department of mechanical engineering two marks with

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www.vidyarthiplus.com Prof.S.Sathishkumar

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DEPARTMENT OF MECHANICAL ENGINEERING

Two Marks With Answers (2017 Regulation)

Subject Code : OAT551 (Open Elective)

Subject Name : Automotive System

Year/Semester : III/V

Author - Biography

Prof.S.Sathishkumar.BE (Mechanical Engineering)., ME (Engineering Design)., MBA (Operations

Management).,MISTE

Assistant Professor, Department of Mechanical Engineering

Vel Tech (Owned By RS Trust) Engineering College, Avadi, Chennai-62

Website : www.kssathishkumar.blogspot.com

Email : [email protected]&[email protected]

Mobile : 9994274071, 9597178818

Face Book : K.s. Sathishkumar

Twitter : K.s. Sathishkumar

http://www.vidyarthiplus.com/

http://www.veltechengg.com/

http://www.kssathishkumar.blogspot.com/

mailto:[email protected]

mailto:[email protected]

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SYLLABUS

OAT 551-AUTOMOTIVESYSTEM

OBJECTIVES:

Tounderstandtheconstructionandworkingprincipleofvariouspartsofanautomobile. To have the practice for assembling and dismantling of engine parts and transmission

system

UNIT I AUTOMOTIVE ENGINEAUXILIARYSYSTEMS 9

Automotive engines‐ External combustion engines –Internal combustion engines ‐classification of engines‐ SI Engines‐ CI Engines‐ two stroke engines ‐four stroke engines‐ construction

and working principles ‐ IC engine components‐ functions and materials‐valve timing –port timing

diagram‐ Injection system ‐Unit injector system‐ Rotary distributor type-Electronically controlled injection

system for SI engines‐CI engines‐Ignition system ‐ Electronic ignition system ‐Transistorized ignition

system, capacitive discharge ignitionsystem.

UNIT II VEHICLE FRAMES ANDSTEERINGSYSTEM 9

Vehicle construction and different Chassis layouts –classifications of chassis‐ types of framesframeless

chassis construction –articulated vehicles‐ vehicle body ‐ Vehicle aerodynamics‐various resistances and its

effects ‐ steering system –conventional – sophisticated vehicle‐ and types of steering gear box‐Power

Steering‐ Steering geometry‐condition for true rolling motion‐Ackermann‟s‐ Devi‟s steering system ‐ types of stub axle – Types of rear axles.

UNIT III TRANSMISSIONSYSTEM 9

Clutch‐types and construction, gear boxes‐ manual and automatic, gear shift mechanisms, Over drive,

transfer box, fluid flywheel, torque converter, propeller shaft, slip joints, universal joints –‐ Hotchkiss

Drive and Torque Tube Drive‐ rear axle‐ Differential‐wheels and tyres.

UNIT IV SUSPENSION ANDBRAKESSYSTEM 9

Suspension Systems‐ conventional Suspension Systems ‐independent Suspension Systems –leaf spring –

coil spring –taper‐lite ‐ eligo,s spring Types of brakes ‐Pneumatic and Hydraulic Braking Systems,

Antilock Braking System (ABS), electronic brake force distribution (EBD) and Traction Control. Derive

the equation of Forces acting while applying a brakes on plain surface ‐ inclined road‐gradient.

UNIT V ALTERNATIVE ENERGY SOURCES 9

Use of Natural Gas, Liquefied Petroleum Gas, Bio‐diesel, Bio‐ethanol, Gasohol and Hydrogen in

Automobiles‐ Engine modifications required –Performance, Combustion and Emission Characteristics of

SI and CI engines with these alternate fuels ‐ Electric and Hybrid Vehicles, Fuel Cell. Turbo chargers ‐Engine emission control by three way catalytic converter system.

Note: Practical Training in dismantling and assembling of Engine parts and Transmission

Systems should be given to the students.

TOTAL: 45 PERIODS

OUTCOMES:

Upon completion of this course, the students will be able to identify the different components in

automobile engineering.

Have clear understanding on different auxiliary and transmission systems usual.

TEXT BOOKS:

1. GanesanV.“InternalCombustionEngines”,ThirdEdition,TataMcGraw‐Hill,2007.

2. Jain K.K. and Asthana .R.B, “Automobile Engineering” Tata McGraw Hill Publishers, New

Delhi,2002.&Kirpal Singh, “Automobile Engineering”, Vol 1 & 2,7thStandard Publishers-, New

Delhi,1997



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GRAPHICAL REPRESENTATION OF AUTOMOTIVE SYSTEM



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UNIT-1

AUTOMOTIVE ENGINE AUXILIARY SYSTEMS

PART-A – (Two Marks)

INTRODUCTION OF AUTOMOTIVE ENGINE

Heat engine defined as ait is a device which transforms the chemical energy of a fuel into thermal energy and uses

this energy to produce mechanical work. It is classified into two types-

(a) External combustion engine

(b) Internal combustion engine

1. Define: Automotive Engine

Automotive engineering is a branch of engineering which deals with everything about automobiles and

practices to propel them. Automobile is a vehicle driven by an internal combustion engine and it is used

for transportation of passengers and goods on the ground. Automobile can also be defined as a vehicle

which can move by conversion of chemical energy to Mechanical Energy

Examples: Car, jeep, bus, truck, scooter, etc.

2. Mention the Classification of Automotive Engine

Automotive Engines are generally classified according to following different categories: Internal

combustion (IC) and External Combustion (EC)

Type of fuel: Petrol, Diesel, Gas, Bio / Alternative Fuels.

Number of strokes – Two stroke Petrol, Two-Stroke Diesel, Four Stroke Petrol / Four Stroke Diesel

3. Write about External Combustion Engine

External Combustion Engine also called as heat engine that derives its heat from fuel consumed outside

the cylinder

Examples: Steam engine

4. Define Internal Combustion Engine

Internal combustion engine is defined as the combustion of air and fuels take place inside the cylinder and

are used as the direct motive force.

5. Mention the Classification of Internal Combustion Engine

1.According to the method of igniting the fuel

(a) Spark ignition engine,

(b) Compression ignition engine and

(c) Hot spot ignition engine



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2. According to the type of fuel used

(a) Petrol engine

(b) Diesel engine

(c) Gas engine (CNG, LPG)

(d) Alcohol engine (ethanol, methanol etc)

3. According to the number of strokes per cycle

(a) Four stroke

(b) Two stroke engine

4. According to the basic engine design

(a) Reciprocating engine (Use of cylinder piston arrangement)

(b) Rotary engine (Use of turbine)

5. According to the working cycle

(a) Otto cycle (constant volume cycle) engine

(b) Diesel cycle (constant pressure cycle) engine

(c) Dual combustion cycle (semi diesel cycle) engine

6. Write the Differentiation between the External and Internal Combustion Engine

S/No External Combustion Engine Internal Combustion Engine

1 Combustion of air-fuel is outside the

engine cylinder (in a boiler)

Combustion of air-fuel is inside the engine

cylinder (in a boiler)

2 It can use cheaper fuels including solid

fuels

High grade fuels are used with proper

filtration

3 Higher ratio of weight and bulk to output

due to presence of auxiliary apparatus like

boiler and condenser. Hence it is heavy

and cumbersome

It is light and compact due to lower ratio of

weight and bulk to output

4 The engines are running smoothly and

silently due to outside combustion

Very noisy operated engine

5 Lower efficiency about 15-20% . Higher efficiency about 35-40%

6. Define Spark Ignition Engine

A spark-ignition engine (SI engine) is an internal combustion engine, it is also called petrol engine, where

the combustion process of the air-fuel mixture is ignited by a spark from a spark plug.

7. State Compression Ignition Engine

Compression-ignition engines also called as diesel engines, where the heat generated from compression

together with the injection of fuel is enough to initiate the combustion process, without needing any

external spark.



https://en.wikipedia.org/wiki/Internal_combustion_engine

https://en.wikipedia.org/wiki/Petrol_engine

https://en.wikipedia.org/wiki/Spark_plug

https://en.wikipedia.org/wiki/Compression-ignition_engine

https://en.wikipedia.org/wiki/Diesel_engine

https://en.wikipedia.org/wiki/Compression_ratio

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8. Write the different between Two Stroke and Four Stroke Engine

S/NO TWO STROKE ENGINE FOUR STROKE ENGINE

1 It has one revolution of the

crankshaft during one power stroke

It has two revolutions of the crankshaft during

one power stroke

2 It generates high torque It generates less torque

3 Its uses ports for fuel’s outlet and

inlet It uses valves for outlet and inlet of a fuel

4 It generates more smoke and shows

less efficiency

It generates less smoke and shows more

efficiency

5 Engines are cheaper and are simple

for manufacturing

Engines are expensive due to lubrication and

valves and are tough to manufacture

9. Enlist the IC Engine Components

Cylinder block

Cylinder Head

Piston

Piston Pin or Gudgeon pin

Connecting Rod

Crank Shaft

Cam Shaft

11. What are the two types of cylinder liners?

1. Dry liners 2.Wet liners

12. What are the functions of piston rings?

To provide a gas tight seal between the piston and cylinder liner to prevent the escape of gases from top

side of the piston to the underside.

13. What are the two types of piston rings?

Compression rings

Oil rings

14. What is clearance volume? And what are its effects?

The volume above the piston, when it reaches TDC is known as clearance volume. The clearance volume

is inversely proportional to the compression ratio.

15. What is the function of piston, connecting rod, crank shaft and cylinder head?

Piston – The piston assembly transfers the force from the power stroke to the crankshaft

Connecting rod – converts reciprocating motion of piston into rotary motion of crankshaft

Cylinder head – it acts as a top cover to the cylinder block. The valves are placed in the cylinder

head in an overhead valve engine.



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16. What are the functions of Piston rings?

Prevention of leakage of gas into the crankcase

Prevention of lubricating oil film.

Easy transmission of heat from piston to cylinder wall.

Balancing of side thrust of the piston.

17. Define manifolds?

The term manifold is applied to the external pipes or castings containing gas passages that connect

the carburetor and the pipes to the inlet and outlet ports of the engine. In order to maintain

maximum velocity of the gases and to ensure the best possible breathing, it is obviously desirable that

the passages should offer minimum resistance to flow.

18. What are the qualities of a good liner?

Strength to resist stresses due to pressure.

Hard to resist wear.

Capable of taking a good bearing surface.

Strength to resist stresses due to heat flow through the liner.

19. What are the forces acting on crank shaft?

i) Centrifugal force ii) Inertia force iii) Twisting and shear forces.

20. Define common rail injection system.

A common rail which is maintaining high fuel pressure is connected to individual fuel injectors of a multi

cylinder engine.

21. What is unit injection system?

It is an integrated direct fuel injection system for diesel engines, combining the injector nozzle and the

injection pump in a single component

22. What is a rotary distributor?

The rotary distributor has a rotating element, which releases a high intensity spark to the individual spark

plugs according to the engine firing order.

23. What is an Electronic ignition system?

The ignition system, in which the mechanical contact points are replaced by electronic triggering and

switching devices, is known as electronic ignition system



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24. State the merits and demerits of Mono point and Multi point fuel injection system?

No. Mono Point Injection Multi Point Injection

1 Single injector is sufficient Separate fuel injector for individual cylinders

2 Low cost High cost 3 Low injection pressure Comparatively higher injection pressure

4 Slightly higher SFC and emissions than Low SFC and engine emissions MPFI

25. What is the function of an ignition system in I.C Engine?

The function of an ignition system is to ignite the air-fuel mixture at the end of the compression stroke.

26. State the requirements of ignition system? And state its types

It should consume minimum of power and produce high intensity spark across spark plug

electrodes

It should have a sufficient spark duration which is sufficient to establish burning of air- fuel mixture

under all operating conditions

It should provide sufficient ignition energy over the entire speed range of theengine

Good performance at high speed

Longer life of contact breaker points and sparkplug

Adjustment of spark with speed & load

27. List out the types of Ignition System

1. Battery ignition 2. Magneto ignition 3.Electronic ignition

28. Write the Different between battery coil ignition and magneto ignition system

S/No Battery Ignition Magneto Ignition

1 Battery supplies current in primary circuit Magneto produces the required current for primary circuit

2 A good spark is available at low speed also Quality of spark is poor in slow speed

3 Occupies more space Very much compact

4 Recharging is a must in case battery gets discharged

No such arrangement required



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UNIT II

VEHICLE FRAMES AND STEERING SYSTEM

1. Define Chassis

A complete vehicle without a body structure is known as Chassis. It comprises of basic structure, power

unit, transmission system, controls and auxiliaries.

2. What are the functions of a frame?

To support the chassis components and the body.

To withstand static and dynamic loads without undue deflection or distortion.

To carry the load of the passengers or goods carried in the body.

3. List out the various materials used in the construction of frame.

Low Carbon Steel - 0.18 or 0.20 % carbon content

High Carbon Steel - 0.25 % carbon content

Alloy Steel – With alloying elements like Ni & Cr.

4. Types of Chassis Frames?

There are three types of frames

Conventional frame Integral frame

Semi-integral frame

5. List out the main components of the Chassis

Frame

Engine or Power plant

Clutch

Gear Box

U Joint

Propeller Shaft

Differential

6. Mention various loads acting on the vehicle frame

Short duration Load - While crossing a broken patch.

Momentary duration Load - While taking a curve.

Impact Loads - Due to the collision of the vehicle. Inertia Load - While applying brakes. Static Loads - Loads due to chassis parts.

Over Loads - Beyond Design capacity. 7. Write the Requirements of Bodies for Various Types of Vehicles The body of the most vehicles should fulfill the following requirements: The body should be light. It should have minimum number of components.

It should provide sufficient space for passengers and luggage. It should withstand vibrations while in motion.



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It should offer minimum resistance to air 8. Name the different kind of resistances to vehicle motion.

Air resistance

Rolling resistance

Gradient resistance

9. What loads are coming to axle?

Vertical bending load due to vehicle weight

Driving torque

Braking torque

Side thrust

10. What are the advantages of frameless construction over the conventional framed

Construction?

Reduced weight and consequent saving in fuel consumption.

Lower manufacturing cost

During collision the body crumbles, thereby absorbing the shock due to impact and thus

providing safety to the passengers.

Compared to framed construction lower body position may be obtained, thus resulting in

increased stability of the automobile

11. What is the different type of steering gears?

a) Worm and wheel steering gear

b) Cam and double roller steering gear

c) Worm and nut steering gear

d) Reticulating ball type steering gear

e) Rack and pinion steering gear

12. Define steering ratio.

It is the ratio of the angle turned by the steering wheel to the corresponding turning angles of the stub

axle. The steering ratio generally used with the present day steering gears vary from about 12:1 for cars

to about 35:1for heavy vehicles.

13. What is power steering?

Large amount of torque is required to be applied by the driver for steering medium and heavy vehicles.

The power steering system provides automatic hydraulic assistance to the turning effort applied to the

manual steering system.

14. What is the advantage of electronic power steering over hydraulic power steering?

No problem of leakage of fluid.

Energy being consumed only while steering.

Steering assistance available even when the engine is not running.

While steering manually lesser force is required compared to a hydraulic system since there is no

fluid to be forced through valves.



http://easyengineering.net/




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15. Write about reversible steering & irreversible steering

Reversible steering

When deflection of the steered wheels due to road surface is transmitted through the

steering linkage and steering gear box to the steering wheel the system is said to be

reversible.

Irreversible steering

When the steered wheels do not transfer any deflection to the steering wheel, the steering

system is said to be irreversible.

16. What is over steering & under steering?

Over steering

When the rear slip angle is greater than the front slip angle, the vehicle tends to move

away from the direction of the side force. This is known as over steer and is advantageous

when the vehicle is moving on roads having many bends and curves.

Under steering

When the front slip angle is greater than the rear, the vehicle tends to steer in the direction

of side force. This is called under steer. This provides greater driving stability especially

when there is a side wind.

17. State Ackermann principle of steering.

The basic principle of Ackermann steering system to obtain true rolling. The Ackermann steering gear

mechanism consists of a cross link KL connected to the short axes AC and BD of the two front wheels

through the short arms AK and BL. Forming bell crank levers CAK and DBL respectively. When the

vehicle is running straight the cross link KL is parallel to AB. The short arm AK and BL both make

angle α to the horizontal axis of chassis.

For correct steering, cot Φ – cot θ = b / l

18. Define centre point steering?

If the imaginary king pin axis and the centre line of the wheel meet at the road surface this condition is

known as ‘Centre point steering’. If this condition is allowed in the front wheels the bending stress and

the splaying couple are greatly reduced.



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UNITIII

TRANSMISSION SYSTEM

1. What is the necessity of transmission system in automobile?

a) Variation of resistance to the vehicle motion at various speeds.

b) Variation of tractive effort of the vehicle motion at various speeds.

2. What is the function of a clutch?

A mechanism which enables the rotary motion of one shaft to be transmitted, when desired, to a second

shaft, the axis of which is coincident with that of the first.

3.What is “clutch free pedal play”?

When the clutch pedal is pressed, the trust bearing is not pressed immediately. Rather a part of the pedal

movement is purposely kept idle. This is done to avoid a rapid wear of the thrust bearing and the clutch

plates and is called clutch free pedal play.

4. Why are cone clutches better than disc clutches?

Since the cone discs are having large frictional areas and welding action, they can transmit a larger torque

than disc clutches with the same outside diameter and actuating force and hence cone clutches are

preferred to disc clutches .But usually cone clutches are mainly used in low peripherals speed

applications.

5. Define slip in the clutch. Write down the causes for it.

A large amount of heat is generated due to which clutch facings wear out rapidly and even burn out. This

is called as slip in the clutch. This may be caused by the following reasons.

Incorrect linkage adjustment

Weak or broken clutch springs.

Worn out facings

6. What are the main components in friction clutch?

Clutch plate

Clutch facing

Pressure plate

Springs

Bearing

7. What do you mean by fluid flywheel?

It is an alternative to clutch, uses fluid for transmitting the torque. It is also called hydraulic coupling.



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8. What is the function of a synchronizer in a gearbox?

It is used for avoids the double declutching. It fitted only on the high gears and on the low and

reverse gears ordinary dog clutches are only provided. This is done to reduce the cost.

9. List out some automatic transmission device.

Epicyclical gear box

Multi plate clutches

Torque convertor

10. Difference between torque convertor and fluid flywheel

Fluid flywheel

The fluid flywheel transmits the same torque given to it b y the engine shaft.

Stator is not there.

Efficiency is low.

Torque convertor

The torque convertor increases the torque in a ratio of about 2:1 to3:1.

Stator is there.

Efficiency is high.

11. What is the function of stator in a torque convertor?

Stator is used for avoid the dragging action on the impeller.

12. Define over drives. What are its advantages?

Overdrive is a device to step up the gear ratio in the car. It is fitted in between transmission

and the propeller shaft.

13. Define propeller shaft and list out various parts of propeller shaft.

This is the shaft which transmits the drive from the transmission to the bevel pinion or worm

of final drive in front engine rear drive vehicles. It is also called as drive shaft. It consists

mainly of three parts

Shaft

One or Two universal joints

Slip joint

14. What is the function of universal joint?

It is a special type of joint between two shafts whose axes are inclined to each

other. Most common example is the Hook’s joint.



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15. List out various steps involved in the overhaul of propeller shaft

Removal of the shaft from the chassis

Dismantling

Inspection and service

Reassembling

Refitting

16. List out three types of final drives

Straight bevel gears

Spiral bevel gears

Hypoid gears

17. What is the need for a differential mechanism in an automobile?

When the vehicle is taking a turn, the outer wheels will have to travel greater distance as compared to

the inner wheels in the same time. If therefore, the vehicle has a solid rear axle only and no other device;

there will be tendency for the wheels to skid. Hence the wheel skidding is to be avoided, some

mechanism must be incorporated in the rear axle, which should reduce the speed of the inner wheels

and increase the speed of the outer wheels when taking turn ; it should at the same time keep the speeds

of all the wheels same when going straight ahead.

18. List out various forces acting on rear axle.

Weight of the body

Driving thrust

Torque reaction

Side thrust

19. List out two type of rear axle drive & rear axle casting

Hotchkiss drive

Torque tube drive

Split type

Banjo or separate carrier type

Salisbury or integral carrier type.

20. What are the functions of brake?

i) To stop the vehicle,

ii) To control speed, when and where required quickly and efficiently,

iii) To control the vehicle while descending along a slope,

iv) To keep the vehicle in the required place after bringing it to rest

even when the operator is not present.



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21.What are the types of brakes?

1. Feed brake 2.Hand brake 3.Mechanical brake 4.Hydraulic brake

5.Vacuum brake 6.Electrical brake 7.Air brake 8.Disc brake.

22. What are the braking requirements?

It should develop maximum possible retarding force irrespective of road conditions

and quality.

The response time should be as minimum as possible.

Must be reliable.

Should be of minimum weight.

Noise and vibration are to be minimum.

23. What are brake drums?

Brake drums are made of steel or alloy of chrome nickel. The walls of the drums are very thin

and made of centrifugal castings. The brake drum assembly is mounted on the wheel bolts between

the hub and the wheel, so as to revolve with the wheel. The drum surrounds the brake shoes. The drum

diameter ranges from 200 to 375 mm.

24. What is a master cylinder?

The master cylinder is the heart of the hydraulic brake system. The master cylinder is the fluid

reservoir for the brake and is operated by the brake pedal.

25. What is tandem master cylinder?

Tandem master cylinder refers to the master cylinder arrangement with two separate cylinders

and reservoir in the same master cylinder assembly. One cylinder to operate the front brakes and the

other to operate the rear brakes. So because of this arrangement even if any one of the cylinders goes

out of order, the other cylinder functions for the operation of the brake

26. What are the merits of air brakes?

More effective: heavy effort at brakes.

Employs only air as working medium which is easily available.

Better control.

Reduced stopping distance.

27. What are disc brakes?

The motor vehicles are now being fitted with disc brakes. It is normally of a caliper type,

consisting of a rotating disc and two friction pads on either side. The disc is made of high grade grey

cast iron. The friction pads are made up of asbestos fibre. The chief advantage of the disc brake is their

resistance to fading.

28. What are the merits of disc type brakes?

Better stability because of uniform pressure distribution over the pads.

Less bearing load on the application of the brake.



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Higher temperature does not affect the disc pads.

Simple design of brake adjuster.

Less weight

Repair and maintenance are easy.

Resistance to fading.

29. What are power brakes?

Normally for operation of brakes some physical effort is applied on the brake pedal. If instead

of physical effort some other external source of power is applied then it is known as power brake. The

external sources may be air pressure, engine vacuum or electrical energy from battery.

30. What are the advantages of power brakes?

Reduces driver’s effort.

Higher braking efficiency.

More rapid in action.

Lesser time lag.

Used in trailers and tractors.

Flexible hose connection.

31. What are the various brake troubles?

Sl.No.

Troubles

Causes

1. Pedal can be moved to strike floor

board without producing braking

action.

1. Normal wear of linings

2. Defective master cylinder

3. Air in system

2. One wheel drag 1. Brakes too tight.

2. Clogged liner.

3. Brake fade 1. Too hot brake drum

2. Glazed lining.

4. Spongy pedal 1. Air in line

2. Poor shoe adjustment.

32. What are the functions of the gear box?

To exchange engine power for greater torque and provide mechanical advantage to drive

the vehicle under different operating conditions.

To provide reverse motion.

To provide neutral position and disallow power flow to the rest of the transmission.

33. What is the necessity of gear box?

To regulate the torque by selecting the appropriate speed range.

To regulate vehicle speed at which maximum torque is available.

To balance the tractive effort with the sum of the various forces tending to

oppose the motion.



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34. Define tractive effort.

Tractive effort is the driving force which acts at the rear wheel to propel the vehicle. To

obtain uniform speed, the total tractive resistance should be balanced by the tractive effort. Tractive

effort is produced at the point of contact of the wheel on the road.

T = Total torque at the wheel / Wheel radius

= n x m x r x T

where,

n = gear box ratio m =

final drive ratio

r = radius of the wheel T =

engine torque.

35.What are the type of gear boxes?

i) Selective type ii) Progressive type

36.What is an epicycle gear box?

This is also known as planetary gear train. One shaft is called sun gear shaft and the other

shaft is called planet carrier shaft. The epicyclical gear box uses no sliding dogs or gears to engage,

but different gear speeds are obtained by merely tightening brake bends on the gear drums, which

simplify gear changing. A three speed gear box provides 3 speed gears: I, II, and top gear. A four

speed gear box provides 4 speed gears: I, II, III and top gear. A five speed gear box provides 5 speed

gears: I, II, III, IV and top gear.

37.What is gear shifting?

The gears are shifted by means of a gear shift lever. In manually operated selective

transmissions, the gear shift lever is located either on steering column or on the floor board. To shift

any gear the clutch pedal is depressed to disconnect momentarily the engine from the transmission.

Then the gear shift lever is moved first to demesh the previous gear and then to mesh the desired

gear. The directions of the first, second, third, neutral and reverse gears are marked on the knob of

the gear shift lever.

38. What is a transfer case?

The transfer case is essentially a two speed transmission located at the rear of the standard

transmission which provides a low and direct gear. It also provides a means of connecting the power

to the front axle. The shifting mechanism is located on the transfer case.

39. How does a tyre being specified?

i) Width ii) Speed rating and diameter iii)Ply rating.



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40. What are the causes for rapid wear of a tyre?

Rapid wear: Operating condition like rough surface, high speed.

Remedy: Maintain correct speed, correct pressure.

41. What is tubeless tyre?

Tubeless tyre does not enclose the tube. The air under pressure is filled in the tyre itself. A non-return

valve is fitted to the rim through which the air is forced inside the tyre. Any hole in tubeless tyre can

be repaired simply by rubber plugging.

42. What are the causes of tyre wear?

i)Incorrect inflation ii)Incorrect caster, camber or toe-in, iii) Over loading , iv) Wrong loading,

v)Misalignment, vi)Unequal tyres vii)Careless driving viii)Worn kingpins.

UNIT-IV

SUSPENSION AND BRAKES SYSTEM

1. What is the need of suspension system?

i) To safeguard the passengers and goods against road shocks.

ii) To pressure the stability of the vehicles while in motion.

iii) To maintain proper steering geometry.

iv) To bear the torque and braking reaction.

2. What is independent front suspension?

The term independent suspension system means any arrangement that connects the road wheels

to the frame; in which the rise or fall of one wheel has no direct effect on the other wheels.

3. What are the advantages of independent front suspension?

More space for engine accommodation.

It enables front springs to be arranged for enough apart to promote under steer conditions,

which is preferable to over steer.

It may provide softer suspension.

4. What is sprung and unsprung weight?

Sprung weight is the weight of all the parts supported by the springs including the weight

of springs.

Unsprung weight is the weight of all parts between the springs and the rod and a portion of

the spring weight itself.



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5. What are the functions of a spring?

To provide cushioning effect for the passengers.

To absorb and store energy.

To prevent or reduce the transmission of road shocks as far as possible.

6. What are spring shackles?

Spring shackles provide the link by means of which the chassis frame is connected to the

leaf spring. The shackles help the spring to spring in and out during flattering and rebounding. This

is provided for lubricating purposes.

7. What is a torsion bar?

A torsion bar is a steel bar which functions by twisting and absorbing shear stress only. This is

generally used in front independent suspension. The energy absorbed per unit volume by torsion

bar is 4 times that of a leaf spring and 3 times that of a coil spring.

8. What are the advantages of torsion bar?

i) Light ii) Occupies less space iii) Stiff iv) Easy to assemble & v) Double acting.

9. What is a shock absorber?

Shock absorber controls the spring action during compression and rebound and prevents

bouncing. To control vibration shock absorber is used.

10. What are the types of shock absorber?

i) Mechanical shock absorber

ii) Hydraulic shock absorber

11. What is a fluid coupling?

This is a liquid coupling used to transmit the engine turning force to a clutch. It is located

between the crankshaft and the clutch. Air is the fluid used as a medium of power transmission.

12. Compare fluid coupling and torque converter.

Sl.No. Fluid coupling Torque convertor

1. Contains only two members impeller And turbine.

Three members impeller, turbine and a stator.

2. Simply a torque transmission unit. Torque multiplication unit 3:1 to 4:1

3. Efficient at high speed. Inefficient at high speeds.

4. Serves as an automatic clutch. Serves as an automatic clutch as well

as torque multiplier.



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13. What are the functions of brake?

iii) To stop the vehicle,

iv) To control speed, when and where required quickly and efficiently,

v) To control the vehicle while descending along a slope,

vi) To keep the vehicle in the required place after bringing it to rest

even when the operator is not present.

14. What are the types of brakes?

i)Feed brake ii) Hand brake iii) Mechanical brake iv) Hydraulic

brake v)Vacuum brake vi) Electrical brake vii) Air brake and viii)Disc brake.

15. What are the braking requirements?

It should develop maximum possible retarding force irrespective of road conditions and

quality.

The response time should be as minimum as possible.

Must be reliable.

Should be of minimum weight.

Noise and vibration are to be minimum.

16. What are brake drums?

Brake drums are made of steel or alloy of chrome nickel. The walls of the drums are very thin and

made of centrifugal castings. The brake drum assembly is mounted on the wheel bolts between the

hub and the wheel, so as to revolve with the wheel. The drum surrounds the brake shoes. The drum

diameter ranges from 200 to 375 mm.

17. What is a master cylinder?

The master cylinder is the heart of the hydraulic brake system. The master cylinder is the

fluid reservoir for the brake and is operated by the brake pedal.

18. What is tandem master cylinder?

Tandem master cylinder refers to the master cylinder arrangement with two separate cylinders and

reservoir in the same master cylinder assembly. One cylinder to operate the front brakes and the

other to operate the rear brakes. So, because of this arrangement even if any one of the cylinders

goes out of order, the other cylinder functions for the operation of the brake.

19. What are the merits of air brakes?

i) More effective: heavy effort at brakes.

ii) Employs only air as working medium which is easily available.

iii) Better control.

iv) Reduced stopping distance.

20. Define disc brakes

The motor vehicles are now being fitted with disc brakes. It is normally of a caliper type,

consisting of a rotating disc and two friction pads on either side. The disc is made of high grade

grey cast iron. The friction pads are made up of asbestos fibre. The chief advantage of the disc

brake is their resistance to fading.



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21. Write the merits of disc type brakes?

Better stability because of uniform pressure distribution over the pads.

Less bearing load on the application of the brake.

Higher temperature does not affect the disc pads.

Simple design of brake adjuster.

Less weight

Repair and maintenance are easy.

Resistance to fading.

22. Define power brakes?

Normally for operation of brakes some physical effort is applied on the brake pedal. If

instead of physical effort some other external source of power is applied then it is known as

power brake. The external sources may be air pressure, engine vacuum or electrical energy from

battery.

23. Mention the advantages of power brakes?

Reduces driver’s effort.

Higher braking efficiency.

More rapid in action.

Lesser time lag.

Used in trailers and tractors.

Flexible hose connection.

24. What are the various brake troubles

Sl.No. Troubles Causes

1.

Pedal can be moved to strike floor

board without producing braking

action.

1. Normal wear of linings

2. Defective master cylinder

3. Air in system

2. One wheel drag 1. Brakes too tight.

2. Clogged liner.

3. Brake fade 1. Too hot brake drum

2. Glazed lining.

4. Spongy pedal 1. Air in line

2. Poor shoe adjustment.



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UNIT V

ALTERNATIVE ENERGY SOURCES

1. What are the general compositions for natural gas?

1. Methane: 85-90% 2. Ethane: 5-7% 3. Propane: 2 % 4/ Carbon dioxide: 3-5% 5. Others: 1%

2. What are the physical properties of natural gas?

1. Colourless 2.Odourless 3. Non-toxic 4. Lighter than air.

3. What is the need for CNG?

a. Rising urban pollution.

b. Rising global concern for environment.

c. Rising vehicle pollution.

4. What are the constraints in natural gas?

d. Gas availability.

e. Availability of CNG equipment.

f. Pipeline network infrastructure.

g. Competition from other fuels.

5. What are the different concepts used in the description of CNG system?

h. Mother-Daughter concept.

i. On-line station concept.

6. What are the advantages of using compressed natural gas over diesel?

j. Natural gas provides clean burning characteristics.

k. Natural gas does not saturate flammable materials.

l. The explosive limit of natural gas mixture is higher than air-diesel mixture.

7. What are the components of LPG pipe line

Vapourizer

Regulator

Safety valve

Mixer

Fuel line

8. What are the methods for using hydrogen into the cylinder?

a. by manifold connection.

b. by direct injection of hydrogen.



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c. by supplementation to gasoline.

9. What are components of an electric vehicle?

Motor.

Power pack.

Onboard charger.

Motor controller.

Energy management.

Regenerative braking.

10. What are the advantages of electric car?

Maintenance cost is low.

Vibration free operation

Lighter in weight.

11. Mention the classification of Hybrid vehicles?

Series Hybrid.

Parallel Hybrid.

12. What are the components of Hybrid cars?

Electric motor.

Generator.

Direct injection gasoline.

13. What is meant by a fuel cell? Mention Types

A fuel cell is a device that harnesses the energy produced during the electro chemical reaction between

hydrogen and oxygen. The products are water and electricity.

Types:

Alkaline fuel cell

Phosphoric acid fuel cell

Direct methanol fuel cell

Solid oxide fuel cell

Molten carbonate fuel cell

14. What is the need of fuel cell?

a) Depletion of conventional types of fuels leading to energy crisis.

b) Low emission required to make a car economic friendly.

c) To attain certain standards of emission control.



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15. List out fuel cell gases

a) Oxygen

b) Hydrogen

16. What are the advantages of fuel cell?

The fuel cell has low emission of pollutants.

The oxygen air bags are varying useful for the passenger.

The fuel cell prevents the depletion of the fossil fuels.

The CO2 exhaled by the passenger is also removed.

17. What are the requirements of hybrid vehicle?

a) Increased fuel efficiency

b) Reduced emissions

c) Increased acceleration capacity

d) Reduced noise emission

18. Write short notes on series hybrid vehicles

The engine runs a motor directly and also charges a battery. Thus the motor thus drives the vehicle

always. The motor can also be used for regenerating braking.

19. What are components of hybrid cars?

a) An electric motor

b) A generator

c) Direct injection gasoline engine.

20. List the advantages of hydrogen fuel used in automobiles.

It can be manufactured from water through electrolysis process

It does not contain carbon. Hence, CO and unburned HC emissions are not present. The flame

speed is highest. Hence it results in high thermal efficiency

It has wide ignition limits.

21. Define detonation and pre-ignition

The abnormal combustion occurring in IC engines is called as detonation. This results in sudden

rate of pressure rise, abnormal heat release, heavy vibrations of the engine and loud noise

operation.

The ignition of the air-fuel mixture before the introduction of the spark in the combustion

chamber is called as pre-ignition.

22. What are the disadvantages of using alcohol as an alternative fuel?

A larger quantity of fuel is required to produce a specified power output. For example, in an

automobile, more fuel is required for each mile driven.

Low boiling points and high vapor pressures of methyl and ethyl alcohol indicate that vapor

Lock could be a serious problem, particularly at high altitudes on warm summer days.







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23. List out the various forms of Natural Gas.

Natural Gas (NG)

Compressed Natural Gas (CNG)

Liquefied Natural Gas (LNG)

24. Write down the components of LPG equipment.

Converter

Mixer

Gas Injector

25. What are the properties of CNG?

Colorless

Odorless

Lighter than air

Non - toxic

26. What are the two types of LPG used for automotive-engine fuel?

Propane based LPG

Butane based LPG

************** Wish You Happy Learning ************



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