In a drum brake system, what action do the shoes perform?

In a drum brake system, the primary action of the brake shoes is to expand against the inner surface of the brake drum to create friction, which effectively slows down or stops the vehicle. When the driver applies the brakes, hydraulic pressure causes the brake shoes to push outward, pressing against the drum's interior. This expansion generates the friction needed to halt the rotation of the drum, and consequently, the wheels attached to it.

This mechanism is essential for the functionality of drum brakes as they convert kinetic energy into thermal energy through friction, thus slowing down the vehicle. The design ensures that the shoes have sufficient surface area to create effective braking performance while allowing for heat dissipation.