The brake is a component used in the brake system to produce the motive force of the motion or movement of the vehicle. In addition to all kinds of retarding devices, vehicle brakes are mostly made of frictional brakes produced by friction between the fixed elements and the working surfaces of the rotating components.

    At present, the friction brakes widely used in various kinds of cars can be divided into two categories, drum type and disc type, according to the different rotating components. The difference between them is that the rotary element in the friction pair of drum brake is the brake drum, the inner surface of its cylinder is the working surface, and the rotating component of disc brake pair is disc brake disc, and the two end face is the working surface.