Differential

A differential has evolved due to the drawbacks of a live axle. Car wheels spin at different speeds while taking a turn. Speed is equal to distance travelled therefore the inside wheel travels a lesser distance than the outside wheel. As a result the inside wheel has to travel at a lower speed than the outside wheel which covers a greater distance. A differential is designed to split the torque from the engine to the two wheels which allows each of the drive wheels to spin at a different speed as the need maybe. 

There are different types of differentials, the simplest is an open differential. There are side gears connected to the pinion gears which are a part of the ring gear housed inside the differential. When the car is moving in a straight line the side gears are locked. The input pinion rotates the ring gear which in turn rotates the axle shaft connected to the wheels.

When the car takes a turn the ring gear spins the pinion gears which rotate the side gear of the outer wheel and the other side gear slows down the rotation of the inner wheel. Thereby equalling the speed of a wheel to the distance covered by that wheel. As a result, there is no wheel slippage during high speed cornering.