How Do Drum Brakes Work?

A drum brake is basically a brake in which friction is created by group of shoes or pads which apply force to the internal part of a drum which is constantly rotating. The drum is linked to a rotating wheel.

Drum brakes, depending on what way the shoes are hinged, can possess a 'self servo' feature. This raises its stopping influence with the absence of any extra effort on the driver's part as the rotation of the drum pulls the shoes around with it, raising the power of the force which is keeping them together. In rear brakes however, one sole shoe possesses this feature. Front drum brakes sometimes make use of two actuating cylinders that permit both the shoes to use the servo feature and also raises the front axle braking force, which is needed to make up for forward weight shift.

When you push on the brake pedal, that pushes fluid from the brake master reservoir through the lines to the brake cylinders, which push the rubber and steel cups out, pushing the brake shoes out against the drums for your stopping force.