Mobility & Vehicles Mechanics: Differential Mechanism Essay


Discuss about the Mobility & Vehicles Mechanics for Differential Mechanism?


A differential is a mechanical device which is used to transmitting torque. It transmit power from drive shaft to wheels. Basically it allow the wheels to rotate at different speeds on different turning radius. This mechanism helps the outer wheel to rotate faster as compared to inner wheel. Proper speed balance of outer & inner wheel is done by differential mechanism.

Aim Of Differential Mechanism

The purpose of differential is to provide equal torque on wheels while allowing them to rotate at different speeds. If we talk about the vehicle in which differential mechanism is not present in this both the driving wheels are forced to rotate at same torque. At different corners inner wheels needs to travel shorter distance as compared to outer wheels so, in the absence of differential the wheel will skid or drag which unbalance the vehicle & damage the road as well as tyres this is cause differential is necessary. It transfers the power at 90?µ’.

Principle & Working

Differential consists of pinion shaft with pinion gear, ring gear which is commonly known as crown & axel shaft gear. Power comes from the engine is transferred to the ring gear through pinion gear. There are two gears one is sun gear while other is planet gear. Planet gear is free to make two kind of rotation one is along the crown & second along its axis. Planet gear is meshed with two side gear.

Let us assume some cases when the vehicle is moving straight in this planet gear will move with ring gear but not rotate on its axis. Planet gear pushes the side gear & both will turn at same speed.

Now consider a case vehicle is taking a right turn now planet gear will play an important role along with the rotation of ring gear it rotates on its own axis now it is having a combined rotation. It is interesting to know that side gear has same peripheral velocity as of planet gear. When the planet gear is spinning as well as rotating peripheral velocity at the left side of the planet gear is sum of spinning & rotational velocity but at right side it is difference of two or left side gear will have higher speed compare to the right side gear. This the way differential manages to turn left & right wheels at different speeds

While taking to left turn the planet gear will stand in opposite direction in order to carry load one more planet gear is usually added. This will help to rotate wheels at different rpm.

Apart from this it also have another function it help in transmitting the power by 90?µ’. A diagram of differential is shown above.

How Design Of Differential Gear Effect Performance Of Vehcile

Change of differential can have tremendous outputs in vehicle performance. According to study engine section is not only one which increases the vehicle performance. Differential option varies according to gearing upgrades. Change of differential gearing is one of the best method to enhance the output. If we use shorter final drive ratio rpm will also increase, with this we get more powerful rpm range than before. As per the general perspective if we are applying proper gear ratio in differential then performance will increase. If we apply shorter gear ratio acceleration will increase by taking fuel economy parallel. Higher the gear ratio higher will be the rpm. Here are some design of differential gear which are used in vehicle.

Various Differential Design

Open carrier differential

As the name suggest open carrier differential in this differential there is not outer casing. The drawback of this differential is there is lack of traction.

Limited slip differential

Now a day’s limited slip differential are mostly used. The main function of this differential is when one wheel is in slippery condition while other is at dry state then this differential comes into an action & provide more power to slippery wheel so that torque distributed will be balanced easily.

Locking differential

A locking differential uses mechanism that allow left and right wheel to lock correspondingly at same speed in this there will be traction. In this state axel will act as spool. A limited slip situation will send some torque to wheel but not enough to give any momentum.

Epicyclic differential

It uses epicyclic gearing which splits the torque in right proportion. Epicyclic gears are also known as planetary gear it is just because the axis of the gear revolve around the sun gear.

Spur differential

This type of gear is used in early section of automobile. It is having spurs only. In this there are no use of bevel gear. Gear used in this is miter gear

Purpose Of Differential Mechanism

The main purpose differential mechanism is to balance the vehicle. When vehicle take a turn outer wheel have to cover more distance as compared to inner wheel so, to avoid this from skidding we use differential. The main advantage of differential is it can be used in both front & rear axle. Power is transmit at right angle with minimum loss of traction.

Problem Faced In Differential Mechanism

Major problem is of noise. When differential is in working condition it produces huge noise.
Regular clunking will indicate of broken ring or any pinion gear.
Rumbling or whirling at speed of 20mph will caused by worn carrier bearing.
Gear ratio have to accurate if not, vehicle will face low performance output.
Improper gear setup leads to more traction.


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2006)): 319–329.

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