Drum Brake

The working parts of a drum brake are contained in a hard metal drum that is attached to the hub of a wheel and revolves with it. Inside, but unattached to the drum, are a pair of stationary curved brake shoes that are normally held away from the drum by springs. When the brake pedal is depressed, fluid is forced through the brake lines and into the wheel cylinder. Pushrods in the cylinder then apply pressure to both shoes, overcoming the spring tension and pressing the shoes against the drum. Hydraulic drum brakes can also be mechanically activated as parking brakes by a cable attached to the lever. When pressure is removed from the brake pedal, springs on the brake shoes force the shoes back to their normal released position. This movement of the shoes forces the pistons inward, returning the fluid to the master cylinder reservoir.