Auto differential can make left and right (or) before and after driving wheels at different speed of rotation mechanism. Mainly by around half shaft 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. Differential is to adjust the left and right wheel speed difference and device. In 4 wheel drive, in order to drive the four wheels, must connect all of the wheels, if the mechanical connection together, the four wheels the car is moving in a curve can't rotate at the same speed, in order to let the cars drive curve basic consistency rotation speed, then need to join the middle differential is used to adjust the speed difference of the front and back. And about differential shell is installed differential shell.
