Differential | Types | Working | Assembly

Hello friends, welcome to all of you again in a new post. Do you all know what is the differential in automobiles? And what does it do? let’s know


What is a differential?

What is the differential? First of all, we know that the engine generates power. And this power goes to the rear wheels through the propeller shaft. Two wheels are attached to the rear axle. The inner wheel and outer wheel, are also known as the right wheel and left wheel. The speed at which the propeller shaft rotates. It is necessary to rotate both wheels at the same speed. When a vehicle is moving straight. So there is no problem then.

But when the car takes a turn. Then if the inner wheel is rotating slowly then the outer wheel should rotate at a higher speed. This is because the track distance of the inner wheel is less at this time. And the distance of the outer wheel is more. If both the wheels rotate at the same speed, then the car will not be able to turn, but

Now you must be wondering how this will happen because the propeller shaft is giving power to the wheels with one stroke. So for this process differential is used in automobiles. In which the motion is transmitted to the wheels using different types of gear mechanisms. You must have understood well what is the differential


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Differential assembly

1. Crown wheel

2 . tail pinion

3. sun pinion

4. star pinion

5. differential bearing

6. spider

7. cage

8. tail pinion bearing


Differential working?

Let us now know how the differential works. So the crown wheel fits in a housing in the differential cage. the tail pinion is fitted with the propeller shaft through a bearing in the housing with the crown wheel.

with this, a flange is fitted. with this, the propeller shaft is fitted through a universal joint. And with the crown wheel, the sun pinion and star pinion are also fitted through bolts.

the sun pinion in the differential cage is attached to the axle shaft. There are two sun pinions. And the sun pinion and star pinion are linked together by a spider.



When the motor vehicle accelerates. So the tail pinion is rotated by the propeller shaft. And the tail pinion rotates the crown wheel. Because of this, the whole cage mounted on it rotates. And the axles in the sun pinion rotate the wheels.

In this situation, if the vehicle is moving on a straight road, then both wheels rotate at the same speed. Because both the sun pinions rotate in line with the differential cage.

But the same if the motor vehicle takes a turn. Or passes through high and sloping places. So there is a different difference in speed in the rear wheels. As well as when the vehicle takes a turn. So in this condition, due to pressure on the inner wheel, its speed decreases.


What is the function of the crown wheel and tail pinion?

You all know that divides the power coming in a straight line to both wheels at 900. In this process, this angle is changed by the rotation of the crown wheel by the tail pinion.

A variety of crown wheel and tail pinion designs and fittings are used in automobiles. The crown wheel and tail pinion transmit the final drive to the wheel by gear reduction in a vehicle.

There is an approximate difference of 1:8 in the speed of these two. This means when the crown wheel makes one revolution. So there are about 8 revolutions of the tail pinion. The crown wheel has 8 times more teeth than the tail pinion. Due to this, the torque increases. There are three types of final drive according to the design of the tail pinion and crown wheel.

Hypoid type final drive

worm gear type final drive

bevel type final drive


differential function

Differential adjustment is a very important function. If the differential adjustment is not correct. So it doesn’t work properly. Due to this, there is also a fear of breaking the teeth of the tail pinion and crown wheel. So differential adjustment is very important. These adjustments are of two types –

According to keeping backlash in the teeth of the crown wheel and tail pinion

In order to make the most perfect contact between the teeth of the crown wheel and tail pinion


Some disadvantages of differential

noise coming from the differential

             Reason                                                                                                                      How to fix

  • Oil is low in the differential housing                                                     Fill the oil right up to the surface
  • A differential bearing has worn                                                              Check bearings and replace bearings
  • Poor adjustment of crown wheel and oil pinion                               Check and correct adjustments
  • Differential cage assembly loose                                                           Check and correct the cage assembly
  • Excessive play between sun pinion and star pinion                         Reduce play by thrust washers


When the vehicle is running in the differential, the heat increases more. To avoid this, proper amount of S. A. E. 90 or E. P. 90 oil should be used for lubrication in the differential. Its level should be checked while servicing the vehicle.


Differential not working doing

The following could be the reasons for the differential not working

Reason                                                                                                                   How to fix?

The axial shaft is broken –                                                              AXIAL Check and replace an axial shaft
The welding of the spline is gone.                                                Welding the spline properly.
Star Pinion has freed                                                                        STAR Pinion connected correctly and replaced if                                                                                                                       necessary
The Crown wheel and tail pinion teeth are broken                 Check and replace them with Correct
The pinion is slipping the flange                                                    tighten the flange
The spline of the axial and sun pinion is worn.                        Tighten both using thrust washers.

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