When you apply the brakes, the brake shoes/linings are pressed against the:

The brake shoes or linings are designed to press against the brake drum when brakes are applied in a drum brake system. This process creates friction, which slows down or stops the vehicle. The brake drum is a cylindrical component that rotates with the wheel, and when the brake shoes press against it, it effectively functions to reduce the speed of the vehicle.

The brake drum is essential in controlling braking because it houses the brake linings, allowing for a more reliable and efficient braking process. This mechanism is a fundamental aspect of how drum brakes operate in heavy vehicles, where air brakes are commonly used. Understanding this function helps drivers appreciate the mechanics behind efficient braking and emphasizes the importance of maintaining the brake drum and associated components for safety on the road.