The brake drum is a fragile gray cast iron material, which is a cast iron piece similar to a hand drum. It is fixed with the tire and rotates at the same speed. When braking, the oil pressure pushes the brake shoe to contact the inner edge of the brake drum, and the friction generated by the contact inhibits the rotation of the tire to achieve the purpose of braking.
The drum brake is composed of brake base plate, brake cylinder, brake shoe and other related connecting rods, springs, spikes and brake drum. At present, it is only commonly used on the rear wheel. Drum brakes are widely used on the rear wheels of small cars because of their low cost and high absolute braking force. However, the brake drum wear rate is high, so the overall cost is high.