Definition of Differential

A special gearbox, designed so that the torque fed into it is split and delivered to two outputs (eg two different wheels on one axle) that can turn at different speeds (for example, when cornering).

Differentials within axles are designed to split torque evenly in normal use. However, a centre differential, which is used between the front and rear axles in four-wheel-drive systems, rather than across a single axle, is often designed to apportion torque unevenly.