Drum brake is mainly composed of brake wheel cylinder, brake shoe, brake drum, support pin, etc. The drum brake has been used in automobiles for nearly a century. However, due to its traveling ability and powerful braking force, the drum brake is still equipped in many models (mostly used in the rear wheels).

The inner cylinder surface of the brake drum of the drum brake is the position plate for the brake plate to generate the brake torque. Under the condition of obtaining the same braking torque, the brake drum diameter of drum brake can be much smaller than the brake disc of disc brake. Therefore, in order to obtain strong braking force, large vehicles with heavy load can only install drum brakes in the limited space of wheel rims.

To put it simply, drum brake is a brake device that uses the static brake shoe in the brake to rub the brake drum that rotates with the wheel to generate friction to reduce the wheel rotation speed. When the brake pedal is depressed, the force of the foot will make the piston in the brake master cylinder push the brake fluid forward and generate pressure in the oil circuit. The pressure is transmitted to the brake wheel cylinder piston of each wheel through the brake fluid. The brake wheel cylinder piston pushes the brake shoe outward again, causing friction between the brake shoe and the inner cylinder surface of the brake drum, and generating enough friction to reduce the speed of the wheel, so as to achieve the purpose of braking.

Key words: brake drum