basic gearbox and clutch

7/23/2019 Basic Gearbox and Clutch

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The expression power transfer system is collective one that covers the clutch,

gearbox, propeller shaft and rear axle

These components have the task of transferring the engine power to the driving

wheels.The components in the power transfer system are:

1. Clutch

.

3. Propeller shaft

4. Rear axle

When both engine (5) and the power transfer system are described as a single unit,

we talk aboutPower train.


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Clutch

A clutch is a transmission component whose purpose is to let the engine run without

the driving wheels being affected. Examples are when the vehicle has to be

stopped or started or when the driver has got to change gear. In cases like thisthe power transfer system has to be disengaged from the engine. This is called

declutching.

The major component of a clutch consist of a plate (1), release bearing (2) and a

disc (3). All are mounted between the engine and the gearbox.

The clutch is operated by a servo-aided system that consists of:

Master cylinder connected to the clutch pedal.

Clutch servo connected to release bearing.

The Clutch function of Interrupting the engine power to the gearbox so that shifting


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Gearbox

A gearbox makes the necessary conversions to the driving power transferred from

the engine to the driving wheels with aid of various power ratios.

There are three basic gearboxes:Manual gearbox

Automatic gearbox

Semi-automatic gearbox

In a Manual gearbox, the driver selects the gear to be shifted.

In an Automatic gearbox, the driver selects a driving program and the gear selection

is carried out by an electronic system and the actual gear changes are

performed by a internal hydraulic control system.

In a Semi-automatic earbox the driver selects a drivin ro ram and the ear

selection is carried out by an electronic system and the actual gear changes are

performed by external pneumatic cylinders.


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Power take-off

Some trucks require driving power for different types of auxiliary equipment. If the

truck is equipped with a tipper platform, concrete mixer or a crane, a power take-off

is required to operate the hydraulic pump.Power take-off is divided into two main categories, those that are dependent upon

the clutch and those that are independent of it.

-

for tippers and cranes.

The power take-off independent on a clutch (2) is driven by the flywheel and is

usually used for refrigerator trucks and concrete mixers.


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Propeller shaft

Propeller shaft

The purpose of the propeller shaft is to transfer the driving power from the

transmission to the final drive.The most common type of propeller shaft consists of:

Driving flange (1) with spider (2) mounted in needle bearings.

Thanks to the universal joint the propeller shaft can turn to various angels caused

by the movement between the transmission and rear axle.

Propeller shafts (3) (4) is made of strong tubular steel, which has been design to

stand up to the maximum torque that is transferred to the rear axle.

The propeller shafts is furnished with sliding splines at the tube end (3) and sleeve

end (4) to absorb the movement between the transmission and rear axle.

Support bearing (5)

If the vehicle has more than one propeller shaft a support bearing is used to

suspend the propeller shafts on the vehicles cross member.


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Final Drive

The main task of the rear axle is to transmit driving power from the engine out to the

wheels.

The rear axle consists of:Rear axle-housing (1), which is made of cast iron and is to support and protect all

axle components.

90.

Driving shafts (3) that transmit the driving power on to the wheels.


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Clutch - Introduction

The clutch is one of the transmission components that enables the engagement and

disengagement of revolution power from the engine to the gearbox.

The clutch (1) is mounted between the engine and the gearbox. Some of itsfunctions are:

- Interrupt the transmission of power from the engine to the gearbox during

.

- Transfer torque from the engine to the gearbox and to the other transmission

components.

Clutch action allows a smooth and progressive torque transmission from the engine

to the

gearbox.

Clutch adalah salah satu komponen yang memungkinkan penghubungan dan

pemutusan tenaga putar dari engine ke gearbox


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For each type of vehicle, there is an ideal clutch, which is calculated in terms of:

- torque;

- vehicle maximum weight (loaded);

- gearshifts ratio;

- type of application;

- tire dynamic radius;

- differential ratio.

These factors will determine the pressure plate diameter, its weight, as well as the

type of disc to

be used.

The clutch should:- transfer torque from the engine to the gearbox without slipping;

- be resistant to high speeds and premature wear;

- eliminate vibrations during the start;

- enable a smooth and quick gearshifting

- absorb engine vibrations.


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Clutch categories

The many types of clutches may be divided into two main categories:

Hydraulic clutch (1)

The torque is transferred from the engine to the gearbox with the help of a hydraulicfluid that

works between the two main components of the hydraulic clutch: the pump rotor

rotor.

Mechanical clutch (2)

Mechanical clutches are composed of one or more discs. Most of them are

equipped with a

dia hra m s rin and the are h draulicall actuated b means of a

hydropneumatic clutch

servo. A pressure plate pushes the disc against the flywheel and transfers the

torque from the

engine to the gearbox.


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Hydraulic clutch

A hydraulic clutch is basically composed of a pump rotor and a turbine rotor.

The rotors are made of propeller blades facing each other.

The pump rotor is installed in the engine output shaft and the turbine rotor isconnected to the

gearbox input shaft.


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Hydraulic clutch - principal of operation

The engine starts to run and causes the pump rotor (1) to rotate. The hydraulic fluid

between

the rotors is forced against the turbine rotor (2).Pressure from the fluid causes the turbine rotor to rotate.

The faster the engine speed, the greater the fluid pressure in the turbine rotor.

The greater the pressure, the faster the turbine rotor rotates.

Through the turbine rotor rotation, the torque is transferred from the engine to the

gearbox and

then the rest of the transmission system that makes the vehicle move.


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Mechanical clutch - main components

Compression plate

The compression plate is a mechanical component made up of:

1. spacing rivet

2. leaf spring

3. compression plate

4. leaf spring attachment

5. ring

6. cover

The compression plate (3) is a strong steel ring that makes pressure against a

disc by meansof helical springs or diaphragm springs.


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There are two types of compression plates:

1. Helical spring loaded compression plate

This type of plate is not currently used in clutches mostly because it is not resistant

to the highspeeds of late engines. Also, its pressure on the disc is dramatically reduced with

facing

, .

2. Leaf spring loaded compression plate

Resistance to high engine speeds, together with a compact design that allows a

smaller housing

(essential for saving space), makes the leaf spring loaded plate a standard in

practically all

vehicles manufactured nowadays. Moreover, the leaf spring design makes it

possible to work

with lower and nearly constant initial loads during the plate life thereby reducing the

clutch pedal

effort.


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There are two types of leaf springs: Push-Type andPull-Type.

Volvo vehicles use the Pull-Typepressure plate.

The Pull-Type has many advantages over the Push-Type.

The main difference between these two clutches is the support bearing displacement.When the clutch pedal is applied, the support bearing is displaced towards the steering

gear

casin and the earbox.

The ends of the diaphragm spring and the pressure plate move away from the disc

disengaging

the engine and the clutch.

The performance of the Pull-Type is superior due to a greater capacity to transfer a higher

torque.

, , -

maintained.

Its new design also reduces the weight to the clutch assembly, which means less weight to

the

vehicle.

It also results in a reduced stress and more uniform plate pressure, even after long use,

means extended system life.


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Clutch disc

The clutch disc (1) is the main element contacting the flywheel engine (2) and the

plate (3).

When engaged, the clutch disc transfers torque from the engine to the gearbox andfrom the

other transmission components to the wheels, making it possible for the vehicle to

.


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The disc is made of steel. Clutch disc (1), damping springs (2), a grooved hub

(3), and a

facing (4).

The dry clutch disc is fiber-faced on both surfaces.Facings are built in non-asbestos materials resistant to the high temperatures

produced when

. .

The steel disc is connected to the hub by means of a friction element with damping

springs.

These springs absorb the engine peaks and vibrations.

The gearbox input shaft is inserted into the splined hole of the disc hub.

When the hub rotates the in ut shaft also turns and transfers the tor ue to the

gearbox.

To keep the load on the clutch disc facings as uniform as possible, the disc is

equipped with a

corrugated plate. This design provides a smooth clutch action and reduces the risk

of

.


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There are two types of clutch discs: a rigid disc and a torsion-damping disc

Rigid disc

In its simplest design, a rigid disc is made of a grooved hub (1) that slides over the

clutch pilotshaft, a drag disc (2), two facings (3) responsible for the friction between the

flywheel engine

, .

In a more modern design, a rigid disc may be provided with segment springs

between the

facings. The segment springs absorb axial motions of the disc and permit slight

sliding, resulting

in smoother engagement.


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Disc facing

Facings are components that provide friction between the plate and the flywheel engine.

Mostly manufactured with organic-based materials (with or without asbestos), the facings

shouldpresent the following basic qualities:

- a high friction coefficient;

- a constant friction coefficient as the tem erature increases

- resistance to premature wear;

- resistance to high temperatures;

- resistance to high speeds;

- do not cause vibrations.

In late model vehicles, facings practically without asbestos have been used, due to their

resistance to wear, when compared with the traditional asbestos facings.

Inorganic-based facings (sintered, ceramic) are restricted to vehicles where a smooth start

is

not very important (tractors, special trucks, racing trucks). The main qualities of these

facings

,

temperatures.

ATTENTION: The use of materials with asbestos is currently prohibited in many countriesdue

to the risk of cancer.


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Clutches may have one or two discs.

- Single disc clutch (1)

- Double disc clutch (2)

Double disc clutches operate the same way as single clutches except for thepresence of

another clutch disc and an intermediate pressure plate.

The intermediate pressure plate is located between the two clutch discs. It is

installed in an

intermediate ring bolted between the flywheel engine and the clutch body.

A double disc clutch has a larger friction area and can transfer a greater torque than

the single

disc clutch.

For this reason, this type of clutch is used in heavy-duty vehicles requiring a larger

torque.

IMPORTANT

While replacing the clutch disc, lubricate the grooves in the gearbox main shaft with

a thin layer

of heat-resistant grease before installing the new disc.


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Clutch bell housing (1)

The function of the clutch bell housing is protecting the clutch from contamination by

water and

dirt. It forms the front of the gearbox, connecting it to the engine casing.Lever anddisengaging shaft (2)

The lever (3) and the disengaging shaft (2) are part of the clutch control. They are

for the transmission of movement from the clutch driving system to the clutch

bearing.


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Clutch bearing

The function of the bearing (1) is to transfer the movement from the disengaging

shaft to the

diaphragm spring.The inner part of the bearing is attached to the revolution direction by the

disengaging shaft and

the clutch

body and the engine.

The clutch bearing is provided with a ring-like spring (2) whose function is to fix the

bearing

proper to the disengaging shaft when the gearbox is installed.


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Clutch operating system

The clutch is driven by a servo-aided system calledHydropneumatic driving

system.

This system consists of a hydraulic master cylinder connected to the clutch pedaland a servo

hydraulic cylinder.

1. fluid reservoir

2. master cylinder

3. hydraulic pipe

4. pneumatic pipe

.

6. register tube

7. clutch fork

The clutch servo increases the hydraulic force generated in the master cylinder,

thereby

noticeabl reducin the clutch edal effort.


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Master cylinder

The hydraulic master cylinder is installed next to the clutch pedal and is responsible

for the feed

pressure to the clutch servo.The master cylinder is also responsible for the generation of the hydraulic power

transferred to

.

The master cylinder requires two basic adjustments for the clutch pedal to operate

properly.

1. The top adjusting bolt (1) adjusts the play between the master cylinders piston

rod and the

piston. This play assures that the piston seal returns to a position just above thehole connecting

to the fluid reservoir. This _eliminates any residual pressure in the hydraulic piping.

2. The bottom adjusting bolt (2) adjusts the clutch pedal stroke and,

consequently, the clutch

servo piston stroke.


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Clutch servo

The clutch servo is located beside the gearbox.

The clutch servo function is to convert the master cylinders pressure into a

movement.This action takes place because the hydraulic pressure generated by the master

cylinder moves

.

The clutch servo also contains a wear indicator valve (1).


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Clutch operation

When the clutch is not applied, that is, the clutch pedal is released (1), the plate

presses the

clutch disc (2) against the flywheel engine.The clutch is connected to the flywheel (3) and transfers engine movement to the

gearbox

.

All the clutch assembly turns in the same engine speed and transfers the torque

from the engine

to the power transfer system.

The support bearing is forced backwards by the spring in the disengaging fork (5).


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Picture showing the whole system.

(1) The pilot valve closes the compressed air passage inside the cylinder and allows

the air to

enter through the exhaust hole.(2) The air exhaust hole is open.

The pressure in the system is equal to the atmospheric pressure.


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The clutch pedal is not applied. The engine is running or not but the vehicle is at

rest and the

gearbox is in neutral position. Or, else, the vehicle may be moving with one the

gears engaged.


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Now, lets see what happens when the clutch pedal is applied.

The master cylinder piston displacement causes an increase in the system

hydraulic pressure.

Due to this increase in the pressure, the reaction piston in the clutch servo startsupward:

(1) the reaction piston is pushed forward, ....

, ...

(3) the exhaust hole closes and prevents the air from escaping.


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Due to the compressed air pressure in the pneumatic chamber (1), the main

piston (2) starts

outward.

When the piston (2) moves outwards, the clutch starts to disengage.The flywheel (4) remains rotating if the engine is running.

The leaf spring (5) and the plate (6) are pulled backwards.

The clutch disc (7) is no longer in contact with the flywheel engine (4) and the

plate (6).


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When the main piston reaches the end of its upward stroke, the hydraulic fluid

occupies its

space and reduces the hydraulic pressure (1).

Remember: the piston is displaced by the compressed air pressure and not by thehydraulic

pressure.

.


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A disengaged clutch makes it possible to start the engine. The engine movement,

however, is

not transferred to the gearbox main shaft because the clutch disc is free, without

pressure.This way, the engine does not transfer torque to the power transfer system.

The driver is then free to shift gears.


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When the clutch pedal is released, the hydraulic pressure reduces to almost

atmospheric

pressure. The pressure spring (4) starts the reaction piston (1) to move

downward and backto its original position and allows the pilot valve (2) to close the compressed air

passage and,

, .

Thus, air comes out of the pneumatic chamber (5) and the main piston (6) starts

downward

by the spring action (7) on the clutch fork.


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Now the clutch is engaged with the flywheel engine again.

The plate presses the disc against the flywheel engine.

The engine transfers torque to the transmission.


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Some adjustments can be made in clutches:

- (1) pedal free valve (clutch pedal)

- (2) driving stroke (clutch servo)

Some inspections should be made regularly:

- in the clutch hydraulic system

- in the clutch pneumatic system

- in the clutch disc(s)

- in the flywheel

- in the pressure plate

Follow the instructions in the Service Manual on Clutches, according to model of

vehicle andtype of clutch.


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Identification and classification of clutch packages

The type of clutch used in a vehicle is identified on the identification plate attached

to the clutch

bell housing.Clutches are arranged as follows:

Version

Disc external diameter (in inches)

Number of discs

Pull-type clutch / Push-type clutch

Manufacturer

Clutches are sorted out according to the support bearing driving direction: pull-type- .


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Clutch wear measurement :

X1 = New disc

X2 = Measured Value

Y = max wear

Y = X2 X1

D = date


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Torque

We call torque the product of the force applied on a body and the length of the

particular lever

arm acting to rotate the body (distance from the point of application to the center ofrotation)

TORQUE = force x distance from the point of application.

,

different lever

length, we need more or less force on a shorter or longer lever arm to achieve the

same torque.

1. If you have a long the lever (distance), the less force you need.

2. If you have a short lever (distance), the more force you need.


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Units.

The force is measured in N (Newton) and length in m (meters). This means that the

product of

force and length, the torque, will have the unit Nm (Newton meter).Example A.

50 N x 4 m = 200 Nm

Example B.

50N x 2 m = 100 Nm


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Gear torque

Gears are mechanical components responsible for the transferring power from a

particular

engine to another gear. This transfer is called gear transmission and it is specifiedby a certain

torque and a certain revolution speed.

,

gear.

The larger the gear diameter, the greater its torque for a given rpm and the slower

the revolution

speed for a given torque.

The smaller the gear diameter, the less its torque for a given rpm and the faster itsrevolution

speed for a given torque.


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Relationship between gears

When two gears mesh, one of them drives the pair(1) and the other is normally driven (2).

The gear that drives the motion is called a driving gear.

The gear that is driven by the motion is called a driven gear.The number of teeth (or the diameter of a gears, since the teeth will have equal spacing) of

the

drivin ear and the driven ear determine the ear ratio between them.

The gear ratio may represent an increase or a decrease in rpm between the driving and the

driven gears.

This is calculated by:

R = Gear ratio

A = N of teeth in the driven gearB = N of teeth in the driven gear

R = A

B

If the driving gear has fewer teeth than the driven gear, the result will be a decrease in rpm.

If the driving gear has more teeth than the driven gear, the result will be an increase in rpm.

The ear ratio is the factor that determines the relationshi between the in ut tor ue and

rpm

and the output torque and rpm in a gearbox.


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If the transmission gear set is made up by two pairs of gears (1), the total gear ratio may be

calculated as

the follows:

A) R = 3612

B) R = 30

15

R = 3:1 x R = 2:1 = 6:1

In our example (see illustration), the rpm is six times lower and the torque is six times

higher (they change

in the same proportion).

Generally, gearboxes are provided with a gear set that performs a high ratio. This set is

called a lanetar

gear(2).

The gear ratio in a planetary gear, when the sun gear works as the driving gear, is as

follows:

A = N of teeth in the sun gear

B = N of teeth in the ring gear

A

Example: 30 + 60 = 3 Relationship 3 : 1

30


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1. 59.999

2. 121.86

3. 5.76


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General Information

A gearbox is a transmission component responsible for the control of the torque

changes in a

vehicle. The torque is altered according to the selected gear in the gearbox.In the absence of a gearbox in a vehicle, that is, if the engine were connected

directly to the

, .

variations

would be insignificant.

Summary

The gearbox control the torque ratios in a vehicle. The higher the torque, the lower

the gear. The

higher the speed, the higher the gear.

Summary

The gearbox control the torque shifts in a vehicle. The higher the torque, the lower

the gear. The

higher the speed, the higher the gear.


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Types of gearboxes

In the last few of years, transmission development has been focused towards

gearboxes.

The aim has been to improve the vehicles driving characteristics and simplify thedrivers job.

A series of gearbox models have been developed that adapt themselves to vehicles

on the tasks to be accomplished by the vehicle.

Gearboxes are basically divided into three types:

Manual gearbox (1): gear shifting is carried out by the driver.

Automatic gearbox (2): gear shifting is fully automatic with the help of information

from sensors

in the gearbox control unit and other control units in the vehicle.

Semi-automatic gearbox (3): the driver selects the gear and an electronic system

controls gear

shifting.


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Manual gearbox - main models

Volvo manual gearboxes may be found in the following models:

R1400/R1700 (1)

VT2014/2514 (2)

SR1700/1900 (3)

R1400 and R1700 (1) gearboxes are provided with 9 gears, 8 front gears and 1 reversegear. (8

orwar spee s + reverse spee . e g es spee s are sync ron se u ereverse

speeds are not synchronised.

VT2014/2514 (2) gearboxes are provided with 14 gears like SR gearboxes.

* S means that the gearbox is equipped with a split gear mounted in the front of the basicspeed

box.

* R means that the gearbox contains a high and a low shift, and that it is directly connectedto

the basic gearbox output.

* VT VOLVO transmission

* 20 or 25 - maximum gearbox torque, 2050 Nm or 2450 Nm.

* 14 number of gears in the gearbox

SR1400 and SR1700 (3) gearboxes are provided with 14 gears (12 forward speeds + 2crawling

speeds + 4 reverse speeds). The 12 highest speeds synchronised, the 4 reverse gears andthe

2 crawling speeds are not synchronised.


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Manual gearbox - main parts

This gearbox is basically divided into four parts:

Clutch bell housing (C) - this housing connects the gearbox to the engine and

protects theclutch.

Split gear (S) - the split gear splits the gears and makes it possible to use high and

.

Basic gearbox (B) - the basic gearbox contains basic gears, reduced gears and

reverse gears.

Range gear (R) - the range gear consists of a planetary gear set that double the

number of

gears in the basic gearbox (B).


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Clutch bell housing

The clutch bell housing connects the gearbox to the engine.

It also protects the clutch.


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Basic gearbox

The basic gearbox contains the gears and shafts that permit gear shifting.

The main shafts are:

- input shaft (1)

- main shaft (2)

- intermediate shaft (3)

- reverse shaft (4)

The gears are positioned on the shafts. There are five gears with synchronised

gearshifts, plus

the reduced gear and the non-synchronised reverse gear.

Note: The reduced gear is also known as CRAWL.


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Basic gearbox - input shaft and main shaft

Input shaft (1)

Also called as primary shaft, the input shaft is responsible for transferring torque

from the engineto the gearbox.

The torque is transferred through the clutch disc.

This shaft is supported by roller bearings in the clutch bell housing.

Main shaft (2)

The main shaft carries the five gears with synchronized gearshifts. These gears

operate freely

through needle bearings and roller bearings.

bearings.


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Basic gearbox - intermediate shaft and reverse shaft

Intermediate shaft (1)

Also called as secondary shaft, the intermediate shaft contains fixed gears only, that is, all

gearsare pressed onto the shaft and always turn at the shaft speed.

The secondary shaft receives the torque transferred from the input shaft and it is supported

on

the clutch bell housing and on the gearbox rear housing.

Reverse shaft (2)

The reverse gear is installed on that shaft.

The reverse gear is positioned between its driving gear, located in the main shaft, and a

takeoff

ear installed in the intermediate shaft.

The purpose of the reverse gear is to change the direction of revolution of the main shaft

and _

output shaft.

When the reverse gear changes the direction of revolution of the main shaft, this reverse

force is

transferred throu h the out ut shaft to the drive wheels and the vehicle moves backward .


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Basic gearbox - selector forks and oil pump

Besides shafts and gears, the basic gearbox also contains selector forks and the oil

pump.

Selector forks (1)Selector forks are responsible for the movement of the coupling sleeves on the

main shaft so

.

Selector forks receive the selector motion through the selector shafts.

They are installed with the help of retainers that, together, make up the selector unit.

Oil pump (2)

Larger gearboxes are lubricated through the use of an oil pump that forces the oil to

all the

gearbox lubrication points.

The oil pump is fastened to the inside of the gearbox. It is driven by a gear

connected to the

intermediate shaft, via the reverse gear.


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Range gear

The gearbox is supplemented with a double speed range gear:

- High range

- Low range

Using the range gear doubles the gearbox basic gears, as required by modern

trucks.

The range gear consists of a planetary system that transfer torque from the main

shaft directly

to the driving gears:

1. planetary gear

2. ring gear

.

4. sun gear

5. planetary carriers

Gear shifting in the range gear is carried out through a pneumatic cylinder (6).


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High range (A)

When the ring gear (1) is locked to the planetary gear carrier by a coupling ring (2),

the entire

planetary rear rotates.Torque coming from the basic gearbox goes directly through the planetary gear.

This means the gearbox operates in high gears.

Low range (B)

The ring gear (3) is locked in the gearbox housing and forces the planetary gears to

turn

between the ring gear (3) and the sun gear (4).

The planetary gear carrier (5) turns on the same direction of the sun gear but _ a

lower s eed.

This means that the torque coming from the basic gearbox is transferred through

the planetary

gears and operates with low gears.


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Range gear operation

A switch located on the gear lever knob operates the range gear.

To select the low range, push the switch down (1). It affect 1st and 3rd gears.

To select the high range, push the switch up (2). It affect 4th and 6th gears.


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Split gear

The purpose of the split gear is to split the gears in the gearbox.

Thus, both the first gear and the other gears have a low and a high gear.

CONCLUSION

Gearboxes with both the split gear and the range gear like SR and VT gearboxes

have 12

synchronized gears, two crawling speed gears and four non-synchronized reverse

gears.


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Split gear operation

Like the range gear, a switch located on the gear lever knob operates the split gear.

Note:

The split gear switch is not the same one as the range gear switch.

To select the high gears put the switch on H (High).

To select the low gears put the switch on L (Low).


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Split gear - high gear

Switching to H (High) on the gear lever knob activates a relay valve (2).


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The relay valve (2) is positioned in such a way that permits the passage of

compressed air to a

pneumatic cylinder (3).


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When the clutch pedal is depressed, the split gear operating valve (1) sends the air

to the



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Split gear - high gear (continuation)

The air displaces the cylinder piston to engages the high gears.

Then, the operating valve shaft in the split gear (1) actuates a switch and lights up a

lamp in thepanel indicating to the driver the high gear is selected.


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Split gear - low

Switching to L (Low) on the gear lever knob (1) activates a relay valve (2).


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The relay valve (2) is positioned in such a way that permits the passage of

compressed air to a



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Split gear - low (continuation)

When the clutch pedal is depressed, the split gear operating valve (1) sends the air

to the



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The air displaces the cylinder piston to engages the low gears.


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Manual gearbox - synchronisation of components

The purpose of the synchronisation is to facilitate gearshifts by adapting the speed

between the

main shaft and intermediate shaft during the shifts.The gearbox is equipped with many synchronisation devices:

1. coupling sleeve

2. coupling ring

3. gear

4. synchronizer ring

5. engaging body


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Synchronising operation

The engaging body is connected to the main shaft through splines. The coupling

sleeve is

geared around the engaging body. The purpose of this sleeve is to displace theengaging body

towards the synchroniser ring and connect it to the coupling ring.

by the

coupling sleeve. The resulting friction in the synchroniser ring matches the speed of

the

engaging body and the coupling sleeve. Upon reaching the same speed, the

coupling sleevemeshes _ with the coupling ring.

In this position, the gear is fully engaged to the main shaft through the engaging

body and can

transmit the torque from the engine to the driven wheels through the output shaft.


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Synchronisation devices operation

The synchronisation set operates as follows:

The synchroniser ring (4) is pressed between the engaging body (5) and the

coupling ring (2) bythe coupling sleeve (1).

The resulting friction in the synchroniser ring matches the speed of the engaging

coupling sleeve.

Upon reaching the same speed, the coupling sleeve engages it self with the

coupling ring.

In this position, the gear (3) is fully engaged to the main shaft through the engaging

body and can

transfer the torque from the engine to the driven wheels through the output shaft.


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Gearbox external components

The gearbox is provided with a series of external components to avoid damage to

the gearbox

and facilitate the shifting of gears.These components vary according to the gearbox model.

Basically, gearboxes are composed of:

1. an inhibitor valve

2. relief valves

3. relay valves

4. solenoid valves

5. an inhibitor valve6. electrical contacts

7. a sensor

8. a control cylinder

A more detailed description of these components will be reviewed in specific

modules on

.


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Manual gear shift

Manual gearshift is operated by a gear lever (1).

The gear lever (1) is supported on a guide bearer (2).

When the gear lever is moved (1), the motion is transferred to the selector-shafthousing (5) with

the help of a driving bar (3) and the control arm (4).

The control arm is connected to the side control shaft (6) in the selector-shaft

housing (2).

The selector-shaft housing (2), in turn, operates the gearbox shafts.


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Gearboxes, VT2014/2514 och VT2014OD/VT2514OD.

These variants were introduced during 1998; VT2014/VT2514 is a reinforced and

further improved SR

1900. The main news was increased maximum torque and new synchronymechanism. Maximum torque

for VT2014 is 2050Nm, for VT2514 is maximum 2450Nm.The control housing is the

,

clutch housing and the clutch servo Cylinder are mounted direct on to the clutch

housing and all gearwheels in the gearbox are helical.

With the new control and new type of synchromesh, shifting force is reduced by

approx 50 %.


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Overview, specifications

.

2. Control housing

3. Clutch pedal

4. Gear lever

5. Clutch servo cylinderThe gearbox is a splitter and range gearbox with 12 fully-synchronised gears, 2 unsynchronised crawler

gears (forward) and 4 unsynchronised reverse gears.

The range housing contains a planetary gear with two gear ratios, low range 3.75:1 and high range 1:1.

In the high-range position, power is transferred directly to the driven wheels via the bevel gear. In the

- , .

The control housing is cast from aluminium and is intended to transfer the motion of the gear lever to the

gearbox shift rods via the wire controls.

The gearbox is disengaged with the aid of the clutch pedal and a hydro-pneumatic clutch servo, which is

mounted directly on the clutch housing. The gear lever is connected to the gearbox mechanically via

wire-cabling; one wire for shift stroke (grey coating) and one wire for select stroke (black coating).

The system attaching the wire cabling to the gear lever and the control housing is colour coded.

Black, gear lever select stroke

White, gear lever shift stroke,

Orange, control housing select stroke

The basic housing of the VT2814B/VTO2814B is now equipped with larger sound plates. The range

housing has also been modified because of a new sound plate.

Specifications:

Manufacturer: Volvo

Designations: VT2814B, VTO2814B

No. of gears:

Forward gears 14

Weight empty: 330 kg

Length: VTO2814B/CD40B-O 1,066 mm

Oil change quantity: 13.5 litresGear ratios: refer to service bulletin 430 28.


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Type plate.

-

information.

This is a specific example, VTO2814B.

V = Volvo

T = TransmissionO = Overdrive

28 = Max. torque 2800Nm

14 = Number of forward gears

B = Version

= .

(SP3190317) = Spare part number.

Service category = Service category G, 1 or 2, refer to service literature 175 09 for description.

Comp. id = Component ID

Serial No = Serial number = 2003/36/1/0001, = year/week/day of manufacture/serial number.

The basic housing of the VT2814B/VTO2814B is now equipped with larger sound plates. The range

housing has also been modified because of a new sound plate.

Specifications:

Manufacturer: Volvo,

No. of gears:

Forward gears 14

Reverse 4

Weight empty: 330 kg

Length: VTO2814B/CD40B-O 1,066 mm

Oil change quantity: 13.5 litres

Gear ratios: refer to service bulletin 430 28.


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Main Component

1. Shift rod, shift fork , fork holder gear 3

2. Shift rod, shift fork, fork holder gear

3. Shift rod, shift fork, fork holder gear C/R

4. Shift rod, shift fork, splitter gear

5. Input shaft

6. Gear wheel splitter gear (low split ) / DD Transmission

7. Gear wheel P1(high split / basic gear 3 / DD Transmission

8. Gear wheel basic gear 1

9. Gear wheel basic gear 2

10. Gear wheel Crawler gear

11. Gear wheel reverse gear

12. Sun wheel13. Intermediate shaft

14. Oil pump gear wheel

15.Reverse gear wheel

16.Reverse Axle

17. Planetary gearing

18. Out put shaft

19. Carrier

20.Shifting fork range.


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Servo synchromesh

.

2. Inner cone

3. Double cone

4. Outer cone

5. Pusher plate6. Diaphragm spring

7. Guide sleeve

8. Engaging sleeve

9. Detent pin/spring (4)

.

A mechanic servo function provides extra power during synchronisation, which makes it easier to change

gear. This design allows the turning torque, which is created when the synchromesh begins to reduce the

rotation speed, to be converted to axial power. This automatically provides the driver with mechanical

servo assistance.

The act of changing gear can be divided into five phases:

A. Neutral

The clutch sleeve is kept in a neutral position, in relation to the guide bushing, using spring-loaded stops.

In this position, no axial power is transferred to the outer cone..

The shifter fork acts on the clutch sleeve, which pushes the stops against the outer cone. This causes an

increase in friction. The friction between the conical surfaces means that the inner and outer cone rotate

in the same direction as the double cone until the outer cone meets the block on the guide bushing. The

block surface on the outer cone connects with the clutch sleeve. The angle of the block surface is

chosen specifically to prevent axial motion of the clutch sleeve until synchronisation is complete.

C. Synchromesh

The friction between the conical surfaces means that the number of revs of the double cone and the

inner and outer cones are adjusted. Since the clutch sleeve is in the blocking position, it cannot be

.

pressure plate.

D. Release

Synchronisation is complete once the double cone rotates at the same speed as the inner and outercone. The block surface is now released and the clutch sleeve is capable of axial motion.

E. Gear engaged

The teeth of the clutch sleeve now interlock with the teeth of the clutch ring and shifting is complete.


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Control housing component :

1.Control housing

2.Stopr cylinder neutral

3.Magnetic solenoid interlock first gear4.Inhibitor valve control housing

5.Reverse light contact

.

7.Lever arm

8.Rod

9.Arm

10.Damper weight

11.Protective clamp

12.Gear selector lever position catch

13.Cam /1 gear catch

14.Axle

15.Gear selector lever

16.Cam / gear position

.

18.Cover


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VT Series pneumatic system :

1.Range Cylinder

2.Spliter cylinder

3.Inhibitor valve range

4.Inhibitorvalve control housing

5.Inhibitor valve split

6.Stop Cylinder

7.Relay valve range

8.Relay valve split

9.Range inhibitor

10.Air filter

11.Gear lever


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Oil flow has increased 20% in comparison with SR 1900.

The oil pump is an excenter pump that is driven by the counter drive shaft via a

gearwheel and a driven

axle, which passes through the reverse axle.The driven axle is equipped with two needle bearings in the reverse axle.

The pump has two by-pass valves. The first(1) ensures that the gearbox is

becomes clogged, and the second(2)protects against high pressure in the system

(e.g. a cold start).


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VT2814B Cooler

The VT2814B and VTO2814B can be fitted with a new water/air cooler at the front

of the truck.

Vehicles which operate in climates where temperatures exceed 30C, and have ahigh gross

combination weight, require extra gearbox cooling.

basic gearbox and clutch

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