Differential assembly is mainly composed of about half axle gear, two planetary gear and gear rack.
Function is when the car turning, or when driving on rough road surface, the left and right wheels at different speed rolling, guarantee on both sides of the drive wheels are pure rolling motion.
The differential is found on all modern cars and trucks, and also in many all-wheel-drive (full-time four-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 rear wheels.
