A differential is a mechanical device that allows the wheels on the same axle to rotate at different speeds, such as when the car is turning. It is a key player that works to apply torque (a rotational force) to the drive wheels. The differential is a gear train with three drive shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others). The main components of a differential are the ring and pinion gears, and it is found on all fuel-burning cars and trucks and also in many all-wheel-drive (full-time four-wheel-drive) vehicles.
The purpose of a differential is to transfer the engines power to the wheels while still allowing the wheels to rotate at different speeds when required). For example, in a turn, the outside wheel must travel farther, which means it must travel faster than the inside wheels. However, for improved cornering abilities, many vehicles use a differential, which allows the two wheels to rotate at different speeds).
A relatively simple design of differential is used in rear-wheel drive vehicles, whereby a ring gear is driven by a pinion gear connected to the transmission. The functions of this design are to change the axis of rotation by 90 degrees (from the propshaft to the half-shafts) and provide a reduction in the gear ratio).
Differentials are low-maintenance, sealed components that are expected to last the life of the vehicle but may have a recommended service interval to check and/or replace the oil.
