What are the differences between drum brakes and disc brakes?

[Myron]

The differences between drum brakes and disc brakes lie in braking force, heat dissipation performance, drainage function, structure, and cooling effect. Braking refers to stopping a moving vehicle, and the brake is a component in the braking system that generates resistance to the vehicle's movement. Currently, friction brakes are commonly used in vehicles, which utilize the friction between fixed and rotating components to produce braking torque. These brakes are further divided into disc brakes and drum brakes. The specific differences are as follows: Different braking force: In terms of braking force, drum brakes provide significantly stronger braking force than disc brakes. This is not because drum brake technology is more advanced but due to their inherent structural characteristics. In a drum brake system, there is a drum-shaped metal component, which is the core part of the drum brake, hence the name. Different heat dissipation performance: Drum brakes operate in a confined space, resulting in poor heat dissipation. During braking, a large amount of heat accumulates, causing the brake shoes and drum to deform under high temperatures, leading to brake fade and vibration, which reduces braking efficiency. Different drainage function: Drainage is another advantage of disc brakes over drum brakes. When water enters the braking system, its impact on braking performance is evident. If the water cannot be drained promptly, braking performance will significantly decline. The enclosed design of drum brakes is clearly less effective for drainage compared to disc brakes. Different structure: Disc brakes have a compact and simple structure, while drum brakes are relatively more complex. However, drum brakes achieve the same braking force with a much smaller diameter than disc brakes. Different cooling effect: Disc brakes have exposed brake shoes, resulting in better heat dissipation and more stable braking performance. In contrast, drum brakes have brake shoes enclosed within the drum, making heat dissipation difficult. Prolonged braking causes the braking force to diminish as heat increases. Principle of drum brakes: Inside the brake drum, hydraulic pressure acts on the pistons of the brake wheel cylinder, pushing the curved brake shoes outward. Alternatively, friction material attached to the brake shoes presses against the inner surface of the drum, slowing the rotation of the drum and axle to achieve braking. Working principle of disc brakes: Hydraulic oil pushes the brake pads against the brake disc through cylinders, generating friction to brake. Disc brakes installed on high-speed shafts come in two torque specifications: 10,000 N·m and 12,500 N·m. The brake disc diameter is 800 mm. Each brake set has four cylinders controlled by a hydraulic system. The features include high braking torque, excellent heat dissipation, adjustable oil pressure, and stepless variation of braking torque during operation.