Differential Intro 2010

7/30/2019 Differential Intro 2010

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Differential Introduction

Rear axle-housing (1) which is made of cast iron and is to support and protect allaxle component. Its bolted on the vehicle suspension.

Final drive (2) with helical gears that turn the driving power through 90

Driving shaft (3) that transfer the driving power on to the wheels


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Main com onent

Rear axle housing (1)

Differential case (2)


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Function of differential

The differential has a job of adjusting the speed of individual drivewheels while retaining the total driving power.

When the vehicle turns corner, the outside wheel has a longerdistance to roll than the inside wheel, which means that it has to

.

If there were no differential and the two wheels were fixed togetherand rotated at same speed when the vehicle turned, one wheelwould have to slip to compensate for the difference in rollingdistance.


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Final drive com onent

Pinion : is the input shaft of the rear axle assembly

Crown wheel : the driving powers is transferred from the pinion to

the crown wheel, which is fitted to the differential housing. Dueto the fact that the pinion and crown wheel rotate at 90 angle to

,wheels via the drive shaft.

The differential is fitted to the differential housing and consist ofdifferential gear, four smaller gears fitted on the spider and twobigger gears, which in its turn are connected to the drive shafts.


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Crown wheel and inion shaft

For smooth and efficient operation, the crown wheel and pinion arematched during manufacture. The crown wheel and pinion arethan marked with a number (4477) to ensure aligned fit. They mustalways be installed together when assembling the final drive.


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Crown wheel and pinion combination

The crown wheel and pinion work together to turn the torque through an angle of90.

The function of this angle operation is to transfer the driving power from engine out

to the drive shaft.Crown wheel and pinion can be found in two different design:

. , :center line.

2. Hypoid helical teeth :the pinion center line is bellow that of crown wheel.This allows that more teeth are in contact and larger torque could betransferred from pinion to crown wheel. The hypoid design is usuallyused in Volvo final drives.

v y u ,which results in a higher capacity to transfer the pinion torque to the crown

wheel.


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The input shaft speed form the propeller shaft is quite highbut the speed is reduced by the final drives. This to make

the wheels turn at suitable speed.

And at the same time increases the torque to the wheels.No of teeth of crown wheel

No of teeth of pinion

Example:

10

Result : 3:1 reduction.


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Differential

The differential consist of :

1. Satellite (smaller gear)

2. Sun gear (larger gear)

3. J ournal led on the s ide


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Drive Shaft

The drive shaft are of forged hardened steel. They are so toughand elastic that than can be twisted nearly a whole turn beforebreaking off.


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Tandem drive

A heavy duty truck is often equipped with a tandem drive, that istwo driven rear axle.

This result in less slip and enhanced grip.The front-most driven axle is equipped with a transfer gear whilethe final drive in the rear-most axle is a standard single gear.


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Differential with transfer gearbox

Power from the gearbox passes via the transfer boxs input shaft(1), the transfer gears differential (2), to the output shaft (3), whichdrives the rear most axle via short propeller shaft.

The transfer gearbox as a gear wheel (4), which uses an additional-

rear axle.


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Differential with transfer gearbox

Power from the gearbox passes via the transfer boxs input shaft(1), the transfer gears differential (2), to the output shaft (3), whichdrives the rear most axle via short propeller shaft.

The transfer gearbox as a gear wheel (4), which uses an additional-

rear axle.


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General

RT2610HV and RT3210HV are two different tandem axles with hub reduction.RT2610HV is dimensioned for engine torque of 3100 Nm, maximum bogie loadingof 26 tonne and a gross train weight of 100 tonne.RT3210HV is dimensioned for engine torque of 3100 Nm, maximum bogie loadingof 32 tonne and a gross train weight of 100 tonne.

Both RT2610HV and RT3210HV consist of two final drives with crown wheel andpinion of the spiral bevel type, and hub reduction. The front final drive also has anintegrated transfer gearbox. The task of the transfer gearbox is to distribute torqueevenly between the two final drives.

Torque from the gearbox is transmitted via the transfer gearbox input shaft to thetransfer differential. From this differential, part of the torque is transmitted via acylindrical spur gear to the front differential gear set, and the rest is transmitted to

e rans er gear ox ou pu s a , w c rves e rearmos ac axe na rve vaa propeller shaft. From the final drives, the torque is transmitted to the wheels viathe drive shafts and hub reduction gear.

The two single axles, RS1352HV and RS1370HV have final drives which are similarto the rear final drives in RT2610HV and RT3210HV respectively. The information inthis service bulletin thus applies to RS1352HV and RS1370HV as well.


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Final drives, front/rear

The final drive design of both axles is spiral bevel. This is a tapered, helical gear,where the centerline of the pinion coincides with the centre of the crown wheel.

Pinion

The axial position of the pinion is adjusted by shims (A) between the final drivehousing and the inner pinion bearing.


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Normal Running

The final drive gears are driven by the transfer gear in the front gear (EV72) of thetandem drive bogie. Power from the engine/gearbox drives both the final drive gearsthrough the transfer gear.

The transfer gear side differentials drive the front final drive gear and the out putshaft to the rear final drive gear.


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The Final Drives Slip

Any difference in rotation speed between the front and the rear final drives is takenup by the transfer gear differentials.

When the difference in speed between the drives become excessive, e.g., When

driving on a slippery surface, one of the differential side gears (the one not slipping)will rotate at twice the speed of the input shaft, while the other differential side gearsremains stationary and the input shaft with carrier and pinions rotate


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Differential Lock Active

The differential can be forced to rotate by the differential lock in the transfer gear,Which locks the input shaft to the front gear in the differential via intermediate gear.


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Differential Intro 2010

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