How Differentials Work

The differential is a device that splits the enginetorquetwo ways, allowing each output to spin at a different speed.

The differential is found on all fuel-burning cars and trucks and also in many all-wheel-drive (full-timefour-wheel-drive) vehicles. These all-wheel-drive vehicles need a differential between each set of drive wheels, and they need one between the front and the back wheels as well, because the front wheels travel a different distance through a turn than the back wheels.

This center differential is often referred to as atransfer case. Someelectric carsdo not need differentials because they have multiple motors which drive the wheels independently of one another.

Part-timefour-wheel-drive systemsdon't have a differential between the front and rear wheels; instead, they are locked together so that the front and rear wheels have to turn at the same average speed. This is why these vehicles are hard to turn on concrete when the four-wheel-drive system is engaged. When the 4WD system is unlocked, the vehicle behaves like a rear-wheel-drive setup with one differential getting power.