What is a Drum Brake?
2 Answers
Drum brake refers to a braking device that utilizes stationary brake shoes inside the brake drum to create friction against the rotating drum attached to the wheel, thereby reducing the wheel's rotational speed. When the brake pedal is pressed, the force applied by the foot pushes the piston in the master cylinder forward, generating pressure in the hydraulic system. Advantages of Drum Brakes in Automobiles: Drum brakes have excellent self-braking properties. As the brake shoes expand outward, the rotating wheel causes the expanding brake drum to twist at an angle during braking—the greater the outward expansion, the more pronounced this effect. Therefore, drum brakes are still commonly used in large vehicles, primarily due to their lower cost. The main difference between drum brakes in large and small vehicles is that large vehicles typically use pneumatic assistance, while small vehicles use vacuum assistance to aid braking. Drum brake manufacturing technology is relatively basic, being the earliest type used in braking systems, making production costs lower than disc brakes. Additionally, the installation of handbrake mechanisms is easier. Some models with rear disc brakes may even incorporate a drum-style handbrake mechanism at the center of the brake disc. Disadvantages of Drum Brakes in Automobiles: The brake drum of a drum brake expands in diameter when heated, increasing the travel distance of the brake pedal and potentially leading to less responsive braking than expected. Therefore, when driving a vehicle with drum brakes, it is advisable to avoid continuous braking to prevent heat fade caused by high temperatures on the brake shoes. The braking system reacts relatively slowly, and the pedal force is harder to control precisely, making it unsuitable for high-frequency braking. The complex construction with numerous components requires adjustment of brake clearance, complicating maintenance.
Drum brakes are a traditional automotive braking system. From a repair perspective, let me explain. The structure resembles a round drum containing two brake shoes. When you press the brake pedal, hydraulic pressure pushes the shoes outward against the drum's inner wall, creating friction to slow the wheel. This design is low-cost and reliable, commonly used in small cars or rear wheels where braking force requirements are lower. The downside is poor heat dissipation – prolonged use can lead to overheating, reduced braking efficiency, and potential noise issues. During repairs, I've noticed older vehicle drum brakes often exhibit uneven wear, so I recommend checking shoe thickness and drum surface wear every two years. Compared to disc brakes, drum brakes are more economical, though modern vehicles increasingly favor disc brakes for better heat dissipation. Overall, drum brakes remain a reliable basic option, particularly suitable for daily commuter vehicles.
