The differences between drum brakes and disc brakes:

1. The most significant difference lies in the field of braking capacity. The braking range of drum brakes is particularly large, and the best braking condition can be achieved in a short period of time. 

The braking effect of disc brakes in the short term is even worse.

2. Compared with drum brakes, disc brakes have a smoother braking process and offer a much more comfortable experience. Moreover, the braking effect of disc brakes is controlled by the depth 

of the brake pad's stroke, making them easier to operate than drum brakes.

3. Disc brakes are designed with holes and heat dissipation components, so they have better heat dissipation performance than drum brakes. Moreover, disc brakes can achieve continuous 

high-frequency application without worrying about the brake pedal fading or failure caused by continuous use.

4. Compared with drum brakes, the structure of disc brakes is simpler. In terms of disassembly and assembly, they are easier to maintain. However, the maintenance of drum brakes is relatively 

inconvenient. It is necessary to adjust the brake shoe clearance in time and remove the brake pedal powder left in the brake drum due to braking.

The design principle of drum brakes is to increase the working pressure on the brake caliper, so that the stationary brake friction pads clamp the rotating brake pads along with the tires. 

The frictional force formed by their contact reduces the rotational speed of the tires, thereby achieving the actual braking effect.

The principle of drum brakes is that the piston rod inside the brake drum promotes the outward movement of the friction lining, generating friction between the friction lining and the inner cavity 

of the brake drum, thereby achieving the braking effect.