The brake drum is a cast iron piece shaped like a tambourine that is fixed to the tire and rotates at the same speed. When braking, use hydraulic pressure to push the brake shoes (Brake Shoes) to contact the inner edge of the brake drum, and the friction generated by the contact is used to suppress the rotation of the tire to achieve the purpose of braking. The drum brake is composed of a brake base plate, a brake cylinder, a brake shoe and the like, and a connecting rod, a spring, a tip nail and a brake drum. Currently only used in the rear wheel. Drum brakes have lower cost and higher absolute braking force and are used more in the rear wheels of small cars. However, its wear rate is higher, so the overall cost is higher.