How do drum brakes operate to stop a vehicle?

Drum brakes function by utilizing the expansion of brake shoes against the inner surface of a rotating drum. When the driver presses the brake pedal, hydraulic fluid is transmitted through the brake lines to the wheel cylinders. This hydraulic action causes the brake shoes to move outward and press against the inner surface of the drum. The friction generated by this contact slows down the drum's rotation and ultimately brings the vehicle to a stop.

The operation of drum brakes is distinct from disc brakes, where pads are squeezed against a flat rotor. Drum brakes are effective because they can provide strong stopping power due to the larger surface area available where the shoes contact the drum. Understanding this mechanism is crucial for recognizing how different braking systems work and the specific components involved in each system's operation.