The function of the moving shoe assembly is to withstand the thrust of the actuator, the normal and tangential forces of the brake drum, and the support reaction force. It is a friction couple component of a drum brake, which not only has the strength and stiffness required as a component, but also has the highest and stable friction coefficient possible, as well as appropriate wear resistance, heat resistance, heat dissipation, and thermal capacity.

Drum brakes are divided into the following three categories:

1. Wheel cylinder brake, which uses the rotating piston to push the brake shoe open;

2. The cam opening brake uses the rotation of the cam to open the brake shoe. According to the force on the cam, it can be divided into two types: unbalanced and balanced. The former is fixedly connected or integrated with the shaft; The latter cam can float on the shaft, and this structure is rarely used due to its serious drawbacks;

3. Wedge brake, which uses the wedging of the wedge rod to open the brake shoes.