Everything you need to know about differential

Having knowledge of differential begins from the working of an automobile engine to the transmission system. Well, the brief explanation is that power production from the engine is transferred to the wheel with the help of the transmission system. The benefit of the differential is to split the power from the engine, making the wheels move at a different speed.

Today we’ll be looking at the definition, functions, working, parts, and applications, as well as the advantages and disadvantages of a differential system in an automobile.


What is a Differential?

A differential is a mechanism that transmits an engine’s torque to the wheels for the purpose of splitting the power, allowing the wheels to move at varying speeds. The differential has no effect when the vehicle is moving straight. The effect occurs when the vehicle is trying to make a turn, resulting in the wheel moving at a different speed.

Diagram of diferential
The complete diagram of differential and its label

Functions of Differential in a Vehicle:

The differential has the following three functions on the vehicle’s wheels:

  • To help the engine power the wheels
  • Transmit the power to the wheels as they rotate at a different speed
  • Act as final gear reduction in the vehicle by slowing the rotational speed of the transmission one final time before moving to the wheel
  • Another function of the differential is to turn the power flow at 90-degree

Major parts of Differential System:

the following are the parts of the differential:

  • Pinion Drive Gear: the differential part transfers power from the driveshaft (prop shaft) to the ring gear.
  • Ring Gear: the ring gear transfers power to the differential case assembly.
  • Spider Gears: this component lies at the heart of the differential.
  • Differential Case Assembly: this part holds the gear and drives the axel.
  • Rear Drive Axle: it transfers torque from the differential assembly to the drive wheels.

Types of Differential:

Below are the types of differential:

  • Open Differential: the open differential splits the engine torque into two outputs and allows the wheels to rotate at different speeds. It is often found in family Sedans and economy cars. In its working, when one tire loses traction, the opposing tire will also lose power.
  • Locking Differential: in the locking type of differential, connected wheels rotate at the same speed, which makes turning very difficult for any vehicle that carries such. It is often seen in jeep wranglers and most full-size trucks.
  • Limited-Slip Differential: this type of differential combines both the open and locking differentials. It is often used in sports vehicles like the Nissan 370Z and the Mazda MX-5 Miata. The differential usually acts as the open differential but locks automatically when slipping occurs. In the limited-slip differential, lock-up is achieved with one of the three ways – Viscous fluid, Clutch park, or a Complex gear train.
  • Torque-Vectoring Differential: this type of differential uses an additional gear train. It fine-tunes the torque delivered to each drive wheel. It is often found in the BMW x5 M or Lexus RC F. Slowing down or quickening the car’s rotation around a corner can be easier.

Read: Types of differential and their functions

Applications of Differential on a Vehicle:

In a vehicle, the differential is designed to drive a pair of wheels as they are allowed to rotate at different speeds. Vehicles without a differential, such as “karts” find it difficult to make a suitable turn as both driving wheels are forced to rotate at the same speed. in its situation, the axle is driven by a simple chain-drive mechanism. When taking a turn with such a vehicle, the inner wheel travels a shorter distance than the outer wheel.

This makes the differential useless because either the inner wheel rotates too quickly or the outer wheel rotates too slowly. However, it results in difficult and unpredictable handling, damaged tires and roads, and stains on the drivetrain. In the applications of a differential in rear-wheel drive automobiles, the propeller shaft helps in the engagement. This is achieved with a hypoid gear (ring and pinion). The ring gear is mounted on the carrier of the planetary chain that forms the differential. This hybrid gear is a bevel gear that changes the direction of the drive rotation.

Working Principle of Differential

The working principle of a differential in a vehicle is quite complicated for the modern version, but it’s interesting. Let me give a descriptive example; if a car is making a turn to the right, the main gear may make 10 full rotations. At that time, the left wheel will make more rotations because it needs more travel, and the right wheel will make fewer rotations as it has less distance to travel. The sun gears which drive the axle half-shafts rotate at a different speed related to the ring gear (one faster, one slower).

This means, 2 full turns each (4 full turns relative to each other), which causes the left wheel to make 12 rotations and the right wheel to make 8 rotations. The rotation of the ring gear is the average rotation of the side sun gears. This causes the transmission in gear preventing the ring gear from turning inside the differential when the vehicle is off. In the working of differential, the input torque is applied to the ring gear (blue), which turns the entire carrier (blue). The carrier is connected to both sun gears only through the planet gear (green).

The torque is transmitted to the sun gears through the planet gear. The planet’s gear revolves around the axis of the carrier that drives the sun’s gears. The planet gear revolves without spinning its own axis, if the resistance at both wheels is equal, which turns both wheels at the same rate. However, if the left sun gear (red) experiences resistance, the planet gear (green) spins as well as revolves. Allowing the left sun gear to slow down, with an equal speeding up of the right sun gear (yellow).

The video below explains how differential works:

Advantages and Disadvantages of Differential:


The following are the advantages of differential:

  • It is resistant to EM (Electromagnetic) interference as differential signals are transmitted on balanced lines.
  • helps in minimizing electronic crosstalk.
  • It can be used for high-speed transmission lines with good quality due to noise elimination and less radiation. Hence Common mode rejection as well as improved power supply rejection can be achieved.
  • Higher overall signal swings can be achieved.
  • It offers inherent cancellation of even order harmonics. Some pre-distortion techniques are employed to reduce odd harmonics.


Despite the great advantages of differential, some limitation still occurs. Think about a rear wheel that has a good grip on one side and is on a slippery track on the other. The car won’t be able to move from its position since the standard differential is sending the majority of the power to the slick wheel in this situation. Limited slip differentials were developed to address this problem.

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That’s all for this article that contains the definition, types, working principles, functions, parts, and applications of differential. I hope you enjoyed the reading, if so kindly comment, share, and recommend this site to other technical students. Thanks!


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