witheither fuel. coolant. or metal chips.

97

ENGINES 7:87

ANSWERS AIR INDUCTIONSYSTEM

1 1 Naturally aspirated. and naturallyaspirated and scavenge blown.

2 Turbo charged

3 Turbo charged and after cooled

2 A naturally aspirated engine uses no aidsto get ail into and out of the engine. Thescavenge blown engine has an enginedriven air pump that forces fresh air intothe cylinders and drives the exhaustgases out.

3 (c) exhaust driven turbine

4 By compressing the air.

5 When operating under full load.

8 (b) cool the inlet air belore it enters theengine

7 Dry element cleaners. pre-cleaners. oilbath cleaners

8 False

9 The vanes create a twist or cyclonicmovement in the air which throws thedust and dirt particles outward and downinto a removeable dust cup. The air thenpasses through the air filter to be furl; ercleaned

10 It reverses direction causing most of thedirt to become trapped by the oil and set-tle out in the sump

11 (c) A red band is visible on the in-dicator

12 Oil from an overfilled cup can be drawninto the engine causing it to run away

13 1 Use caution when working around arunr.ng engine with an open intakebec 'use rags. loose clothing. etc.car be drawn into the intake.

2 Never leave an open intake on astopped engine Cover it withsomething hard such as plywood.

14 When the restriction indicator indicatesthe need, or at the intervals recom-mended by manufacturers. More often inseverely dusty conditions.

15 The steam will only force the dirt to thecenter of the element

16 False

17. The same oil as is used in the engine.

18 (c) Lint and other contaminants appearon the underside of the element.

98

7:66 ENGINES

ANSWERS EXHAUST SYSTEM

1. (c) muffle engine noise.

2. (d) a. b and c are all correct.

3. (a) 6 to 8.

4. Sharp bends cause too much restriction.

5 Carbon monoxide can find its way intothe cab.

6. Ensure that there is adequate ventilationfor the deadly exhaust gas, carbonmonoxide.

7. By running your hand a few inches abovethe pipe.

99

ENGINES 7:89

ANSWERS - FUEL AND FUEL SYSTEMS

1. fuel tankfuel pump

carburetor

2. (d) all of the above.

3. difference in pressure.

4. ($1) give a richer mixture for cold starts.

5. .. . propane. butane.

6. (c) stored under pressure

7. vaporizes before it reaches the car-bu;etor. whereas gasoline is vaporized inthe carburetor.

8. .. . converter ..

9. It burns cleaner than the other two fuels:its exhaust contains less carbonmonoxide.

10. A diesel engine injects fuel directly intoeach cylinder. A gasoline engine deliversa mixture of fuel and air to the com-bustion chambers.

11. (c) both (a) and (1)1 are right

12. LPG tanks must be heavier and strongerbecause the fuel is stored underpressure.

13. (c) Microns.

14. (d) fuel pump and carburetor.

15. shuts off the fuel when the system is notoperating.

16 1 the fuel tends to be impure.2. injection parts are precision made

and dirty fuel will damage them.

17. (b) camshaft.

18. False.

19. ... overtighten ...

20. Each fuel has its limits as to how much itcan be compressed and still burnproperly.

21. (b) diesel.

22. Octane is a measure of anti-knockproperties. The higher the octane ratingthe less tendency the fuel has to knock.

23. It does not vaporize readily and couldcause hard starting.

24. Cetane number measures the ignitabilityof the fuel; the higher the cetane numberthe shorter the period.

25 1. protection of fuel quality.2. safety

26. A light-colored tank reflects sunlight.Thus the tank is cooler and not as muchfuel evaporates.

27. ... gum one month threemonths.

28. Paint the tank a light color. and shadethe tank.

29. (d) 24 hours.

30. (c) fill the tank at end of each shift orday.

31. False.

32. LPG is stored in a pressurized tank andtherefore has no loss due to evaporationand no deterioration with time.

33. three to four inches so that the dirt andwater that have settled don't get drawnup witn the fuel.

34. 1. fuel lines for leaks and damage.2. water accumulation in water trap or

primary filter.3. momentarily open the tank drain to

check for contaminants.4. clean the tank breather.

35. (d) fill the new filter with fuel before in-stalling it.

36. air ...37. (c) fuel strainer frosts up.

7:90 ENGINES

TASKS ENGINES

PREVENTIVE MAINTENANCE SERVICE ONCOCLING SYSTEMS

DAILY AND ROUTINE MAINTENANCECHECK

1. Check any liquid cooling system for leaks.for the condition of hoses. the tension ofbelt(s). the condition and operation of tl'eshutters and fan. for dirt accumulation andpossible air flow restriction of radiator.and for the level and condition of coolantPerform any minor repairs such as ad-justing. tightening. cleaning. or report anysuspected unsafe operating conditions toa journeyperson.

SCHEDULED MAINTENANCE

1. Using the correct tools and proceduresstated in the service manual.

(a) Drain the coolant.

(b) Reverse-flush the radiatorengine block.

(c) Remove, test. install thermostat.(d) Install new filter element (if equip-

ped).

(e) Fill the system with water/anti-freezesolution and run the engine until thesystem is up to operating tem-perature. Check the coolant level.and top up if low. Check the coolingsystem to ensure it has no leaks.

2. Using an anti-freeze hydrometer. test thecoolant to make certain there is sufficientrange against freezing of coolant for yourregion.

PREVENTIVE MAINTENANCE SERVICE ONLUBRICATION SYSTEMS

DAILY AND ROUTINE MAINTENANCECHECKS

1. Check the oil for water or fuel con-tamination Report if contamination isfound.

2 Check the oil level. and if low. top it upwith the correct type of oil.

3 Check the lubrication system for leaks. forthe condition of lines or hoses. and checkthe operation of breathers and vents. Doany minor repairs. or report suspectedunsafe operating conditions


Using the correct tools and procedures statedin the service manual:

1. Drain the oil sump and filters.

and 2 Remove and clean the filler housings. andcorrectly install new filters. being carefulto keep filters and gaskets clean.

3 Insert and tighten drain plugs. and fill thesump with the correct types and amount ofoil.

4 Start and run the engine and check thecomplete system to ensure there are noleaks

101

5 Stop the engine. wait for five minutes andrecheck the oil level. adding oil Ifrequired.

SERVICE REPAIR ON LUBRICATIONSYSTEMS

When oil contamination is found in a machineOr an internal component has failed. performflushing procedures

1. Drain the complete system.

2 Remove, flush and re-install the oil coolerand connecting lines. and clean the filterhousings.

3 Install the flushing oil, run the engine.stop and drain the system

4 Repeat normal filler installation. oil fill-upand running and checking procedures.

ENGINES 7:91

PREVENTIVE MAINTENANCE ONAIR INDUCTION SYSTEM

DAILY AND ROUTINE MAINTENANCECHECKS

t. Practice safely when working aroundopen air inlets on a running enginerags. loose clothing. etc.. can be suckedinto the manifold

Practice cleanliness when working on airinduction systems all pipes. ducting.lifter housings must be absolutely cleanon assembly

2. Run the engine and check the air cleanerrestriction indicator (if equipped). Stop theengine, carefully inspect all air inductionpiping and replace any cracked ordamaged sections, remembering tolighten all clamps.

3 Inspect the turbo charger and/or blowerfor evidence of nil leaks. and if any arefound make minor repairs, With theengine running check the turbo chargerand/or blower for excessive noise. Reportif a problem is suspected.


Consulting the service manual. do preventivemaintenance service on pre-cleaner and aircleaner(s):

t. Oil bath type thoroughly wash the oilcup and the element and change the oil,

2. Dry type disassemble the cleaner.clean the container housing. clean orreplace the filter element and reassemble.

EXHAUST SYSTEMS

SAFETY

t. Practice safely when removing and in-stalling exhaust parts. If the engine haslust been running the parts will be hot.Exhaust parts. especially on largemachines, can by heavy.

ROUTINE MAINTENANCE CHECK

1 Completely inspect an exhaust system forleaks and for loose components and makeany necessary minor repairs.

SERVICE REPAIR

1. Get experience installing exhaust sy- Icomponents such as mufflers. piping andmounts. When installation is complete runthe engine and check to ensure there areno leaks.

FUEL SYSTEM

SAFETY

1. Practice safety with regard to fuel com-bustibility. Practice absolute cleanlinesswhen working with fuel and fuel systems.

ROUTINE MAINTENANCE CHECK

1. Visually inspect a complete fuel systemfrom the tank to the engine (to includeshut-off valve. lines or hoses. filters, trans-fer pump and return line) for leaks ordamagq. Do any minor repairs and/orreport unsafe operating conditions.


1. On a vehicle equipped with a dieselengine:

(a) Open the drain on the fuel supplytank sufficiently to remove any ac-cumulation of water and dirt.

(b) Check the water trap and drain ifrequired.

(c) Install new fuel filter(s).

(d) Bleed the system to remove air.

(d) Start the engine and check to ensurethere are no leaks.

102

BASIC ELECTRICITY 8:1

FUNCTIONS OF ELECTRICITYIN HEAVY DUTY VEHICLES

Electricity performs many important functionsin the Heavy Duty Vehicle and Equipmentfield. Electricity is used to:

1 Supply power to turn the eagine over forstarting.

2. Provide the spark ignition for each cylin-der in a gasoline engine.

3. Provide power for all the lights on avehicle:

head lightstail lightsstop lightssignal lightsdash warning lightscab light

4. Operate the horn.

5. Supply power for electrical gauges suchas:

fuel level gaugeoil pressure gaugetemperature gauge

6. Power electrical accessories such as.

radioheaterair conditionerwipers

7 Power many varieties of magneticallyoperated controls such as:

starter switchestransmission shift controlshydraulic valves

8. Supply power to maintain the batterycharge level.

ELECTRON THEORY

This block begins with a discussion of theElectron Theory. the most widely accepted ex-planation of electricity.

Before you can understand what electricity is.you first have to have a bases picture of enatom. All elements are made of billions ofatoms. Atoms have particles called electronsin orbit around a core of protons; the numberof electrons is the same as the number ofprotons. Electrons have a negative (-)charge. while protons have a positive (+)charge. The siinplest atom is hydrogen havinga single electron in orbit around a singleproton. Uranium is one of the most complexelements with 92 electrons and 92 protons.Models of the two atoms are shown in Figure8-1.

Kuonoll

.e0446,,

PROTON

0Pli ELECTRON 0

4NAre:04.t'''`

HYDROGEN ATOM

7

(8-1)URANIUM ATOM

Counesy N John Deere Ltd

In their natural state atoms have an equalnumber of positive protons alid negative elec-trons. The atoms are therefore electricallyneutral. This neutral state, however can bealtered. If an electron is attracted away froman atom. the atom will have a positive chargesince it will have one more proton than elec-tron. Or vice versa, if an electron is added toan atom, the atom will have a negative chargebecause it has one extra electron.

The element copper is widely used in elec-trical systems because it is a good conductorof electricity. The reason for copper's goodconductivity can be explained by looking at adiagram of its atom (Figure 8-2)

0 :111k

f

is A.1(8-2) r

STRUCTURE OF - Courtesy 01A COPPER ATOM

.John Deere Ltd

COPPER ATOM

104

8:2 BASIC ELECTRICITY

The copper atom contains 29 electronsdistributed in four separate shells or rings.Notice that the outer ring has only one elec-tron; it is this one electron that makes coppera good conductor of electricity. Becausethere is only one electron in its outer orbitwhere many could theoretically fit, and be-cause this electron is quit t a distance fromthe positively charged nucleus that attracts orbinds the clectrons to the atom, the copperatom does not hold onto the electron toostrongly. Therefore. copper atoms have thetendency to both give up or accept an elec-tron in its outer orbit.

Consider what happens in a copper wirewhere there are a string of copper atoms witha positively charged atom at one end (i.e., theatom has no electron in its outer ring) and anatom with negative charges at the other end(i.e.. the atom has an extra electron, that istwo electrons in its outer ring). Since positivecharges attract negative charges, thepositively charged first atom will attract thenegatively charged electron in the outer orbitof the second atom.

This electron will jump over to the positivelycharged atom giving the atom the electron itwas missing in its outer ring (Figure 8-3).

The first atom has achieved a neutral state.out now the second atom is left with no elec-tron in its outer ring, and so it has a positivecharge Its positive charge attracts thenegatively charged electron from the thirdatom. The third atom will attract an electronfrom the fourth, the fourth from the fifth, andso on The second to last atom will take anelectron from the last atom which beingnegatively charged has two electrons in itsouter orbit. Now all the atoms along the rowhave the right number of electrons in theouter ring. In the process electrons havepassed from atom to atom. drawn to thepositive end aicng the line of atoms from thenegative end. Looked at in terms of thedirection that the electrons move, a flow ofelectrons has taken place from the negativeend to the positive end. This last statement is

the definition of electricity. Electricity IS theflow of electrons from atom to atom in a con-ductor in the direction of negative to positive.

Of course. the above description of electronflow is simplified On an actual cross sectionr T a copper wire there are billions of copperatoms and so billions of electrons will bepassing amongst them. These electrons willcontinue to flow as long as the positive andnegative charges are maintained at each endof the wire By adding new electrons to thenegative end of the wire and by taking elec-trons away from the positive end of the wire asthey get there (this is what a battery does) theelectrons or electric current will flow in-definitely.

A basic idea of electricity is by no means easyto grasp Electricity is spoken of as flowing ina wire. just as water is said to flow in a hose.But water is a real substance that you can seeand touch Elect icity on the other hand, is nota substance You cannot point to a materialand say that is electricity Rather, electricity isa force of attraction that causes conductorelectrons to move and thus to have energy.Having no substance itself, the force of elec-tricity uses the substance of the conductor tocarry its energy. Like the wind, electricity canbe felt. the results of its energy can be seen,but electricity. itself, can't be looked at andexamined.

BASIC FACTORS OF ELECTRICITY

There are three basic factors of electricity:

currentvoltageresistance

Current

The flow of electrons through a conductor iscalled an electric current and is measured inamperes. One ampere is a current of 6.28billion billion electrons passing a given pointin the conductor in one second. The currentor amperage of a circuit, then, is a measure ofhow many electrons are flowing in the circuit.

Voltage

One end of a current carrying conductor hasa positive charge, and the other end anegative charge. The strength of the chargedepends on how many extra electrons thereare at the negative end or conversely howmany electrons are missing at the positive

105


end. The greater the number of extra elec-trons (or missing electrons) the greater thecharge or the difference between the twoends. Voltage is the term used :43 measure thestrength or force of the attraction between thepositive and negative charges. Of course, thestronger the charges at eitner end the greaterwill be their force of attraction for oneanother, or their voltage.

Voltage is the force that causes a flow ofcurrent in a conductor. Voltage can begenerated by a storage battery or by agenerator. Note that voltage is a potentialforce and can exist even when there is nocurrent flow. For example, a storage batterycan have a potential of 12 volts between itspositive and negative terminals, and thispotertial exists even though no conductorsare connected to the posts. Voltage, alsocalled potential differences is stored in a bat-tery in the form of a surplus of electrons at thenegative post and a corresponding lack ofelectrons at the positive post. When a con-ductor is attached to the posts the surpluselectrons at the negative post will travel to thepositive post. As the electrons arrive, thepositive post transfers them back through thebattery to the negative post, maintaining thedifference between the posts.

Resistance

All conductors offer some resistance to theflow of current. Resistance is caused by:

1. Each atom resisting the removal of anelectron due to its attraction toward thecore.

2. Collisions of countless electrons andatoms as the electrons move through theconductor. The amount of resistancedepends on the material of the conductor,its thickness or diameter, and its length.

In a circuit the resistors are the electrical ac-cessories, the lights, the electrical motors, thegauges, etc.

The basic unit of resistance is the ohm. Oneohm is the resistance that will allow one am-pere to flow when the potential is one volt.The symbol for ohms is -n- .

ELECTRIC CIRCUIT VERSUS A HYDRAULIC CIRCUIT

The chart below compares an electrical circuit with a hydraulic circuit.

ElementCompared

HydraulicCircuit

ElectricCircuit

circuitfluid flows in hydraulic

lines to operate hydrauliccylinders

electrons flow in copperwires to operate electric

accessories

source of energy pump battery, generator

flow rate gallOnS per minute amperes (electrons persecond) (I)

working energy pressure voltage (E)

resistance friction loss ohm (R)

106

1J -


BASIC ELECTRICAL CIRCUIT

A basic electrical circuit has three parts(Figure 8-4):

voltage source such as a batteryresistor such as a light bulba conductor such as copper wire toconnect the circuit

-T

CONDUCTOR

BATTERY RESISTOR


An ammeter measures the current in an elec-trical circuit, a voltmeter the volts. and anohmmeter the ohms (Figure 8-5).

AMMETER

BATTERYRESISTOR

VOLTMETER

(8-5) Courtesy of John Deere Ltd

Knowing the basic information about an elec-trical circuit means knowing the volts. ampsand ohms in the circuit. An electric& formulacalled Ohm's Law relates these three quan-tities:

E (volts) = I (amps) x R (resistance)

Because there are three quantities. there arethree formulas'

E = IRE

I =R

R

If you know any two of the quantities you canfind the third by applying the above formulas.For example. if you know the amps (I) and theohms (A). multiplying the amps times theohms will give the volts (E). Or if you know theohms (R) and the volts (E), dividing the voltsby the ohms will give the amps. An easy wayto remember these formulas is by using thetriangle in Figure 8-6 (A similar triangle wasused in Hydraulics with pressure. force andarea.)

(8-6)

Look at the triangle, as you read these for-

mulas E = IA, I R = to see how thetriangle works. Ft 1

Sample Problems

1 A circuit has 12 volts and a resistance ofthree ohms What is its amperage?

Solution:

You know the volts and the ohms so usethe formula for the amps:

I =

1I =

2

3

or amps =volts

ohms

four amps.

2 Whal voltage is needed to send a five ampcurrent through a 8 7 ohm resistor?

Solution:

You know the amps and the ohm so usethe formula for the volts'

E = IR or volts = amps x resistance

E = 5 x 8.7

In 43.5 volts

ELECTRICAL TERM DEFINITIONS

Conductor Any substance that is a goodtransmitter of electricity All metals and manyliquids are considered conductors. In generalany substance composed of atoms with lessthan four electrons in its outer orbit is a con-ductor.

Insulator Opposite to a conductor. Anysubstance that is a poor transmitter of elec-tncity. Insulators usually have more than four

107


electrons in their outer ring. Glass, plastic.mica, bakelite and rubber are examples of in-sulators.

Closed Circuit A closed circuit has (Figure8-7):

1. a circuit path with no breaks in it.

2. a resistor to control the amount of currentflow.

(8-7)Open Circuit in an open circuit the circuitpath is opened either by a switch or by abroken wire. In Figure 8-8 the current can'treach the light because its path is broken. Alllight circuits in homes are open circuits whenthe switch is in the off position.

(8-8)

Short Circuit A short circuit occurs in a cir-cuit when the current can take a shortercourse, bypassing the route it was supposedto take. In Figure 8-9 the lamp won't light be-cause the current is short-circuited.

(8-9)

CONDUCTOR CREATING ASHORT CIRCUIT

In a short circuit there is little resistance sincethe current is not travelling through theresistor (the light). Looking at the formula

voltsamps = , if the ohms. the quantity youohms

are dividing by. is very small because of theshort circuit, it means that the amps will belarge. So large. in fact, that the conductorwould be burned up and destroyed.

DIRECT CURRENT ANDALTERNATING CURRENT

Direct current (DC) travels in one directiononly whereas alternating current (AC) con-stantly reverses direction. Batteries produceDC and therefore all the electrical ac-cessories used on heavy duty vehiclesoperate on DC.

WATTS

Watts measure electrical power; watts arefound by multiplying volts x amps. In a simpleclosed circuit having 12 volts and 2 amps. thenumber of watts is 12 x 2 = 24. The circuit isconsuming 24 watts of electrical power. Theamount of electrical power is usually stated inkilowatts (kw): 1000 watts = 1 kilowatt.

108


BASIC ELECTRICAL SYMBOLS

+ POSITIVE --0- CONNECTION

-'"' NEGATIVE

F--- BATTERY

-4AAr-- RESISTANCE OR LOAD

_L.. GROUND-..

o !GI; TION COIL

Cr-CI DISTRIBUTOR CONTACTS

--I CONDENSER OR CAPACITOR

--> '.."--SPARK GAP

(8.10)

109

( CONDUCTORCROSSOVER

DC GENERATOR

DC MOTOR

OR AC GENERATOR

--95:634\- INDUCTOR (SOLENOID)

---11100.41-SWITCH (OPEN)

(6) LIGHT BULB

-011----DIODE (ONE-WAY)


TYPES OF ELECTRICAL CIRCUITS

There are three types of circuits (Figure 8-11)

I I

SERIES

SERIES several resistorsconnected so that currentcan take only one path

Series Circuits

(8-11)

PARALLEL

PARALLEL: more than onepath for the current to flow.Resistors are side by sideand provide separate routesfor the current.

A basic series circuit may have a three-ohm(3 .a) resistor connected to a 12-volt battery(Figure 8-12).

12-1+T

4 AMPS1

3S1


To find the current. use Ohm's Law, where

I = E 12 4 amperes. or 4 amps.R 3

The series circuit in Figure 8-13 has a twochm resistor and a lour ohm resistor con-nected to a 12 volt battery.

(8-13)

COurt03Y of John Deere Ltd8 VOLTS


+ISERIES PARALLEL

SERIES PARALLEL: hassome resistors connected inseries and some connectedin parallel.

In a series circuit. the total circuit resistanceis equal to the sum of all the resistors. In thiscircuit, the total circuit resistance is 4 J 2 = 6ohms. The current from Ohm's Law is:

12 ...1 = E= = c amperes.

R 6

Voltage across the two-ohm resistor can befigured using Ohm's Law: E -= IR = 2 x 2 = 4volts. For the four-ohm resistor, E = 2 x 4 =8volts. These values are called the voltagedrops. and the sum of all voltage drops in thecircuit must equal the source voltage. or 4 + 8= 12 volts. An ammeter connected in the cir-cuit will read two amps, and a voltmeter con-nected across each resistor will read fourvolts and eight volts.

In summary. series circuits have the followingfeatures:

1. The current through each resistor is thesame. Ohm's Law states that if a circuithas a given amount of volts and ohms.then a set quantity of amps will be drawnthrough the circuit. Since the amps travelonly one path, they are the samethroughout the circuit. Think of thiscurrent travel in terms of the electrontheory. A set number of electrons set outfrom the negative terminal to travel to the

I0


positive terminal. Since they can take onlyone route. the number of electronstraveling (i e . the number of amps) will bethe same at any point in the circuit

2 The voltage drops in a series circuit.Unlike current. voltage is not the samethroughout the circuit When an electronsets out from the negative terminal it has acertain strength of charge or attraction(i e.. volts) for the positive terminal. Butthere are resistors in its path. Theseresistors weaken the electrons force of at-traction because part of their force orstrength is needed to get through theresistor. Thus as the electronprogressively travels through resistorsmore and more of its strength or attractionfor the positive terminal is used up. Over aseries of resistors. so many volts will beused to get the electrons through the firstresistor. so many through the second andso on. the amount of volts used up at eachresistor depending on how large theresistance is. After pushing their waythrough the last resistor they have littlestrength or voltage left. This progressiveconsumption of voltage to get throughresistors is called voltage drop. Since thevoltage drops after each resistor, voltagevaries throughout the circuit Note that thesum of the drops equals the total voltageat source.

Parallel Circuits

1. In a series 4, suit the electrons (or amps)have one path to follow and thus the am-perage is the same throughout the circuitNot so in a parallel circuit. In a parallelcircuit the amps have two or more paths tofollow The parallel circuit in Figure 8.14has two paths for electrons to take

(8-14)

+

Electrons set out from the negative ter-minal. Some of them take the 31L route tothe positive terminal, and some the 612route. (Note the electrons will take thepath of least resistance so that twice asmany will lake the 3 -11 route as will takethe 61L route.) Since the number of elec-trons is split up among the two circuits,the amps will vary at different locations ofthe parallel circuit. The sum of the ampsfrom all the circuits will equal the totalamts of the circuit.

The current through each resistor orbranch of the circuit can be figured usingOhm's Law. For the six-ohm resistor,A 12 ,=E= = z amps.

A 6

For the three-ohm resistor. 1 =12

= 43

amps. The total current supplied by thebattery is 2 + 4 = 6 amps (Figure 8 -15),

6 AMPS,

4-6 AMPS(8-15)

CourtesY of John Deere Ltd.

The total resistance of the parallel circuitis equal to the voltage divided by the

total current or12-- = 2.n..6

2. In a series circuit voltage drops after eachresistor and therefore full voltage is notpresent at each resistor. The opposite istrue in a parallel circuit: full voltage isavailable at each resistor. Why is . fullvoltage present in parallel circuits?Examine the parallel circuit in Figure 8-16.

t 6.rL

111

(8-16)

3


An electron starts out from the negativeterminal with a 12 volt charge or attractionfor the positive terminal As seen above,some of the electrons will take the routethrough the 6stresistor to get to thepositive terminal and some electrons willtake the route through the 3 ohm resistor.The electron reaching the 6 Aresistor hasa 12 volt attraction because it hasn't gonethrough any other resistors to drop notwill it have to go Through any other ones.The same can bb said of the electronreaching the 3 IL resistor. This electrontoo has a 12 volt attraction because ithasn't gone through nor will it have to gothrough any other resistors.

In summary. parallel circuits have thefollowing features:

(a) The voltage across each resistor isthe same.

(b) The sum of the separate currentsequals the total current in the circuit.

(c) The current through each resistor willbe different if the resistance valuesare different.

Series Parallel Circuits

Series parallel circuits are not commonlyfound on vehicles: therefore. they won't bediscussed here.

COMPARISON OF SERIES ANDPARALLEL CIRCUITS

Both the series and parallel circuits in Figure8-17 have three 4 ohm circuits.

_AM/4n.

4a

X 1348

+I L12V

SERIES

(8-17)

Series Circuit

Resistance: 4 + 4 4. 4 = 12 ohms

Amperage: amps = volts=

12_ = 1 ampohms 12

Power: volts x amps = 12 x 1 = 12 watts

+12V

PARALLEL

Courtesy of John Deere tad

. resistance = 12 ohms: amperage = 1 amp power = 12 watts

Parallel Circuit

voltsAmperage: amps =v_ =

12_ = 3 ampsohms 4 3 amps

3 amps

TOTAL 9 amps

Resistance: equivalent resistance is:

volts 12ohms = = = 1.3 ohms

circuit 1circuit 2circuit 3

Power

Fresistartm = 1.3 ohms:

amps 9

= volts x amps = 12 x 9 = 108 watts

amperage = 9 amps power = 108 watts I

112


In Summary:

Series circuit high resistance. low amperage. low power (wattage)

Parallel circuit low resistance. high amperage. high power

Most circuits in vehicles are parallel circuits.

MAGNETISM

Electricity is closely related to magnetism.The effects of magnetism were first observedwhen naturally found fragments of iron orecalled lodestone were seen to attract otherpieces of iron (Figure 8-18).

(8-18) MAGNETISMCourtesy of John Deere Ltd

it was further discovered that a long piece oflodestone iron, ore. when suspended in air,would align itself so that one end alwayspointed toward the North Pole of the earth(Figure 8-18). This end of the iron bar wascalled the north pole, or N pole, and the otherend the south or S pole. Such a piece of ironore was called a bar magnet. The bar magnetis the basic part of the compass, anavigational aid that has been used for over1.000 years.

Magnetic Fields

Further study of the bar magnet revealed thatan attractive force was exerted upon bits ofiron or iron filings even though the iron filingswere some distance away from the barmagnet It was clear that a force existed in thespace close to the bar magnet This spacearound the magnet to which iron filings are at-tracted is called the field of force or magneticheld

The theory of magnetic lines of force can bedramatized by sprinkling iron filings on apiece of paper resting on top of a bar magnet.When the paper is lightly tapped. the ironfilings line up to form a clear pattern aroundthe bar magnet (Figure 8-19).

S POLE

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N POLE

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IRON IRONFILINGS FILINGS

(8-19) MAGNETIC FIELD OF A BAR MAGNETCourtesy of John Deere Lld

The pattern shows that the lines of force areheavily concentrated at the N and S poles ofthe magnet. and then spread into thesurrounding air between the poles. The con-centration or number of lines at each pole isequal, and the attractive force on the ironfilings at each pole is equal. Notice that theforce of attraction on bits of metal is greatestwhere the concentration of magnetic lines isgreatest For a bar magnet. this area is next tothe two poles.

Taking two bar magnets and experimentingwith their polarities, you will find that unlikepoles. north and south, are attracted to oneanother while like poles, north and north orsouth and south. repel one another. The forceof attraction gets stronger as the two unlikepoles are drawn closer together, andcorrespondingly, the force of repulsion getsstronger as the two like poles are pushedcloser together. Stated briefly this basic lawof magnetism is: unlike poles attract. likepoles repel (Figure 8-20).

UNLIKEPOLESATTRACT

LIKEPOLESREPEL

(8-20) MAGNETIC FORCES BETWEEN POLESOF BAR MAGNETS


113


Just as there are good end poor conductors ofelectricity, so there are good and poormagnetic materials. Iron has good magneticproperties whereas wood, paper, glass, cop-per. zinc are less magnetic.

How Magnets Are Made

An ordinary iron bar can be converted into amagnet in a number of different ways. Onemethod is to stroke the iron with anotherpiece of iron that has already beenmagnetized. The effect of inducingmagnetism into the iron bar is calledmagnetic induction. Another method ofmagnetic induction is simply to place an ironbar in a strong magnetic field (Figure 8-21).

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(8-21) MAGNETIC INDUCTION OF AN IRON BARCourtesy of John Deere Ltd

The lines of force in the field passing throughthe iron bar will cause the bar to become amagnet as long as it is located in the field. Ifthe bar is withdrawn from the field of force,and if its composition is such that it retainssome of its induced magnetism, it is then saidto be permanently magnetized and is called apermanent magnet. Most permanent magnetsare made of hard metals composed of alloys.(Soft metals will not retain much of theirmagnetism.) Some of the more commonmagnetic alloys are nickel-iron andaluminum-nickel-cobalt and magnets usingthe alloys are trade-named ALNICO magnets.Permanent magnets ar9 found in manyshapes, including the horseshoe magnetwhich concentrates the lines of force in asmall area between two poles (Figure 8-22).Horseshoe magnets are widely used in volt-meters and ammeters.

(8-22) FORMING A HORSESHOE MAGNETCourtesy of John Deere Lid

Summary of Magnetism

Every magnet has an N and S pole. anda field of force surrounding it.

Magnetic materials are acted uponwhen located in a field of force.

Unlike poles attract and like polesrepel.

An unmagnetized piece of iron can be-come a magnet through induction.

ELECTROMAGNETISM

An experiment with a compass and a wirecarrying current reveals the connection be-tween electricity and magnetism. When acompass is held over the wire, the needleturns crosswise to the wire (Figure 8-23).Since the only thing known that will attract acompass needle is magnetism, it is obviousthat the.zurrent in the wire creates a magneticfield around the wire.

S

CURRENTCARRYING

(8-23) WIRE

ELECTRIC CURRENT CREATES ITS OWNMAGNETIC FIELD


The nature of the magnetic field around thewire can be seen when a current-carrying wireis run through a piece of cardboard, and ironfilings are sprinkled on the cardboard. Theiron filings align themselves to show a clearpattern of concentric circles around the wire(Figure 8-24).

1

....., S., \( I'... .... 's \ N

i Illtio'-,-% , \ % ,.._ s% , , .

, , , t t ;I i /r , r'"'-

I t, It rt,'1,Mt)tilt 1, , \, , --//1/

\: ,:,_\_:::::::::::-,C:1/"//1% , \ s .. I' / / /

113 DIRECTION OF(8-24) CURRENT FLOW

,=0

r

114

Courtesy of John Deere lid


The circles are more concentrated near thewire than farther away. Although the ironfilings on the cardboard show only the patternin one plane., remember that the concentriccircles extend the entire length of the current -carrying wire.

When a current is travelling in one directionand a compass is placed in the elec-tromagnetic field. the needle aligns itself sothat magnetic lines enter its S pole and leaveits N pole. If the direction of the current ischanged the compass needle reverses itsposition and points in the opposite direction.Thus it can be concluded that:

Electro-magnetic lines have direction, andthey change that direction when thecurrert flow is reversed in the wire.

Points About Electromagnetism

1 The number of lines of force, or strengthof the magnetism. increases as thecurrent through the conductor is in-creased. More current creates a strongerfield. If a compass is moved farther awayfrom the conductor. a point finally isreached where the compass is unaffectedby the field. If the current is then in-creased. the compass needle will be af-fected and will again indicate the direc-tion of the magnetic field (Figure 8-25).

ONE AMPERE

NEEDLEUNAFFECTED

(8 -25)

NEEDLEALIGNED

THREE AMPERESCourtesy of John Deere Ltd

115

When a number of conductors are placedside by side, the magnetic effect is in-creased as the lines from each conductorjoin and surround all the conductors. Theratio of increase can be seen in thefollowing:

Two conductors lying alongside eachother carrying equal currents in thesame direction create a magneticfield equivalent to one conductorcarrying twice the current.

2 If two adjacent parallel conductors arecarrying current in opposite directions,the direction of the field is clockwisearound one conductor and coun-terclockwise around the other. When thetwo wires are placed close together. as inFigure 8-26, you car see that there is aconcentrated field between them becausethe fields from the two wires mergetogether. Since both lines of force are run-ning in the same direction there is astrong field between the conductors. Amuch weaker field exists to the outside ofthe wires.

STRONG FIELD BETWEENCONDUCTORS

CARRYING CURRENT INOPPOSITE DIRECTIONS

(8-26)

CONDUCTORS TEND TOMOVE APART


The strong held has an important effect onthe two conductors in as much as theyhave 4 tendency to move away from oneanother. Putting this observation into ageneral statement current carrying wireswill tend to move out of a strong field andinto a weak field.


3. When two adjacent parallel conductorsare carrying current in the same directiona magnetic field. clockwise in direction,will be formed around each conductor,with the result that the magnetic lines be-tween the conductors oppose each otherin direction. Thus the magnetic field be-tween the conductors is cancelled out.leaving essentially no field in this area(Figure 8-27). The two conductors willthen tend to move toward each other. thatis, from a strong field into a weak one.

....'.., 41I

C");;r"flet)\\*...., i

N.....1t...."4.P .``*--...."MAGNETIC FIELD

BETWEEN CONDUCTORSCANCELS OUT

CONDUCTORS TENDTO MOVE TOGETHER

(8-28) DIRECTION OFCURRENT FLOW

Courtesy of John Deere Lid.

All the lines of force enter the inside of theloop of wire on one side and leave it onthe outside Given the angles of the forcesand the fact that the inside diameter of theconductor is smaller than the outsidediameter. the lines of force are more con-centrated on the inside of the loop than onthe outside. A single loop of wire carrying

(8-27) current is called a basic electromagnet.


In points 2 and 3 above. the magneticfields were from two current carrying con-ductors. The same principle could bededuced using a conductor and amagnetic field from a magnet: the con-ductor would be pushed away from themagnetic field when the conductor's fieldand the magnet's field ran In the samedirection; and conversely the conductorwould be pulled towards the magnet'sfield when the two fields run in oppositedirections. This push and pull reaction be-tween a conductor and a magnet's field isthe basic principle of an electric motor aswill be seen in the discussion of a startingmotor.

4. A straight current-carrying wire whenformed into a single loop still has amagnetic field surrounding it. The lines ofmagnetic force, however. have a differentpattern (Figure 8-28).

Electromagnets

Rather than one loop. an electromagnet has anumber of current carrying loops combinedtogether to make a coil as illustrated in Figure8-29.

(8-29)

CONDUCTOR IN SEVERAL LOOPS MULTIPLIESTHE MAGNETIC FIELD


116


The strength of the resulting magnetic held isthe sum of all the single loop magnetic fieldsadded together With lines of force leaving thecoil at one end and entering at the other. anorth and south pole are formed at the coilends, the same as in a bar magnet. If thecurrent direction through the coil is reversed.the polarity of the coil ends will also reverseThe above core could be called an elec-tromagnet Useable electromagnetics.however, have another -11a, ,t a . .onaround which the iC 3C wrappt(Figure 8-30)

((( /A 'IA` 'a 7I

(8-30)IRON CORE INCREASES FIELD STRENGTH


The strength of the magnetic field at the N andS poles is increased greatly by adding theiron core. The reason for this increase is thatwhile air is a very poor conductor of magneticImes, iron is a very good one. The use of ironin a magnetic path may increase the magneticstrength 2500 times over that of air.

The strength of the magnetic poles in an elec-tromagnet is directly proportional to both ther.umber of turns of wire and tne amount ofcurrent flowing in the coil (Figure 8-31).

1 AMP

4

1000PANS

r""

MIN

10 AMPS

100TURNS

1000 AMPERE TURNS

(8-31)Courtesy or John Deere Ltd

An electromagnet having one ampere flowingthrough 1000 turns, and another elec-tromagnet having 10 amperes flowing throught00 turns will each have a field strength of

117

1000 ampere turns. The attraction onmagnetic materials located in the magneticfield of each of these electromagnets will bethe same.

Summary Of Electromagnetism

-lectricity and magnetism are relatedbecause a magnetic field surrounds aconductor that is carrying current.

-- An electromagnet has a N pole at oneend of the iron core and an S pole atthe other end. much like a bar magnet.

Every magnetic field has a completecircuit that is occupied by its lines offorce.

An electromagnetic field gets strongeras more current flows through its coils

ELECTROMAGNETIC INDUCTION

From the point of view of electricity.something eery important happens when aconductor is moved across a magnetic field: avoltage is induced in the conductor. Thisvoltage is called electromagnetic induction.Electromagnetic induction (i.e.. inducedvoltage) can be observed by doing thefollowing connect a sensitive voltmeter to theends of a straight wire conductor Move thewire conductor across the magnetic field of ahorseshoe magnet As the wire moves acrossthe field the voltmeter will register a smallvoltage (Figure 8-32).

CONDUCTORMOVEMENT

11111.PlieVOLTMETERREADS VOLTAGE

MOVING CONDUCTOR ACROSS MAGNETICFIELD VOLTAGE IS INDUCED

CONDUCTOR (8-32)MOVEMENT

VOLTMETERREADS NOVOLTAGE

MOVING CONDUCTOR PARALLEL TOMAGNETIC FIELD NO VOLTAGE

IS INDUCEDCourtesy of John Deere Ltd


If the wire is moved parallel wtih the lines offorce. no voltage will be induced (Figure 8-32).The conductor must cut across the lines offorce in order to induce a voltage.

Since a conductor cutting across the field hasvoltage, it is a source of electric current. justas a battery is. and must have a positive and anegative end.

In a battery the positive and negative ter-minals are permanent. Electromagnetically in-duced voltage, on the other hand. does nothave permanent polarity; the positive andnegative end can change depending on whichdirection the wire is moved through themagnetic field. Figure 8-33 illustrates thischange in polarity and corresponding changein current flow.

CURRENT FLOW

(8-33) DIRECTION

CURRENT FLOW

Courtesy or John Deere Ltd

In the previous examples. if. instead of movingthe wire across the field, the held is movedacross the wires, the same voltage andcurrent flow will be induced in the ware.Therefore. it can be concluded that voltagewill be induced in a conductor cutting acrossa magnetic field when there is relative motionbetween the two. Either the conductor canmove. or the magnetic field can move.

Strength Of Induced Voltage

Three factors affect the strength of inducedvoltage:

1. The strength of the magnetic field.If the magnetic field is made stronger. byusing a larger horseshoe magnet forexample, more lines of force will be cut bythe conductor in any given interval of timeand the induced voltage will be higher.

2. The speed at which lines of force are cut-ting across the conductor.If the relative motion between the con-ductor and magnetic field is increased,more lines of force will be cut in any giveninterval of time and so the voltage will behigher.

3. The number of conductors that are cuttingacross the lines of force.In the example on the previous page oneconductor was passed through tne fieldand a voltage was induced. If two wireswere moved across the field twice asmuch current would be induced; if threewires. three times as much. and so on.Electrical motors, generators, coils. useloops of wire rather then straight wire asconductors. When a straight wire con-ductor is wound into a coil and movedacross the field. all the loops of wire are inseries and the voltage induced in all theloops will add together to give a highervoltage.

Note that the strength of induced voltage isrelated to the power needed to move the con-ductors across the magnetic field, or viceversa. When current is induced in a con-ductor, a magnetic field forms around the con-ductor. So the magnetic field of the conductormoves through the magnetic field of themagnet Since an interaction occurs betweenthe two fields, a resistance is set up againstthe movement The more induced current, thestronger the resistance Therefore. as theamount of induced current increases and thusresistance increases. more power will beneeded to move the conductors across thefield The practical application of this fact isthat the more current a generator or alternatorproduces. the more power is needed to turnthem.

118

4

.

r-.o.


Summary Of Electromagnetic Induction

Stronger magnetic field equals moreinduced voltage.

Faster relative motion equals morevoltage.

More conductors in motion equalsmore voltage.

More current induced equals morepower to move conductors through themagnetic field.

The basic electricity. magneticism. and elec-tromagnetism discussed above give the prin-ciples that electrical components are built on.Clearly understood. these principles will helpyou in diagnosing and repairing electricalparts.

ELECTRICAL TEST EQUIPMENT

To accurately test and diagnose electricalproblems, good test equipment is necessary.If values for voltage. current and resistanceare not measured with suitable test meters.only a guess can be made as `') what defectexists in the circuit.

The following discussion will look at volt-meters, ammeters. Pnd ohmmeters. What issaid about the three meters separately alsoapplies to modern testers which often com-bine two of the three meters in one test unit(e.g., battery starter tester).

Voltmeter

A voltmeter (Figure 844) measures thestrength of electrical potential or voltage in acircuit.

(8-34) VOLTmETER

Counesy of John Deere Ltd.

119

Because the moving coil in the voltmeter isvery small and sensitive, the current throughthe coil must be limited to safe values. To limitcurrent to a safe amount, voltmeters are con-structed with a high resistor in series with thecoil. The voltmeter scale is calibrated ac-cordingly to indicate the true voltage.

Voltmeters are connected across (in parallelwith) the voltage to be measured. as shown inFigure 845.

I(8-36)

CONNECT VOLTMETER IN PARALLELCourtesy 0 John Deere Lid

coA0

Ammeters

An ammeter measures the flow of electricalcurrent in ampere*. Two types of ammetersare used, a shunt ammeter and a tong am-meter.

Shunt Ammeters

Opposite to a voltmeter, the shunt ammeterhas a low resistance shunt connected inparallel with the moving coil. The shunt sec-tion of the parallel circuit, therefore, conductsmost of the current being measured leavingonly a small portion to flow through the coil.Always connect an ammeter in series in a cir-cuit: never connect it across .the voltagesource (Figure 8-36). If connected acrosS, orin parallel. the meter could be damaged.

I

L

0A0

(8-36)ALWAYS CONNECT AMMETER IN SERIES

Courtesy of John Deere Ltd.

Tong Ammeter

Tong ammeters measure the amps in a circuitby measuring the Strength of the magneticfield that surrounds the current carrying con-ductor. The advantage of a tong ammeter isthat you can test without disconnecting anywires. Current is measured by simply openingthe tongs and placing them over the wire.However. a tong ammeter is not as accurateas a shunt ammeter.

,


Ohmmeters

An ohmmeter (Figure 8-37) measures theresistance or ohms in a circuit

(8.37) OHMMETERCourtesy of John Deere Ltd

An ohmmeter has its own current supply, a drycell battery, and should always be used on adead circuit. Never connect an ohmmeter to alive circuit as the external voltage maydamage it. Keep the dry cell switched offwhen the ohmmeter is not in use.

Battery-Starter Tester

A battery starter tester (Figure 8-38) has avoltmeter and an ammeter combined into oneunit. The tester will do a complete test on thebattery and starting circuit.

x

(8.38) BATTERY-STARTER TESTER(VOLT-AMPERE TESTER)


CARE AND SAFE PRACTICES WITHELECTRICAL TESTING EQUIPMENT

The accuracy of electrical test equipment willdepend on how well it is looked after. Followthese simple rules for care and use of theequipment:

1. If in doubt of voltmeter, ammeter, ohm-meter hook-up procedures. refer to in-structions for the machine.

2. Do not overload the meter. Check themeter setting before connecting the meterinto the circuit. For example, some volt-meters can have four different settingranges that fall between 4 and 40 volts,One setting would be used when testing a12 volt system, and a higher setting wouldbe used on a 24 volt system.

3 Remember the basic rule applied to eachmeter:

(a) Voltmeter connected in parallel

(b) Ammeter connected in series

(c) Ohmmeter connected to a deadcircuit only.

4. Avoid connecting the meter backwards asreversing the connections is hard on themeter. Most meter connectors are colorcoded, red for positive, black for negative.

5. Keep the instruments clean. Cover themwhen not in use or store them in a cleanarea.

6. Avoid testing in hot areas around anengine as heat can burn or damage themeter connectors.

120


QUESTIONS ELECTRICITY THEORY

1. Electricity flows in a conductor in thedirection of:

(a)

(b)

(c)

(d)

negative to neutralnegative to positive

positive to negativepositive to neutral

2. Electricity is a form of:

(a)

(b)

(c)

(d)

heat

light

energy

magnetism

3. True or False? The term current meansthe flow of electrons through a con-ductor.

4. Briefly explain the term voltage.

5. All conductors offer some resistance tothe flow of current; the basic unit ofresistance is the:

(a) diode(b) thermistor

(c) ampere

(d) ohm

6_ List the three basic parts of an electricalcircuit.

7. Match the unit of electricity with themeter used to measure it.

(a) Voltage (a) Ohmmeter

(b) Current (b) Voltmeter(c) Resistance (c) Ammeter

8. Use the formula for Ohm's Law tocalculate the current flow in a circuit thathas 12 volts potential and a resistance offour ohms.

9. Briefly describe a conductor.

10. Briefly explain the difference between aclosed circuit and a short circuit.

11. Current flow can be direct or alternating.All accessories used on automotive andheavy duty vehicles operate on

current generallyreferred to as _______.

12. What does the term watt refer to and howis it determined?

121

13. List the three types of electrical circuits.

14. Parallel circuits are most commonly usedin automotive and heavy duty vehicles.Parallel circuits have:

(a) high resistance low amperage

(b) high resistance high amperage(c) low resistance high amperage(d) nieCium resistance medium am-

perage

15. The lines of force created around a barmagnet is referred to as the

The law of magnetismstates that

16. What does a bar magnet and a wire con-ducting electricity have in common?

17. An electromagnet is made by forming aconductor into a coil and passing acurrent of electricity through the coil.What is needed to complete this basicelectromagnet?

18. A common term for expressing thestrength of an electromagnet found bymultiplying the current flow times thenumber of turns in the coil is:

(a) flux turns

(b) current turns(c) magnetic turns(d) ampere turns

19. What is the term used to describevoltage produced by a conductor cuttingacross lines of force?

20. True or False? Current is induced whena conductor moves across a magneticfield but not when the field moves acrossthe conductor.

21. Match the following test instruments withthe correct method of connecting theminto a circuit:

(a)

(b)

(c)

Ohmmeter (a) connected inseries

Ammeter (b) connected inparallel

Voltmeter (c) connected to adead circuit


22. To avoid damaging test meters throughreverse polarity the test leads are colorcoded for identification. The standardcombination is:

(a) red for negative, yellow for positive

(b) black for positive, green fornegative

(c) red for negative, black for positive

(d) red for positive. black for negative

22. What are the three factors that affect thestrength of the induced voltage createdby electrunagnetic induction?

24. Two adjacent conductors carryingcurrent in the same direction will tend to

one another.

25. Two adjacent conductors carryingcurrent in the opposite direction will tendto one another.

122


LEAD ACID STORAGE BATTERIES

A battery stores energy for all the electricalcircuits in a vehicle the starting, charging.ignition, and accessory circuits. On demandthe battery produces a flow of direct currentto operate the electrical components in thesecircuits. Battery current is produced bychemical reaction between the activematerials of the plates and the sulfuric acid inthe battery fluid or electrolyte Electrolyteconsists of 36% sulfuric acid and 64% water.

BATTERY CONSTRUCTION

A battery is made up of a number of individualcells in a hard rubber case. The basic units ofeach cell are positive and negative plates(Figure 8.39). Negatively charged plates havea lead surface, gray in color; the positiveplates have a brown lead peroxide surface.Both negative and positive plates are weldedtogether in separate groups. Plate groutos ar'interconnected, as shown below. 1' r thatthere is one more plate in the negative gi. upthan in the positive, allowing negative platesto form the two outsides when the groups areinterconnected.

Each plate in the interlaced plate group iskept apart from its neighbor by porousseparators which allow a free flow of elec-trolyte around the active plates. The completeplate assembly is called an element.

TERMINALPOST

NEGATIVEPLATEGROUP

Elements in different cells are connected inseries. The cells are separate from oneanother and so there is no flow of electrolytebetween them.

Batteries have negative and positive posts orterminals. The positive post is larger to helpprevent the battery from being connected inreverse polarity. The positive terminal has a +marked on i.s top, and the negative post a -.Other possible identifying marks on or nearthe Posts are a "pos" and a "neg".

Conventional batteries have vent caps foreach cell: these caps cover access holesthrough which the electrolyte level can bechecked and water added. The access holesalso provide a vent for the escape of gasesformed when the battery is charging. The newso called maintenance-free batteries have novent caps. The electrolyte, for all practicalpurposes, is sealed in. There is however onesmall vent hole to allow any internal pressureto escaoe.

Courtesy of John Deere Ltd.

PLATE STRAPCASTING

SEPARATOR

ELEMENT

POSITIVEPLATEGROUP

(8 -39) CONSTRUCTION OF A STORAGE BATTERY

aw

123


Each cell in a storage battery has a potentialof about two volts. Six-volt batteries containthree cells connected in series, while 12-voltbatteries have six cells in series. For highervoltages, combinations of batteries are con-nected in series. in Figure 8-40 two 12-voltbatteries are combined to give 24 volts


Note that batteries of the same voltage canproduce different amounts of current. Thereason for this is that the amount of current abattery can produce is dependent on the num-ber and size of its plates. The more platesthere are the more chemical reactions cantake place between the electrolyte and theplates and, therefore. a greater amount ofcurrent is produced. Thus. if two 12-volt bat-teries have a different number of plates. theone with the greater number will supply morecurrent.

BATTERY ELECTROLYTE

The electrolyte in a fully charged battery is aconcentrated solution of sulfuric acid inwater. It has a specific gravity of about 1.270at 27'C, which means it weighs 1.270 timesmore than water. The solution is about 36%sulfuric acid (112S0,) and 64% water (H20).

Battery Water

The purity of water for battery use has alwaysbeen a controversial subject It is a fact thatwater with impurities hurts the life and per-formance of a battery. The question is doesthe impure water harm it in a significantamount? The controversy can be simplyresolved by saying that you don't have to usedistilled water. but it is better for the battery ifyou do.

BATTERY OPERATING CYCLES

A battery has two operating cycles:

discharging cyclecharging cycle

Discharging Cycle

When a battery is supplying current. it isdischarging. The chemical reactions in adischarging battlry are as follows:

Positive I-lefts are made of lead peroxide(Pb02). The lead (Pb) rer-cts with the sulphateradical (SO) in the electrolyte (H2SO4) to formlead sulfate lPhSO4). Al the same time theoxygen (0,) in the lead r enixide ,Jins with thehydrogen (1-.! in the clec'rolyte to form water(H20).

Negative Plates are made of lead. This leadalso combines with the sulfate radicals in theelectrolyte to form lead sulfate (PbSO4). Thesereactions are illustrated in Figure 8-41.

loommiciOAD

Pb b O1H,

Hi SO,

DISCHARGINGCourtesy of John Deere Ltd(8-41)

In the discharging process. then, leadsulphate forms on both the positive andnegative plates making the two plates similar.These sulphate deposits account for the lossof cell voltage because voltage depends onthe positive and negative plates being dif-ferent. As the battery progressivelydischarges more lead sulphate is formed atthe plates and more water is formed in theelectrolyte.

Note that although the SO, radical leaves theelectrolyte, it never leaves the battery.Therefore, never add any additional sulfuricacid (1-12SO4) to a battery. The extra SO, wouldonly cause the battery to self discharge at ahigher than normal rate. Water is the only sub-Cara in a battery that has to be replaced.

Charging Cycle

The chemical reactions that take place in thebattery cell during the charging cycle areessentially the reverse of those which occurduring the discharging cycle:

1. The sulphate radical leaves the plates andgoes back to the electrolyte replenishingthe strength of sulphuric acid.

124

..

8:22 BA SIC ELECTRICITY

2 Oxygen from the water in the dischargedelectrolyte joins with the lead at thepositive plate to form lead peroxide. Thechemical reactions during charging areillustrated in Figure 8-42.


THE BATTERY AND THECHARGING CIRCUIT

Batteries operate in a charging circuit with agenerator or alternator. The battery suppliescurrent to circuits and becomes discharged.The generator or alternator sends current tothe battery to recharge it. Operation of thecharging circuit varies with the engine speed.When the engine is shut off. the battery alonesupplies current to the accessory circuits. Atlow speeds. both the battery and generatormay supply current. At higher speeds. thegenerator may take over and supply enoughcurrent to operate the accessories and alsorecharge the battery.

TYPES OF BATTERIES

There are three types of batteries:

dry-charged

wet-charged

maintenance-free

Dry-Charged Batteries

A dry-charged battery contains fully-chargedelements. but it contains no electrolyte. Onceactivated with electrolyte it is essentially thesame as a wet-charged battery. A dry-chargedbattery retains its full state of charge as longas moisture is not allowed to enter the cells Ifstored in a cool. dry place. this type of batterywill not lose part of its charge on the shelfprior to being used.

Activating Dry-Charged Batteries

The activation of a dry-charged battery isusually done at the warehouse where the bat-tery is purchased or in the field by a dealer. Tomake sure the correct electrolyte is used and

the battery is properly activated, manymanufacturers furnish a packaged electrolytefor their dry-charged batteries along with in-structions for activation. These instructionsmust be carefully followed.

Wet-Charged Batteries

Wet-charged batteries contain fully-chargedelements and are filled with electrolyte at thefactory. A wet-charged battery will not main-tain its state of charge during storage, andmust be recharged periodically. Duringstorage, even though a battery is not in use, aslow reaction takes place between the elec-trolyte and the plates causing the battery tolose its charge. This reaction is called self-discharge.

The rate at which self-discharge occurs variesdirectly with the temperature of the elec-trolyte. A fully charged battery stored at a tem-perature of 38°C will be almost completelydischarged after a storage period of 90 days.The same battery stored at 15'C will be onlyslightly discharged after 90 days.

Wet-charged batteries. therefore. should bestored in the coolest place possible whichdoesn't allow the electrolyte to freeze. Notethat a wet-battery which is kept fully chargedwill not freeze unless the temperature goesbelow 60 'C. where as a discharged batterywith a specific gravity of 1.100 will freeze at8 'C.

Sulfated Wet-Charged Batteries

Wet-charged c Aeries which are stored forlong periods of time without recharging maybe permanently damaged by the formation ofhard dense lead sulfate crystals on the plates.To prevent these crystals from forming. wet-batteries in storage should be brought to fullcharge every 30 days.

Comparison Of Wet and Dry-ChargsdBatteries

In terms of storage. dry-charged batterieshave a big advantage over wet-charged bat-teries because they require less maintenance.For this reason most parts supply places. havestocked the dry-charged batteries. It now ap-pears. however. that maintenance-free bat-teries with their sealed-in electrolytes aregoing to replace the conventional batteries.and so parts suppliers won't have a choice.The maintenance-free batteries. will have tobe maintained in storage like the conventionalwet type.

125

,

TEST INDICATOR(TERMINAL LOCATIONS ARE

SHOWN IN FIGURE 5)

BASIC ELECTRICITY

Maintenance-Free Batteries

In an effort to reduce battery maintenance,and to make batteries more dependable andlast longer, the "maintenance-free batteryhas been developed. Indications are thatthese new batteries will mrke the con-ventional battery obsolete. A maintenance-free battery is similar in shape to a con-ventional battery but it has no filler caps. Theelectrolyte is completely sealed in. Note theterminals on the two maintenance-tree bat-teries in Figure 8-43: one has stainless steelthreaded terminals and the other has sealedterminals located on the side of the battery.

Also note on these batteries the state ofcharge indicator. To date this indicator isfound only on Delco batteries. The indicator isa built-in hydrometer having a small greenball that floats when the gravity of the elec-trolyte IS 1.225 or higher. The indicator shouldnot be used as a quick and easy way of tellingif the battery is good or bad, charged ordischarged. It must be read according to con-ditions set down by the manufacturer

Characteristics Of Maintenance-FreeBatteries

1. Since the electrolyte IS sealed in, the bat-tery has a life time supply of it. Thus the

TESTTERMINALS

INDICATORFINGER GRIP

HANDLES_.......0°"--

(8-43)

8:23

Courtesy ci Delco Division ofGeneral Motors Corporation

battery level doesn't have to be checkedand problems of over or undlrfilling thecells are eliminated.

2. Gases are produced during the dischargeand charging process The gases rise tothe top of the case, are trapped by theliquid gas separator. cool and condense.then drain back to the electrolyte reser-voir. Internal pressure that may occur isreleased through a small vent hole. theflame arrestor vent, in the side of thecover.

3. Maintenance-free batteries have plategroups like conventional batteries, but thegroups are constructed differently.Another difference is that the plates areenclosed in envelopes that act as theseparators and also collect sediment asthe plates crumble with age (Figure 8-44).The envelopes are bonded together andpermit the element to be placed on thebottom of the case. In contrast. theelement in a conventional battery is raisedin the case to give room for sediment tocollect and not touch the plates. Havingthe element rest on the bottom of the tankallows considerably more electrolyte tocover the plates and thus battery ef-ficiency is improved

126

#4

be


STATE-OF-CHARGE INDICATOR

HEAT-SEALED COVERS

STAINLESS STEEL TERMINALS

FINGER GRIPS

LIQUID/GAS SEPARATOR

PLATE STRAPS AND TERMINALS

EXTRUSION-FUSION INTERCELL CONNECTION

EPDXY-ANCHORED PLATE ELEMENT

SEPARATOR ENVELOPE

ELEMENT ON FLAT CASE BOTTOM

Delco Dovtsion ofGeneral Motors Corporation (8-44)

CAPACITY RATINGS OF BATTERIES

As was mentioned earlier, the factors in-fluencing battery capacity. i.e.. the amount ofcurrent a battery can produce, are the num-ber. size and thickness of the plates and thequantity and strength of the electrolyte. Newcapacity ratings for batteries were adopted in1971 by the Society of Automotive Engineers(SAE) and the Battery Council International.

Batteries are given two ratings:

cold power ratingreserve capacity

Cold Power Rating

Cold power rating gives the amount of powerthe battery has for starting on cold days; thisrating is the number of amperes the battery at-18 C (0 F.) can deliver over 30 seconds andnot fall below a voltage of 1.2 volts per cell.the minimum voltage required for dependablestarting.

The cold power rating is the more important ofthe two ratings because it deals with the bat-teries main lob. starting. Many low priced bat-teries can deliver only 200 amps: more power-ful batteries will deliver 525 amps under thesame conditions The cold power rating of thebattery should match the power requirementsof the engine it has to start If an engine undercold conditions required 400 amps to start, ob-viously the cheaper battery delivering only200 amps would be inadequate.

127

Reserve Capacity

The reserve capacity rating gives 4.e numberof minutes a new fully charged battery willdeliver 25 amperes at 27'C while maintaininga voltage of 1.75 volts per cell. Since 25 ampsis the power drain required to keep ignition,lights and other electrical accessories going.what this rating indicates is how long thevehicle will operate if the generator or alter-nator fails. in other words, if the chargingsystem of the machine breaks down, howmany minutes do you have to seek help?

VARIATION IN BATTERY EFFICIENCYOR TERMINAL VOLTAGE

Battery voltage is not constant; a 12-volt bat-tery does not deliver 12-volts at all times.Three main factors affect the terminal voltageof a battery:

temperature

operating cycle (charging ordischarging)

state of charge

Temperature

A battery produces current by chemical reac-tions. by sulfuric acid acting on the positiveand negative plates. At lower temperaturesthe chemicals don't react as fast andtherefore the battery has a lower voltage. Theeffect of temperature on terminal voltage is

,i

1


illustrated in Figure 8-45. At 27 C a battery is100% efficient; it has full cranking power. At-39 C a battery is only 30% efficient. Sincethe engine is harder to turn over in cold tem-peratures, the net effect of temperature onStarting is that as it gets colder the battery be-comes smaller while the engine becomeslarger.

1011%

68%

46%

311%

Centigrade

165%

2511%

3511%

(8-45)HOW COLD WEATHER AFFECTS THE BATTERY

AND THE ENGINE WHEN STARTINGCourtesy of John Deere Ltd

Starling difficulties may occur during hotweather after a machine has been worked andthe engine is hot Difficult hot starts are morecommon with large. high compressionengines. An air conditioning unit is also acontributing factor. The point here is that youcannot use a lower capacity battery when amachine is working in a warm climate. Thesame size battery as the machine would havein a cold climate must be used.

Operating Cycle (Charging or Discharging)

When a battery is being charged. its terminalvoltage increases. the amount of increasedepends on the charging rate. Note thatregulators are required on charging systemsto control the voltage increase so that the bat-tery is not overcharged. When a battery isdischarging. its terminal voltage decreases.the amount of decrease depends on thedischarging rate.

State of Charge

The higher a battery's state of charge (up tomaximum charge). the greater is its terminalvoltage.

POINTS ON BATTERY USEAND REPLACEMENT

1. When replacing batteries, be sure toreplace the battery with one at least equalin capacity to the original.

2. A larger battery than the original may beneeded if accessories such as an air con-ditioning unit are added to the vehicle'selectrical circuit.

3. A high-output generator may be needed incases where electrical loads are ex-cessive or where a vehicle operatesmostly at idle speeds. This high-outputgenerator will help keep the batterycharged and increase its service life.

M. The cheapest battery is not always thebest buy. For example, three batteries inthe same group size may vary in price. butthey also vary in cold power rating. in con-struction and in warranty period. Dividethe price by the months of warranty andyou may find the most expensive batteriesare really the cheapest per month of ex-pected service.

5. A final word on replacing batteries: oneout of every four batteries returned forwarranty has nothing wrong with it exceptthat it is discharged. Be sure to checkwhether a battery can be rechargedbefore thinking about replacing it.

PREVENTIVE MAINTENANCE ONBATTERIES

Visual Inspection

A battery should be visually inspected duringthe daily-walk-around check. and also in-spected at any time that scheduled main-tenance is done on the battery. Points to lookfor are:

1. Inspect the battery case for cracks andleaks. A leaking battery should bereplaced. Before putting in a new batterywash down the battery box with a solutionof water and baking soda.

128


2 Inspect battery posts. clamps and cablesfor breakage, loo'ae connections.corrosion.

3. Note whether the top of the battery isclean and dry. Dirt and electrolyte on topof the battery causes excessive self-discharge.

4. Nothing will damage a battery quickerthan allowing it to jump around. 8e surethe battery carrier is solidly mounted andin good condition and that the hold-downfirmly grips the battery. Also look for anybolts protruding into the bottom of the bat-tery box.

5. Inspect the battery for raised cell coversor a warped case, either of which may in-dicate the battery has been overheated orovercharged.

CORROSION

I

Any problems found during the battery in-spection should be attended to immediately. Ifa battery case is damaged and leaks, the bat-tery will have to be replaced. Before installinga new one, thoroughly wash the battery boxwith a solution of baking soda and water. Thiswill neutralize any acid that has leaked fromthe battery. Similarly. corroded battery cablesshould be removed from the battery andwashed in a baking soda solution. Whenreconnected they should be coated with ananti-corrosive agent such as a spray or asmall amount of grease. Hold-downs that areloose or missing must be repaired. Also watchfor bolts protruding in the bottom of the bat-tery box. Placing a thin sheet of plywood un-der the battery is always a good idea.

DIRT ON TOP OF BATTERY

,; 11111P

%IVsi

NW.

LOW WATER LEVEL

(8-46)

129

PLUGGED VENTS

CRACKS

LOOSE CABLEOR POST

BASIC ELECTRICITY

Checking and Adding Water

(This information will of course not apply tow maintenance-free batteries.)

Of the four chemicals in a conventional bat-tery lead, lead peroxide. sulphuric acid andwater water is the one that has to bereplenished. The usual recommended intervalfor checking a battery is every 30 hours ofoperation or 1,000 miles. During warmweather, checks may be required more often.Evidence of large amounts of condensationon the top of the battery and low electrolytelevel can Indicate an overcharging condition.if this problem continues to occur, have thecharging system checked.

Fill the battery with clean water, preferablydistilled water. In any case, avoid usinq waterthat has a high mineral content as the mineralwill ultimately shorten the life of the battery.Fill only to the bottom of the fill hole; anyhigher will cause unnecessary spillage. Avoidspilling water on the battery top and use apaper towel to dry the top when completed.Figure 8-47 shows two types of battery fillers.

8:27

(8-47)

AUTOMATIC FILLER

Removing, Cleaning and Installing Batteries

When removing a battery or batteries. followthese recommendations:

1. If multiple batteries are used, make adiagram of the circuit so that you cancorrectly reconnect the batteries.

2. Disconnect the ground cable first, using abox wrench to loosen the terminal bolts.Use a terminal puller to remove thecables; do not hammer on the batteryposts When installing the battery, con-nect the ground strap last. A terminalpuller is shown in Figure 8-48.

(8-48)

130TERMINAL PULLER


3. Remove the battery holddowns andcarefully lift the battery out. The method oflifting will depend on the location and sizeof the battery. For conventional batterieswith lead posts, a carrying strap (Figure 8-49) is the safest method.

STRAP CARRIER(8-49)

Whatever the method of lifting out the bat-tery, be careful not to drop it because thecase easily cracks. Try to keep the batteryclear of your clothing since battery acideats through cloth.

4. Clean the battery with a solution of waterand baking soda, then dry it. Clean theterminals with a terminal brush or scrapethem with a knife or screwdriver. Cleanthe cables in a similar fashion.

5. When installing the battery, use cautionnot to over tighten the hold-down as itcould crack the case. It is a good practiceto protect the bottom of the case with athin piece of plywood.

6. Make sure that the cables sit down on theposts (Figure 8-50). Coat the cables withan anti-corrosive agent such as grease orvaseline. Anti-corrosive sprays are alsoavailable.

INCORRECT CORRECT

TERMINALCLAMP

CASE

(8-50)

131

BASIC ELECTRICITY

BATTERY QUESTIONS

1. The current a battery will producedepends upon chemical reactions withinthe battery between the sulphuric acidand both the sponge lead in the negativeplate, and the:

(a)

(b)

(c)

(d)

lead sulphate in the positive platelead acid compound in the positiveplate

lead peroxide in the positive platelead zinc in the positive plate

2. Basically what does the element in a bat-tery cell consist or?

3. When does this battery element becomea cell?

4. Each cell of a lead-acid battery iscapable of producing approximately howmuch voltage?(a)

(b)

(c)

(d)

3 volts1 volt2.6 volts2 volts

5. True or Faise? The positive post of abattery is the larger of the two.

6. The electrolyte in a fully charged batteryhas a specific gravity at 80°F. of ap-proximately:

(a)

(b)

(c)

(d)

1.380

1.160

1.250

1.270

7. True or False? When a battery be-comes discharged the two plates be-come chemically similar thus accountingfor the loss in cell voltage.

8. When a battery is discharged the elec-trolyte has an increased percentage of.

(a)

(b)

(c)

(d)

sulphur

sulphuric acidwater

hydrogen

9. Briefly state the advantage of a dry-charged battery over a wet-charged one.

10. Is a maintenance-free battery dry or wet-charged/

8:29

11. What provision is made within a main-tenance-free battery to permit theelements to be placed on the bottom ofthe case?

12. What claims are made of maintenance-free batteries?

13. What three factors affect batteries' ter-minal voltage?

14. What are the two ratings given to bat-teries and briefly explain each.

15. Tare or False? At lower temperaturesbattery chemicals react faster andtherefore the battery has higher voltage.

16. When selecting a battery, the cold powerrating should match

17. The presence of dirt and electrolyte ontop of the battery causes excessive

18. To neutralize spilled battery electrolyte(a necessary safety precaution) amechanic should keep on hand a quan-tity of:

(a)

(b)

(c)

(d)

distilled waterbaking soda

sulphuric acidvaseline

19. Of the four essential chemicals in a lead-acid battery which one has to bereplenished occasionally?

(a) lead

(b) lead peroxide(c) sulphuric acid(d) water

20. When removing a battF y you shouldfirst:

(a) disconnect the insulated terminalcable

(b) loosen the battery hold-down

(c) disconnect the grounded terminalcable

(d) drain the electrolyte

132


21. A good practice to prevent corrosion andbad connections when reinstalling bat-tery cables is to:

(a) make sure they are clean and dry(b) make sure they are properly

tightened

(c) coat them with grease or vaseline(d) all of the above are necessary

133


BATTERY TESTING

A battery must supply a flow of current andmaintain a voltage Tests can be carried outthat will tell if a battery is doing its job Thetests for conventional batteries and the testsfor maintenance-free batteries will bediscussed separately. Four tests are used onconventional batteries:

1. Hydrometer for specific gravity.

2. Load tester capacity test.

3. Light load test individual cell voltage.

4. Three minute last charge test.

The state of the battery must be consideredwhen deciding what test to use. Questionssuch as these would be asked: was water ad-ded before testing? Is the battery charge par-tially down or is it completely dead/ Not all ofthese tests are required to fully test a battery.Usually two tests will give a fair indication ofthe battery's condition.

Hydrometer Test

A battery hydrometer (Figure 8-51) works on aprinciple similar to the antifreeze-testinghydrometer discussed earlier. Electrolyte isdrawn into the hydrometer's sight glass andthe float in the glass rises to a level of specificgravity. This level indicates the strength of thebattery's charge. Good hydrometers have athermometer built into them to give a tem-perature correcting factor. Batteryhydrometers. it should be oointed out. will notbe used on the new mail -.---rice-free bat-teries because the electrolyte in these bat-teries is sealed in.

SQUEEZE BULB

GLASS TUBE BASE PICK-UPFLOAT TUBE

R 45$ THERMOMETER

(8-51) HYDROMETERCourtesy or John Deere Lid

Hydrometers are the most common batterytester found in shops. Although a hydrometercan give a fairly good indication of a battery'scondition, the, are not foolproof. For example,a battery could have a poor internal con-nection between the cells making it unable to

produce a high current flow. Yet when testedwith a hydrometer the battery could give agood specific gravity reading. Hydrometerreadings on old batteries can also be decep-tive. The old battery could maintain an evenspecific gravity reading, say 1.235, but it maynot be able to produce an adequate amount ofcurrent.

Below are the procedures for making aspecific gravity reading on a battery with ahydrometer.

Caution: Always have a paper towel handyto hold over the end of thehydrometer when it is lifted fromthe cell. A paper towel is betterthan a rag because the towel willbe discarded whereas the rag islikely to be left around or put intoan overall pocket and the acid willquickly eat the cloth. Be verycareful not to spatter acid on yourskin or worse still to get it in youreyes. If acid contacts the skin,rinse the contacted area with run-ning water for 10 to 15 minutes. IIacid splashes into the eyes, forcethe lids open and flood the eyeswith running water for 10 to 15minutes. Then see a doctor atonce. Don't use any medication oreye drops unless prescribed by adoctor.

Specific Gravity Test:6 and 12 Volt Batter!

Note: If water has been recently added to abattery, a hydrometer will not give anaccurate reading of the battery's stateof charge.

1. Using a hydrometer, remove enough elec-trolyte from one cell to allow the float tomove freely without touching the top orbottom. Hold the hydrometer vertically toprevent the float from touching the sidesof the barrel.

2. With your eye level with the float take thefloat reading and record ft.

3. Note the electrolyte temperature:If the battery temperature is not at 27 "C.add 4 points (.004) soecific gravtiy to thefloat reading for each 5- above 27"C, orsubtract 4 points (.004) specific gravityfrom the float reading for each 5' below27". Most good hydrometers have a tem-perature corrected scale.

134

4


4 Repeat the above test on all remainingcells.

5. Note the amount of variation in the cell'sspecific gravities.

Unless otherwise specified, all cellreadings should be within 30 points (.030).If cell variation exceeds this amount, anunsatisfactory condition is indicated. Fur-ther tests should be performed.

6. Determine the battery's state of charge bylocating its specific gravity on the Per-centage of Charge Table below.

Percentage of Charge TableFully charged specific gravity varies in dif-ferent types of batteries. Typical valuesare given below:

State ofCharge

Standard SpecificGravity as Used inTemperate Climates

Specific Gravity inCells Built with

Extra Water Capacity

Specific Gravity asUsed in

Tropical Climates

Fully charged 1.280 1.260 1.225

75% charged 1.250 1.230 1.195

50% charged 1.220 1.200 1.165

25% charged 1.190 1.170 1.135

Discharged 1.130 1.110 1.075

(8-52)

TEMPERATURE CORRECTED HYDROMETER

135

TEMPERATURECORRECTED

SCALE


Load Tester

A load tester gives the truest picture of a bat-tery's condition. if the specific gravity is 1.225or better. a load test (capacity test) can bedone on the battery. If. however. the specificgravity is less than 1.225. then a light load test(a test of the individual cells) will have to beused Also. if water had to be added to thecells at the time of testing. use the light loadtest since you can't take the specific gravityand know that it is 1.225 or better. Figure 8-53shows a typical battery load tester or batterystarter tester

AMMETER

VOLTAGESELECTORSWITCH

AMMETER LEADS

wLOAD CONTROL

(8-53) KNOB

VOLTMETER LEADS

Courtesy of Sun Electric Corporation

136

.1-


Typical Load Test Procedures

1. Connect the tester's ammeter and volt-meter leads as shown in Figure 8-54A.

2. Turn Control Knob clockwise until the Am-meter reading is exactly three times theAmpere Hour Rating of the battery. (Exam-ple: 180 Amperes for a 6U AH battery.)

3. Maintain the load for 15 seconds, note thevoltmeter reading. and then turn the Con-trol Knob back to OFF position.

If the voltmeter reading was within thegreen band, 9.6 volts for a 12 volt battery.or 4.8 volts for a 6 volt battery, or washigher, the battery has good outputcapacity. Although the battery may passthe load test it may still require somecharging to bring it up to peak per-formance.

Note: When cold, a battery has a lowerdischarge capacity. If a cold bat-tery fails to pass the capacity test,let it stand until the battery tem-perature reaches 27°C, and thenretest it.

Courtesy of Sun Electric Corporation

Light Load Or Individual CellVoltage Test

A light load test is used rather than a load testif the specific gravity of the electrolyte is lessthan 1.225. This test is done with what arecalled battery cell probes which are attachbJto the load tester voltmeter leads (Figure 8-54B) with the voltmeter set on the 4 volt scale,the voltage of each cell is tested and if avariance of more than .1 volt between in-dividual cells is found, the battery should bereplaced. See the load tester instructionmanual for light load testing procedures.

STEELPROD

CADMIUMPROBE

LEADCONNECTOR

(8-54s, Courtesy of Sun Electric Corporation

137


Three Minute Fast Charge Test

The three minute fast charge test is done on avery low or dead battery (one that has failedthe load test) and indicates whether the bat-tery will accept a charge. The three minutetest can be done with equipment found inmost shops today a fast charger and an ac-curate voltmeter.

Note that performing the three minute test ona battery that has nearly a full charge will givean inaccurate reading. Below are a voltmeterand a charger connected to a battery for athree minute fast charge test.

Typical Procedures For A Three Minute FastCharge

1. Connect the voltmeter and the charger asshown below.

44

161

0 **Ili**40

)e

2. Adjust the charging switch to obtain acharge rate as close as possible to 40amps. for a 12 volt battery, or 75 amps. fora 6 volt battery.

3. After three minutes. while the charger isstill operating on fast charge. observe thevoltmeter reading. If the reading is beyondthe green band or exceeds 15.5 volts on a12 volt battery of 7.75 volts on a 6 volt bat-tery, the battery is sulphated or worn-outand should be replaced.

REDCLIP

BLACKCLIP

CH=

(11=exicza

Potion*serum

(8-55) Courtesy of Sun Ste:ono Corporation

138


SUMMARY OF TESTINGCONVENTIONAL BATTERIES

1. Take the specific gravity reading and notethe result. No more than .030 points be-tween cells is acceptable.

2. If 1.225 or better, do a Capacity or Loadtest. At the end of 15 seconds. the voltageshould not be less than 9.6 volts for a 12volt battery or 4.8 volts for a 6 volt battery.

If the battery passes these two tests. it isconsidered to be satisfactory for service.If a battery fails the load test, do a threeminute fast charge on it to see if it willtake a charge

3. If the specific gravity is less than 1.225and there is not more than .030 volts be-tween cells. perform a light load test. Ifthere is a variation of more than .1 voltsbetween cells, the battery is defective.

4 If the electrolyte is too low for a readingand water is added to the cells. perform alight load test.

5. If the battery is really low or dead. performa three minute fast charge test on it. If thevoltage does not exceed the maximumlimit (see fast charge instruction manual).do a light load test to finalize thediagnosis. If the voltage exceeds themaximum limit in three minutes, it usuallyindicates that the battery is sulphated orold.

139


TESTING MAINTENANCE -FREE BATTERIES

Since the electrolyte is sealed into main-tenance-free batteries, obviously a specificgravity test or a light load test can't be used. Aload test, therefore, is the test used on main-tenance-free batteries. Below are testingprocedures recommended by Delco for theirmaintenance-tree batteries.

Step 1: Test Indicator (Figure 8-56)

1. Green Dot VisibleProceed to Step 3. Note: On rare oc-casions. after prolonged cranking, thegreen dot may still be visible. Should thisoccur. charge battery as described in"Battery Charging Procedures" section.then proceed to Step 2.

2. Dark Green Dot Not VisibleCharge the battery as outlined under "Bat-tery Charging Procedures" section aadproceed to Step 2.

On rare occasions. the test indicator may turnsight yellow. in this instance the batteryshould not be tested. Replace the battery.

BATTERY CHARGEOK, FLUID LEVEL OK:

BATTERY TOP

Step 2: Remove Surface Charge

Connect 300-ampere load across terminals for15 seconds to remove surface charge from thebattery. If maintenance-free battery is invehicle. connect to terminals. If out of vehicle.attach load clamps to adapter charging toolas shown (Figure 8-57). For Delco 1200,remove cables. attach load alligator clamps tocontact lead pad as shown (Figure 8-58).

INSULATOR STRAPPREVENTS TOOL SEPARATIONAND LOSS WHEN NOT IN USE

BATTERY CHARGELOW, FLUID LEVEL OK:

BATTERY TOP

(8-57)

ADAPTER CHARGINGTOOL ATTACHEDTO TERMINALS

Courtesy of Delco Division ofGeneral Motors Corporation

BATTERY CHARGE UNKNOWN,FLUID LEVEL LOW:BATTERY TOP

-.............

4.--.............i1r...00Darkened IndicatorWITH GREEN DOT Darkened Indicator

NO GREEN DOTLIGHT OR BRIGHT

INDICATOR, NO GREEN DOT.."---........msio---gimmilm- -----.----,----.......---

CAN BE JUMP STARTED, (8-56)TESTED OR CHARGED

*CHARGE MAY STILL BE SUFFICIENT TO START VEHICLE

140

DO NOT JUMP START,TEST OR CHARGECourtesy of Delco Divisionof General Motors Corporation


IMMO

4111111MI

IP w"--"ag-

HEX NUT ALLIGATOR CLAMPS

LEAD PAD (8-58)

ALLIGATOR CLAMPS I HEX NUTi

LEAD PAD

ALLIGATOR CLAMPS CONTACTING LEAD PAD FOR TESTING AND CHARGING DELCO 1200 BATTERY

Counesy 01 Delco Division ofGeneral Motors Corporation

Step 3: Load Test

1 Connect voltmeter and specified load across terminals.

MODEL LOAD* MODEL LOAD*

49-5 210 Amperes 85-4 130 Amperes55-5 180 Amperes 85.5 170 Amperes59-5 210 Amperes 87-5 210 Amperes71-5 230 Amperes 89-5 230 Amperes81-5 230 Amperes 1200 235 Amperes

* See -Charging and Testing Adapters' section

2. Read voltage after 15 seconds with load connected. then disconnect load.

3. If minimum voltage is 9.6* * or more, battery is good.

4. If minimum voltage is less than 9.3* *, replace battery.* * This voltage is to be used for battery ambient temperatures of 70 F and above For tem-

peratures below 70 F, use the following:(21 C)70 F & (16 C) (10'C) 4 '0) (-1 C) ( -7'C) (-12 C) (-18'C)Above 60 F 50 F 40 F 30'F 20'F 10'F O'F

Minimum Voltage9.6

----9.1 8.9 8.7 8.59.5 9.4 9.3

141

1i


QUESTIONS BATTERY TESTING

1. The chemical energy within a battery canbe determined by the use of:

(a) a hydrometer

(b) a voltmeter

(c) an ammeter

(d) an ohmmeter

2. When testing the specific gravity of abattery. the allowable variation betweencells should not exceed'

(a) .060

(b) .010

(c) .300

(d) .030

3. A typical load or capacity test of a 12-voltbattery requires that 180 ampere load beapplied for 15 seconds and that thevoltage must not fall below:

(a) 6.9 volts

(b) 9.6 volts

(c) 11.1 volts

(d) 8.6 volts

4 When doing a light load or individual cellvoltage test. the allowable voltage dif-ference between cells should not ex-ceed:

(a) 1 volt

(b) .5 volts

(c) .01 volt

td) 25 volts

5. True or False? A three minute fastcharge must only be done on a low ordead battery and tells whether or not thebattery will accept a charge.

6. What is the recommended test for main-tenance-free batteries?

142


CHARGING BATTERIES

While an engine is running, the battery ischarged by the generator. Eventually,however. the battery charge wears down andif not attended to it won't have enough powerto start the engine. When a battery's state ofcharge is low. it should be recharged. Therecharging can be done while the bat.Jry is inthe vehicle or it can be taken out.

There are a number of different batterychargers, but they can be classified under twogeneral types.

Constant Current Chargers

A constant current charger does just what itsname implies, supplies a constant or setamount of current to the battery. The recom-mended charging rate is 1 amp per positivebattery plate per cell; e.g., if a battery has fivepositive, plates per cell, it should be chargedat 5 amps. Most batteries that are slowcharged with a constant current charger willtake five to six amps

Constant Voltage Chargers

A constant voltage charger supplies the bat-tery with a constant voltage during thecharging period, for example, 15 volts for a 12-volt battery. This charger will charge the bat-tery at a fairly high amperage when the bat-tery is low. and then as the battery builds upcharge the amperage tapers off, almost tonothing as the battery becomes fully charged

Constant current are much more commonthan constant voltage chargers.

Chargers can be either (1) slow charge's. (2)fast charger or (3) trickle chargers. or theycan be a comb:nation of these.

Slow chargers are used to completelyrecharge a dead battery: they can take up to48 hours. Fast chargers are used for a quickboost (from 114 hour to 1 hour) and won t doas complete a job as slow chargers. Somechargers have the dual capacity to provideeither a fast or slow charge.

Trickle chargers are used to keep a batteryup to full charge. they are especially good forbatteries that are little used or for wet chargedbatteries being stored

CHARGING CONVENTIONAL BATTERIES

Time is usually the main factor when decidingwhether to fast charge or slow charge a bat-tery. Obviously. it's better to slow charge abattery because you get a mom thoroughcharging job (fast charging takes place onlyon the surface of the plates). However, youdon't always have the time (24 to 48 hours) todo a slow charge, and in such cases fastcharges have to be done.

Slow Chargers

Constant Current Chargers

A slow charger can be either constant currentor constant voltage (constant current,however, is most common). The constantcurrent charger in Figure 8-59 is chargingthree 12-volt batteries connected in series.

(8-59)CONSTANT CURRENT SLOW CHARGER


Chargers have printed on them tne maximumnumber of batteries that they can charge, e.g.,five 12-volt batteries (total 60 volts) and ten 6-volt batteries (total 60 volts).

The example shown would have the voltagecontrol set at 36 volts (3 x 12), and the chargerate control set at approximately one amp perpositive plate per cell, usually five to six amps.When there are a number of batteries of dif-ferent sizes on the charger, average out thecharge rate. On some of the new chargers,you don't have to bother counting oraveraging out the positive plates. Thesechargers have a yellow, green and red bandon the charge rate indicator and recommendthe control be set to stay in the green range.

143


To connect a constant current charger startwith the black lead (negative) from thecharger and connect it to the negative post ofthe first battery Then take the red positivelead from the charger and connect it to thepositive post of the last battery. Now usinggood jumpers. connect the batteries, positiveto negative to complete the series circuit.

Recheck all the connections by turning theconnectors slightly on the posts. Finally turnthe charger on and adjust it to the correctcharge rate.

The state of charge of a battery beingcharged should be checked with ahydrometer twice a day if possible. The totalcharging time wit, vary depending on thestrength of the charge to begin with, but at theend of 48 hours batteries should be fullycharged If a battery becomes fully charged(i e . its specific gravity is 1.275 or over) before48 hours is up. remove it.

Constant Potential (Voltage) Chargers

Constant potential chargers are connected tobatteries in parallel as shown in Figure 8-60.The maximum number of batteries a chargercan handle will be marked on the charger.

(8-60)


The voltage control is set at a specifiedvoltage. e.g..15 volts for a 12-volt battery. Thecharge rate is automatically sensed by thecharger: the rate will be high when thedischarged battery is first connected to thecharger and will gradually taper c 3 as the bat-tery becomes fully charged.

When connecting up batteries in parallel to aconstant voltage charger. start with the blacklead (negative) and connect it to the negative

( -) post of the first battery. Then take the redlead ( positive) from the charger and connect itto the positive (t) post of the first battery. Nowusing good jumper cables connect up the bat-tery's negative to negative and positive topositive.

As with a constant current charger. check thespecific gravities of the charging batteriestwice a day and remove the batteries whenthey are fully charged.

Fast Chargers

Fast chargers will give a battery a highcharge rate for a short period of time. usuallyno more than an hour. They are portable(Figure 8 .61) in contras; to slow chargers thatare usually mounted on a wall or sit in thesame position on a be nch. Portable fast-chargers can charge a battery while it is inthe vehicle. Generally. only one battery at atime is charged on a fast charger. Note thatmany modern fast chargers have a capacity toslow charge a battery as well.

144

(8-61)



POINTS TO WATCH FOR WHENFAST CHARGING

1. Whenever a battery is charged.especially last charged. never allow theelectrolyte to exceed 51 C (125 F).Overheating. in effect overcharging. candrastically shorten the life of a battery.The temperature on conventional bat-teries can be taken with the hydrometerthermometer. The rubber case of main-tenance-free batteries will be hot to thetouch when the electrolyte reaches 51 C.

2. Watch the color of the electrolyte whenfast charging batteries. As a battery agesthe electrolyte will become discolored bysediment. During a fast charge thesediment is stirred up and could get trapped between the plates. causing a short.If such a short occurs lower the chargerate.

SUMMARY OF GOOD PRACTICESWHEN CHARGING BATTERIES

1. Before connecting conventional bat-teries to a charger make sure:

(a) the battery tops are clean

(b) the electrolyte is up to the correctlevel

(c) the caps are loosened or removed toallow the gases formed duringcharging to escape.

2 All chargers. slow or fast. need 110 voltsalternating current supply.

3 Always make sure a charger is turned offwhen connecting it to a battery. Alsowhen charging a battery while it is in thevehicle, turn off all electrical ac-cessories.

4. Disconnect the battery cable before fastcharging the battery in the machine. Thisis especially important with AC chargingsystems where the alternator can bedamaged.

5 When cc.inectrng any charger. observethe correct polarity negative tonegative and positive to positive. Mostchargers today are polarity protected.

6 Make sure connections are solid beforeturning on the charger.

145

7. Charger settings:

Voltages:

(a) on a constant slow charger set thevoltage to match the number of voltsin the batteries you are charging.

(b) on a constant potential charger setthe voltage for a 12-volt or 6voltbattery(ies).

(c) on a fast charger set the voltage fora 12-volt or 6-volt battery.

Amperage:

(a) on constant current slow chargerset amperage to one amp perpositive plate per cell (usually fiveto six amps); or if the charger has acolor indicator set it in the greenband.

(b) on a constant potential chargerthere is no current setting.

(c) on a fast charger set the amperageto either a high or low setting.

8. Charging Time:

(a) When stow charging a battery do aspecific gravity check twice a day tosee if the battery is fully charged.Do not go on charging a fullycharged battery.

(b) Set the fast charge time 1/4 hour to1 hour. Watch that the battery doesnot overheat.

9. Always turn the charger off beforedisconnecting it to prevent any sparksfrom accidentally igniting explosivehydrogen gases given off duringcharging.

*It- P 32,A7,v


, 411'.

11 .1111.*41.-

.,

ls;

(8-62) Sparks or flames near a battery that is being charged may ignite explosivegases causing a dangerous explosion.

Courtesy of Delco Division ofGeneral Motors Corporation

10. Never charge a battery in a place wherethere maybe any chance of sparks, e.g..in any area where welding or grinding isdone (Figure 8-62).

11. Check with the hydrometer thermometerto see that the electrolyte does not ex-ceed 51°C. On maintenance-free bat-teries touch the battery case to see thatit is not hot.

12. Recheck the electrolyte level on com-pletion of the charge.

146


CHARGING MAINTENANCEFREEBATTERIES

Maintenance-free batteries are charged withconventional battery charging equipment.One manufacturer's recommendations forcharging their maintenancefree batteries aregiven in Figure 8-63. Note the difference incharging times compared with conventionalbatteries the slow charging rate for main-tenance-free batteries is less than that forconventional batteries. and vice versa the Iasicharging rate is longer.

12 VOLT MAINTENANCEFREE BATTERY CHARGING GUIDE (Defeo)

DO NOT CHARGE A BATTERY IF THE GREEN DOT IS VISIBLE

NOTE On rare occasions following prolonged cranking. .he green dot may still bevisible Should this occur. a boc ^targe of 20 ampere-hours is recom-mended

DO NOT CHARGE A BATTERY IF THE TEST NDICATOR IS LIGHT YELLOW.DISREGARD IT

(Stop charging when the green dot appears orwhen the maximum charge shown below is reached)

Constant CurrentBattery Model Slow Charging Rate Fast Charging Rate

55-5. 85-4. 85-5 5A ft 10 Hours 20A 0 2% Hours

10A ft?.. 5 Hours 30A #i 1% Hours

49-5: 59-5 5A is 15 Hours 20A 'l 33/4 Hours

71-5. 81-5 10A '4,% Ph Hours 30A 13: 2% Hours

87-5. 89-5: 1200 40A d 2 hours

50A .@ 1% Hours

To avoid DAMAGE. the charging rate must be reduced or temporarily halted d

1 The battery case feels hot (51 C).

2 Violent gassing or spewing of electrolyte occurs.

After charging in accordance with the tables. even though the green do1 does no'appear. the battery is still sufficiently charged for testing.

(8-63) Comesy of Delco Division ofG...erat Motors Corporation

-147

_of


JUMPER CABLES

When a charger is not available, a commonpractice to start a vehicle with a dead batteryis to use Jumper cables and a battery pack.

Good Practices When Jumping

1 Before connecting jumper cables be sureall tne electrical accessorie3. lights, radio.wipers, etc. are off.

2. Observe voltage when Jumping. Jump a 6-volt battery with a 6-volt battery. not a 12-volt as arcing (electricity lumping acrossa gap) could occur. bringing with it thedanger of tire.

3. Observe polarity when jumping. Connectthe jumper cables negative to negativeand positive to positive (since you are justreplacing the existing power source).Connect the cables in this order:

(a) connect one cable clamp to thepositive terminal of the dead batteryand then connect the other end to thepositive terminal of the booster bat-tery.

(b) connect the second clamp to thenegative terminal of the dead batteryand then connect the other end to thenegative terminai of the booster bat-tery. Wrong polarity will cause arc-ing.

4. When removing the cables be sure tokeep tl,e clamps separated until they aredisconnected from the source. if they gettoo close arcing could occur

5. Never use a fast cnarger as a booster tostart an engine.

6 Maintenance-free batteries have jumpingprocedures tnat can differ from jumping aconventional battery. Check the marufac-turer's recommendations.

7. Use the shortest cables possible becausethe longer the cables tne more the voltagedrops.

8. Maintain good clamps on the jumpers toensure the best possible connection witha minimum voltage drop.

148

i


QUESTIONS BATTERY CHARGING

1 The recommended slow charging rate fora battery is one amp per positive plateper cell If you have a 15 plate 6-volt bat-tery, i.e.. 15 plates per cell. what wouldbe the correct charge rate?

(a) 15 amps

(b) 7 amps

(c) 8 amps

(d) 45 amps

2 Which does a better job of charging abattery. a fast charger or a slow charger?Briefly explain why

3 Wt. slow charging batteries on a con-stant current charger connect the bat-teries in

(a) parallel

(b) series(c) series or parallel

4 What are the two important things towatch for when fast charging a battery?

5 Care must be taken while working nearbatteries that are charging because aspark could explode thegases being given 011 from the chargingprocess

(a) nitrogen

(b) hydrogen

(c) carbon dioxide(d) helium

6 True or False? Overcharging a batterydoesn't hurt it.

7 When fast charging a battery in a vehiclewith an AC charging system, it is a goodpractice to

(a)

(b)

(c)(d)

remove the fan beltkeep the charge rate lowdisconnect a battery cabledisconnect the voltage regulator

149

8 Compared to a conventional battery. amaintenance-free battery when fastcharged requires'

(a)

(b)

(c)

(d)

a longer chargea shorter chargeabout the samea very low charge

9 A charger should be turnedbefore connecting it to a battery.

10. True or False? When boosting with jum-per cables doubling the voltage of theboosted battery is permissible providedthat the polarity is the same and thecables are quickly removed after theboost is given.


BASIC STARTING CIRCUIT

A basic starting circuit has four parts (Figure8-64):

The Battery supplies energy for the cir-cuit.

2. The Starter Switch activates the circuit.

3. The Starting Motor Switch connects thebattery to the starter motor and in somecases engages the motor drive with theengine flywheel.

4. The Starting Motor drives the flywheel tostart the engine.

wK

pBATTERY

MOTOR SWITCH

STARTERSWITCH

(8-64) BASIC STARTING CIRCUIT

The starting circuit converts battery electricalenergy into starting motor mechanical energyto crank the engine. How cio the four basicparts c! the starling circuit work together tostart a vehicle? When the starter key is turnedon by the operator. a small amount of elec-trical energy flows from the battery to thesolenoid and back to the battery through theground circuit (Figure 8-65)

(8-65) Courtesy of Jonn Deere Ltd

-;STARTING

MOTOR

MI

FLYWHEEL

Courtesy 01 John Deere LW

The current received by the solenoid movesthe solenoid plunger and engages the pinionwith the flywheel (Figure 8-66)

KEY SWITCH

X 1361

SOLENOID

STARTING MOTOR

150

(8-66)Courtesy 01 John Deere Ltd

tS


The plunger also closes the switch inside thesolenoid between the battery and startingmotor completing the circuit and allowing alarge amount of electrical energy to flow intothe starting motor The starting motor rotate:the pinion which in turn rotates the flywheel tocrank the engine (Figure 8-67).

Ft 1;e:STARTING MOTOR 1mr

(8-67) STARTING CIRCUIT IN OPERATION3) STARTING MOTOR CRANKS ENGINE


In the basic starting circuit above a solenoidswitch was used. There are other types ofstarting motor switches which will bediscussed later.

THE STARTING MOTORThe starting motor cranks the engine. Per-forming this heavy job requires a special typeof electrical motor that must:

1. Operate for short intervals under greatoverload.

2. Produce very high horsepower for its size.

To give the principles of a starting motor abasic ele:tric motor is constructed below:First start with two pole pieces. The poles setup a magnetic field between them running ina direction from north tr south (Fie:re 8-68).

POLE PIK'S

MAGNETIC "N...FIELD

X 451Courtesy of John Deere Ltd

To increase the strength of the magnetic fieldbetween the pole pieces. wrap a wire over thepoles and pass a current through it. This wireis called a field winding (Figs st 8-69).

(8-69)

X I.3e6Courtesy of Jonn Deere Ltd

Now take a loop of wire and pass a currentthrough it A circular magnetic field is formedaround the wire. Note the direction of theelectromagnetic field (Figure 8-70).

FIELD WINDING

CURRENTFROM

BATTERY

MAGNE TIC Fl ELO

Courtesy of Jonn Deere LtdA hiee

Placa the loop of wire in the magnet; field be-twpon the pole pieces and pass a currentthrough the wire (Figure 8-71).


N


Recall from the earlier discussion on elec-tromagneticism the roinciple that a currentcarrying wire with its surrounding magneticfield has a tendency to move from a strong toa weak magnetic held Look at the field pat-terns w hen the loop cuts through themagnetic field (Figure 8-72)

*%kMirrilt?,,,INJ111,,Vir,11,1, II d

(8-72' DIRECTION OF CURRENT

Lefthand side of loop: The lines of force ofthe loop run in a circular pattern. coun-terclockwise The polar lines of force run in astraight-line from north to south On the un-derside of the loop. the loop lines of force runthe same way as the polar lines of forcecreating a strong combined force However.on the top side of the loop. the loop lines offorce run counter to or against the polar linesof force. cancelling each other out andcreating a weak field

Now applying the principle that the wire willmove from a Strong to a weak field. the loop ispushed upwards

Righthand side of loop: The opposite of thelefthand side occurs By looking at the lines offorce you can see that a strong field iscreated on top of the loop and a weak fieldunderneath it Thu s the loop gets a pull down-wards

Since the loop is pushed upwards on the left-nand side and pulled downwards on the right-nand side. it moves This loop represents asimple armature Note that if the direction ofthe current was changed in the loop. the loopwould move in the opposite direction

So far the loop (armature) has moved But itmust do more than move, it must rotate Here'swhere the commutator and the brushes comein (Figure 8-73) Attached to each end of theloop is a split ring half, These half rings arethe commutator Resting against these nngtare two blocks of copper compound calledbrushes The brushes are connected to thebattery

COMMUTATORSPLIT RINGS

BRUSHES

(8-73)

Current comes from the battery to the brushesvia the held winding. The brush on the left-hand side passes current to a commutator halfring and the current travels through the loopout the other commutator split ring. to theother brush and back to the battery. As theloop begins to move each brush slides on acommutator half ring. When the loop reachesthe top of its circle. the brushes will slide fromone half ring to the other. Thus. the currentwill always enter on the left side and exit onthe right. and the loop will keep getting itspush upwards on the lefthand side and pushdownwaras on the rig hthand side. The result:the loop keeps rotating in the same direction.(Note that this explains why the commutatorring is split. If it wasn't split the loop wouldget pushed first one way and then the other.and it wouldn't rotate.)

152


An actual starting motor will have not one. buta number of loops. and each loop will be at-tached to a section of the commutator ring(Figure 8.74)

BRUSHES

(8-74) ARMATURE FOR STARTING MOTOR


In summary. a starting motor has pole piecesand field windings. an armature, brushes andcommutator. and a drive shaft to carry therotary motion to the pinion and flywheel(Figure 8-75)

BRUSHES

SHAFT

COMMUTATOR

POLEPIECES

FIELD WINDINGS

ARMATURE 1.,.

(8-75) ARMATURE AND BRUSHES INSTARTING MOTOR

Courtesy of John Deere LW

SWITCHES FOR STARTING MOTORS

Starting motors must be switched on to startan engine, but must be immediately switchedoff once the engine starts Four types of start-ing motor switches are used

manual switchmagnetic switchsolenoid switch

series-parallel switch

Manual Switch

A manual switch (Figure 8-76) is a simplehandoperated device that opens or closes acircuit Everytime you flick a light switch in aroom you are operating a manual switch.

BATTERY

STARTING -MOTOR

HEAVY SWITCH

x /3??

(8.76) A MANUAL SWITCHCourtesy of Jonn Deere Ltd

The manually operated starting switch may bemounted where it is directly accessible to theoperator. or it may be mounted on the startingmotor and made accessible by variousdevices such as a hand lever

Magnetic Switches

A review of electromagnetism is necessary tounderstand a magnetic switch and a solenoidswitch A current carrying coil. you remember.Ncis ;-,, magnetic field

he electromagnetic field is made stronger byplacing a soft iron core in the coil: the corehas the same poiarity as the coil If the corehas freedom to move and is placed at one endof ti coil, it will also assume the polarity ofthe col (Figure 8-77)

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11Atke-- CO L IMIMMIIMM.et, t""

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-

(8-CoL7a7ie)sy of John Deere Ltd

153

aInImMiler

BASIC ELECTRICITY

Tnerefore. the ad;acent poles of the core andcoil have opposite polarity. and the core willbe drawn into the center of the coil whencurrent flows through it As soon as thecurrent stops flowing the field collapses andthe core is free to move away from the coil.Tnis movement of the core in and out of thecoil is the principle of operation of themagnetic and solenoid switches

Tne magnetic switcn is mounted on thestarting motor frame like some manual swit-cries It is operated by a magnetic coil that isconnected to the battery through a start con-trol 3n the starter switch

STARTER SWITCH

8:51

STARTER CONTROL SWITCH

WINDING

PLUNGER

MAGNETICSWITCH

RETURN SPRING

MAGNETICSWITCH

X 1379

(8-78) MAGNETIC SWITCH CIRCUITCourtesy of Jonn Deere Ltd

The magnetic switch works as follows: theswitch (Figure 8-79) has many turns of a smallwire wound around a hollow core. Floating inthe core is a plunger with one end acting as acontact between the two main switch ter-minals. These terminals are connected inseries with the starting motor. Usually a smallspring holds the plunger away from the mainterminal contacts.

When the circuit to the coil is closed. a strongmagnetic field is created in the core. causingthe plunger to overcome the spring tensionand complete the circuit between the terminaicontacts. When the core contacts the ter-minals. the main circuit to the starting motoris completed and the engine is turned over.When the engine starts and the control circuitIs opened at the starter switch. the magneticheld collapses and the spring forces theplunger to its original position. The startingmotor circuit is open and the starting motorstops turning

CONTACT DISK

BENDIX DRIVE

1380

STARTING MOTOR

TO BATTERIES

BATTERYTERMINAL

MOTORTERMINAL

(8-79) A TYPICAL MAGNCTIC SWITCH CIRCUITCourtesy of Jonn Deere Ltd

Solenoid Switch

The solenoid switch (Figure 8-80) is verysimilar to a magnetic switch. but in addition toclosing the circuit. the solenoid provides amechanical means of shifting the startingmotor pinion into mesh with the flywheel ringgear.

RETURN SPRING

SOLENOIDSHIFTLEVER

PINION

A 1391

(8-80) SOLENOID SHIFT LEVER


154


The solenoid switch has two coils of wirewound in the same direction (Figure 8-81)The pull-in winding is made up of heavy wireconnected to the motor terminal of thesolenoid and through the motor to groundThe hold-in winding has an equal number ofturns of line owe with one end connected tothe ground These coils are energized directlyfrom the battery through the start position onthe starter switch

HOLD-INWINDING

SOL ENOID

PLUNGER

SHIFT LEvER

PULL-INWINDING

CONTROL SWITCH

r)

r- -t MOTORIk TERMINAL

CONTACT DISK 1

OVERRUNNING JILCLUTCH STARTING MOTOR

TO BATTERY

(8-81) SOLENOID CIRCUITCourtesy 0 John Deere Ltd

When the operator turns the starter switch.current flows to the starter solenoid Since thesolenoid coils are wound in the same direc-tion. current flows in the same direction.creating a strong magnetic field which pullsthe plunger into the field (Figure 8-82).

KEY SWITCH MAGNETIC FIELD

WINDINGS

(8-82) SOLENOID PLUNGER STARTING TO MOVEAS STARTER SWITCH IS TURNED ON

Courtesy Of John Deere Ltd

The initial plunger movement engages thedrive pinion with the flywheel ring gear. Fur-ther movement of the plunger closes theswitch contact points within the solenoid, per-mitting a heavy flow of current from the bat-tery into the starting motor to crank theengine Note that this heavy flow of currentdoes not enter the solenoid. When the pointswithin the solenoid close the heavy pull inwinding is shorted out. Thus the only currentin the solenoid during the starting period is inthe fine hold-in winding.

When the engine begins to run and the starterswitch is released. several things happenquickly First. current through the starterswitch to the solenoid is cut off. Then a strongreturn spring pushes out the solenoid plunger.breaking the circuit from the battery to thestarting motor and simultaneously pulling thepinion out of mesh with the flywheel ring gear.

Series Parallel Switch

Some heavy duty engines. especially diesels.require a high voltage to start Cold weatherand other adverse starting conditions con-tribute to the need for the high startingvoltage.

A high output starting motor on a 12-volt cir-cuit is adequate to start some large engines.Other heavy duty engines. however. requirestarting motors that will use two 12-volt bat-teries for a total of 24 volts. By using a 24-voltbattery supply. these high volt motors canproduce much greater starting speeds.

The problem with this high voltage circuit isthat although the 24-volts is needed for start-ing, 12-volts is adequate for electrical ac-cessories once the engine is going A series-parallel switch solves this problem. When thetwo batteries are needed for starting. they areconnected in series to deliver the 24-volts tothe starting motor. Once the engine is startedthe circuit is connected in parallel so that onlyone battery is used for normal electricaloperations

155


(Figure 8-83) shows a series-parallel switchfor a 24-volt starting circuit.

GENERATOR;12 VOLT)

REGULATOR (12-vOLT1

I

12vOLTBATTERY

TO L'GHTSAND ACCESSORIES

V.AMMETER

;BOTH BATTERIES/ 12-VOLT

STARTING% BATTERYs

A SWITCH sNos

SERI S PARALLWITCH

FUSE

SOLENOIDSWITCH

t24 VOLT,AMMETERBAT B1

STARTING MOTOR (24-vOLT!

(8 -83) SERIES - PARALLEL SWITCH FOR 24 -VOLTSTARTING MOTOR OPERATION


Operation during starting is as follows

As the starting switch is closed. the solenoidcoil within the series-parallel switch isenergized creating a magnetic force which at-tra:ts the senes-parallel switch plunger. Theplunger closes the two main switch terminalsand connects the two batteries tn series withthe starting motor

At the same tome. the starling motor solenoidcircuit is completed by a set of pointsmechanically closed by the series-parallelswitch plunger The battery-to-starting motorcircuit is completed and the starter turns over

After the engine IS started and the startingswitch IS released. the two batteries becomeconnected in parallel when the series-parallelswitch goes into a neutral position This cir-cuit permits operation of the machine's elec-trical equipment at a normal system voltage of12-volts A more detailed description of theseries-parallel starter switch and circuit willbe given in future training

STARTING MOTOR DRIVES

After electrical power is trar -mitted from thebattery through a switch to the starting motor.some type of connection IS needed to put thisenergy to work. The last link in the startingcircuit is the starling motor drive. The drivemakes it possible to use the mechanicalenergy produced by the starting motor.

The starting motor armature revolves at a highspeed to produce turning power. Since theturning speed required to start an engine iscomparatively slow, the starting motor isequipped with a small drive pinion whichmeshes with the teeth of the flywheel ringgear. The result IS a gear reduction with thearmature revolving as much as twenty timesfor every revolution of the flywheel. Thus thestarting motor can develop high armaturespeeds and considerable power while turningthe engine over at a lower speed. When theengine starts it speeds up immediately andmay soon reach 2000 RPM. Two thousandRPM's at the flywheel would mean twentytimes that much at the starting motor pinionSuch a terrific speed would destroy the ar-mature. and so a method is necessary todemesh the pinion from the flywheel once theengine starts. Starter drives. therefore musthave the capacity to both mesh and demeshthe pinion with the flywheel ring gear.

Types Of Starter Drives

There are many different starter drives, butthey all can be classified under two basictypes according to the way they are engaged

1 Inertia drive

2 Clutch dnve

Inertia Drives have a pinion gear that isweighted on one side to aid In meshing anddemeshing with the flywheel A Sendix driveis an example of an inertia drive.

Clutch Drives are shifted into mesh bysolenoid switches Two examples of clutchdrives are Overrunning and Sprag clutchdrives Note that there is a direct relationshipbetween starter drives and starter switchesInertia drives use straight magnetic switches.while clutch drives use solenoid switcheswhich have a shifting mechanism

156


inertia Drives

Bendix Drive

The Bendix drive uses both the accelerationof the armature and centrifugal force actingon the counter weighted pinion to move thepinion into mesh with the flywheel Before theignition switcn is turned on. the Bendix driveis out of mesh with the flywheel ring gear(Figure 8-84)

ARMATURE SHAFT

DRIVE PINICN.am

...... WM

r,...--%.

Lisiiro

/ )1).,

44,

Illr4=WitOrA0

SLEEVE/MOBOO

X 2387

SPRING FLYWHEEL_

(8-84)BENDIX Dr.iVE ENGAGING FLYWHEEL AS

ENGINE IS CRANKEDota,esv Jonn O4.. .1 e Lid

When the starting switch is closed and thebattery voltage is fed to the motor. tne ar-mature shalt accelerates rapidly The piniongear, due to centrifugal force acting on thecounter-weight, runs forward on the revolvingscrew sleeve until d meets or meshes with theflywheel gear (Figure 8-85).

_ ANION

'v; SPRINGki.f188

(8-85) BENDix DRIVE PINION FULLY MESHEDuuriesy 0, John Demo Ltd

157

When the pinion becomes fully meshed. itsforward motion stops. locking the pinion tothe rotating armature shaft The heavy springcushions the shock to the armature shaft, asthe shaft starts to turn the flywheel Thisspring also acts as a cushion when crankingthe engine and when the engine backfires

When the engine starts. the flywheel rotatesfaster than the armature shaft. causing thepinion to turn in the opposite direction on thescrew and spin itself out of mesh (Figure 8-86) Thus the engine is prevented from drivingthe starting motor at an excessive speed.

X 2.389

(8-86) BENDIX DRIVE PINION SPINNING OUTOF MESH AFTER ENGINE STARTS

tuutiesy of Jonn Deere Ltd

When spun from the flywheel the centrifugaleffect of the weight on one side of the pinion,holds the pinion to the sleeve in an in-termediate position until the starling switch Isopened and the motor armature comes to rest.As long as the operator keeps the startingmotor switched on with the engine running.the starting motor will free speed in the in-termediate position This free speeding is notgood for the armature and is the reason thatthe starter switch should be released Im-mediately after the engine has started

Certain precautions must be observed inoperating a Bendix-type starting motor If theengine backfires with the pinion meshed withthe engine flywheel, and the starting motor isoperating, a terrific stress is placed on theparts The stress occurs because the motorarmature attempts to spin the drive pinion rnone direction while the engine. having back-fired. turns the drive pinion in the oppositedirection This clash cf opposing forcessometimes breaks or wraps up the Bendixspring

Engine ignit nn timing should be checked andcorrected to overcome backfiring


Another problem with a Bendix drive can oc-cur during repeated attempts to start anengine When the engine is coming to rest itoften rocks back. or rotates in reverse. for partof a revolution If the operator attempts to re-engage the drive pinion at the instant theengine is rocking back. the drive housing orthe Bendix spring may be damaged.

To prevent such damage. the operator shouldalways wait at least live seconds between at-tempts to crank so that the engine stops turn-ing

Variations in Bendix Drives

1 The foto -thru starter drive (Figure 8-F7)incorporates some designs into the stan-dard Bendix di we that overcome theproblems with the Bendix mentionedabove A folo-thru has a detent pin whichlocks the drive in the cranking position toprevent disengagement on false starts.This pin is thrown out by centrifugal forcewhen the engine runs and the pinion thendisengages

DRIVE SPRING DENTIL CLUTCH

SCREWSHAFT PINION AND

ANCHOR PLATE BARREL

DRIVE HEAD (8-87)courtesy of Deice Division ofGeneral Motors Corporation

Another protective feature of the Polo -thrudrive is the dentil clutch. a precision madeone way clutch which drives in one direc-tion and slips in the other Since the shaftwill slip in the non drive direction. thestarting motor is protected Irom enginebackfire

The folo-thru is the most common type ofinertia drive used today.

2 Some heavy-duty cranking motors use afriction-clutch Bendix drive. This type ofdrive functions in much the same manneras other Bendix drives. However. it uses aseries of spring-loaded clutch plates. in-stead of a drive spring. that slip momen-tarily during engagement to relieve shock.

Clutch Drives

Overrunning Clutch Drive

The overrunning clutch drive (Figure 8-88) isone of the most widely used drivemechanisms; it meshes and demeshes thedrive pinion with the flywheel

The overrunning clutch uses a shift lever toactuate the drive pinion The pinion. togetherwith the overrunning clutch mechanism, ismoved endwise along the armature shaft andinto. or out of. mesh with the flywheel. Theshift lever may be operated either manually orby a solenoid.

SHIFTLEVER

ZM

yor

41_4 1", 11

PINIONSTOP

OVERRUNNINGCLUTCH

(8-88)Courtesy 01 Joni Deere Lid

Operation of the overriding clutch is asfollows

The drive pinion in its neutral position is outof mesh and separated from the flywheel ringgear When the starting switch is closed.current flows to the solenoid. closing theswitch circuit As the solenoid switch closes.the shift lever moves the pinion into mesh andthen completes the circuit to the startingmotor. If the pinion and the flywheel teethmeet instead of meshing. the spring-loadedpinion rotates the width of one-half tooth anddrops into mesh as the armature starts torotate

When the armature shaft rotates duringcranking. small rollers in the clutch becomewedged aga,st the shift collar attached tothe pinion. This wedging action locks the

158

2


pinion gear to the clutclp which is splinedtne armature shalt. and causes the pinion torotate with the shaft (Figure 8-89).

to Sprag Clutch Drive

The Sprag Clutch Drive (Figures 8-90 and 8-9 r) is used primarily on larger starting motorsto carry the high torque required to turn overhigh-compression engines. The Sprag ClutchDrive is constructed and operates like theOverrunning Clutch Drive. except that a seriesof sprags replace the rollers in the clutchassembly.

ARMATURESHAFT

ROLLERS

PINION GEAR

COLLAR

(8-89)OVERRUNN11%3 CLUTCH ORP, E ENGAGED

Jvfin opese Lid

Wher, the engine starts. the flywheel spin:. thepii ion gear faster than the armature.re'easing the rollers ar,c1 unlocking the pinionliorn Ulf armature. releaspng the rollers andunlocking the pinion from the armature shaftThe unlocked pinion still meshed with theflywheel. rt,nS at flywheel speed (overruns)safety anc, freely until the switch is openedand the shift lever pulls the pinion out ofmesh This fea:ure prevents the armature frombeing driven at excessive speed by tneengine

SHOULDERBAFFLE

COLLAR. SLEEVE .OAND SHELL ASSEMBLY

Courtesy of Delco Onns:on ofGeneral Motors Corporation

(8-91)

RETAINERCUPS

The Sprag Clutch Drive operates as follows:

Movement of the shift lever against the collarcauses the entire clutch assembly to movealong the splined shaft until the pinion teethengage the flywheel ring gear. If the teethmeet instead of meshing, continuedmovement of the shell and spiral splinedsleeve causes the pinion to rotate and clearthe teeth. The compressed meshing springthen forces the pinion into mesh with the ringgear If the pinion does not clear before thetwo retainer cups meet. shift lever movementis stopped by the retainer cups and theoperator must start the engagement cycleover again. The shift lever stopping preventsclosure of the switch contacts to the motorwith the pinion not engaged. On the secondattempt. the pinion will engage in a normalmanner.

PINION

SPRAGS

Y

CUPPED PINIONSTOP

SPRINGPINION

SHIFT COLLAR

(8-90)SPRAG CLUTCH DRIVE


SPLIT WASHER

DISASSEMBLED VIEW OF LATE TYPEHEAVY OUTY SPRAG CLUTCH

DRIVE ASSEMBLY

-

159


With the pinion engaged and the switchclosed. torque is transmitted to the pinionthrough the sprags. The sprags tilt slightlyand are wedged between the shell and sleeve.When the engine starts. the ring gear drivesthe clutch faster than the armature. and thesprags tilt in the opposite direction freeing tilesleeve and pinion and allowing them tooverrun the shell and armature. When theswitch is openea the shift lever pulls thepinion out of mesh To avoid prolongedoverrunning, the starting switch should beopened as soon as the engine starts.

REMOVING AND INSTALLING STARTERS

When removing and installing starter motors.the following precaution and good work prac-tices should be followed'

I First. remove the ground strap from thebattery Then install a 00 NOT OPERATETAG on the controls.

2 Tao all wires before disconnecting them.Pieces of masking tape work well fortagging

3 Starter motors. especially large ones. arewavy, so be sure to support a motor whenremoving Ins flange bolls

4 Check tne flywheel ring gear conditionbefore reinstalling the starter motor. If it isbadly worn or damaged. the ring gearsnout(' be repaired

5 Wnen installing the motor be sure totighten the flange bolts evenly

160

...


QUESTIONS STARTER MOTOR

1 The starting circuit converts electricalenergy of the battery into

.._ _ __. _. _______ _ to crank the engine'

(a) kinetic energy(b) hydraulic energy

(c) pneumatic energy

(d) mechanical energy

2 True or False A starting motor isdesigned to operate for short intervalsunder great overload.

3 The principle of an electric motor is thata current carrying conductor is placed ina magnetic held and the interaction be-tween the two fields causes:

(a) currenl to flow in the field winding(b) a fo -..'e to be exerted on the con-

ductor

(c) current to stop flowing in the con-ductor

(d) an equal force on the conductor

4. The operation of magnetic, solenoid andseries-parallel starter switches dependson:

(a) friction and magnetism(b) a core tightly wrapped around a coil

(c) movement of a magnetized core intoand out of an electromagnetic coil

(d) two bar magnets applying a force toeach other

5. What is the main difference between amagnetic starter switch and a solenoidstarter switch?

6 A series-parallel switch is used to

(a) connect two batteries in series forstarting and in parallel for charging

OA connects four batteries in parallelfor starting and returns two of themto series for charging and ac-cessory loads

(cl keeps the starter from overloadingthe batteries

(d) connects two batteries in parallelfor starling and in series forcharg in g

7 List the two basic functions of the starterdrive

8 What is the first step before attempting toremove a starter motor?

(a)

(b)

(c)

(d)

lack the vehicle upcheck the ring gear conditionremove the battery ground strapremove the fan belt

9 Why is the drive pinion center weightedon an inertia drive such as a Bendix?

10 An overrunning clutch mechanism allowsa clutch drive pinion to safely _____ --the starter motor armature shalt when theengine starts

11 There is a direct relationship betweenstarter drives and starter switches. Iner-tia drives use ___ _ _____ switches.Clutch drives use .____ - switches.

161


CHARGING CIRCUITS

A charging circuit does two lobs:

recharges the battery-- generates current to operate electrical

ac eessori es

There are two kinds of charging circuits'

DC charging crcuits (use generators)AC charging circuits (use alternators)

DC Charging Circuits have a generator andregulator (Figure 8 -92).

REGULATOR

flaN))i 111114VIP

gAMMETER GENERATOR

GROUND

(8-92)DC CHARGING CIRCUIT

BATTERY


Driven by the engine, the generator makeselectrical power :n the form of alternatingcurrent (current that moves in one direction,and then in the other) Through the use of acommutator and brushes. the generatorchanges the alternating current (AC) intodirect current or DC which moves in onedirection only.

The regulator does the following three ,obs"

1 Opens and closes the charging circuit be-tween the battery and generator.

2 Prevents overcharging of the battery.

3 Limits the generator's output to a safeamount.

AC charging circuits have an alternator and aregulator (Figure 8 -93).

IGNITION SWITCH

AMMETER

REGULATOR

ALTERNATOR

GROUND

BATTERY

(6-93) AC CHARGING CIRCUITCourtesy of John Deere lid

An alternator is similar to a generator in that itproduces AC current, but it differs in the wayit changes AC to DC. Alternators use an elec-tronic device called a diode rather thanbrushes and a commutator to change the ACto DC.

The function of a regulator in an AC chargingcircuit is to prevent overcharging of the bat-tery and to limit the alternator's voltage outputto a safe amount. Many modern regulators aremade with transistors and are referred to assolid state.

OPERATION OF A CHARGING CIRCUIT

All charging circuits operate in three stages'

1. During starting the battery supplies all thecurrent.

2. During peak operation the battery helpsthe generator supply current.

3 During normal operation the generatorsupplies all current and recharges the bat-tery

In both AC and DC charting circuits, the bat-tery starts the circuit when it supplies thecurrent to start the engine The engine thendrives the generator (or alternator) whichproduces current to take over the operation ofthe ignition, lights and other electrical ac-cessories. The battery will help out duringpeak operation when the electrical loads aietoo much for the generator (or alternator)

162

s


The three stages of the charging circuit areillustrated in Figure 8-94

operation and function. A starting motor usescurrent to turn its armature and shaft and itsfunction is to produce working power. Agenerator uses engine power to turn its ar-mature and its function is to produce elec-tricity. Figure 8-95 illustrates the parts of abasic generator. (Note that an actualgenerator has not one but many loops.)

FIELDWINDINGS

POLES

BATTERY SUPPLYINGLOAD CURRENT

BATTERY

GENERATOR AND BATTERYSUPPLYING LOAD CURRENT

GENERATOR SUPPLYING LOADCURRENT AND CHARGING BATTERY


DC CIRCUITS

GENERATORS

The make-up of a basic generator is stmilar tothat of the basic starting motor previouslydescribed. Both have an armature. poles. afield winding. brushes and a commutator.However. there is a major difference in their

FIELDWINDINGS

CURRENT PRODUCED BYELECTROMAGNETIC

INDUCTION

X u.s7 (8-95)COMPLETE PARTS OF BASIC GENERATORS


The earlier discussion of electromagnetismshowed that when a conductor was movedthrough a magnetic field. a current was in-duced in the conductor. The direction of in-duced current depended on the direction inwhich the conductor passed through the field.Generators use this principle of elec-tromagnetic induction to produce current.

Looking at the illustration of the basicgenerator in Figure 8-96. consider the clock-wise rotation of the loop through the magneticfield During the first half of the revolution(Figure 8-96f the top of Side A cuts throughthe magnetic field first. whereas the bottom ofside 8 is first to cut the field. In this half of therevolution. then. the loop has current inducedin it that travels away from Side B towardsSide A. During the second half of therevolution. the field cutting is reversed. Thetop of Side 8 is the leading edge. while thebottom of Side A is leading. Thus the currentflows in the opposite direction. away fromSide A towards Side B The result is alter-nating current

163


FIRST HALF OF SECOND HALF OFREVOLUTION REVOLUTION

(8-96)

The generator must convert this AC to DC.The commutator and brushes perform theconversion. The brushes slide on. or brush.the commutator ring. Since the ring is split thebrush on the left side is always in contact withthe side of the loop that is pushing up throughthe magnetic field. and the brush on the rightside is always in contact with the *I de of theloop that is going down through the field.Thus the current always flows in the samedirection

Three factors will affect the induced currentthat an actual generator produces

1 The strength of the magnetic held.

2 The number of wire conductors on the ar-mature (i e . the number of loops)

3 The speed of the armature.

Note here. as was mentioned earlier. that themore current a generator (or an alternator)produces. the more resistance there is againstthe armature Thus. the more current you drawfrom a generator or alternator. the harder it isto turn. This IS the reason that drive belts forgenerators and alternators must have theproper tension so that they don't slip duringpeak demands

Need To Regulate The Generator

Looking at the diagram of a basic generator.you can see that current produced by thegenerator is also used to supply its own fieldcircuit. Such an arang -lent causes aspiralling increase in the amount of currentproduced The reason is as follows-

1 The more current the armature produces.the more current is sent to the field circuit

2 With this additional current. the magneticfield becomes stronger

3 With a stronger magnetic field, morecurrent is induced in the armature

4 And so it goes, the amount of currentspiralling upwards.

If this increase in current went unchecked.the generator would burn up Thus. the needfor a regulator The regulator controls theamount of current and voltage the generatorcan produce. Besides having current andvoltage limiters. the regulator has a cutoutrelay that closes the circuit between thegenerator and the battery when the generatoris running and opens it when the generator isstopped. This relay allows the generator tocharge the battery. but does not allow the bat-tery to discharge through the generator whenthe generator is not running.

AC CIRCUITS

Alternators

The alternator (also called an AC generator)is the heart of the AC changing circuit. Alter-nators are generally more compact thangenerators and can supply a higher current atlow engine speeds. Since in recent yearsthere has been an increase in the use of electrical accessories at low or idle enginespeeds. alternators are more common todaythan generators

Basic Operation Of An Alternator

Whereas a generator induces current bymoving a conductor through a stationary field.an alternator induces a current by doing theopposite. by moving the field across astationary conductor.

A basic alternator can be made by rotating abar magnet inside a single loop of wire As WSrotated current is I duced in the wire (Figure8-97)

LOADCIRCUIT

164

ROTATINGMAGNETIC

FIELD

(8-97)courtesy of Jonn Deese Ltd


If the magnet is rotated the other way. thecurrent will flow in the opposite direction Thefaster the magnet is turned the more current isinduced

However, an alternator made with a barmagnet rotating inside a single loop of wire isnot practical because very little voltage andcurrent are produced Air is not a good trans-mitter of magnetism. and only a few lines offorce will come out of the North pole and en-ter the South pole Production of current is im-proved when the loop of wire and the magnetare placed inside an iron frame (Figure 8-98).The iron frame provides a form to which theloop of wire can be attached It also acts as aconducting path for the magnetic lines offorce. greatly increasing the number of linesof force between the N and S poles. With theincreased lines of force comes more inducedvoltage. and thus a more useful alternator

ROTOR

J

STRONG FIELDWEAK FIELD

IIP\CONDUCIORAIR PATHHIGH IRON FRAMEL OWRELUCTANCE RELUCTANCE

.seJldMAGNETIC LINES OF FORCE


In an alternator the rot-- tagnet is calledthe rotor. and the loop and outside frank.assembly is called the stator. A rotor and astator from an actual alternator are shown inFigure 8-9t, Note that the stator has not onebut many loops of wire wound in threeseparate :oils. Also note that the rotor is not abar maprietic but pole pie :es and an elec.troma;netic held winding. The rotor is drivenby the engine and the field winding is sup-plied current from the battery.

165

SLIP RINGS

(8-99)ROTOR

Courtesy of Delco-RemyDryisron of General Motors Corporation

(8-99) STATOR

Courtesy 01 Delco-fierily Division ofGeneral Motors Corporation

The current induced in the stator by the rotoris alternating current and it must be changedto AC before it can be used by the electricalaccessories An alternator uses diodes tochange the AC current to DC A diode is anelectronic device that will allow electricity toflow through it in one direction but not in theother The discussion here won't go into whythe diode allows passage of electricity oneway but not the other: this information can befound in any modern book on electricity. Inelectrical diagrams the symbol for a diode is,OF. which means that current canflow through the arrow but not through the


vertical line. Without going into detail, thediodes are located in circuits such that theysend the alternating current received from thethree stator coils all in ths same directionresulting in a DC current. To understand howdiodes work follow the path of the currentthrough the six diodes in Figure 8-100.Remember that the current can only flow inthe direction of the arrow through the diode.

1. From coil A through coil B and C andback to A again

2. From B through A and C and back to Bagain

3 From C through A and B and back to Cagain

FIELDTERMINAL

RECTIFIER DIODES

(8-100)Courtesy 01 Jonn Deere Ltd

BATTERY

Need To Regulate The Alternator

Alternators like generators must haveregulation. The type of regulation, however, isdifferent in the two systems. Generators. asyou will recall, required a cutout between thebattery and generator. in addition to currentand voltage limiters. Since alternators usediodes. they don't need a cutout (i.e.. currentcan only go from the alternator to the battery.it can't go the other way). Nor do they need acurrent limiter because the coils are con-structed so that the current they produce issell limiting What regulation alternators doneed. though, IS a voltage limiter. Voltage out-put is controlled by limiting the amount ofcurrent in the field circuit. By limiting thevoltage output of the alternator, the amount ofcurrent produced IS in correct proportion toboth the demands of the battery in its various

slates of charae and the demands of the elec-trical system (up to, of course. the alternator'slimitations).

There are many variations of alternator andgenerator regulators and these will bediscussed in later courses.

166


PREVENTIVE MAINTENANCE SERVICE OFCHARGING SYSTEMS

Removing and installing generators and alter-nators is a fairly straight forward job.However, there are a few suggestions that willhelp you do a better. safer job:

I First, remove the ground strap from thebattery.

2 Wrien multiple wires are used on thegenerator, tag the wires as they aredisconnected

3. On some vehicles. several accessoriesmay be driven from a multiple groovecrankshaft pulley, and to replace any ofthe inside drive belts you will have toremove all the outs;de belts first. Also. onvehicles where special equipment hasbeen installed or accessories relocated, itmay be necessary to remove these itemsbefore you can replace a drive belt.

4 Generators. especially large ones. areheavy; support a generator whenremoving the mounting bolts.

5 Check the condition of the drive belt andits sheaves and :heck the sheave align-ment (see the section on belt maintenancein Block 7. Engines).

6 When installing generators. position themso that the spacers are in the rightlocation.

7 Check belt tension using a belt tensiongauge or the belt depression method (see"Engines"). The most common chargingsystem problems are caused by worn orimproperly adjusted drive belts. Preven-tive maintenance on generators stresses,therefore. that belts be checked regularlyfor alignment and tension.

167


QUESTIONS CHARGING SYSTEMS

1. During normal engine operation thegenerator or alternator:

(a) helps the battery supply current

(b) supplies all current(c) recharges the battery

(d) both (5) and (c)

2. A generator changes the alternatingcurrent it produces to direct current bythe use of:

(a) an accumulator and brushes(b) a commutator and windings

(c) a commutator and brushes

(d) an accumulator and diodes

3 List the three jobs the regulator must doin a DC charging system.

4. An alternator changes AC to DC by theuse of:

(a) resistors

(o) transistors

(c) diodes

(d) thermistors

5. A regulator on an AC charging systemhas one job to do:

(a) Omit the voltage to a safe value

(b) limits the current to a safe value(c) opens and closes the charging cir-

cuit

(d) control alternator speed to controlcurrent output

6 Briefly explain the difference in the waythat current is induced in a generatorand in an alternator

7 True or Fr.P.ze? The most commoncharging system problems are caused byworn or imprope.iy adjusted drive belts.

168

41.


IGNITION SYSTEM

The purpose of the ignition system is to takethe low voltage of the battery and create highvoltage at the spark plugs to fire the engine.This purpose is accomplished by means of aninduction coil. points and a condenser. Theignition system must deliver the high voltageto the right spark plug at the right time in or-der to get maximum power from combustion.

The ignition circuit has two separate circuits(Figure 8-101)

Primary low-voltage circuitSecondary high-voltage circuit

The Primary Circuit is the oath for low-voltagecurrent from the battery

It includes these parts'

1 Ignition Switch

2 Coil Primary Winding

3 Distributor Contact Points

4 Condenser

Tne Secondary Circuit is the high voltagepath for current stepped up by the coil It in-cludes these parts

1 Coil Secondary Winding

2 Distributor Rotor

3 Distributor Cap and Secondary Winding

4 Spark Plugs

SPARKPLUGS

SPARK

PLUGS

ego

OISTRIBUTOR

<11

CONDENSOR

IGNITION SWITCH

BATTERY =in PRImARYCIRCUiT

1=I SECONDARY CIRCUITX336-5 (8-101) MAGNETIC FIELD

IGNITION CIRCUIT (BYPASS TYPE SHOWN)Courtesy of John Deere Ltd

IGNITION CIRCUIT OPERATION

The ignition circuit can be naturally separatedinto (1) the operations before the distributorpoints open and (2) the operations after theyopen.

Operation Before The Distributor PointsOpenBefore the engine is started. the distributorpoints are closed (Figure 8-102)

1\

DISTRIBUTOR PRIMARYCAP TERMINAL

PRIMARYTERMINAL

ROTORCONTACT

POINTS(CLOSED)

BREAKERCAM

CONDE.ISER DISTRIBUTOR

(8-102) COIL

OPERATION BEFORE THE DISTRIBUTORPOINTS OPEN

GotaloSy nl Joni) 1)etfo Ltd

PRIMARYWINDING

169


When the ignition switch is turned on. currentflows from the battery into the primary win-dings of the coil, as shown in dark lines. Fromtne primary winding the current at lowvultage simply travels through the closeddistributor points and back to ground Thecurrent creates a magnetic, field around theplummy winding and since the secondarywiring is wound underneath the primary. the;,econdary. too. nas ,:: magnetic field around it

Operation After The Distributor Points Open

As the engine rotates in starting. it drives thedistributor shalt and the breaker cam. Thebreaker cam opens the distributor points. andthe second phase of ignition Degins asillustrated in Figure 8-103

SPARKPLUG "...-

TERMINAL

SPARKPLUGS

The surge of induced voltage in the primarywinding is absorbed by the condenser Thesurge of induced voltage in the secondarywinding which. 'or reasons that will be ex-plained later. is much higher. travels to thedistributor cap. The rotor inside the distributorcap turns to a spark plug terminal and directsthe voltage surge to the correct plug throughinsulated cables. At the spark plug, highvoltage current flows down the center wire orelectrode and on reaching the tip jumps thegap to the plug's ground electrode As thecurrent jumps it creates a spark.

The complete cycle of current coming into theprimary winding, stopping. and inducedcurrent travelling from the secondary windingto the distributor cap and spark plugs hap-

DISTRIBUTORCAP SECONDARY

WINDING

CONTACTROTOR POINTS

(OPEN)

BREAKERCAM

(8_103) CONDENSER

OPERATION AFTER THE DISTRIBUTORPOINTS OPEN

, , ,,t jrrin Opere Ltd

DISTRIBUTOR

As the points open. the flow of current in theprimary circuit is stopped instantly StDppingthis current collapses the magnetic field thathas built up around the two windings Collaps-ing the field induces a current (discussedmore fully below) in the two coils. since thereis a magnetic field moving across a con-ductor You remember the. if a conductor ismoved through a magnetic field (the principleof a generator) or vice versa if the magneticfield is moved across the conductor (the prin-ciple of the alternator) a current is induced inthe conductor

COIL

pens 'rpm 100 to 300 times a second depen-ding on the speed of the engine.

One other point must be made about theignition circuit as a whole. Going back to thefirst diagram in this section, notice theresistor on the primary circuit and also notethe dotted line that bypasses this resistor.Such an arrangement is called a bypassignition system. When the ignition key is turn-ed on. full battery voltage 'lows through thedotted red line. resulting in a hotter spark forfirst ignition. When the ignition switch isreleased. primary current flows through thesolid line and resistor to the coil. In a 12-voltsystem. the resistor reduces voltage by halfand allows the use of a 6-volt coil The smallercoil gives longer to the distributor points.condenser. and coil because it creates lessheat.

170

t


Having seen how current flows in an ignitionsystem the individual parts of the system willbe discussed

Wiring In The Primary Circuit

Primary wiring is low voltage wiring. 16 or 18gauge plastic insulated. stranded copper wire.that carries current at battery voltage throughthe primary ignition circuit The connectors atthe ends of the wire are usually crimped orsoldered on

Ignition Coil and Condenser

The center of the coil (Figure 8-104) is a softiron core The secondary winding of fine wireis wrapped around this core. One end of thesecondary winding is connected to the high-tension terminal. the other end to the primarywinding

SEALING NIPPLE

HIGH TENSIONTERMINAL

COIL CAP

PRIMARYTERMINAL

SECONDARYWINDING

PRIMARYMOOING

IRONCORE

LAMINATION

PORCELAININSULATOR

(8-104) IGNITION COILCourtesy 01 Jonn Deere Ltd

The primary winding of heavy wire is wrappedaround the secondary winding. There are ap-proximately 100 times less primary loops thansecondary ones. The two ends of the primarywinding are attached to the primary terminalsin the coil cap. One of these terminals is con-nected to the power source. the other is con-nected to the distributor points.

\ shell of laminated material is placed aroundthe windings and core as shown. The core.windings. and shell are then encased in ametal container. The container is filled witheither oil or insulating material and sealedwith the coil cap The cap is made of a shapedinsulating material with the two primary ter-minals and one high-tension terminal moldedinto it.

171

The coil performs the key function in theignition circuit, it steps up battery voltagefrom 6 or 12-volts to 15 to 20 thousand volts.enabling a spark to occur at the spark plug.

Coil Operation

Keep in mind the electromagnetic principle ofthe coil. when a magnetic held crosses over aconductor a voltage is trieJced in that con-ductor. The faster the field travels and themore conductors there are. the greater the in-duced voltage.

1 Current at battery voltage travels to theprimary winding in the coil. As currentbegins to come into the primary winding, amagnetic field starts to build around it.and since the secondary winding is wrap-ped underneath the primary the samemagnetic field crosses over to the secon-dary winding. As the field builds up. somevoltage is induced in the secondary win-ding but not enough to send a sparkacross the gap at the spark plug.

2 This greater voltage that produces thespark is induced as follows The contactpnints are opened and current is im-mediately cut off to the primary coil. Cut-ting off the current causes the field tocollapse very quickly. and thus the fieldtravels back over the secondary windingsmuch faster than it came across. (Notethat the electromagnetic field doesn't justdisappear when current is cut off: it mustcollapse or fall dawn much like. a brickbuilding would : The fast collapsing fieldcrossing back over the many loops in thesecondary winding induces a very highvoltage that sends a surge of current up toa spark plug to jump the gap and causethe spark needed for ignition of the fuel.

"4 While the high voltage is being induced inthe secondary winding. what is happeningin the primary winding? As the fieldcollapses. a voltage is self-induced in theprimary winding as well as the secondary.However. the voltage is much less thanthat of the secondary because the primaryhas approximately 100 times fewer loops.

The self-induced voltage in the primarywinding tries to push a spark across thepoints in an attempt to keep the currentflowing And there is enough inducedvoltage to send a spark across when thepoints first start to open and are not veryfar apart Such a spark would damage the

BASIC ELECTRICITY

points and decrease the rate of heldcollapse. To prevent sparks at the points acondenser is used.

The condenser IS connected across thepoints as illustrated in Figure 8-105.

DISTRIBUTORFOIL

A,

1;7INSULATION

COILPRIMARY

TERMINAL

8:69

HIGH-TENSIONTERMINAL

Courtesy og Jonn Deere Ltd CONDENSER

(8-105)

Instead of the induced voltage pushingcurrent across the points. the current issent into the condenser. The condenser ineffect catches the induced voltage fromthe primary winding. The condenser issoon full or cnarged up and the voltage esready to try again to push the sparkacross the points. but by this time ther,oints are open too wide for a spark to bepushed across The delaying tactics of thecondenser prevent current from crossingthe points and in so doing allow the fieldin the coil to continue to collapse.

rt should be pointed out that contrary towhat was said above sparking is not 100%eliminated from the points. During the firstmillionth of a second that the pointsseparate. there is a very small sparkproduced across the points. It is this smallspark that accounts for some pitting andwear on the points.

Set vice Note On The Polarity Of The Coil

Whenever the primary leads are disconnectedfrom the coil. observe the correct polaritywhen reconnecting them. Wrong polarity ofthe coil IS not a serious problem. but cancautae damage over a long period of time. Acoil that is incorrectly connected to the powersource and the distributor will require an extra4000 to 8000 volts to create the sparkMisfiring can result as the voltage required torump the spark gap increases. Figure 6-106illustrates proper coil connections.

DISTRIBUTORPRIMARY

TERMINAL

PRIMARYTERMINAL

TO IGNITIONSWITCH

1111 NEGATIVE-GROUND SYSTEMS

(8-106) POSITIVE-GROUND SYSTEMS

CORRECT POLARITY OF THE COILCo, -esy ct JOnn Deere 110

On negative-ground systems. the negativeprimary terminal is connected to thedistributor.

On positive-ground systems. the positiveprimary terminal is connected to thedistributor.

Most coils have the polarity signs imprinted inthe cap by each terminal.

IGNITION DISTRIBUTOR

The distributor does three lobs. It.

opens and closes the primary circuittimes the high voltage surgesdelivers current to the spark plugs

Distributor Parts Can Be Put Into ThreeGroups

Primary CircuitOperation

drive shaftbreaker cambreaker plate

contact points

172

Timing

drive shaftbreaker camcentrifugal

advancecontact points

Delivery

drive shaftrotorcap


Operation Of The Distributor

As the distributor drive shaft turns. a cam lobepushes the breaker lever tubbing block. Thisaction opens the contact points. stopping thecurrent flow in the coil's primary circuit(Figure 8-107)

PLUG

POINTS ROTOROPEN

CAM LOBES

DISTRIBUTOR

(8.107)Courtesy 01 John Deere Ltd

COIL

RUBBING BLOCK

The collapsing field and the resulting high-voltage surge an the coil's secondary windingforces current into the center terminal of thedistributor cap. The distributor rotor receivesthis current and delivers it to the proper sparkplug to fire the engine

Meanwhile. the distributor cam lobe hasmoved away from the rubbing olock andspring tension brings the points back intocontact (Figure 8-108)

POINTSCLOSED

COIL

DISTRIBUTOR


The primary circuit is again complete andcurrent flows until the next lobe opens thepaints. The cycle then repeats itself.

In this way a spark is created as each lobe ofthe cam opens the contact points. The com-plete cycle for each spark takes place at avery high speed. A typical distributor is shownin Figure 8-109.

BREAKERLEVER

ROTOR

CAM

CONDENSER

BREAKERPLATE

HOUSING

173

DRIVESHAFT

ADVANCEMECHANISM

(8-109) CUTAWAY OF DISTRIBUTORCourtesy of Jonn Deere Ltd

Distributor Parts

Drive Shaft is driven at one-half engine orcrankshaft speed by the engine camshaft. Itdrives the centrifugal advance mechanism(described later). the breaker cam. and therotor.

Breaker Cam is slip-mounted on the driveshaft and pinned to the centrifugal advance.The cam has one lobe for each engine cylin-der.

Breaker Plate Is a mounting for the contactpoints and condenser It also has a terminalwhich connects the points and condenser tothe primary circuit -

Contact Points Assembly consists of twocontact points. a breaker lever and a breakerlever spring All three are mounted on a basewhich is attached to the breaker plate. Thetwo points are usually made of tungsten. Oneis foxed to the base. the other is attached tothe breaker lever and aligned with the first.

0


The breaker lever is mounted on a pivot pin tothe assembly base The lever is made of metaland has a nylon or bakelite rubbing blockThe breaker lever spring 6s attached to thebreaker lever The spririg holds the lever tothe cam after each cam lobe passes the rub-bing b:,ck

Rotor is mounted on the upper part of thebreaker cam A flat side of the rotor hub fitson a flat side of the cam In this way the rotorwill fit in only one position. On the top of therotor. a spring metal piece is in contact withthe center terminal of the distributor cap Arigid piece completes the circuit to eachspark plug terminal in the cap as the rotorturns. The rotor itself is molded of a plasticmaterial which makes it a good insulator.

Distributor Cap is also molded of a plasticmaterial Brass or copper contact inserts areembedded in the cap. These contacts areequally spaced around the cap and lead to thespark plug terminals in the top of the cap. Thecap is notched into the housing to prevent in-correct installation.

CENTRIFUGAL ADVANCE MECHANISM

An advance mechanism it a device whichtakes engine speed into account and timesthe spark to occur while the piston is in itsbest position to be driven by the expandinggases For the purpose of discussion, assumethat the engine piston must be at 12° past topdead center for full combustion force (Figure8-110). The 12° past top center stays the sameregardless o' the engine speed.

120PASTT 0 C

IDLE

(8.110)Cuortesy of Jonn Deere Ltd

AsSiime also that it takes 0 002 seconds toreach the full force of combustion. and that at1000 revolut.ons-per-minute (RPM) the pistonwill travel 16 degrees during this time. Thespark at this speed. therefore. must come atfour degrees before top dead center so that

the piston will be at its optimum 12° positionat combustion (Figure 8-1t1) II the enginespeed is doubled to 2000 RPM. the distancethe piston would travel is also doubled to 32degrees. and the spark. therefore. must occurat 20 degrees before top dead center to givemaximum power to the piston (Figure 8.111).

SPARK1

BEFORET C

12

PASTTOC

AT 1,000 ENGINE RPM

SPARK

BEFORETO C

12

PASTT D C

AT 2,060 ENGINE RPM

SPARK TIMING OF TilE ENGINE COMBUSTION(8.111)

coliesesy .11 Jonn Deere Ltd

It has been shown that spark timing must beadjusted to engine speed. The advancemechanism makes this adjustment. The mostpopular type of advance mechanism is a cen-trifugal advance. its main parts are twoweights. a weight base and two springs(Figure 8.112).

CENTRIFUGAL ADVANCE MECHANISM

CAM

ADVANCEEIGHT

WEIGHTBASE

PINCONNECTING

WEIGHTSPRING

(8-112)

PRIMARYLEAD


e weight base is part of the distributor driveshaft. The springs are connected to the base.while the weights are placed on the base. Thedistributor breaker cam has two pins whichconnect it to the springs and weights.

174

1


At idle speed the breaker cam is pinned to thebase and rotates with the drive shaft. The camlobes then open the points at a preset timesuch as four degrees before top dead center.

NO ADVANCE FULL ADVANCE

OPERATION OF CENTRIFUGAL ADVANCE

(8-113) Courtesy of Jonn Deere Ltd

As tree engine speeds up, centrifugal forcethrows ,he weights out against spring tension'Figure 8-113) When tha weights move outthey twist the breaker Jarn so that the camlobes strike the breaks+ lever earlier Thus thecontact points open earlier and the spark isadvanced As the engine slows down. thesprings grsdually return the breaker cam andweights to their original position

The centrifugal advance is calculated in a setratio et spark advance to engine speed: at fullthrottle it gives complete spark advanceCylinder conditions, however, are not asregular as the set advance-speed ratio mightimply There is a lime, at part throttle forexample. when the cond:tior,s during com-pression and combustion are such that morespark advance could be used. At part throttlethe amount of air taken into the engine isrestricted and a vacuum can develop in theengine inta. e manifold, allowing less fuel andair into the cylinder The amount of vacuum inthe manifold is determined by the enginespeed and the throttle opening With less air-fuel mixture entering the cylinder and with themixture being slightly riches e . not as muchair). the mixture will burn slower In such at.:tuation spark must take place sooner Thecentrifugal advance can't advance the sparkany further because it is in a set speed-ad'. -ince ratio The furthc- advance is ac-complished by a vacuum advance mechanism(f=igures 8-114)

(8-114) VACUUM ADVANCE MECHANISMCourtesy of Jonn Deere Ltd

The vacuum advance uses an air-tightdiaphragm connected to an opening in thecarburetor by a vacuum passage. Thediaphragm is connected by linkage to thedistributor housing or the Vreascer plate.

When a vacuum at the intake manifold drawsair from the diaphragm chamber. it causes thediaphragm to rotate the distributor breakerplate in the opposite direction of drive shaftrotation. The breaker lever contacts thebreaker cam lobes sooner and advances thespark.

A combination of the centrifugal and thevacuum advance mechanisms gives a sparkadvance unit which is sensitive to all speedand load conditions.

Other parts of the ignition system yet to bediscussed are secondary wiring, a ballastresistor, and spark plugs.

SECONDARY WIRING

Secondary wiring carries the induced coilvoltage (20.000 volts or more) first from thecoil's high tension terminal to the distributorcap and then from the outside distributor capterminals to the spark plugs. Because of thehi,h voltage they carry, these wires must beheavily insulated. The insulation must be oilresistant and must also be able to withstand afair amount of heat as the wires run close tothe manifolds.

Until the early sixties, secondary wiring wasmade of about 16 gauge copper or aluminumwire. At that time, wiring with carbon im-pregnated liners or cores was introduced. Thecarbon impregnated core provides art. 'stance path for the high voltage surgeswhich helps eliminate radio and television in-terference from the ignition system.

1 75


Other improvements have followed. such asgraphite saturated fiberglass cores and softsilicone insulation that allow the wire towithstand more heat and generally make itmore durable.

The ends of secondary wiring that fit onto thedistributor cap. the coil tower. and the sparkplugs are equipped with insulating boots. Theboots either slide over the cable or are bond-ed to It

BALLAST RESISTOR

Earlier. a bypass ignition system was men-tioned. When starting. a bypass circuit takesfull voltage to the coil for a hotter spark. butonce the engine starts. battery voltage passesthrough a resistor which cuts the voltage tothe coil. The decreased voltage. because itgenerates less heat, gives longer life to thepoints. condenser and coil. The resistor usedIS called a ballast resistor.

Instead of a ballast resistor. some manufac-turers use a resistance wire which is con-nected between the ignition switch and theCoil. Note that there IS no bypass circuit here.When the conductor is cold at starting. vir-tually full voltage is sent to the coil. but as theconductor heats up the resistance increasesand reduces the voltage.

SPARK PLUGS

When the topic of electrical circuits was in-troduced. it was said that no current flowed inan open circuit In most cases this IS true.However. if the opening in the circuit is smalland a strong voltage is present. the circuitcan still be completed. Strong voltage willforce the current to jump the opening or gapto complete the circuit. Such a jumping ofcurrent occurs at the spark plug gap to com-plete the ignition circuit

Spark Plug Operation

A spark plug (Figure 8-115) has two con-ductors or electrodes One is connected bywire to the distributor cap and the other ISconnected to ground The two electrodes areseparated by a small opening or gap

STEEL

SHELL

TERMINAL

INSULATOR

SEALING MATERIAL

I-REACH-

1,41 SPARK GAP---".

ELECTRODES

(8-115) SPARK PLUG CONSTRUCTIONCourtesy of John Deere Lid

The iligh voltage surge comes in through theterminal, travels down the central electrodeand then jumps the gap to the bottom elec-trode. After the complex ignition act.on thatyou have seen at the coil and distributor.current jumping The gap to create a sparkseems rather simple. The spark. however. isno: just any spark. it must be of the correct in-tensity and duration to cause efliciert fuelcombustion. Spark plugs must be carefullyconstructed tr, give such a controlled spark

Plug Construction

All spark plugs have basically the same partsas the one shown above. Variations in plugsresult from these parts being designed dif-ferently. Spark plug parts are discussedbelow.

Outer Shell

Each spark plug has a steel outer shell. Thetop of the shall IS hex-shaped for tighteningthe plug when installing it The lower part of

1 76


the shell is threaded and screws into thecylinder head. The grounded electrode ex-tends out from the lower part of the shell Agasket slips over the threaded portion of theplug and rests against the flange at tne bot-tom of the upper part of the shell The gasketserves two purposes, it seals the plug againstcompression loss and provides a path for thetransfer of heat to the cooling system. Notethat instead of a gasket and flat flange someplugs will use a tapered seat.

The distance from the flange to the end of theplug threads is called the reach. The roach ofa spark plug is very important in plug selec-tion A plug with too long a reach will extendtoo far into the combustion area Not only willthe plug run hotter, but it is also in danger ofbeing hit by a piston or valve A olug witn tooshort a reach will run cold and cause misfiringdue to fouled electrodes

The engine's Service Martial will give theexact spark plug soecif,cations for eachengine.

.,park Plug Insula:or

The insulated core or insulator is mounted .the outer shell Insulators are usually made ofsuch insulating materials as wr..te ceramic orporcelain The material must withstand ex-treme heat. cooling and vibration The insulator is held in position and shielded Iromthe outer shell by an inside gasketsealing compound Beside., olding the cen-ter electrode. the ins 1-Or _ a snield for theelectrode so that ant will flow onlyth,ough the electrode The exposed upperportion of the insulator must be kept clean toprevent current from escaping Many plugshave ribbed insulators to discourage dirtbuild-up.

Spark Plug Electrodes

The electrodes are usually made of a metalalloy that can withstand constant burning anderosion The gap between the two electrodesis of prime importance in plug operation. Tnisgap must be set to exact enginespecifications If the gap is too narrow thespark will be weak and fouling and rntshi ngwill result: if too wide. the gap may work vr ?IIat low speeds. but at high speeds cr het yloads it will strain the cc:I and nat. semisfiring. The .S4rfaces of the two electrodesat the spar, ing point or gap should be pa: leland have squared corners to give the evr, anta better lump across the gap.

Heat Range Of Plugs

The heat range of a spark plug is another im-portant plug characteristic. Heat range refersto the plugs ability to transfer heat at the firingtip to the engine's cooling system. A plug'sability to transfer heat is determined by thedistance the heat must travel. A short in-sulator seat quickly carries heat from the coreleaving a cold plug A long insulator seatallows the core to retain maximum heat andmakes a hot plug (Figure 8-116).

COLDPLUG

HOTPLUG

SHOPT NOSE CONE LONG NOSE CONE(8-116)Courtesy of John Deere Lid

Engine design and operating conditions willdecide whether a hot or a cold plug shot beused.

Generally. an engine which operates at fastspec ,::6 or heavy loads. i.e., the engineoperates hoL will require a cold plug so thatthe heat will transfer quinkly. On the otherhand. an engine that usuzNly operates at lowor idle speeds will use a hot plug. The 1.30tplug will burn off the deposits that form on aplug's electrodes when an engine operate,. atSew speed' for long periods of time.

177

BASIC ELECTRICITY

Hot and cold plugs. the two extremes, are notthe only plugs available. For more normalengine operations, a plug that is somewherebetween hot and cold is used. In Figure 8-117note the length of heat travel in the differentplugs. as indicated by the length of thearrows.

ENGINECOOLINGSYSTEM

8:75

1:OT MEDIUM HOT MEDIUM COLD COLD

(8-117)" SPARK PLUGS OF VARIOUS HEAT RANGES Courtesy or ..10,1 Deere Lid.

CAM ANGLE (DWELL) AND BASIC TIMING

Cam Dwell

Cam dwell is the number of degrees duringthe rotation of the cam that the points remainclosed (Figure 8-'. 8).

POINTSOPEN

POINTS

POINTSCLOSED

POINTSOPEN

CAMANGLE

CAM DIRECTIONOF ROTATION

(8-118) CAM ANGLE (DWELL)Courtesy (A Juan tieere Ltd

Cam dwell is necessary to insure completebuild-up of the magnetic field within the cool,or why:' * Called Coil saturation. If coilsaturation is not reached. the amount of in-duced voltage from the coil will be reduced.

Cam angle will give a low spark at highSpelds and cause ;misfiring. Excess camangle allows the poi Its to remain closed too

long resulting in burned points that makestarting difficult.

Cam angle and timing are directly related;one degree of cam angle change equals onedegree of timing change. The relationship isImportant because as the rubbing block onthe contact points wears. the cam angle willincrease and so throw the timing out.

Cam dwell defines contact point operation interms :f cam rotation and closed puints.Another way to look at point operation is interms of the length of the gap between thepoints when they are fully open. If points areset according to cam dwell, a dwell meter isused; if they are set by point gap. a feelergauge is used. Both the cam dwell and thepoint gap should be measured to get a correctsitting of the contal points.Basle TimingSetting the cam dwell or ooint gap is the firststep 'n adjusting the disti'butor. The secondstep is called setting the basic or initialliming. Basic timing is adjusting thedist:ibutor so that the spark occurs at thecorrect time to give full combustion power.The distributor ,- adjusted by loosening theclamp and rotating the distributor in itsmounting.

Basic timing Is set with a timing light orstroboscope (described later) while theengine is idling and there is no influence fromthe Centrifugal advance.

178


PREVENTIVE MAINTENANCE OFIGNITION SYSTEMS

Removing And Installing Spark Pings

Pull the wire from the plug by grasping theterminal, not by pulling on the wire.

After loosening the plug. but beforeremoving it. always clean the area aroundthe spark plug by blowing. wiping. orbrushing (Be sure to protect your eyes.)Cleaning in this way will prevent dirt fromfalling into the cylinder after plug removal.

3 Use a deep-well socket to remove thespark plugs Also remove the gaskets withthe plugs (if used).

4 II the plugs are to be reused. be sure tonote whicn cylinder each came from. Thecondition of the spark plug can tell you alot about the operation of a particularcyclmder

5 When replacing spark plugs, it is best toreplace all of them at the same time totake full advantage of new plug per-lormance and economy.

6 When installing spark plugs with gaskets.be cure the gaskets are in place Thegaskets act as a seal to prevent loss ofcompression around the plug. Without agasket. the reach of the plug would alsochange. affecting plug operation.

7 Remember another point about gasketsMost manufacturers recommend installingnew gaskets with both new and recon-ditioned spark plugs Always remove the9Id gasiiet from the spark plug Never usebotn the old anti the new gaskets as plugreach would be aflected

8 Tighten It ,e spark plugs to the torquespecified 9 e service manual II a torquewrench is not available. tighten the plugunit! you leel it seat then turn it one-half

three-quarter turn more (With steelgaskets. tighten one-quarter turn afterseating )

9 Connect the spark plug wires to theproper plugs

Tightening spark plugs to the correctspecif cations cannot be over-emphasizedOver torquing at best can make thq plugs dif-ficult to remove and at worst can break theplug off at the threads Under torqued. looseplugs result in poor heat transfer and reducedplug Me

SPARK PLUG SERVICING

Spark plug service has three steps (Figure 8-119)

inspection

cleaninggap adjustment

CHECK

CRACKS

WIPE CLEAN

CLEANELECTRODES

FILE AND RE-GAP

REPLACEGASKET

CLEANINSULATION

UNTILWHITE

(8-119)MAINTENANCE OF SPARK PLUGS

Courtesy 01 Jonn Deere Lid

Inspection Of Spark Plugs

In most shops the practice is to replace plugsafter a reasonable service life or if they givetrouble. Whether plugs are reused or not. allfailed plugs should be carefully examined, astheir condition can tell you many things aboutthe state of the engine.

Cleaning Spark Plugs

Although cleaning spark plugs probably won'tbe a general practice. occasionally you maywant to clean them.

1 A sand-blasting machine is used toremove deposits from the insulator andelectrodes. Carefully inspect the plug af-ter blasting to insure that all the sand hasbeen removed. as engine damage couldresult ti any was left on the plugs.

2 Do not use a power wire brush to cleanthe plugs Most plug manufacturers do notrecommend this method.

179


3 Badly fouled plugs should be replaced Itis doubtful that sand blasting can remove311 the deposits from such plugs

4 Clean the threads with a wire hand brushor a powered soft wire brush wheel.

5 Wet. oily plugs may require cleaning witha petroleum solvent before abrasivecleaning

6 Before gapping the electrodes. file themwith a sinzill point tile to flatten their sur-face at the firing point and to square upthe edges (Figure 8-120). Squaring thesurface edges can reduce spark voltagerequirements even more than cleaning theplugs does.

FILE

Al $731

ELECTRODE

(8-120)FILLING THE SPARK PLUG ELECTRODES


Adjusting Spark Plug Gaps

1 Whether a plug is new or used. alway,check the gap before you install it (Figure8-121)

.4

0 63 mm(025")

(8-121)CHECKING THE SPARK PLUG GAP

(-ourtesy 0 John Deere Ltd

Use a wire spark plug gauge to check thegap The wire gauge will give a true gap

: - '

reading even if the electrode surface isnot flat

2. If the gap is too wide. the plug may needreplacing.

3. Use a bend nq tool to adjust the gap tospecificati, Often the bending tool ispart of the luge as shown. After ad-justing. check 4,, be sure the electrodesurfaces are parallel.

4 Never bend the center electrode as youmay crack or break the insulator tip.

ADJUSTING THE CONTACT POINTGAP OR CAM DWELL

Generally points, like plugs, are replaced aftera reasonable service life or when they givetrouble. If it is necessary to reuse contactpoints because new ones are not available.dress the contact surfaces with a fine oilstone. Be sure to clean the points thoroughlybefore installing them.

The correct way to set points is first with afeeler gauge and then with a dwell meter. If adwell meter is not available extra care shouldbe taken with the feeler c auge settings.

1. Adjust points with a feeler gauge: Withthe breaker cam posit.oned so that therubbing block touches a cam lobe at itshighest point. adjust the points with afeeler gauge to manufacturer'sspecifications

2 Adjust points with a dwell meter: A °wellmeter can be part of a distributor machineor it may be a separate portable unit. Thelatter is the most likely to be found in aheavy duty shop Following directions.connect up the dwell meter. crank theengine and adjust the points to thespecific dwell angle.

Note:

If the cam angle reading on the meter variesmore than two degrees between lobes look fora won; drive shaft or bushings.

It a problem is encountered in trying to obtainthe correct setting. check for the followingpossibilities:

improper spring tension

wrong contact point assemblyworn breaker camworn distributor shaft and bushing

180


USE OF TIMING LIGHT

Once the point gap or cam dwell has been adjusted. the basic or initial timing can be setBasic timing is done while the engine isidling The object of basic timing is to matchup the timing mark on the turr:ng crankshaftpulley (on the flywheel on some olderensures) with a fixed mark or timing pointeron tile timing cover or housing. To match upthese marks a timiiig light (a st000scopiclight) is used The timing light is connected tothe vehicle's battery and to the number onecylinder spark plug lead. Every time numberone cylinder fires. the light will flash. Directedat the fixed mark and the crankshaft pulley.the flashing light will make the pulley appearto stand still, and you will be able to see howfar the two marks are out. Or ::e you have seenthat the timing is out. loosen the distributorholding clamp and while sial watching thetiming light turn the distributor one way or theother to bring the two marks together (Figure8-122) With the marks matched up. tightenthe holding clamp, stop the engine andremove the timing light.

A4230,

(3 .122) TIMING MARKS (TYPICAL)Courtesy of General Motors Corporation

Two points to note when setting the timing:1 Be sure the idle speed is as spec,:ied by

the manufacturer.

2. Moat manufacturers recommend that thevacuum line to the advance unit bedisconnected when setting basic timing.Don't forget to reconnect the line after thetiming has been sc.t.

1 81

WIRING HARNESS

Wiring for electrical accessories in vehicles isbound together in trunk lines called a wiringharness. A vehicle may have tour or five har-ness lines supplying electricity to differentparts of the vehicle. Branch wires come oftthe harness trunk and connect up to theirspecific accessories. The harness sheath canbe made of rubber. cloth. plastic, plastictubing or can simply be electrical tape wrap-ped around the wires. Two points whenworking on a harness:

Care must be taken when installing, a har-ness not to interfere with any moving partsof the vehicle Install clips correctly sothat they do not pinch the wires and causeshort circuits.

2 Individual wires can be replaced by run-ning a new wire around the harness. Donot try to thread new wires through theharness Attach the new wires to the har-ness with tape or clips. Be sure to cut oftthe defective wire right where it comesout the harness.

Replacing Wiring

1 Since the size of wiring is related to theload it must carry. always replace a defec-tive wire with the same gauge wiring asthe original. Never use undersized wiringbecause it will overheat and possibly burnthrough.

2 When installing additional accessories ona vehicle. such as extra lights, and anexisting circuit is used. the circuit mayhave to be re ,,ired with heavier wire tocarry the au, load.

The gauge or size of an electrical wiredepends on'

(a) Total lengtn of the wire in the circuit.

(b) Total amperes that the wire will carry.

Refer to a wire catalogue for wire size andload carrying capacity.

3 When replacing a faulty wire end. it is bestto solder the connection onto the wire.Use only rosin core ler. 1 he otheralternative is a crimp .. wire connector.Crimp-on connectilns a okay in a cleanenvironment. but if the ..re used in acorrosive area the ^or.: $cliuns tend todeteriorate. Crimp-on connectors shouldbe fastened with crimping pliers.

r

I

r

N

\


FUSES

From the discussion on basic electricity youremember that given a set voltage source,such as a battery. the amount of current isgoverned by the amount of resistance in thecircuit. You can see the current resistancerelationship in the formula:

amps = volts

ohmsAs the resistance (ohms) gets greater thecurrent (amps) gets smaller, and vice versa.as the resistance gets smaller the current getsgreater.

In a vehicle all electrical circuits have aresistor of some kind to control the amount ofcurrent flow. What would happen. though, ifan overload or a short circuit occurred?Current would rapidly increase to the pointwhere the wire would burn up. To protectagainst si.ch excessive amounts of current,fuses or circuit breakers are connected to thecircuit. When the current gets beyond a safelevel the fuse blows, breaking the circuit andstopping the flow of current

A fuse consists of a fine wire or thin metalstrip enclosed in a glass or fire resistant pieceof tubing Most fuses used in industrial equip-ment are of the small replaceable type asshown in Figure 8-123.

(8-123)

Courtesy or Jowl Deere Ltd

The fuses for all the circuits in the vehicle arelocated in a central fuse panel where they canbe easily replaced.

Points On Fuses

1 BLOWN FUSES ARE USUALLY CAUSEDBY

(a) A short circuit in the electrical circuitcaused 63y defective wiring or adefective component (lights. motor,etc )

(b) An overk.ad in the circuit caused bya surge of electricity passing throughthe circuit.

(c) Poor contacts in the electrical circuit

(d) Overheatir g in the circuit caused byoverloads or poor contacts.

(e) Use of incorrect size fuses in the cir-cuit.

(f) Fuse located too near a hot areasuch as an engine or a heater.

(g) Vibrations near the fuse. causing thefuse contacts to come loose.

2. If a fuse is blown by overloading the glasswill be clear; if blown from a short circuitthe glass will be dark.

3 If the fuse in a circuit repeatedly blows.and no short circuit exists, it means thatthe circuit is overloaded and is not meantto carry the loads being placed upon it.

4 Always place a blown fuse with one ofthe same size. Never use a fuse with ahigher amperage rating as it may causeserious damage to the circuit it is sup-posed to protect.

182

8:8C BASIC ELECTRICITY

QUESTIONS IGNITION CIRCUIT

1. Briefly state the purpose of the ignitionsyste m

2 What are the two circuits of an ignitionsystem. State what each circuit consistsof and what. in general terms. is thevoltage.

3 What is the purpose of the primary circuitin the ignition system?

4 What occurs in the ignition coil when thepoints open?

5. Self-induced voltage in the primary win-ding of the coil is absorbed by the

(a)

(b)

(c)

(d)

wires

battery

distributor

condensor

6 The ignition ballast resistor in theprimary circuit'

(a) is connected in series for crankingand parallel for operation.

WI is connected to bypass for startingand series for operation

(c) is used to decrease ignition currentd'iring cranking

(d) If.. only required for dual ignitionsystems.

7 In the ignition coil one end of the secon-dary winding is connected to the hightension terminal and the other end to the

(a)

(b)

(c)

(d)

rotorprimary windingcondensor

points

8 How can reverse coil polarity be correc-ted

(a)

(b)

(c)

(d)

change the battery polaritychange the ignition codreverse the secondary wiresreverse the primary wires

9 What three jobs must the distributor per-form?

10 The distributor is driven at

(a)

(b)

(c)

(d)

crank shaft speed

one-half crarie.shaft speed

twice crankshaft speedOnequarter crankshaft speed

11. The centrifugal advance mechanismcontrols the spark timing by sensingengine'

(a) temperature(b) power

(c) speed

(d) oil pressure

12 A is used in conjunctionwith a centrifugal advance mechanism toimprove spark timing.

13 A ballast resistor used in the ignitionsystem improves the Ide of me:

(a) cod

(b) condensor

(c) points

(4) all the above

14. A spark plug:

(a) makes the spark to fire the air-fuelmixture

(b) increases the spark intensity

(c) controls the spark timing

(d) provides a gap for the spark to jumpacross inside the combustion cham-ber

15. What term is used for spark plugoperating temperature?

(a) heat travel

(b) reach

(c) the number system

(d) heat range

16. What determines the heat range of aspark plug?

(a) engine horsepower

(b) number of cylinders(c) engine design and operating con-

ditions(d) whether the engine is a two stoke or

four stroke

18d

BASIC ELECTRICITY 811

17 Dwell may be defined as the number ofdegrees of cam rotation when the pointsare

18 As the cam angle increases the sparktiming wilt'

(a) advance

(b) retard

(c) not change

19. What two methods can be used to set thepoints?

20 What are the effects of loose or under-torqued spark plugs?

21 True or False? Generally speaking, sparkplugs should be replaced as a set

22. True or False? Badly fouled plugs shouldbe replaced rather than cleaning them.

23 What effect does filing the gap have on aused spark plug's performance?

24 What is the rec(46,-.^..anded tool forchecking spark plug gap?

(a) flat feeler gauge

(b) stepped feeler gauge(c) wire feeler gauge(d) dial indicator

25 When adjusting the initial timing using atiming light. tt is recommen led that theengine be and the

be disconnected

26 The gauge oi size of e!ectrioal wiringdepends on

(a) the size of battery(b) the total length of the wire in the cir-

cuit

(c) the total amperage that the wire willcarry

(d) both (b) and (c) are correct

27 True or False? If a fuse keeps blowingand there is no short circuit. put in aheavier fuse

28 To obtain the best possible connectionwhen replacing wire ends. they shouldbe

(a) crimped on(b) pushed on

(c) soldered on 184


ANSWERS ELECTRICITY THEORY

1. (b) negative to positive.

2 (c) energy.

3. True.

4. Voltage is the force that causes currentto flow in a conductor.

5. (d) ohm.

6. Voltage source. e.g.. batteryResistor. e g . light bulbConductor, e.g.. copper wire

7 (a) to (b)`41:4 to (c)

(c) to (a)

E 128

R 4= 3 amperes

9 Any substance that as a goo° transmitterof electricity.

10 A closed circuit has a resistor to controlthe amount of current flowing in the Cir-cuit In a short circuit the current takes ashort cut by passing the resistor Sincethe short circuit has no resistor, currentbecomes very high and will usually burnout the conductor (or fuse :f there isone).

11. .. direct OC

12. West a measurement of electricalpower found t elying volts timesamperes

13 Series, Parallel, SdriesParallel

14. (c) low resistance high amperage.

15. ... magnf .c field. Like poles repel.unlike poles attract

16. Both have a magnetic field surroundingthem. The stronger the current in s con-ductor. the stronger its magnetic field.

17. Place an iron core in the center of thecoil.

18. (d) ampere turns-49 Electromagnetic induction

20 False Either the conductor movingacross the field or the field across theconductor will induce a current.

21. (a) to (c)(b) to (a)(c) to (b)

22. (d) red for positive. black for negative

23 1. Strength of the magnetic field.2. The speed at which the lines of force

are cut.3. The number of conductors cutting

across the lines of force.

24. . . move towards -

25 .. move away from

165


ANSWERS BATTERIES

1 (c) lead peroxide in the positive plate.

2. negatlie plate grouppositive plate groupseparators and connecting straps

3. When it is immersed in the electrolyte

4. (d) 2-volts.

5. True.

6. (d) 1.270

7. True

8. (c) water

9. Prior to use, a dry-charged batteryretains its full state of charge providedno moisture enters the cells. whereas awet charged battery requires periodicreotwgirlg to maintain its charge

10. Wet-charged.

11. The plates are enclosed in envelopeswhich act as separators.

12. They require less maintenance, are moredependable and will last longer.

13. Temperature, battery's operating cycle,and the state of the battery's charge.

14 Cold power rating the amount ofpower or amperage that a battery willsupply for starting on cold days.

Reserve capacity the period of timethat a battery by itself (i.e., without thegenerator or alternator) will supply anadequate amount of power to operate avehicle's electrical circuits.

15 False.

16. . .. the power requirements of theengine it must start.

17. ... self discharge.

18 (b) baking soda

19 (d) water

20 (c) disconnect the grounded terminalcable

21 (d) all of the above are necessary.

N

186

44 .


ANSWERS BATTERY TESTING

1 (a) a hydrometer

2 (d) 030

3 (b) 9.6-volts

4 1-volt

5. True

6 A load test

z

187


ANSWERS BATTERY CHARGING

1 (b) 7 amps 7 positive plates and 8negative plates.

2 A slow charger because it does a morethorough job of chemically renewing theplates.

3 (b) series.

4 1 The temperature should not exceed15 C (125 F)

1 The electrolyte shouldn't becomecloudy with sediment.

5 (b) Hydrogen

5 False. It is damaging to batteries toovercharge them

7 (c) disconnect a battery cable

8 (a) a longer charge

9 . off . .

10 False


ANSWERS STARTER MOTOR

1 (d) mechanical energy.

2 True

3 (b) a force to be exerted on the con-ductor

4 (c) movement c..f a magnetized core intoand out of an electromagnetic coil.

5 The magnetic switch completes the cir-cuit between the oatte.y and the startermotor. whereas the solenoid not onlycompletes the circuit, but also provides amechanical means of shifting the startermotor pinion into mesh with the flywheel.

6 (a) connect two batteries in series forstarting and in parallel for charging.

7. 1 Transmits drive torque from the star-ter motor to the engine flywheel

2 Provides a gear reduct:on.

8 (c) remove the battery ground strap

9. Centrifugal force acts on the coun-terweight and causing the pinion to spininto and out of mesh with the flywheel

10 ... overrun ...

11. ... magnetic ... solenoid ...

189


ANSWERS CHARGING SYSTEM

1. (b) supplies all current.

2 (e) a commutator and brusnes.

3. 1. opens and closes the charging cir-cuits.

2. prevents overcharging of the battery.

3. limits the generator's outout to a safelimit

4. (c) diodes

5 (a) Limit the voltage to a safe value.

6 In a generator current is induced bymoving conductors through a stationaryfield.

In an alternator current is induced bymoving a held by a stationary conductor.

7. True.

190


ANSWERS IGNITION CIRCUIT

1 To take low voltage from the battery andcreate nigh voltage to fire the engine.

2 Primary Circuit ignition circuit.primary winding in Coll. points and con-denser. low voltage.Secondary Circuit secondary windingin coil, distribution cap and rotor andspark plugs; high voltage.

3 To create and collapse a magnetic fieldin the ignition coil.

4 The magnetic field created by thecurrent flow through the primary windingcollapses across the secondary windinginducing a high voltage in the secondarywinding.

5 (d) condenser

6. (b) is connected to bypass for startingand series for operation.

7 (b) primary winding

8 (d) reverse the primary wires

9 1. opens and closes the primary circuit.

2 times the high voltage surges.3 delivers the current to the spark

plugs.

10. (b) one-half crankshaft speed.

11 (c) speed

12. .. vacuum advance ...

13. (d) All of the above.

14. (d) provides a gap for the spark to jumpacross inside the combustion chamber.

15. (d) heat range

16. (c) engine design and operating con-ditions.

17 .. closed.

18. (b) retard

19. Use a dwell meter to set the cam dwell.or a feeler gauge to set the point gap.rhe dwell meter is the most accuratemethod.

20. Poor heat transfer which will shortenplug life.

21. True.

22. True.

23. Filing reduces the voltage requirement tosend a spark across the gap.

24. (c) wire feeler gauge.

;5. ... idling .. . vacuum line to the advance

26. (d) both (b) and (c) are correct

27. False.

28. (c) soldered on.

191


ELECTRICITY TASKS

BATTERIES

Preventive Maintenance On Batteries

1. Safely usv jumper cables to start avehicle.

2. Completely service a battery:

(a) Remove the battery using correcttools and safety procedures.

(b) Clean the battery with baking sodaand water and dry off the case.

(c) Check the water level and add waterif low.

(d) Test the battery as accurately as youhave equipment for. If you have a bat-tery test meter, follow the msiter'soperating instructions.

(e) Charge the battuu. Get experienceusing both slow and fast chargers.

(I) Install the battery ensuring that thebattery box and hoiddown are ingood condition.

STARTING MOTOR AND GENERATOR

Safety

1. Practice safety by disconnecting the bat-tery before working on any electrical com-ponent to prevent short circuits.

Routine Maintenance Check

1. Check the condition and tension of thegenerator belt(s). If necessary adjust thetension. If the belt(s) are not serviceableinstall and adjust a new one(s).

2. Check the condition of the generatorpulleys, and repair or rerlace, ifnecessary. Check pulley alignment.

Service Repair

1. Remove and install a starter motor and agenerator using the correct tools andprocedures outlined in the servicemanual.

IGNITION SYSTEM

1. Service the spark plugs on an engine.Remove the plugs. clean, gap and reinstall them. or if the plugs are not serviceable replace them with ones of thecorrect type and heat range as stated inthe service manual. Using a torquewrench, tighten the plugs to the torquegiven in the service manual.

2. If ignition testing equipment is available,check and adjust dwell and ignition timingto the specifications stated in the servicemanual.

3. Get experience working with electricalwiring:

(a) Select correct wire sizes.

(b) Solder wire ends using rosin coresolder.

(c) Fuse circuits for a safe amperagedraw.

(d) Install a fight or similar electricalcomponent, ensuring it has goodgrounding.

192

BLOCK

Winches

WINCHES 9:1

TRACTOR MOUNTED WINCHES

A tractor mounted winch (Figure 9-1) is a sim-ple gear reduction assembly mounted at therear of the machine. By using cables, thesewinches can reel in heavy loads or hold theloads while they are dragged the winchesare driven either by a:

1. Live power take-off (P.T.O.) shaft (Figure9-2) from the torque converter

2. Live P.T O. shaft tram a manual trans-mission (not common today)

3 Hydraulic motor.

I

(9-1)Courtesy of 1-1vSter Company

Drums on winches are large, spool-shaped,steel castings. They're driven by the winchesreduction gearing (Figure 9-3). Cable (wirerope) is attached to the drum and is woundonto the drum's surface or lagging.

REDUCTIONGEARING

Cangani oneoll year train (9-3)

Courtesy of Carco Winch Products

Most crawler tractors have single drum win-ches However. some special application trac-tors will use two or more drums and eachdrum will have its own controls. For example.multiple drum winches would be uSee on atractor doing yarding work in logging or on atractor working in electrical transmission lineconstruction. The discussion in this manuallimits itself to single drum winches.

(9.2) Courtesy ol Caterpillar Tractor Company

194

9:2 WINCHES

Cable may be wound onto the drum in one oftwo ways overwind or underwind Overwindwinds from the top of the drum and un-derwinds from the bottom (Figure 9-4)

IJNDERWINDING(9-4)Couriosy of !Oster Company

WPM

OVERWINDING(9-41

Courtesy of HySiet Company

Performance and SpecificatIonsPSIPSM (Power Shift/Power Shift Manual)

There are advantages and disadvantages inboth ways of winding. Overwind tilts the loadso it doesn't dig in. but when loads are heavythis lilting can cause the tractor to rear. Con-veesely. underwind gives a straight pull thatwon't cause the tractor to rear but the loadwill have a tendency to dig in. Unless an un-derwind is requested. winches come from thefactory set for overwind.

I t is a major job to change from overwind tounderwind or vice versa. Internal changes toboth the winch gearing and the line positionhave to be made. Also. if the machine has anautomatically applied mechanical brake. it toorequires alterations.

TRACTOR WINCH RATINGS

Tractor winches are rated according to their"line pull" and their "line speed". Line pullmeans the maximum amount (in kilograms orlbs.) of pulling strength a winch can exert onits cable. while line speed is simply the speedat which the cable travels faster. Line speedwill vary with the tractor horsepower. the sizeof the drum. and the layers of cable wrappedaround the drum (i e.. cable travels slower asmore of it wraps around the drum) Drum size(i.e.. cable capacity) IS another factor In ratinga winch. One manufacturer's ratings orspecifications for its different winch modelsare shown in Figure 9-5

(9-5)

MODELAPPROXIMATESNIPPING WT

RARE DAUMr LINE PULL

UM SPEED{depending onttoMor lip)

CASTE CAPACITIESORUM

DIMENSIONS1%" l 1 is- l r ti- 1/4" ti," l env - A S C

740 5113.0mm 21271b 500001) 5010 S60 rim moo 230 ft 30011 440 ft *I m 18 to 121tmF50 111Cop. Drum 112710 r.0.000 lb 5910 150 fpm 215 11 306 fl 42011 500 ft 8 in 19 m i3Nin0.00 SM. Drum 3264 10 80.0001b 5010 1501pm 185 0 2500 3400 476 0 1210 22 m 1314m040 111-Cop. Drum 325410 00,000 lb 50113 150 Om 260 ft 316 tl 4200 675 ft 9 la 221n 14%in

.1 A Std. Drum 4086 lb no coo lb saw 00Ipm 166 0 200 0 270 0 MO II 13 m 24 en 12 In4,120 iii-C.p.Onin 405610 120,00010 5010 160 fpm 225 ft 3001t 400 II 525 11 101n 24 in 140fin

NOTE Potionnanb, figures bison on Dower town of OM *nowthrow Wino fine NANO will very valn to quo converterGetout *mot is dependent on *none loud end Weed

195Comm rtOSY Of CarCo Winch Pppclioc ts

WINCHES 9:3

TYPES OF SINGLE-DRUMTRACTOR-MOUNTED WINCHES

There are three main types of tractor-mountedwinches

1. direct drive sliding gear

2. power shift hydraulic control constantmesh gear

3. hydraulic drive

Direct drive and power shift winches aredriven by the tractor engine through use of aPT 0. shaft. A hydraulic drive winch is drivenby a hydraulic motor.

stationary. The gear positions would bemechanically actuated by a shift lever afterthe engine clutch had interrupted power tothe P.T.O. shaft. Note that free spool for quickwind out can be obtained by ieleasing thebrake when the winch is in neutral.

DIRECT DRIVE SLIDING GEAR

A simplified view of a direct drive sliding gearwinch is shown in Figure 9-6. A direct drivewinch has no clutch. Before the winch can beshifted. the master clutch between the engineand transmission has to be disengaged sothat power to the P.T.O. shaft is interrupted.

(9-7) NEUTRAL, DIRECT DRIVE

(9-7) FORWARD. DIRECT DRIVE

t FTOSmAFT2 BEVEL GEAR3 BEVEL GEAR SHAFT4 2N0 REDUCTION PINIONS 2N0 REDUCTION GEAR6 BRAKE SHAFT7 INTERMEDIATE MOON8 0NTERMEDIATE Gem9 DRUM PINION

10 ORum GEARii DAUM12 INTERMEDIATE PINION13 CLUTCHm SHIFTER SHAFT16 BRAKE WHEEL

(9-6)Courtesy of Hyster Company

Figure 9-7 shows the power flow or gearmovement when the winch is in neutral. for-ward and reverse. The shaded gears andshafts are moving. the unshaded ones are

(9 -7) REVERSE. DIRECT DRIVE

Courtesy of HySter Company

196

9:4 WINCHES

Other points about direct e,ive win.:.hes

Lubrication is by splash. The winchcase or housing serves as the oil reser-voir and it has drain, fill. and on levelplugs

Line pull power is controlled by theengine speed.

Brakes for these winches are usuallyan external contracting bane-typelocated outside the gear case in aseparate compartment. The band cor-tracts around a gear shaft, thus holdingthe gear and stopping the drum fromturning. The brake is a dry-type anu iscontrolled by a lever beside the shiftlever (Figure 9-8).

BRAKELEVER

A hydraulic pump. located either critside or in-side tha winch supplies the pressure and flowto operate the clutch packs. Power shift win-ches have the advantage over direct drivewinches of being able to winch-in or winch-out while the machine is moving. Figures 9-9and 9-10 show power shift winches.

Power shift winches have either a single ordouble lever control The double lever modelhas one levee for shifting into forward. reverseor neutra: and anotner lever to apply thebrake A single lever model curies out all ofthese operations with one lever the brake isapplied witomatically when the lever is movedfrom forward or reverse to neutral. and viceveiza. the brake is released when the lever ismoved from net.tral to tine of the gears. Onboth models the shifting lever activates the

SHIFTLEVER

0.8)

Courtesy 01 Carco Win-h :Nactuets

POWER SHIFT WINCHES

A power shill winch has virtually the ;amedrum and set of gears as a direct drive winch.Both winches are driven by a live P.T.O shaftWhere they differ is in the way that the win-ches are shiftea To shift a direct drive winchthe engine master clutch is disengaged andthe winch s sliduig gear is mechanically shif-ted. Power shift winches. on the other hand.have hydraulically activated clutch packs andconstant mesh gears for shifting. Two clutchpicks are used. one forward and one reverse

EXTERNALCONTRACTING

BAND

hydraulic control valve which sends hydraulicpressure to apply one of the multi-disc clutchpacks. The clutch packs then set the constantmesh gears in a forward or reverse mode.Generally. brakes on power winches arespring applied and hydraulically released Thebrakes are external contracting band or multi -aisc.

Power shift winches. like direct drive winchescan free spool. Some manufacturers offer anoptional free spool lever which operates adisconnect gear that allows cable to be freelydrawn from the drum. In the case of a singlelever power shift. the lever has a free spoolposition where the winch is in neutral and thebrake is not applied. Figures 9-9 and 9-10show power shift winches. note the clutches

197

WINCHES 9:5

-s

w6E

$ PIO Si-.4412 avec GEAR3 01vEt GfAti ., AF 14 2ND Ilk oveilqp, porvuov5 ?NO *It Our.1soN GE AR8 BRAKE VoAs .i $141EnklEOA1f eiNsOlso8 $0416 Awl 01A: e <A AR9 01tv$A P1000N

10 ['RUM (AAA:1 f ftvso12 641E foot 0,A1E PINION13 011. (.1.1,11CH

14 OIL BRAKE1$ CONTROL VALVE

Courtesy of Hyster Company

Wax W120

The housing of both powershif. -1 direr.Idrive winches serves as an oil -ervoirHowever. lubri..alion is only partly by ;,.ash.The remainder of the lubrication (and cooling)is carried out by pressure fed oil The oil ispressurized from art engine dr,,en pump.

'9-9)Power Controlled

SUCTIONSTRAINER RETURN FILTER

SOLID BARCABLE GUARD

MULTIPLE DISCFRICTION CLUTCHES

CAST STEEL CASE

(9-101

SINGLE LEVERCONTPOL

iPRESSURE LUBRICATED

BEVEL PINION

...-i,SPRING-APPLIED,HYDRAULICALLYRELEASED BRAKE

Courtesy of Carco Welch Products

198

9:6 WINCHES

HYDRAULIC WINCHES

Hydraulic winches can be installed on anyvehicle that has an adequate hydraulicsystem They are not limited to crawlers. Themain advantage of a hydraulic winch overP T 0 shaft-driven power shift and direct drivewinches is that the hydraulic winch can bemounted wherever ycu want it providing thathydraulic lines can be connected to it.

Two Types of hydraulic winches. sliding gearand planetary. are illustrated in Figures 9-11and 9-12 and are discussed below.

Hyd aulic Motor \:-reversible io 14.6.1

provide 2 speeds t,

\N.in each 'e;

-.4-,winch direction ,e.

Duai Controls-separaie brakeand shift leversfor positivecontrol

The sliding-gear hydraulic winch works thesame as the direct drive model describedearlier. The only difference is that it's drivenby a hydraulic motor rather than by a P.T.O.shaft. The hydraulic motor is driven by ahydraulic pump mounted on the engine. Theplanetary model shown here has twoplanetary gear sets. one in the primary drivehousing and one in the final drive housing.The primary drive housing contains ahydraulic motor which drives trse sun gear ofthe primary reduction gear set The ring gearis held by a spring-applied brake. and outputpower is transmitted by the planet carrier to ashaft which passes through the center of the

Solid Bar Cable Guard

PRIMARYPLANETARYREDUCTION

HYDRAULICGEAR

MOTOR

Cast Steel Case

Manual Brake withreversible bandOptionalOverrunning Brake

(9-11) SLIDING GEAR HYDRAULIC DRIVE WINCHCourtesy of Carco Winch Products

WINCH BARREL

(9-12) PLANETARY HYDRAULIC DRIVE WINCHCourtesy of Gearmatic Company

199

FINAL PLANETARYREDUCTION

WINCHES 9:7

winch barrel to the sun gear of the finalplanetary reduction. The ring gear in the finalplanetary is also held. The planet carrier isconnected directly to the winch drum by asplined hub and thus transmits power to thedrum In this planetary arrangement a doublereduction is obtained Note that the planetarygear sets operate in either direction depen-ding on which way the hydraulic motor isdriven

Two types of brakes are used on thisplanetary winch; one brake permits a highreverse line speed and the other gives auniform line speed in both reel-in and reel-outdirections. Lubrication is by splash. as it is inthe sliding gear hydraulic winch.

Hydraulic planetary winches are very commonand are available in a variety of sizes andcapacities.

Winch clutches. brakes and hydraulic systemsare described below.

WINCH BRAKESThere are two main types of winch brakes:

1. External contracting band brakes

2. Multi-disc brakes

EXTERNAL CONTRACTING BAND BRAKES

External contracting band brakes are thesame type of brakes that are used for crawlersteering. The band brake works in con-junction with forward and reverse gearsgiving control over the load when it is beingraised or lowered. Some band brakes aremanually applied with a separate lever.whereas others are applied automatically.Automatic brakes are usually spring-appliedand hydraulic-release. Hand applied brakesare used where more accurate winch controlIS desired. In the powershift winch in Figure 9-13 the automatic band brake is shown on thewinch, while the manual brake is inset. Noteon the automatic brake the hydraulic releasecylinder and the large brake apply spring.Also note the optional heavy duty brake lust tothe left of the large gear driving the drum.Some winch models offer dual braking for ad-ded safety and load control. This second bandbrake is lever applied.Optional HeavyOtsty Brake

Multiple DisciFriction Clutches

OptionalAutomaticBlair*

J-120-PSO

OPTIONAL HEAVYDUTY BRAKE

SYSTEM

Stow SpeedGears

(9-13) STANDARD MANUAL BRAKE SYSTEMCourtesy of Carco winch Producis

9:8 WINCHES

AUTOMATIC BRAKE OPERATION

AUTOMATIC BRAKE ONPOWERSHIFT WINCHES

The brake is applied in neutral position(Figure 9-14) When the control lever is movedaway frc -.eutral. eithe to reel-in or reel-outposition. oil pressure 83 led to the brakerelease cylinder to release the brake At thesame time oil is sent to the clutch packs toengage the clutch. Moving the control back toneutral simultaneously releases the clutchand dumps oil from the brake release cylinderallowing the brakes to be spring applied Thebrake itself can either be a contracting bandor multi disc

NEUTRAL-0°

0.

The brake wheel is held stationary by a brakeband that is applied with a lever. The hub issplined to a driven shaft. and the hub andpawl assembly rotate around the inside of thebrake wheel ratchet ring. When cable i5reeled in. the panel slides over the ratchetring When the control is moved from reel-into neutral. the pawl engages with the nearestratchet tooth and locks the. hub to the brakewheel automatically stopping any further feedout

If cable reel-out or free spool is desired theband brake is released by the brake lever.When the band is released. the brake wheelwill revolve with the engaged pawl assemblyand the cable will feed out.

This automatic brake can be used for un-derwind or overwind. Overwinding is stampedon one side of the brake assembly. and un-derwinding on the other side (Figure 9-16).

(9-14)

COureSty of Carco Winch Products

AUTOMATIC BRAKES ON DIRECTDRIVE WINCHES

One manufacturer of wincheS. Hyster. has anover-running brake referred to as automatic.This brake is offered as an option to the stan-dard bralce band. Its operation is shown inFigure 9-15 and described below.

PAWLASSEMBLY

DIRECTIONOF REEL-8N

BRAKE WHEELiS HELD STATIONARY

BY BRAKE BAND

BRAKE WHEELRATCHET RING

RATCHET HUB AND PAWLREEL ASSEMBLY ARE

SIDE VIEW DRIVEN BY THE(9-15) BRAKE SHAFT


V, WI

COWieSy 0/ Hyster Contonv

The assembly must be installed on the brakeshaft so that the desired wind faces outward.Also. the brake wheel must match the wind.

201

WINCHES 9:9

MULTI-DISC BRAKES

Some models of winches are now usinc an oilcooled multi-disc brake similar to that inFigure 9-17. This disc brake is spring-appliedby the belleville spring and hydraulicallyreleased When the tract )r is stopped. or thewinch control is in neutral, spring pressureapplies the brake by squeezing the splindeddiscs of the pack together against a pressureplate. When the control is moved to reel-in(forward) or reel-out (reverse). oil pressure isapplied to the piston and releases the brakes.

THRUSTRING

COOLINGOIL LINE

COVER

HUB

CAGE

PRESSUREPLATE

FRICTION DISC.(11 RECYD1 PISTON

HOUSING

PUSH ROD

SEPARATOR PLATE(10 RED.D)

PISTON

BELLEVILLESPRING

COOLING OILOUTLET(4 PLACES)

PRESSURE INLETFITTING

(9-17)

202

COurlosV 00 HYSter Company

910 WINCHES

POWER SHIFT CLUTCHES

Clutch packs used in powershift winches aresimilar to those used in powershift trans-missions and in crawler steering clutchesThe packs are muitidisc made up of exter-nally splined steel discs alternating with in-ternally splined. lined discs (Figure 9-18) Thesize of the pack its diameter and thickness, isdependent on the size of the winch Clutchpacks for forward and reverse are usuallyidentical on larger winches. but on smallerwinches the packs for the two gears can varyin size Winch clutch packs are hydraulicallyapplied and spring released

CLUTCHPISTON

BELLEvILLESPRINGS

CLUTCH DISCS

Besides lubricating the gears, oil in the winchhousing also acts as a hydraulic fluid to applythe clutch packs. Winch oil is usually thesame type as that used in the tractor's trans-mission. 011 pressure for the winch is usuallysupplied by an engine driven pump (Figure 9-19). Hoses connect the pump with the winch.When the engine is running. the pump cir-culates pressurized oil through the controlsystem to apply the clutches and release thebrake and also to lubricate the winch. Notethat the winch housing acts as a radiator tocool the oil as well as acting as the oil reser-voir

(9-19)

(9-18)

Colatesy of Hyster Company

HYDRAULIC PUMPDRIVEN OFF THE ENGINE

203

PTO

Connnsy of Hyste( Company

WINCHES 9:11

Figure 9-20 shows a winch hydraulic system.Note the suction and pressure filters whichprotect the pump. control valve, clutches andthe rest of the system from any contaminantsin the Oli Also note the relief valve whichregulates oil pressure in the system

(9-20)

PUMP

TO PRESSURE

GAUGE

FORWARDPRESSURE

ANO COOLINGOIL UNE

REVERSE

PRESSURE*NO COOLING

OIL LINE

SUCTIONFrk TER

PRESSURE

FILTER

CONTROLVALVE

REVERSE

BRAKE CLUTCH

COOLING 'Wm HANOIOIL LINE

OILDUMP

BRAKEVALVE FORWARD

ASSEMBLY iLEP T HANOI

11(


A recent change in winch design by onemanufacturer includes the hydraulic pump aspart of the winch unit. The pump IP located in-side the winch housing and IS eriven by thePTO shaft (Figure 9-21).

PUMP

(9-21)

VALVE

FILTER

SUCTION:, SCREEN

Courtesy of Hysier Company

204

9:12 WINCHES

The advantage of a winch with a self-contained hydraulic pump is that it eliminatesthe need for hydraulic lines between the trac-tor and the winch thus greatly simplifyingremoval and installation procedures(especially on machines using other back-endequipment such as a ripper) The only linesfrom the winch to the tractor are a controlcable and a gauge pressure line Eliminatingthe hydraulic lines means that there is nochance (or a suction hose leak and much lesschance of contaminating the oil whenremoving and mstalltng the winch

WINCH OPTIONS

A high capacity drum and a lairlead (Figure 9-22) are two examples of options offered forwinches A bolt-on fainead permits the cableto be reeled-in at an angle without damagingthe cable.

(9-22) High-capacity drum

Courtesy 01 Carco Winch Products

(9-22) Three - roller fairtead

Courtesy of Coico Winch Products

205

WINCHES 9:13

QUESTIONS TRACTOR MOUNTEDWINCHES

1 List the three methods used to drive trac-tor mounted winches

2 Cable may be wound on a drum in one oftwo ways

(a) Left or right.(b) right or loose(c) Forward or backward(d) Overwind of underwind.

3. True or False? Overwind lifts the load sothat it does not dig in. but on a heavyload this lifting can cause the tractor torear

4 Winches are normally shipped from thefactory set for

5 Tractor winches are rated by the

(a)

(b)

(c)

(d)

Line speed.

Size of drumLine pull in (Kilograms or lbs.).(a). (b) and (c) are all correct.

6 List the three common types of tractorwinches

7 To shift gears on a sliding gear. tractormounted winch the

(a)

(b)

(c)

(d)

Engine must be slowed downTractor's master clutch must bedisengaged.

Tractor must be moving.Transmission must be in gear.

8. How are gears shifted in a powershiftwinch/

9 Both sliding gear and powershift win-ches depend mainly on a

system for lubrication.

10 What is the main advantage of ahydraulic winch over a mechanical drivewinch?

11 The Iwo common types of fakes usedon winches are

(a) Hydraulic and air.

(b) Disc and shoe(c) Band and multi-disc(d) Band and shoe.

12 On a powershift winch equipped with asingle lever conVol. the brake will be:

(a) Spring-applied and spring-released.

(b) Hydraulic-applied and spring-rr leased.

(c) Spring-applied and hydraulic-released.

(d) Hydraulic-applied and hydraulic-released.

13 On a direct drive winch with anautomatic ratchet and pawl brake. theoperator may. without releasing thebrake.

(a)

(b)

(c)

reel -in.

reel-out

do neither.

14 Besides housing the components and ac-ting as the oil reservoir, what other im-portant function does the winch housingperform?

15. What is the function of a fairlead?

16. What are the two main hydraulic com-ponents that are needed to drive ahydraulic winch?

206

9:14 WINCHES

PREVENTIVE MAINTENANCE SERVICEOF TRACTOR MOUNTED WINCHES

SCHEDULED MAINTENANCE CHECKS

The location of the winch often hinders itsmaintenance. being situated by itself at theback of the tractor. it tends to get forgotten Awinch. like any other gear component,requires periodic inspection of the unit and oillevet checks and oil changes Scheduled oilchanges are necessary because after a winchhas worked a complete shift. its housing iswarm. and when the machine is shut down thehousing is surrounded by cool. night air. Thiscool air causes condensation to form in thehousing thereby contaminating the oil. If thiswater-contaminated oil is not changed atregular intervals. damage such as prematurebearing failure or faulty hydraulic control willOccur.

Following is an example of a Preventive Main-tenance Table (Hyster Company) for both adirect drive and a power controlled winch.The table has two schedules. an hourlyschedule and a daily-weekly-monthlyschedule. If the winch is operated more thaneight hours a day the hourly schedule shouldbe followed. If the winch operates eight hoursor fess a day the daily-weekly-monthlyschedule should be used. The alphabeticalletters in the table refer to letters in Figures 9-23 following the table.

SAFEGUARD MAINTENANCE AND SERVICE INSPECTION SCHEDULE

ITEM

SCHEDULE (Hour/Period)

QUAN TYPE I PROCEDURE8/dy

501wk

50013 mo

1000/6 mo

2000/1 yr

Oil Level(Direct Drive)

.,/ CHANGE

18 Gals SAE 90 MIL-L-210513. for tem.peratures above+10°F SAE 10,M1L-L-2104B. orMIL-L-45199Series 3, for tem-peratures +10°Fand lower

Check winch on at levelplug 0 on right side ofwinch Add oil asrequired at plug E,Drain oil at plug and°.NOTE When checkingwinch oil level on win-ches mounted on power-shift tractors slop engineto obtain correct readingFor winches mounted ondirect drive tractors.disengage tractor masterclutch to obtain correctreading

CAUTION. If winch isnew or overhauled drainafter 50 hours ofoperation. then flushrefill. replace pressurefitter element and servicesuction filter

Oil Levet(PowerControlled)

../ CHANGE

20 Gals Automatic Trans-mission Fluid"DEXRON*, fortemperaturesabove -10°FSAE 5W. MIL-L-2104B. or MIL-L-45199 Series 3,for temperatures

10°F and lower

Brake andTransmissionCompartments(Direct Drove/

/ Variable Water and or oil-.

Remove plugOand dramany accumulation ofwater or oil in brake corn.kartment Replace plugV). Loosen plug 0 anddrain any accumulationof water in a heavy film of

207

WINCHES


9:15

ITEM

SCHEDULE (Hour Period)

(WAN TYPE PROCEDURE8'dy

50wk

500;3 mo

1000'6 mo

2000/1 yr

AutomaticBrake(OptionalDirect DriveOnly) (Cont

SERV

I

0E

Mobil Oil(Mobil -tempGrease #1)

Shell Oil(Derma Grease 1)

Standard Oil(Chevron Indus-trial Greases

Texaco (Ther-matex EP #1)

Union 011(Strona HT-1)

Sun Oil (Suna-plex 991 EP)

BP Australia(EnergreaseHTB2)

high temperature greaseon ratchet ring. pawlassembly. and hub DONOT completely fillautomatic brake assem-bly with grease or at-tempt to grease bakethrough the vent plug.

CAUTION Always installOil seals so that vs ofboth seals are pointinginward

Cable GuideRollstOptiOnan

Multi-purposeGrease

Lubricate two greasefittings()

Fair lead(Optional)

...

Multi-purposeGrease

Lubricate six greasefittings O.

SwivelingDrawbar(Optionaio

Mu Ili-PurposeGrease

LubrocM one greasefitting (4).

PressureFilter (PowerControlledOnly)

CHANGE

One Refer to ParisManual

Replace with Hyster azproved filter element IS.Coat 0-ring and backupring with multi-purposegrease to ensure a leakproof seal between frIterand case

Bevel GearShaft Locknut

J Refer to PartsManual of neces-sary to replacelockwasher

Pry lockwasher tangsaway from IOCknut flatsand rettghten locknut to200 ft-lbs torque Bendlockwasher tangs overlocknut flats transmission

1

J

9:16 WINCHES


ITEM

SCHEDULE (Hour:Periodl

OUAN TYPE PROCEDURE8'dy

50wk

500'3 mo6

1000mo

2000.t yr

Brake andTransmissionCompartments(Direct Drive)(Cont)

compartment Tightenp lug 0 when oil appears.

Handling Gear ,' Fewdrops

SAE 30 Lubricate fulcrum pinconnections and othermoving parts at end ofeach eight hour shift

Suction Filter(Power Con-trolled Only)

SERVI

CE

One Peter to PartsManual

Remove suction filter eclean thoroughly. andreinstall

CAUTION If winch is newor overhauled. removeSuction filter @after first50 hours Of operition.clean thoroughly andreinstall

CAUTION Suctionmanifold cover gasketmust be in good condition to prevent airleaks Replace withHyster approved gasket

Suction HoseC lamps(Power Con-trolled Only)

Check both ends of sucton hose to see that hoseclamps are TIGHTRetighten hose clamps asnecessary

Control Cables N. Check both ends of eachcable housing to see thatthey are securely anchored Retighten setscrew Uboll. or bracketbolt as applicable Checkwinch end of power con-trol cable for condition ofroll pin anchor

AutomaticBrake(OptionalDirect Drive0,14

SEFl

v

C

High tempera-hire grease asfollows

Atlantic Rich-held (Thermo-grease

Remove automatic brakeassembly° Disassembleand clean automaticbrake assembly corn-ponems Pack the twobearings with a high tem-perature grease

209

Service Instructions

WINCHES

(9-23)

7 4:00,4.442i4

9:17

OIL LEVEL PLUG

1

0 FILL PLUGTRANSMISSION

DRAIN PLUG

BRAKE COMPARTMENTDRAIN PLUG

'210Courtesy 01 Hyster Company

WINCHES

Figure (9-24) shows the two filters and theirlocations on one model of winch. Whenreplacing loiters. be sure to clean thehousings thoroughly and install new sealrings Also check for leaks after start up

Service Instructions

CU

0.RING

BACK-UP RING

FILTER ELEMENT

FILTER CASE-

SUCTION FILTER PRESSURE FILTER

(9.24) SUCTION AND PRESSURE FILTERS, POWER CONTROLLED WINCH

211

Counftsy of Ilystef Company

WINCHES 9:19

WINCH ADJUSTMENTS

DIRECT DRIVE WINCHES

Direct drive winches require periodic (1)tightening of the brake to compensate for nor-mal running wear, and (2) minor adjustmentsto the control linkages These adjustmentscan be made quickly Below are examples oftypical brake and linkage adjustmentprocedures

(9-25) BRAKE BAND ADJUSTMENTDIAGRAM DIRECT DRIVE WINCH

couriesy of HyStet Company

To adjust the brake band. proceed as follows(Figure 9-25)

1 Remove the small brake cover from theloft-hand side of the winch

2 Push the brake handlever to its fullrelease position

3 Loosen jam nut A

4 Turn adjusting link B until there is ap-proximately 1 32-inch clearance betweenthe brake Land and brake wheel or untilthere is just enough clearance to prevent*brake drag'

5 Tighten jam nut A

6 Replace the brake cover

To adjust the positioning of the Brake Hand-lever. proceed as follows (Figure 9-26)

1 Adjust the brake band.

2 Loosen cable rod-end jam nut

3 Adjust the control cable at the winch con-trol housing-end until dimension C is ob-tained (distance between the cable-endand the centerline of the rod-end pin).

4 Tighten the jam nut

5 Push the Brake Handlever to the lullrelease position.

6 Adjust the push-pull cable at the BrakeHand lever end until dimension D is ob-tained Tighten jam nut.

W396

A= 2-518" 6=15/16 1/8" 0=4.3/4"

19-26} ADJUSTMENT OF BRAKE LINKAGEDIRECT DRIVE WINCH

Courtesy of Hysier Company

POWER SHIFT WINCH ADJUSTMENT

Power controlled winches require ii) ad-justments on mechanical parts such as bandbrakes (note multi-disc oil controlled brakesdon't need adjusting) and (2) pressure checksand adjustments on the hydraulic systemCheck service manuals for checks and ad-justments or. individual powershift winches

Figure 9-27 gives an example of the pressurechecks called for by one manufacturer. Thesechecks wouid be done with the hydraulic testbox described earlier to test crawler brakeand clutch hydraulic controls. If the pressureat any point is not within the allowable limits.the service manual will list the likely causesand stale what service repairs would have tobe done to correct the problem. Always makethese pressure tests to locate the probelmbefore removing a winch. Its quite likely thewinch may not have to come off.

2.12

,/

9:20 WINCHES

Service instructions

. -PRESSURE, PSI

PRESSUREPDRT FORWARD NEUTRAL REVERSE

BRAKEOFF

A 220 (± 101 35 MAX. 220 (-110) 220 f± 5)

8 2201± 10) 2,5 2.5 2.5

C 2.5 2,5 220 (±10) 2.5

D 220 (± 10) 2.5 220 (I 10) 220 (± 101

E 15.30 10.13 15-30 15-30

HYDRAULICPUMP PRESSURE

FILTER

SUCTION MANIFOLDWITH SUCTIONFILTER

Ur. FOOTVALVE

CONTROL 0VALVE

CONTROL-0-,CABLE

CLUTCHPRESSURE LINE

BRAKE PRESSURELINE

COOLING OILRELIEF VALVE

OILBRAKE

REVERSEOIL CLUTCH

FORWARDOIL CLUTCH

CLUTCHPRESSURE LINE

W 3 32c

(9-27) HYDRAULIC SYSTEM PRESSURE CHECKS Come-15v d Hyster Company

REMOVAL AND INSTALLATION OFTRACTOR MOUNTED WINCHES

To remove a tractor mounted winch follow thestep by step procedures outlined in the ser-vice manual. Because of their weight. safety isa main concern when removing winches. Theaverage winch will require a lifting devicewith a minimum capacity of 3000 lbs. (1360.8kg) Cleanliness is also an important concern

in winch removal. for example. b )(ore un-bolting the winch clean the winch and therear of the tractor to prevent dirt from enteringthe winch housing or the tractor transmissioncase Another clean work practice is to coverthe opening in the rear of the tractor alterremoving the winch and PTO shalt Typicalremoval procedures for a Powershift Winchare given in Figure 9-28.

213

WINCHES 9:21

Note that removal of the winch's pump fromthe tractor requires a separate set ofprocedures that will be found in the servicemanual

Warning: If winch is to be disassembled thecable must be removed. Use ex-treme care wnen removing thecable-end ferrule from thy drumWhen the cable lock is resooved.the cable may spring out with ex-treme force.

VIEW FROM TOP OF WINCH

INTAKE MANIFOLD

SUCTION

-*****..r.-

PUMPpsFsuReLINE

CONTROLCABLE-----, I

GAUGE VIPRESSURELINE

STEP I Remove suction hose from intakemanifold Disconnect pump pressureline Disconnect gauge pressure ima

CONTROLCABLE PIN

CAPS CREW

CONTROLVALVE

4CABLEBRACKET/

ROLL PIN

STEP 2 Remove access cover plate Remove cot-ter pin and detach blade end of controlcable from control valve spool clevisRemove capscrew holding cable bracketto housing. and pull out control cable Itnecessary to remove cable bracket,remove roll pin.

(9-28)

7 /8 -IN UNCx 2 1/2-IN(63.50 mm)CAPSCREWS(2 RECrp).4

3000 lbs.(1360.8 kg)

, MINIMUM

At4

STEP 3. Connect lifting device to winch.Winch will be balanced when connectedas shown.

STEP 4. Drain the oil horn the winch.

SUCTIONMANIFOLD / COVER

4 RED /(OUTSIDE)

MOUNTINGPAD

STEP 5. Remove suction manifold and coverRemove the eight nuts and lockwashersattaching winch to mounting pad.

NOTE When removing the eight nuts. loosenall nuts slightly. then pry winch awayfrom mounting pad. Loosen all nutsagain and pry winch again. Continuethis sequence until winch can beremoved.

214


Nar

9:22 WINCHES

QUESTIONS MAINTENANCE AND REPAIROF TRACTOR MOUNTED WINCHES

1 True or False/ Because of the heavyweight of winches. safety is a main con-cern when removing them.

2 Whet is the main source of oil con-tamination on tractor mounted winches/

3 If a winch is operated for less than eighthours a day. what maintenance scheduleis recommended?

(a)

(b)

(c)

(d)

Hourly maintenance schedule

Daily. weekly. monthly schedule

Once a year checks are enoughMaintenance only when required

4 Referring to the section taken from a ser-vice manual on winch maintenance, findthe interval at which the suction filtershould be serviced

S True or False Winch band brakes requireno periodic adjustments.

6 True or False Multi-disc brakes requireno periodic adjustment.

7 What instrument is used to test thehydraulic controls on a power shift winch/

(9-29)Courtesy 01 EtucyrusEne Co01 Canada Ltd

Winch installation procedures will be found inthe service manual. Having installed thewinch and reconnected all the fittings. checkthe following prior to operating the winch.

1 No leakage.

2 Proper oil levels.

3 All mounting nuts are tightened tospecifications.

4 All covers are securely installed.

5 All hydraulic hoses are properly routed toprevent chafing.

6 The hydraulic pump is primed The pumpshould have been primed during in-stallation by filling the suction hose withhydraulic oil.

HOIST WINCHES FOR CRANES,EXCAVATORS AND YARDERS

The history of cable operated machines goesback a long time. Steam driven, partial swingshovels were made over 140 years ago.During the years steam changed to diesel orelectric, the partial swing became a full 360swing. and new versions of cable machinesappeared such as a dragline. a clamshell, ahoe.

Until about 1950 nearly all excavator shovelspowered their buckets by cable winding onand off drums Today cable-drum systems onexcavators have all but disappeared havingbeen replaced by hydraulically operatedbuckets Cable operation. however. is stillwidely used for cranes, draglines. clamshells(Figure 9-30) logging yarders and loaders. andlarge electric mine shovels Cable machinesare divided into three main sections (Figure 9-29)

1 lower works (can be crawler mounted ortruck mounted)

2 upper works (the revolving unit)

3 front end (the attachments)

An even simpler division is to speak of (1) thebasic machine and (2) the convertibility Thebasic machine is the lower and upper works.The convertibility is the front end and is sonamed because front ends are convertibledepending on the type of work it is to do abasic machine can have a crane. a clamshell.a shovel a dragline mounted to it Note thatnot all cable machines are convertible Largemining shovels. for example. are made foronly one lob and have a permanently mountedfront end

215

WINCHES 9:23

Crawler Machine

(9-30)

216

Courtesy of BucyrusErie Coof Canada Lid

9:24 WINCHES

HOIST WINCHES

Tractor mounted winches. as discussedearlier. run independently of the main tractoroperations, a single drum is mounted at theback of the tractor and is used when needed.On the other hand. hoist winches for cranes,excavators and yarders are an integral part ofthe machine's working machinery. They aremounted on the upper works and are used tooperate the machines digging, lifting.shoveling implement (Figure 9-31). Multiplewinches are used on hoist systems. the num-ber. size and arrangement of the winchesdependent on the make. size and rigging ofthe machine

(9-31)

217

Courtesy of BucyrusEno Co.of Canada Ltd.

WINCHES 9:25

CABLE OPERATION

There are a number of cable circuits on ahoist winch system and the cable in each cir-cuit is always tight In any given circuit oneend of cable is attached to a drurr. while theother end is threaded or reeved over a numberof sheaves and Then :s either (1) fastened to apart of the working implement (2) returned tothe drum and fastened at a different locationof the drum or (3) fastened to a fixed point onthe machine. Through the actions of clutchesand brakes. cable is reeled on and off thedrums to control the movement of the bucket.boom. load. etc.

CABLE OPERATIONS ONLOGGING YARDERS

Earlier. it was said that cable was always tightin hoist winch systems. One exception to thisrule is a logging yarder (Figure 9-32) Yardersuse much larger drums and considerablymore cable than shovels or cranes. and thecable runs a lot looser.

There are numerous ways yarders can berigged. one way is shown in Figure 9-33. Apartfrom all the guy lines. this yarder cable systembasically consists of three lines (1) astationary line (skyline) on which the carriageruns (2) a line (main line) and (3) ahaul-back line The haul-back Irne runs onsheave blocks that are attached to stumps

The main line and the haul back lines eachhave their own drums and are attached at thecarriage. The main line drum is larger be-cause it does the heavy work. Logs are at-tached to the carnage by choker cables. andthe main line pulls in the logs on the skyline.The logs are released at their desired locationnear the yarder. and the haul back line pullsthe carriage back out again on the skyline topick up more logs.

iw

(9

(,,, 0 . .1.114 Ltd

(9-33)

218

9:26 WINCHES

BASIC WINCH ASSEMBLY

There are a number of differences in hoistwinches such as size. ways of mounting andactivating mechanisms. A common hoistwinch arrangement is Shown in Figure r1-34:this winch is convertible and can be rigged foran excavator, hoe. crane, dragline or a clam-she II

SWING PROPELCLUTCH GEAR

SWING - PROPELCLUTCHES

HOR SWINGPROPEL SHAFT

TRANS.SHAFT

CHAINDRIVE

CLUTCH(RAISING)

FRONT DRUM

llriilIII

rr

lure;;

iiiIr

arr

11::1111 1; I.

O1111

mt

DRUM SHAFT GEAR

CHAIN DRIVE(LOWERING)

I

CLUTCH & BRAKE(LOWERING)

GEAR DRIVE(RAISING)

MULTIPLE STRANDCHAIN DRIVE

POWER UNIT

(9-34)

219

CLUTCHand BRAKE

REAR DRUM

BOOM HOIST DRUM

Courtesy 01 BucyrusEr* Co01 Canada Ltd

WINCHES 9:27

This basic hoist winch arrangement consistsof two main drum shaft units, one front andone rear. plus a small hoist drum further to therear. The drums are not in line but are parallel.Mounted crossways near the centre of therevolving platform. the drums are positionedto give balance to the whole assembly. Themain drum shaft units are supported bybearings that rest in precision bored supportsin the machinery deck. Older machines usedbronze or babbitt bearings but modernmachines use anti-friction bearings. Thebearings and supports ensure perfect shaftalignment and gear fit. Figures 9-35 and 9-36show two examples of drum shafts resting inbearing saddles. In Figure 9-35 caps are usedto retain the shalt assembly in place; in Figure9-36 the upper half of the gear case forms thebearing cap

Courtesy of S Maddi Lid (9-35)

BEARINGSADDLES

HOIST DRUM f..:-.2iv;SLY

INTERMEDIATE HOISTPINION SHAFT

HOIST BRAKE

HOIST BRAKE SHAFT

(9-36)

Courtesy of Harnischfeger Corporation mil

220

9:28 WINCHES

DRUM OPERATION

As is seen in Figure 9-37. drums are mountedon bearings over the drum shafts. and thus adrum shaft can rotate without turning thedrum. The internal expanding clutch assemblyis attached by a clutch shaft to tte drum shaft.When the clutch is engaged. the drum shaftdrives the drum: when the clutch isdisengaged the drum shaft and clutch rotatefreely inside the drum An external con-tracting bard brake encircles the drum.

BEARING

DRUM

WIRE ROPE

BRAKE

CLUTCH

DRIVER- OR CLUTCH

SHAFT

PITCH DIA

SHAFT' 1324

.W.11L71:C73

FIRST WRAP

0-37)

221

Courtesy of Bucyrus -Erie Co01 Canada Ltd.

A

WINCHES 9:29

WINCH POWER TRAIN

Figure 9-38 illustrates a winch power trainThe power unit droves the transfer shaft andgears by a drive chain (multiple strand) Thesmall gear on the transfer shaft (dotted linesbehind the large transfer gear) is meshedthe large gear on the rear drum shaft which inturn is meshed with the large gear on the frontdrum shalt When the power unit is running.all the parts shown are turning Note that withthis gear arrangement. the front and rear drumshalt rotations are opoosite

FRONT ORUMSHAFT GEAR

Engaging a drum clutch will cause the shaftand drum to turn as a unit, thereby reeling inthe cable attached to the drum Releasing theclutch puts the arum in a free state and anypull on the cable will turn the drum and cablewill be reeled out. The cable and drum can bestopped and held by the band brake

The brake just mentioned works independentof the clutch Some winch br4ices on the otherhand, operate in conjunctibOwith the clutchWhen the clutch is engaged the brakeautomatically releases and. vice versa. whenthe clutch is disengaged the brake is applied

REAR DRUMSHAFT GEAR

TRANSFER SHAFTand GEARS

(9-38)

222

DRIVE CHAIN

9:30 WINCHES

A variation on the basic hoist winch assemblydiscussed above is to add an additional clutchto each of the front and rear drum shafts(Figure 9.39). These clutches allow a toad tobe lowered under power.

SWING PROPELCLUTCH GEAR

SWINGPROPELCLUTCHES

HOR. SWINGPROPEL SHAFT

TRANS.SHAFT

CHAINDRIVE

POWER LOWERINGCLUTCH

(REAR DRUM)

POWER LOWERINGBOTH DRUMS

FRONT DRUM

mr REAR DRUM

DRUM SHAFT GEAR

CHAIN DRIVE(LOWERING)

& BRAKELOWERING

POWER LOWERINGCLUTCH

(FRONT DRUM)

r...--BOOM HOIST DRUM

CLUTCH(RAISING)

GEAR DRIVE(RAISING)

,M11111N

POWER UNIT

MULTIPLE STRANDCHAIN DRIVE

(9-39)

223

Courtesy Of Bucyrus-Erse Coof Canada Ltd

WINCHES 9:31

Each of the power lowering clutches has asprocket attached to it. This sprocket is con-nected by a drive chain to a sprocket on theopposite hoist drum. Notice what happenswhen a load is lowered under power from thefront drum:

1 Remember from the description on winchpower flow that the two drum shafts turn inopposite directions.

2 When the load is to be lowered from thefront drum. the drum's main clutch isdisengaged. leaving the drum free torotate in either direction. Of course. thedrum will be braked until everything is setfor the load to be lowered.

3 Attached to the rear drum shaft. the powerlower clutch for the front drum isengaged. thus engaging the drive chainand causing the rear drum shalt to drivethe front drum

4. Since the rear drum shaft turns in a direc-tion opposite to the front. the front drumwill unwind or lower the load under power.

This procedure would work in reverse to lowera load from the rear drum.

DRUMS AND DRUM LAGGING

Drums are made in various diameters. linecapacities. and shapes to suit the work amachine must do A yarder drum (Figure 9-40)for example. has a high capacity drum be-cause it uses a lot of cable

9:32 WINCHES

The drum working surface or the surface onwhich the cable winds is called the drumlagging Lagging is made in split halveswhich are bolted to the drum frame There aretwo main types of lagging, grooved laggingand smooth tapered lagging. Thickness is animportant characteristic in lagging. Becauseit increases the drum diameter. a thickerlagging will give faster line speed but the linewill run with less power. On the other hand. athinner lagging will give more line power butslower line speed. Since lagging is bolted on.it is convertible. the type of lagging and itsthickness may be changed to suit the par-ticular tront-end attachment mounted to themachine Figure 9-41 illustrates types oftagging.

ti 6°00 00 0

0 00 0

0

00

SPLIT LAGGING WITH GROOVES

(9 -41)

if

i-_,-_,G 1 1.1I '

Y---r.

m

POWER LOADLOWERING CLUTCH

F:c:st CLUTCHAND BRAKE

GROOVED LAGGING

SWING

Grooved lagging guides the cable into placeand prevents the cable from flatteningSmooth tapered lagging works in thefollowing way the cable is anchored to thesmall diameter end As the cable is reeled ineach wrap slides on the smooth surfacetowards the narrow diameter end until snugagainst the previous wrap Thus the cablewinds evenly on the drum The types oflagging by different front ends are listedbelow

Magnet Work:

Hoisting - Grooved LaggingPull In

Dragline:

Hoisting Grooved LaggingPull In Grooved Lagging

Smooth Lagging

Hook and Clamshell:

Holding Smooth LaggingClosing -- Smooth Lagging

ICLUTCH

(9 -41)

SMOOTH TAPERED LAGGING

Courtesy of Bucyrus -Ene Co.of Canada Ltd

Controlled Load Lowering:

Hoisting Smooth LaggingLowering Smooth Lagging

Following are instructions for installinglagging Lagging installation is relatively sim-ple provided you observe the following items

1 Clean the boiled surfaces of both thedrum and the lagging to remove burrs.rust and paint If the mating surfaces arenot luite flat. lightening the bolts willresult in warping the drum slightly Thiswill produce unequal braking and brakelining wear

2 Be sure to line up the lagging with thelubrication fittings so the drum bearingsmay be serviced easily when necessary

3 Torque the bolts in a cross pattern

225

WINCHES 9:33

HOIST WINCH CLUTCHESBRAKES AND CONTROLS

BASIC HOIST WINCH BRAKE

The external contracting band brake has beenused for many years on horst winches and isstill used today. The band is wrapped aroundthe outside of the brake drum (like a steeringclutch brake) and has lining riveted to its in-side lace Smaller bands are one piece:generally. larger bands are two or more sec-tions bolted together to form the circle. Thesections make the large bands easier toremove and install. The ends of the bandshave eyes to connect the bands to their ac-tuating mechanism The complete band brakeand control assembly is attached to the mainframe on the machine. The band brake inFigure 9-42 is spring-applied and sir-released.

BRAKEBAND

(9-42)Courtesy of Bucyrus-Ene Coof Canada Ltd

Various types of controls have been used withband brakes manual linkage. hydraulic.spring apply air release.* and full air Aircontrolled is most common today.

BASIC HOIST WINCH CLUTCH

Like the band brake. the expanding shoeclutch (Figure 9-43) has been used for manyyears on hoist winches This clutch workssimilar to the wheel brake principle of a shoecontacting a drum The difference. though. isthat with a brake the shoe must stop the drum.whereas with a clutch the shce must join itselfby friction to the drum to drive it

CLUTCH SHOE

AIR CYLINDER

(9-43)(APPLY CLUTCH)

Courtesy of Bucyrus-Ene Coof Canada Ltd

In a hoist winch the clutch shues and ac-tuating mechanism are mounted to the clutchassembly. The clutch assembly is splined orkeyed to the drum shaft and revolves with it.The friction surface that the clutch actsagainst is the inside of the brake drum. Clutchshoes have lining material riveted to theirouter surface. The shoes are mounted on theclutch assembly so that they pivot at one endand move toward the friction surface at theother end. Actuation for the shoes is byhydraulic or air cylinders. Once the cylindershave expanded the shoes the clutch joins thedrum shaft with the cable drum and the Iworotate together

Besides expanding shoe clutches. hoist win-ches use external contracting band clutchesContracting band clutches are applied wherethe winch band brake would normally bepositioned and so the brake has to be movedto another location These clutches arehydraulic or air actuated

9:34 WINCHES

Demands for clutches and brakes which willwithstand heavier loads and will require lessmaintenance have brought advances in thebasic band brake and expanding or con-tracting shoe clutch Three examples of thesenew clutches are

1 Expanding air tube, multi-disc clutches.Witchita Clutches (Figure 9-44) as onecommon type of these clutches called.are frequently used on logging yarders.When air is applied to the air tube thediscs and pressure plates are squeezedtogether to provide the drive. Not shown inFigure 9-44 is the drum which surroundsthe clutch assembly. The drum is thedriven member and the hub which iskeyed to a shaft is the drive. A witchitaclutch setup is similar to a steering clutchused on a crawler.

EXPANDINGAIR TUBES

FRICTIONDISCS

mo

-v. 4 ,4":$40-**

41-sr

a+ 19,

(9-44) WITCHITA AIR CLUTCH ca"ne" ofWitchila Company

Expanding air tube brakes are also made.Instead of the one or two discs on air clut-ches. expanding air tube brakes have anumber of discs

2 Air tube clutches used in conjunction witha contracting band clutch. The air tubeand band assembly surround the drumWhen air is applied to the air tubes. theband shoes are forced towards the drum.joining the two and providing a drive.

FAWICK AIR CLUTCH

Courtesy of Fawick Co

3. Magnetic clutches are used where elec-tric power is available such as on an elec-tric mining shovel They are calledMagnelorque Clutches (Figure 9-46).

OUTER MEMBER

CLUTCH-0.SHAFT

1,411ER MEMBER

PINIONSLEEVE

(9.46) A SIMPLIFIED VIEW OFTHE MAGNETOROUE

Courtesy of Harnischfeger Corporation Pam

227

I A

WINCHES

The clutch shaft and outer magnetorquemember are driven by the main motor.Since the inner magnetorque member isseparated from the outer member bybearings. the driven outer magnetorquecan turn without causing the inner mem-ber to rotate. Only when the inner andouter members of the magnetorque arecoupled together magnetically, do bothmembers turn. When the operator placesthe hoist controller in the ON position. theouter driven member coils ate energized.thus creating a strong magnetic fieldwhich couples the driven outer member tothe inner member. When the innermagnetorque unit turns. the pinion sleevedoves the hoist drum

Magnetorque characteristics are suchthat a slight slip between the inner andouter members will cause a large increasein the amount of torque delivered by themagnetorque.

The repair of a magnetorque unit requires.in most cases. that the entire unit andclutch shaft be removed

CAB CONTROLSFOR CLUTCHES AND BRAKES

Examples of mechanical and air cab controlsfor hoist winch clutches and brakes areshown in Figure 9.47

(9-47) MECHANICAL CONTROLSCourtesy of SucyrusEne Coof Canada Ltd

(

9:35

(9-47) AIR CONTROLS

Counesy of SucyrusEne Co.of Canada Ltd.

Two types of valves are used on air controls.Graduated valves are used where variabletouch control is desired and poppet valveswhere the response must be fast and im-mediate

HOIST WINCHES ONHYDRAULIC CRANES

Hydraulic hoist winches are used on modernhydraulic cranes. The power train to operatethe winches is as follows: the crane enginedrives hydraulic pump(s). the pumps generatethe flow and pressure to operate hydraulicmotor(s). and the motors drive the hoist win-ches. By eliminating the mechanical geartrain, drive and control mechanisms thesehydraulic winches have greatly simplified thewinch assemblies and deck machinery ofmechanical hoist winches. Hydraulic winchestake less space. have simpler controls. andrequire fewer adjustments.

Cepending on the manufacturer. hydraulichoist winch controls may be direct control orpilot control. However. the trend on hydrauliccranes and on other hydraulic machines istowards pilot controlled valving.

228

9 :3b WINCHES

Figure 9-48 shows a simplified view of themain hoist drum on a hydraulic crane Notshown. but also usually found on the crane.are auxiliary winches (1 or more) for sup-plementary hoisting

MAIN HOIST CIRCUIT

MAIN HOISTCONTROL LEVER

MAIN HOISTCONTROL LINKAGE

rCONTROL

IVALVES---ta..

uren

COUNTERBALANCE <crVALVE

FREE FALLCLUTCH CYLINDER

ii

L._ 1 r _I

FRO PUMP MAINHOIST

9i

HYDRAULICMOTOR

AUTOMATIC BRAKERELEASE CYLINDER

FREE FALLVALVE MECHANICAL

BRAKE BAND

AUTOMATIC BRAKE

(9-48)Courtesy of BucyrusErse Co0 Canada Ltd

229

e/

WINCHES 9:37

QUESTIONS HOIST WINCHES

1 Referrmg to a cable machine. brieflystate what is meant by

(a) the basic machine(b) the convertibility

2 In contrast with tractor mounted win-ches. the cables on shovel hoist win-ches

(a)

(b)

(c)

(d)

(e)

are smallerrun tight at all times.run within a number of closed cir-cuits

are largerboth (b) and (c) are right.

3 Compared to a cable on a shovel or acrane. logging yarder cable is

(a) shorter and runs tighter(b) longer and runs looser.

(c) shorter and runs looser.(d) longer and runs tighter

4 list three basic ways in which hoist win-ches differ

5 Power to drive a hoist drum is trans-mitted from the drum shaft to the drumby

(a) a clutch.(b) a brake

(c) a combmatior. clutch and brake.(d) gears

6 What prevents a drum from free wheelingwhen the drive is disconnected?

(a)

(b)

(c)

(d)

clutch brakeclutchbrake

mechanical lock

7 When power lowering is desired for afront hoist drum. the power loweringclutch would be mounted on the

(a)

(b)

(c)

(d)

rear drum shaft.front drum shaftmain drive shalt.hnrozontal propel shaft

8. How would the drums on a logging yar-der differ from those used on a crane orshovel?

9. What are the two common types of drumlagging?

10. Increasing the thickness of the laggingincreases the drum diameter and causesthe line speed to

(a) decrease.

(b) increase.

(c) stay the same.

11. True or False? In controlled load raisingand lowering. smooth drum lagging isused

12. What is the advantage of making largebrake bands in multiple pieces ratherthan in one piece?

13. The most common method for applyinghoist winch brakes on today's machinesis by

14 Give two methods used to apply shoe orband clutches on winches

15. What advantage do multi-disc expandingair tube clutches and brakes have overthe older designed expanding shoe andcontracting band ones.

16 The drive and driven members on amachine using magnatorque clutchesare coupled together by

(a)

(b)

(C)

(d)

friction.heat.

mechanical force.magnetic field

17. True or False? Magnetorque clutchcharacteristics are such that a slight in-crease in slip between the drive anddriven members will cause a largedecrease in the torque delivered by themagnetorque.

18. What are the advantages of ahydraulically driven hoist winch over amechanical hoist winch/

230

9:38 WINCHES

REMOVAL AND INSTALLATION OF CRANEEXCAVATOR AND YARDER

HOIST WINCHES

Removal and installation of a hoist winch is arelatively straight forward )0b. On mostmachines the winch is generally mounted sothat drum shaft assemblies come out as a unit,as seen in Figure 9-49.

procedures on specific machines.

ADJUSTMENT ON CONTRACTINGBAND CLUTCH

DRAG CLUTCH BOOM HOIST SWING CLUTCHAND BRAK! BRAKE

19-49)Courtesy of BucyrusEne Coof Canada Ltd.

SOME POINTS WHEN REMOVINGAND INSTALLING HOIST

WINCH COMPONENTS

1 Before attempting to remove a drum shaftassembly. place the working implementcontrolled by the drum shaft in a safelylowered position and remove the cablefrom the drum

2 Tag all hydraulic or air lines that areremoved

3 When the bearing caps and related ac-cessories have been removed. attachslings so that they provide a safe. evenand balanced lift to the shaft assembly.

SCHEDULED MAINTENANCE CHECKS,ADJUSTMENTS AND LUBRICATION

ON HOIST WINCHES

Like most clutches and brakes. hoist winchclutches and brakes require periodic ad-justment to compensate for normal runningwear A clutch slipping under load or a brakenot holding the drum indicates that ad-justments are needed. Tremendous strain isapplied to these clutches and brakes andallowing slippage to go unchecked will soonlead to the parts failing.

Typical adjusting procedures are given below.one for a contracting band clutch and one fora contracting band brake Always refer to theservice or operator's manual for the adjusting

(9-50)Adjustment of contracting band clutches isrecommended for smoother application andless maintenance to the air chamber assem-bly. To make the adjustment. disengage theclutch so that no air is left in the chambers.Then adjust the setscrew (Figure 9-50) to ob-lam a 1/32" clearance. all around. betweenthe clutch surface and the lining.

CLUTCH BAND LINERS

Clutch band liners wear more rapidly on thefixed end than on the moving end.-AMERICAN- clutch bands are made withboth ends alike so that after a period ofoperation in one position. they may be rever-sed to give additional service life.

The clutch band liners should be examinedperiodically for wear. and they shoulu berenewed before they become thin enough topermit the rivets to contact the clutch surfaceand c,..se scoring. When Innings have to berenewed. care must be exercised in their in-stallation to ensure that they are tightly andsmoothly riveted to the band. and that thebands are liot bent out of shape. Afterreplacing the bands. they must be checked for"out-of-round- and 81 necessary. hammeredback to shape to secure good contact at allpoints.

231

EXAMPLEADJUSTMENT OF CONTRACTING

BAND BRAKE(American Hoist and Derrick Co.)

C

WINCHES 9:38

MAIN HOIST BRAKE ADJUSTMENT

BRAKES ARE SHOWN INRELEASED POSITION

REACHROD

1 8" (318 mm)

(9.51)

1 With new or newly relined band set gap onmetal portion of band at point "B" to 1-1/2" (381 cm)

2 Disconnect spring loaded air brakes byremoving pin "G" from clevis "L"

3 Adjust pedal to operators preference byextending or retracting reach rod. Generalsetting is so the full line pull may be heldin the last notch of the pedal latch

4 Set lifter "A" at dead end with brake set030" ( 762 mm) clearance.

5 Make sure that guide "C" is free of bothband and guide bars on band.

6 Set 1:Itsr "D" at live end with brake set to060" (1 524 mm) clearance.

, ,\.,..6

Courtesy of American Hoist and Derrick Co

7 Adjust lifter spring -E- so that It has am-ple lifting force to disengage band whenbrake IS released, but be very careful thatthe spring IS not lightened to the pointwhere there is no recoil left in It.

8. Test with load and make final and allfuture adjustments at split "B".

9 Adjust the devises "L" on the brakechamber rods until they can be connectedto the brake pedal linkage. The hoistbrake pedal and brake valve (on leverstand) must be released (air in brake).Allow 1/8" (3 18 mm) clearance betweenthe back of brake chamber and the nutand washers on the brake chamber rod.

232

9:40 WINCHES

LUBRICATION FOR HOIST WINCHES

Lubrication for hoist winches will be found inservice manuals. The more mechanical thehoist machinery the more lubrication points itwill have Most of the bearings for deckmachinery, operating levers. shafts. bellcranks. etc . have grease fittings tapped direc-tly into the bearings Location of these fittingsas w II as other points on the deck machinerythat require lubrication will be shown in themanual on lube carts. A chart may show in-dividual drum shafts or it may show a com-Mete deck plan. Some charts also include thetype of lubricant and lubrication intervalExamples of lube charts are shown in Figure9-52 and 9.53

TO LURETHISFITTING.REMOVEFRONTCLUTCHGUARD

MAIN & AUXILIARY HOIST DRUM ASSEMBLY

SHAFT & DRUM BEARINGSUSE ITEM #2-6 MONTHS

I:

THESE FITTINGS AREREACHED THROUGHHOLES IN LAGGINGS

(9-52)

233

Courtesy of Amencan Hoistand Derrick Co

BOOM CLUTCHBEARINGITEM #26 MONTHS

WINCHES

BOOM HOIST CLUTCH SHAFT ASSEMBLY

LUBRICATION

SHAFT BEARINGSITEM #2 DAILY

MAIN HOIST CLUTCH ASSEMBLY

(9-52)

Courtesy of American Hoistand Derrick Co

THIRD DRUM CLUTCH ASSEMBLY

9:41

CLUTCH LEVER PINSITEM #8 WEEKLY

(9-52)

234

Courtesy of American Hoistand Derrsck Co

9:42 WINCHES

LUBRICATE MOTORS ANDGENERATORS ACCORDINGTO INSTRUCTIONS ONMOTOR OR GENERATOR.

MAGNETORQUESEALS

2 POINTSEVERY 200 HOURS

MPG

COUPLINGS2000 HOURS

MPG

EXCAVATOR LUBRICATION (HOIST MACHINERYLUBE POINTS ARE STARRED (* })

HOIST DRUM SEALS2 POINTS

EVERY 200 HOURSMPG

HOIST GEAR CASE80 GALLONS

GO

SWING GEARCASE RH

40 GALLONSGO

THE LUBRICATION RECOMMENDEDIS BASED ON OPERATION OF THEMACHINE EIGHT HOURS EACH DAY,FIVE DAYS PER WEEK LUBRICATIONSCHEDULES SHOULD BE ADJUSTED ONTHIS BASIS.

SYMBOLS

MPG - MULTIPURPOSE GREASEGO GEAR OILGL - GEAR LUBRICANTMO MOTOR OIL

10 - INSULATING OIL

WORM SHAFT SEALi POINT EVERY 200 HOURS

MPG

AIR COMPRESSORCHECK EVERY 40 HOURS

DRAIN AND REFILLEVERY 1000 HOURS

MO

MAIN OIL CONTACTORSCHECK EVERY 1000 HOURS

45 GALLONS10

40 HOUkSRACK

PINIONSGL

DIPPER TRIPI POINT - DRUM BEARING(SEE MOTOR NAMEPLATE)

1 POINT - RING GEARSWING GEAR EVERY 120 HOURS

CASE LH MPG40 GALLONS

GO

(9 :>3)

235

Courtesy of Harnischfeger Corporation P&H

WINCHES 9:43

QUESTIONS MAINTENANCE OFHOIST WINCHES

1 What is the first step that must be donebefore removing a hoist winch drum andshaft assembly?

2 An indication that adjustments to theclutch and brakes on a hoist winch arerequired is that the winch

(a) operates slowly.

(b) applies and releases with difficulty.(c) will not release(d) slips under load.

3. A typical adjustment procedure for a shoeclutch requires that the adjustment bemade so that the clearance between theshoes and the drum is approximately:

(a) 1/4"

(b) 1/32"

(c) 1/64"

(d) 1/8"

4. True or False? Hoist winch assembliesshould be lubricated on a "wheneverrequired'. basis

5. Referring to the excavator lubricationchart (Figure 9-53). find at what intervalthe hoist drum seals are grea...ed and whattype of grease is used.

236

9:44 WINCHES

WIRE ROPE

Wire rope comes in a number of diameters.cross sectional constructions and strengths Ithas many uses in the heavy duly mechanicalfield. a few of which are shown in Figure 9-54and 9-55.

(9-54) CRANE OR CLAMSHELL

BOOM PENDANTS Th4

BOOM LINE

r ,., ,A....

I

HOLDING LINE

CLDSING LINE

TAG LINE

BOOM LINEThHOIST LINE

CROWD LINE17

RETRACT LIN

.

''Apr1/1

TRIP LINE

eg -t

(9-54) POWER ;HOVEL (EXCAVATOR)

237

WINCHES 9:45

DRAGLINE

BOOM PENDANTS

(9-54)

4 PART BRIDLE SLING

Lengthof

Sling(SL)

(9-54)

Courtesy of Marlin and BlackWire Ropes Ltd

WIRE ROPESLING

Courtesy of Martin and BlackWire Ropes Lid

238

WINCHES

LOGGING

(9.55) Courtesy of S Madill Lld

WINCHES

The parts of a wire rope are the wire, thestrand. and the core (Figure 9-56).

9:47

The cross section of a common six strand wirerope is shown in Figure 9-57.

(9-57)Courtesy o1 hilatten and BlackWire Ropes Ltd

MEASURING A WIRE ROPE

The diameter of a wire rope is identical to thatof a circle which would surround the rope. Togauge a rope be sure that the faces of thecalipers are in contact with the crowns of twoopposite strands and not in contact with fourstrands (Figure 9-58). To be certain that thecalipers are in the correct position rotatethem around the rope: the greatestmeasurement is the correct size.

Nato: After a rope has been in use it issometimes possible to get two"correct" readings of its size that varyconsiderably. Differer t readings canoccur when the rope has lost its shapedue to crushing or when there iscorrosion or core damage at in-termittent points along the rope.

(9-56)CORE WIRE STRAND

Courtesy of Marten and BlackWire Ropes Ltd

240

(9-58)

INCORRECT

Courtesy of Marten and BlackWere Ropes Ltd

9:48 WINCHES

CORES

The core in a wire rope is the central sectionaround which the strands are laid. Cores canbe made of fiber or steel.

Fiber Core

Fiber cores can be made of vegetablefibers such as manila. lute or sisal.although increasing use Is being made ofmanmade fibers. Polypropylene. for exam-ple. offers the advantage of betterresistance to rotting. drying out and otherforms of deterioration than natural fibers.

The main function of a fiber core is tocushion the steel strands duringoperation. Also because the core isusually impregnated with lubricant beforemanufacture. it acts as an internallubricator during the operation of therope. Fiber core are the most flexible wireropes.

2. Steel Cores

A steel core is usually a small separate orindependent wire rope referred to as anIWRC An IWRC normally has a core andsix strands (Figure 9-59). A wire strandcan also be used as a steel core on fairlynon flexible rope. such as guy wires(Figure 9-59)

A steel core adds strength (7,4%minimum) and provides resistance tocrushing. Additional strength is not theonly reason for specifying a steel core.Where a steel core is required excessiveheal in the operation of a rope couldcause charring of the fiber. An IWRC isalso essential (or maximum performanceon such applications as shovel hoist lines.draglines. etc.

19 wire Wend 6x25IWRC

(9-59)

Courtesy ot Marpn and oinkwire Ropes Ltd

WIRES

Wire on a wire rope varies in its diameter andthe type of steel d is made of The steel willrange from having great strength to havingless strength but more durability or resistanceto fatigue. Note that it Is wrong to think thatthe rope with the strongest steel isnecessarily going to be the best for every lobFor example on a given lob. a rope made witha ductile flexible steel may out perform andout last a rope made of a steel with a higherbreaking strength.

When corrosive conditions warrant ropeprotection over and above normal lubrication.wire Is galvanized.

STRANDS

CHARACTERISTICS OF STRANDS

t Strands are classified by the number ofstrands on a rope and the number of wiresper strand

NO. OFCLASSIFICATION STRANDS

6 7 66 19 66 378 - 19

241

WIRES PERSTRAND

7

16 to 2627 toIt, to 26

1

WINCHES 9:49

2 The wires on a strand have different crosssectional patterns. three of the most com-mon are shown in Figure 9-60.

SEALE CONSTRUCTION

One layer of wires is laid over an equal number of smaller wires. with thesame length and direction of lay. The wires in the outer layer are supportedin the valleys between the wires of the inner layers

,11il

FILLER CONSTRUCTION

In this construction. the outer wires are supported by half their number ofmain inner wires with an equal number of small filler wires.

WARRINGTON SEALE

A strand construction in which one laver of wires is composed of alternat-ing large and small wires. The length of lay and number of wires in eachlayer. are equal.

In larger Size wire ropes. more than one of the above basic constructions may be integrated in asingle strand. (9-60)

3 Most wire rope today is preformed. that is.each wire and strand is preset to the exacthelical shape it will take in the finishedrope A preformed rope won't unravelwhen cut Preformed wire rope is moreflexible. lasts longer. and is easier tosplice (F1; 3-61)

242


9:50 WINCHES

BALANCED PREFORMED NON-PREFORMED

4. Lays of Wire Rope

(Martin and Black Manual). The term "lay"has two meanings in reference to wirerope.

(a) When used to describe the directionof rotation of wires the term is usuallyapplied to two basic lays:

Regular Lay is applied where thewires turn in the opposite direction tothat of the strands in the rope. Theouter wires of the strands are parallelto the rope axis (Figure 9-62).In Langs Lay, the wires in eachstrand are laid in the same directionas the strands of the rope (Figure 9-62) The outer wires of the strands areat an angle to the rope axis and muchKiger lengths of the individual wiresare e, posed

(9-61)rl

REGULAR LAY

243

Courtesy of Martrn and BlackWire Ropes 1.1d

(9-62)

LANGS LAY

Courtesy of Marton and BlackWire Ropes Lid

The advantages and disadvantagesare.

Regular Lay: Greater resistance tocrushing on drums than Langs Lay; itshould always be used on a singlepart Isle. or when one end is free torotate.

WINCHES 9:51

Lange Lay: More flexible and offersgreater resistance to abrasion thanRegular Lay ropes. Only applicationswhere both ends are fixed aresuitable for Langs Lay rope. it shouldnot be used with a swivel terminal.Langs Lay cable is used on powershovels and draglines and for minehoisting.

Right or left lay is determined by thedirection in which the strands arelaid in the rope The strands in a leftlay rope (Figure 9-63) run to the leftfrom the top to the bottom (whichever way you look at the rope).Strands in a right lay rope (Figure 9-63) run to the right from top to bot-tom The vast majority of ropes areright-regular lay.

(9-63)Right Lay

Left Lay

(b) The term lay is also used as a ropemeasurement. One rope lay is thelength along the rope which onestrand takes to make one completespiral around the core.

being good maintenance policy. periodicinspection of all wire rope in critical liftingservice is required by governmentregulations. and records of the inspectionmust be kept. Wire rope should bereplaced when a qualified inspector feelsit can no longer safely do the job it was in-tended to do.

Points on Inspecting Wire Rope

(a) When checking wire rope. the ropeshould not be in motion or should notbe supporting a load: it should haveno stress on it.

(b) All rope used in vertical lifting ser-vice should be checked and eachrope must be considered separately.

(c) Inspections should be done weekly.

(d) There are certain points along anygiven rope which should receivemore attention than others. sincesome areas will usually be subjectedto greater internal stresses. or togreater external forces and hazards.Although different types of cable ap-plications will have different criticalpoints (Figure 9-64) some commonones are:

Pick-up Points These are sectionsof rope which are repeatedly placedunder stress when the intitial load isapplied. Examples are the sections ofrope in contact with sheaves.

End Attachments Al each end ofthe rope. two things must be in-spected. the fitting that is attached tothe rope. or to which the rope is at-tached. and the condition of the ropeitself where it enters the attachment.

(9-63) Courtesy of Leschen Wire Rope Co

WIRE ROPE INSPECTION

Eventually all wire rope deteriorates to apoint where it is no longer serviceable orsafe. Regular inspections. therefore. arenecessary to ensure that the rope :s in ac-ceptable working condition. Besides

244

Abuse Points Frequently. ropesare subjected to abnormal scuffingand scraping such as where the ropecontacts cross-members of a room.Look for bright or shiny spots on therope.

9:52 WINCHES

(9-64) CABLE CRITICAL POINTS

5 An inspection of wire rope should includechecks for the conditions below (Figure 9-6r.). If any of these conditions are found.the strength of the rope is in question andthe possibility of replacing it should beconsidered.

EXTERNAL ROPE DAMAGEOR ABUSE

Rope Abuse Kinking. drum crushing, birdcaged and trapped rope are shown in Figure 9-65.

An "OPEN KINK An "OPEN KINK" after straightening fumemisplaced wires and strands}

(9-65) Courtesy of Marten and BlackWire Ropes Ltd

245

WINCHES 9:53

A rope with snagged wires resulting from "DRUMCRUSHING"

A BIRD CAGE which haS been forced through atight sheave

(9-65) Courtesy of aotatun and Black (9-65)Wire Rope Ltd

A rope that has been 'TRAPPED after lumpingoft a sheave

Corrosion look for serious corrosion in therope

End Point of Cable Check (1) for brokenwires where the rope is attached to the fixture(Figure 9-66) and (2) that the fixture is firmlyattached to the rope or that the rope is firmlysecured to the drum.

(9-66)

One manufacturer recommends that anybroken wires at the dead end of a cableshould be cause for cutting off a section.preferrably at least three feet beyond thebroken wires Refasten or re-socket the rope.

Also check for:

1. The core showing through more than onepair of strands.

2 Evidence of improper lubrication of therope Evidence of the rope overheating orcoming in contact with an electrical cir-cuit.

3. The amount of wear on outer wires. TheOperating Engineer's Manual recom-mends that wire rope should be replacedwhen the wires in the crown of the strandare worn to lees than 60% of their originaldiameter (Figure 9-67).

ti

--1.41

(9-67) Rope whiCh has been worn due to ABRASION(Note even wear around the strands).

Courtesy of Martin and BlackWire Ropes Ltd

246

,t`

0

9:54 WINCHES

DIAMETER MEASUREMENT AND BROKENWIRE COUNT

Reduction in Rope Diameter: Measure therope diameter and compare the reading withthe Original diameter. A marked decrease canindicate a serious weakening of the rope

Broken Wire Count: Broken wires areprobably the most common sign of ropedeterioration because it's normal for runningrope to break wires near the end of its ser-viceable life. Two broken wire counts aremade over one lay length of rope.

1 Count the number of broken wires In onerope lay length on the worst section ofrope It is important that the worst sectionbe used for the count because that is theweakest section of rope Note that thiscount totals the broken wires in all thestrands in the one lay length.

2 Count the number of broken wires in onestrand in the lay length. Again. the worststrand or the strand with the most brokenwires should be counted.

The number of broken wires permitted perlay or per strand per lay is specified ac-cording to the rope size. For example. theOperating Engineer's Manual. using acount for total broken strands per lay.recommends that rope should be replacedwhen

(a) three broken wires are found in onelay of 6 x 7 wire rope

(b) six broken wires are found in one layof 6 x 19 wire rope.

LOOKING FOn BROKEN WIRES

A close search should be made for brokenwires (Figure 9-68) With a sharp awl, pick andprobe between wires and strands lifting anywires which appear loose or move ex-cessively.

Note that flexing a rope can often revealbroken wires that may not be visible when therope is straight (Figure 9-69)

(9-68) BROKEN WIRESCourtesy of Martin and BlackWire Ropes Lid 247

(9.69)Courtesy of Martin and BlackWire Ropes L1C

- ---.-

WINCHES 9:55

Records of inspections, as mentioned earlier. must be kept An example of a Rope In,pection recordsheet is given below Diameter Loss and the number of wire breaks would be recorded and com-pared to allowa'...ie tolerances

Ropedescrip-

lion(hoist,swing

line, etc.)

Date ofInstal-lation

Date ofInspec-tion &Inspec-

tor'sInitials

Rope Condition

Date ofRemoval

Nomdia, in.(whennew)Col 1

Currentdia,In.

Lossof

dia, in.Col 2

No. ofwire

breaksin oneropelay

Cot 3

No. ofwire

breaksIn onestrandof one

layCol 4

(

INSPEC. DRUMS AND SHEAVES

The general condition of drums and sheavesshould also be checked A thorough checkingof sheaves involves checking each sheavewith a groove gauge The drum should be ob-served in operation to check the drum wind

In summary a recommended order ofprocedures for carrying out a wire rope in-spection is

I Measure diameter. Record.

2 Count broken wires (a) in one lay. (b) inone strand in one lay. Record

3 Check rope end points

4 inspect the rope end to end for externaldamage and abuse. Try to find the causeof damage and see if it can be preventedfrom happening again.

5 Inspect le sheaves and drums

LUBRICATING WIRE ROPE

Wire rope has moving parts. Each time a ropebends over a sheave or straightens from aslack position. many strands move or slideagainst each other. Therefore to prevent ropewires from wearing lubrication is rh. essary.An equally important reason for lubricatingrope is to prevent the wires from corroding.Wire rope should not be allowed to rust: rustyrope is dangerous as there is no knownmethod of inspecting it to determine itsrema .zing strength.

No set rule can be given concerning thefrequency of lubrication The frequency willdepend on the conditions to which the rope issubjected The severity of the duty and thedegree of corrosiveness will have to serve asan .ndex in determining the need forlubrication Proper luhricant should be usedThe lubricant should be thin enough topenetrate the strands to the core. but not sothin that it will run off the rope. The bestlubricant is a fairly thick, semi-plastic type.which is applied hot. in a thinned condition.This type of lubricant will penetrate while hotand then cool to form a plastic filler andcoating. which will resist the penetration ofwater

248

9:56 WRICHES

Three methods of applying lubricant to wirerope are illustrated in Figure 9-70. Each hasits advdrilages. and no single method isrecommended in preference to the others Themost convenient method should be used

LUBRICANT

POUR.ON METHOD

(9-70)

SPLIT BOX METHOD

SPLIT BOX METHOD-funnel shapedtax fitted with burlap or wiper at outletend.

BURLAPWRAPPER

THE POURON METHOD-oil should behot, yet adhesive. Always hold thewiping swab behold the sheave.

BATH METHOD

BATH METHOD-for applying heavier-bodied lubricant at high temperature.

' Gas burners or steam heat may be usedto maintain temperature of lubricant.Rope should rim through slowly.

CUTTING WIRE ROPE

When wire rope is to be cut. swings shouldbe placed on each side of the cut line toprevent underlaying of the strands. A seizingIS shown in Figure 9-71. The se:zing on the leftis loose to show how it's wrapped On theright is the tightened seizing

ROPE WOULD BE CUT HERE

(9-71)

On preformed wire rope. one seizing on eachside of the cut is usually considered to be suf-

Counesy of HarniShteger Corporation P.51-1

AM.

14,

ficient. On non-preformed wire ropes less than7/8 inch in diameter. two seizings on eachside are recommended. On non-preformedwire ropes over 7/8 inch in diameter. threeseizings are recommended.

Three basic methods are recommended forcutting wire rope:

1. Abrasive cutting tools. A suitable abrasivecutting machine will cut cable.

2. Shearing tools. Wire cutters can be usedto cut through smaller ropes. while specialblade-action tools and a hammer are usedfor larger sizes.

3. Flame. Welding equipment can be used toburn cuts through wire rope. Flame cut-ting isn't recommended if the wire strandsneed to be free after the cut as the torchtends to weld the strands together.

249

WINCHES 9:57

STORING WIRE ROPE REELS

Wire rope reels should be stored in a coveredarea if possible and on pallets or timbers

CLAMPS AND SHEAVES

WIRE ROPE CLAMPS

Clamps are used to

Form a loop in a rope in order to attachthe rope to a fixture (Figure 9-72).

CLAMPSMETAL EYE

(9-72)

Courtesy of Marton and BlackWire Ropes Lid

2. Form loops to attach two ropes together.The metal eyes are connected together.

The U-Boll in Figure 9-73 is a very commontype of clamp used with wire rope. Properly at-tached U-Bolts are fairly efficient clamps: im-properly attached they are unsafe.

(9-73) U-BOLT

Courtesy of Crosby GroupDivision of American Float and Derrick

Another type of clamp is the Double Saddle orFist Grip clamp (Figure 9-74). These clampsare better than U-bolts because they can't beInstalled incorrectly (i.e., they are the same onboth ends) and they cause less damage to thewire rope. Also, a fist grip loop requires lessrope turnback than a U-bolt loop and con-sequently fewer clamps are needed. In spiteof the advantages of Double Saddle clamps.U-bolts still seem to be the most commonclamp used, perhaps because they arecheaper and more readily available.

(9-74) DOUBLE SADDLE CLAMP

Courtesy of Crosby GroupDivision 01 American HolSO and Derrick Co

250

9:58 WINCHES

SHEAVES

A sheave (pronounced shiv) is a wheel with agrooved circumference around which a ropeturns A clothesline pulley is a sheave.Sheaves used on heavy duty machines aremade of steel and either turn on or with anaxle Tnese sheaves have either a bronzesleeve bearing or anti-friction bearings andgenerally have grease fitting(s) that must belubricated (Figure 9-75).

(9-75)

SHEAVE CROSS SECTION

Courtesy 0 Marton and BlackWire Rope Lid

7//7. I V/74

The groove on a sheave is made to fit a par-ticular size rope One of the major causes ofpremature rope failure is having sheaves andropes incorrectly matched. A groove that istoo small will pinch and distort a rope.wearing or damaging one or both rope sidesToo large a groove gives the rope no lateralsupport which can cause the rope to flattenand the wires and strands to be displaced(Figure 9-76)

GROOVECORRECT

GROOVE TOO(9 -76) LARGE

II you need to match a sheave to a rope firstmeasure the sheave with a groove gauge(Figure 9-77) Knowing the sheave size youcan check with a rope manufacturing com-pany the rope size suitable for it.

251

(9 -77)GROOVEGAUGE


GROOVE TOOSMALL

Courtesy of Malin and BlackWore Ropes Ltd

3-

.

WINCHES 9:59

Bending over sheaves is a factor that affectswire rope life. As the rope bends over asheave or winds on and off a winch drum.especially under load, it is subjected to addedstress. The less bend the rope IS forced tomake the less strain imposed on the rope. The"Diameter- of the sheave, therefore. is alsoimportant to rope operation. Wire rope life in-creases as the ratio of sheave diameter torope diameter increases A chart is given inFigure 9-78 showing the minimum sheavediameter size to rope diameter size

(9-78)

MINIMUM DIAMETERS:A Sheave or Drum of too small diameter will hasten "fatigue" in any wirerope. The following table gives recommended minimum sheave treaddiameters:

,.. For 6 x 7 construction 42 x rope diameter

i:For 6 x 25 Flattened Strand construction 36 x rope diameterFor 18 x 7 construction 34 x rope diameter

is For 6 x 19 Seale 30 x rope diameter28 x rope diameterFor 6 x 21 Filler ,.

O For 6 x 25 Filler 25 x rope diameter(13

=(a For 6 x 26 construction 26 x rope diameter

For 6 x 31 construction 24 x rope diameterFor 6 x 36 construction 22 x rope diameterFor 8 x 19 SealeFor 6 x 41 construction

21 x rope diameter20 x rope diameter

For 6 x 43 . 21 x rope diameterFor 8 x 25 " 18 x rope diameter

Figure 9-79 illustrates sheave applications ona power shovel.

SHEAVES

BOOM LINE

SHEAVES

Courtesy of Marton and SlackWore Ropes Ltd

HOIST LINE

' ". A .

$ 1 o t.S

Err

RETRACT LINETRIP LINE

Courtesy of Bucyrus -Ene Co(9.79) of Canada lid

252

9:60 WINCHES

Multiple sheaves are used on some machinesto gain mechanical advantage Increasing thenumber of lines and sheaves reduces thespeed of the load being Idled but increasesthe amount of load that can be lifted. Theshovel in Figure 9-30 has a two part line to thebucket giving d a mechanical advantage oftwo In other words. the bucket can lift twiceas much as it could with one line to it

REMOVING AND INSTALLING WIRE ROPE

TAKING WIRE FROM A COIL

When unreeling wire rope. it is important thatthe coil or reel rotate as the rope unwinds. Ifthe coil or reel does not rotate. the wire will betwisted as it is uncoiled. and kinking willresult

Kinking is caused by the rope taking a spiralshape as the result of unnatural twist in therope Figure 9-80 shows the progressivestages of a kink. and the end result

1

2

55==z7ssz3

(9-80) KINKING OF WIRE ROPE

Part 1 of the illustration shows the beginningof a kink At this stage. no harm will be done ifthe loop is immediately thrown out to preventfurther kinking.

Part 2 of the illustration shows the effect ofthe application of a load to a kinked line. Therope has been seriously strained and is nolonger safe for maximum service.

Part 3 shows the condition of the rope afterthe kink has been straightened out. Strandsand wires are out of position. This createsunequal tension and strain and will cause ex-cessive additional wear on the damagedareas.

Figure 9-81 shows the correct methods forunreeling ropes from coils or reels.

WRONG WAY RIGHT WAY

WRONG WAY RIGHT WAY

WHEN UNREELING OR UNCOILING WIRE ROPEDO NOT ALLOW ROPE TO FORM A LOOP IF

LOOPS ARE FORMED KINKING WILL RESULT

(9-81) UNREELING WIRE ROPE


Another acceptable method of reeling rope offa reel is to place a shaft through the center ofthe reel and support the shaft so the reel canrevolve as the rope is pullei off. If this methodIs used. the reel should not be allowed torevolve so rapidly that it throws rope oil reelthe rope off slowly.

253

WINCHES 9:61

REWINDING ROPE

When unwinding rope from its storage reel toanother reel or a drum. the rope must bereeved from the top of one reel to the top ofthe other. It is also acceptable for a.) un-derwind to reel from the bottom of one reel tothe bottom of the other reel or drum. Byfollowing either of these procedures. you willavoid twisting the rope (Figure 9-82).

WINDING ROPE ON A DRUM

On grooved drums the cable will be laid in thecorrect position by the grooves. but onsmooth faced drums. such as on a tractormounted winch. attention must be given togetting an even lay on the first layer. When in-stalling a new line on a tractor mountedwinch. attach the line to the drum in the over-wind or underwind position. whichever thewinch is set up for (most mounted winches areset for overwind). Then attach the other end toa firm tail-hold and winch the machine back-wards to load the drum. Watch that the firstlayer winds tight and snug. It the first layer iswound correctly. the rest of the cable shouldwind evenly on the drum. Caution: Keephands clear of winding cable.

RIGHT

WRONG

(9-82)

254

Courtesy of Martin and Blackwere Ropes Ltd

9:62 WINCHES

Figure 9-83 illustrates the correct way to at-tach left and right lay rope to a drum that hasprovision for attaching the cable to either sideand that can be overwound or underwound.Note the point of view is from behind thedrum.

PROPER WIND '3 FORRIGHT L

(Use right r,...rod)

PROPER WINDING FORLEFT LAY

(Use left hand)

OVERWIND UNDERWINDLeft to Right Right to Left

(9-83)

ATTACHING U-BOLTS

U-Bolts must be attached in the right numbersand in the right sequence to the correct sideof the cable.

OVERWINDRight to Left

ATHE RIGHT WAY

UNDERWINDLett to Right


BTHE WRONG WAY

I.! 1111111

In Figure 9-84. A the right way. the saddle ofall the clips bears on the five part of the ropeand the U-bolt bears on the dead part. Whenthe U-bolt bears on the live side as in Figure9.84, B the wrong way. there is a possibility ofthe rope being kinked or deformed

(9-84)

255


WINCHES

The table in Figure 9-85 shows the correctnumber of clips to be used for each size ofrope with the proper spacing between them.

9:63

DIAMETER OF ROPE NUMBER OF CLIPS

vii4"

SPACING CENTERTO CENTER

2222333

23.4"23/4"

3"33/4"VA"4"4"

1'2

4445566

4W'

6"7"7PAr

9"

2"

667

91,4

10%"12"

Alter the wad is appised to the rope. lessen the tension and retighten the clips This will compensate forthe natural diameter reduction of the rope under load

The cable clamps should be put on in a setsequence Alter selecttng the number ofclamps according to the rope size andfiguring out how long the dead end of therope must be 10 give correct spacing betweenthe clamps. attach the damps in the followingorder (Figure 9-85)

Step I

Step 2

Step 3

Step 4

Attach the clip that is farthest fromthe eye Tighten it to the recom-mended torque.

Attach the Clip that is closest to theeye Firm it. but do not tighten.

Attach all other Clips. equallyspaced. between the first two Clips.Firm, but do not tighten them.

Apply tension to the rope at the eyeand tighten all clips that haven'tbeen tightened. The torque on theclips should be checked after therope has been operated

(9-85)

(9-85)


Courtesy of Martin and BlackWire Ropes Lid

ATTACHSECOND

ATTACHTHIRD

256

ATTACHFIRST

9:64 WINCHES

ATTACHING DOUBLE SADDLE CLIPS(FIST GRIP CLIPS)

Since double saddle clips are the same onboth ends they can't be put on incorrectly.Fewer of these clips are needed than U- bolts;check the manufacturers recommendation forthe number of bolts per cable size. Thesequence of attaching the clips would be thesame as for U-bolts.

REEVING WIRE ROPE

Reeving means installing or rigging wire ropeto a machine attaching the rope to thedrum, passing rope over sheaves, andgenerally arranging the cable into itsoperating circuit. Figure 9-86 shows thereeving on a large mining shovel. Since thisparticular machine has a fixed boom angleand a power operated crowd, it has only thehoist drum circuit to reeve.

HOIST DRUMCABLE (2)))*

% i\dCABLE(1)

LOWER WW UPPERSHEAVE SHEAVE

LINELOCATIONS

DRUM

Courtesy .31 Harnischfeger Corporation pm

TWO BOOMPOINT SHEAVES

EQUALIZERSHEAVES

(9-86) HOIST REEVING DIAGRAM

This cable system uses two cables of identicallength and size The cables are attached oneto either side of the drum. Each cable ispassed over the boom point sheaves. downaround the lower or bucket sheave. back overanother boom point sheave, returning to thehoist drum near its center. Cable is thereforeattached in four places to the drum. and whenthe line is winding. the two cables can appearto be four Figure 9-87 shows the locationswhere the cable is attached to the drum. andthe anchors by which it is attached. Note thelour bets of grooves the line runs in: the twocables on the outside wind towards the insidewhereas the two central lines wind towardsthe outside.

CENTER DRUMCABLE ANCHORS

SIDE CABLEANCHORS

257

(9-87)

WINCHES 9:65

The cable system described above would beused on such a shovel as the one n Figure 9-88 Note that in this side view, only one boompoint sheave can be seen and only one of thefour drumlines is visible.


BOOM POINT(9-88)

An example of reeving for a boom is shown inFigure 9.89

NOTE THIS PENDANT LENGTH TO SUITCENTER SECTION OF BOOM

41-----BOOM

PENDANT YOKE

ROPEANCHOR

(9-89)

A-FRAMESHEAVES Courtesy of Bucyrus -Erne Co

of Canada Ltd

i

9:66 WINCHES

THE REEVING OF TACKLE BLOCKS

Tackle blocks give mechanical advant ge'the more lines the blocks have the greater theload that can be lifted with the same pullingforce. Note the reeving patterns on the sets oftackle blocks in Figure 9-90.

SHACKLEBLOCK

1 PARTOF LINE

HOOKBLOCK

2 PARTSOF LINE

It is good practice to use a shackle block asthe upper one of a pair and a hook block asthe lower one A shackle IS much stronger.s.a;. a hook of the same size and the strain onIle upper block Is much greater than the

10%41 one. The lower block supports only thegoat- Ai/hems the upper block carries the loadas well as the hoisting strain. Also a hook ismore convenient on the lower block becauseit can more readily be attached to or detachedfrom the load. Note that when reeving a set ofblocks where the rope leads from a block thathas more than two sheaves, attach the rope toone of the center sheaves so that the hoistingstrain IS placed on the center of the block.

3 PARTSOF LINE

(9-90)

4 PARTSOF LINE

S PARTSOF LINE


259

WINCHES 9:67

SELECTING TACKLE BLOCKS

A problem can arise in the shop or field indeciding what number of line Tackle Block touse When you know the weight of the load tobe lifted and the line pull of the winch or hoistdrum that will do the pulling, the followingchart (Figure 9-91) will give you the number ofline parts of the Tackle Block to use:

Numberof Partsof Line

Ratio forBronzeBushedSheaves

Ratio forAnti-Friction

BearingSheaves

1 .96 .98

2 1.87 1.94

3 2.75 2.88

4 3.59 3.81

5 4.39 471

6 5.16 5.60

7 5.90 6.47

8 6.60 7.32

9 7.27 8.16

10 7.91 8.98

11 8.52 9.79

12 9.11 10.6

13 9.68 11.4

14 10.2 12.1

15 10.7 12.9

16 11.2 13.6

17 11.7 14.3

18 12.2 15.0

19 12.6 157

20 13.0 16.4

21 13.4 17.0

22 13.8 173

23 14.2 18.3

24 14.5 18.9

(9-91)

Courtesy 01 Martin and stackWire Ropes 1 +/

EXAMPLE PROBLEM

The load you want to lift is 72.480 lbs . and thesingle line pull of the hoistdrum is 8000 lbs.The tackle sheaves you will use have bronzebushings.

Step 1: Find the ratio of load weight to line

lPlune pull 8000

Step

load weight = 72480- = 9.06 ratio

Step 2: Look up the ratio. or the one closestto it. either in the Bronze BushedSheave column or the anti-frictionbearing sheave column. When youfind the ratio. look over on the sameline to the first column which givesyou the Number of Parts of line touse. In this case the 9.06 is closest tothe 9.11. and so a tackle block with12 line parts is needed.

260

4

4.

9:68 WINCHES

QUESTIONS WIRE ROPE

1 Wire rope is made of three basic partsWhat are they?

2 When measuring the diameter of wirerope. is the caliper placed on the crownsof two opposite strands or in contact withfour opposite strands?

3 As cable gets thicker. less of it can bewound on a drum. Using the table onpage 2 find the difference in feet be-tween the amount of 5/8" cable that canbe wound on a F-50 Hi-cap drum and theamount of 1" cable.

4 Give two functions that a fiber core willprovide in a wire rope

5 What are the advantages of steel core ina wre rope)

6 True or False') The rope with thestrongest steel Is the best for every jobBriefly support your answer

7 he figure 6 x 7 used to classify strandsin a wire rope means

(a) there are 42 wires per strand.(b) there are 6 wires per strand and 7

strands in the rope.(c) there are 6 strands in the rope and 7

wires per strand.

(d) there are 42 wires ir. the completerope iricludirg the core

8 When wire rope is preformed. it meansthat each wire arrl strand is preset to anexact shape

9 List at least two advantages of preformedwire rope

10 In one of its mech. js the term "laydescribes the direction of rotation ofwires in a rope What are the two basiclays and briefly describe the differencebetween them Give an example whereeach is used

11 The term lay- also rpplies to the direc-tion of rotation 01 the strands in a ropeWhich is the most common. left lay orright lay')

vi/h-t is the mrst common sign of wirea deterioration?

rue or False? When inspecting a wireope. it should be supporting a load?

14 Wire rope inspections should be done:

(a) daily.

(b) weekly.

(c) monthly

(d) yearly.

The frequency of lubrication of wire ropedepends on

(a) its size.

(b) length.

(c) severity of duty and corrosive con-ditions.

(d) weather conditions.

16. What are cable clamps used for?

17. True or False? A sheave groove that istoo large is better than one that is toosmall.

18 Briefly explain how the diameter of asheave affects wire rope life.

19 When installing a new line on a tractorwinch drum.

(a) hold onto the line and guide it ontothe drum when operating the winch.

(b) use your foot to guide the line ontothe drum when operating the winch.

(c) tail hold the line to a stump or treeand wind the line onto the drumwhile pulling the tractor backwards.

(d) the line will spool automaticallywhen it is wound on.

20 Correctly hstalled cable clamps shouldbe arranged so that the:

(a) clamp saddles are all on the live endof the line.

(b) clamp saddles are all on the deadend ol the line.

(c) clamp saddles are alternated be-tween the live c..d dead ends ol theline.

(d) it doesn't matter.

261

WINCHES 9:69

21. When forming an eye on the end of a1/2" piece of cable, the minimum numberof U-bolt clamps that can be used is:

(a) 2

(b) 3

(c) 4

(d) 5

22. When reeving tackle blocks. increasingthe number of line parts over sheaves:

(a) increases the mechanical ad-vantage.

(b) decreases the mechanical ad-vantage

(c) no change in mechanical ad-vantage: just decreases the liftingspeed

(d) no change in mechanical ad-vantage: lust increases the liftingspeed.

262

9:70 WINCHES

ANSWERS TRACTOR MOUNTED ANSWERS MAINTENANCE AND REPAIRWINCHES OF TRACTOR MOUNTED WINCHES

1 Live P.T 0 from a torque converter.Live P.T.O. through a manual trans-mission.

Hydraulic motor.

2 (d) Overwind or underwind

3 True.

4 Overwind

5 (d) (a). (b) and (c) are all correct.

6 Sliding gearPower shift.

Hydraulic

7 (b) Tractor's master clutch must bedisengaged

8 By hydraulically applied clutch packs

9 Splash.

10 A hydraulic winch can be mounted inmost cases. in whatever location itsrequired. provided that hydraulic hoescan be connected to power it.

11 (c) Band and multi-disc

12 (c) Spring applied and hydraulicreleased

13 (a) Reel in

14 The housing acts as a cooler to cool thehydraulic oil

15 Provides a guide for the cable. allowingthe cable to be reeled in at an anglewithout being damaged.

16 A hydraulic pump and a hydraulic motor.

263

1. True.

2 Condensation.

3. (b) Daily. weekly. monthly schedule.

4. 500 hours or 3 months

5. False.

6. True.

7. Hydraulic ,est box.

WINCHES 9:71

ANSWERS HOIST WINCHES

1. The basic machine refers to the lowerand upper works.The convertibility refers to variousremovable front ends which enable themachine to do dilierent types of work.

2. (e) Both (b) and (c) are right.

3 (b) Longer and runs looser.

4. (1) Size.

(2) Ways of mounting.(3) Activating mechanisms

5 (a) A clutch

6 Brake

7. (a) Rear drum shaft.

8 The yarder drums have much largercapacity.

9. (1) 3rooved.

(2) &tooth tapered.

10 (b) Increase

11 True

12. The multiple pieces are easier to removeand install.

13 Air

14. (1) Hydraulic

(2) Air

15. They are stronger clutches and brakesand can withstand heavier loads andhigher heal under increased machinehorsepower

16 Magnetic field.

17 False

18. The hydraulic winch.

(1) lakes less space.

(2) has simpler controls.

(3) requires fewer adjustments.

1.

ANSWERS MAINTENANCE OFHOIST WINCHES

Ensure that the working implement con-trolled by the drum she:* is in a safelylowered position and tension is off thecable.

2. (d) Slips under load.

3. (b) 1/32"

4. False. They require regular, scheduledlubrication.

5. Every 200 hours with multi-purposegrease.

264

9:72 WINCHES

ANSWERS WIRE ROPE

wire

strand

core

2 On the crowns of two opposite strands

3 600 ft for the 518" cable and 215 ft. forthe 1" cable: so the difference is 600215 -... 385 ft

4 A fiber core:

(1) provides a cushion for the steelstrands

(2) Acts as an internal lubricator.

5 A steel core:

11) Adds strength.

(2) Provides resistance to crushing.(3) Gives heat protection

6 False. A rope with a ductile. flexible steelmay out-last a rope made of a steel witha higher breaking strength

7. (c) There are 6 strands in the rope and7 wires per strand.

8 Helical.

9. Preformed wire rope

(1)

(2)

(3)

(4)

Won't unravel when cut.Is more flexible.Lasts longer.

Is easier to splice.

10 Regular Lay wires in the strands la;parallel to the rope.Lang's lay wires in each strand lay inthe same direction as the strands of therope.

Regular lay general purpose rope.

Lang's lay applications where bothends are fixed such as a hoist cable on ashovel

11 Right lay.

12. Broken wires.

13 False

14. (b) Weekly.

15 (c) Severity of duty and corrosive con-ditions.

16 To form a loop in a wire rope in order toattach the rope to a fixture.

17 False

18 The less bend the wire rope is forced tomake the less strain will be imposed onthe rope. With less strain a rope will lastlonger

19 (c) Tail hold the line to a stump or treeand wind the line onto the drum whilepulling the tractor backwards.

20 (a) Clamp saddles are all on the liveend of the line

21 (b) 3.

22 (a) Increases the mechanical ad-vantage.

265

WINCHES 9:73

TASKS WINCHES, HOISTSAND CABLES

TRACTOR MOUNTED WINCHES


1. Change the oil and filters and do minoradjustments as outlined in the servicemanual

SERVICE REPAIR

1 Remove and install a crawler winchassembly using the correct tools. liftingequipment. rigging equipment and safetyprocedures outlined in the servicemanual

CRANE AND SHOVEL HOIST WINCHES


1 Consulting the service manual. lubricate.do minor clutch and;or brake adjustments.inspect air lines or hydraulic lines andmake any minor repairs or replace anydamaged fines

SERVICE REPAIR

1 Remove and install a hoist winch from asho,lel or crane using the correct tools.lifting equipment. rigging and safety prac-tices outlined in the service manual. Rein-stall the cable when complete.

CABLES, CLAMPS AND SHEAVES


1 Under the assistance of a journeyman.make a cable inspection on both standingand running cable such as would be foundon a shove! or crane. Write a report to in-clude the measurements necessary tocheck the cable and note any signs offailure (See sec 54 18 W.C.B. RegulationsParagraph 23 Wire Rope Rejectioncriteria )

SERVICE REPAIR

1 Demonstrate correct care. handling andstorage of cable

2 Install a new drum cable on a crawlermounted winch.

(a) Select the correct cable size andlength.

(b) Attach the cable to the correct sideof the drum for either an over or anunder wind.

(c) Attach the other end of the cable to asecure tail hold and load the drum bywinching the crawler backwards.

3. Make an eye on a piece of 1/2" (12 mm)cable. using a thimble and wire rope cableclamps of correct size. number andplacement to meet W.C.B. safety stan-dards.

266

document resume - eric resume. ce 039 362. ... preventive maintenance service on. changing engine...

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