Automobile Blog April Archive

In an automobile and other four-wheeled vehicles, a differential is a device, usually consisting of gears, that allows each of the driving wheels to rotate at different speeds, while supplying equal torque to each of them

Purpose: A vehicle's wheels rotate at different speeds, especially when turning corners. The differential is designed to drive a pair of wheels with equal force, while allowing them to rotate at different speeds

History: There are many claims to the invention of the differential gear, but it is likely that it was known, at least in some places, in ancient times.

Functional description: Power is supplied from the engine, via the gearbox, to a driveshaft (British term: propeller shaft), which runs to the rear axle

One undesirable side effect of a differential is that it can reduce overall torque - the rotational force which propels the vehicle

There are devices for getting more traction from vehicles with differentials. One of these is the limited slip differential (LSD), the most well known of which is the clutch-type LSD. With this differential, the side gears are coupled to the carrier via a stack of clutch plates, which limits the speed difference between the two wheels

A relatively new technology is the electronically controlled active differential. A computer uses inputs from multiple sensors, including yaw rate, steering angle, and lateral acceleration and adjusts the distribution of torque to compensate for undesirable handling behaviors like understeer