Which component within a drum brake system presses against the drum to slow the vehicle?

Which component within a drum brake system presses against the drum to slow the vehicle?

• A. Brake shoes
• B. The wheel cylinder
• C. The brake pedal
• D. The air valve

Answer: (A)

In a drum brake system, stopping power comes from the brake shoes pressing against the inner surface of the rotating drum. The brake shoes are curved pieces with friction material on their outer face. When you apply the brakes, hydraulic pressure from the wheel cylinder pushes the shoes outward so they bear against the drum. The friction between the shoe lining and the drum slows the wheel and converts the vehicle’s kinetic energy into heat. The wheel cylinder does the pushing, but the part that directly presses against the drum is the brake shoes themselves. The brake pedal simply activates the hydraulic system, and the air valve isn’t part of this hydraulic drum brake function.