In drum brake systems, which component causes the shoes to press against the drum?

In drum brake systems, which component causes the shoes to press against the drum?

• A. S-cam
• B. Master cylinder
• C. Wheel cylinder
• D. Brake shoe lever

Answer: (A)

In drum brakes, the part that actually makes the shoes press against the drum is the S-cam. When you apply the brakes, hydraulic pressure from the master cylinder reaches the wheel cylinders, which push a rod that rotates the S-cam. As the S-cam turns, its cam profile spreads the two brake shoes outward toward the drum, forcing them into contact and creating the braking friction. The wheel cylinders provide the force, and other components like the brake shoe levers help mount and support the shoes, but the S-cam is the mechanism that converts that hydraulic action into the outward movement that presses the shoes against the drum.

In drum brakes, the part that actually makes the shoes press against the drum is the S-cam. When you apply the brakes, hydraulic pressure from the master cylinder reaches the wheel cylinders, which push a rod that rotates the S-cam. As the S-cam turns, its cam profile spreads the two brake shoes outward toward the drum, forcing them into contact and creating the braking friction. The wheel cylinders provide the force, and other components like the brake shoe levers help mount and support the shoes, but the S-cam is the mechanism that converts that hydraulic action into the outward movement that presses the shoes against the drum.