The working principle of the brake is mainly from friction. The friction of the brake pad and brake disc (drum) and the tire and the ground is used to convert the kinetic energy of the vehicle to the heat energy after friction to stop the car. A good and efficient brake system must provide stable, sufficient and controllable braking force, and have good hydraulic transmission and heat dissipation capabilities to ensure that the force applied by the driver from the brake pedal can be fully and effectively transmitted to the master cylinder. And various pumps, and avoid hydraulic failure and brake decline caused by high heat. The brake system on the car is divided into two types: disc and drum, but in addition to the cost advantage, the efficiency of the drum brake is far less than that of the disc brake.