The drum brake system consists of the following components:
When mechanical force is applied by the driver to the brake pedal, the force is converted into hydraulic pressure by the master cylinder. The hydraulic force is directed to the wheel cylinders moving the brake shoes against the friction surface of the brake drum. The friction of the brake shoes on the brake drum causes the slowing or stopping of wheel rotation and the vehicle.
Ford Focus Principles of Operation
Brake System
Applying the brake pedal uses lever action to push a rod into the brake booster
which, through the use of vacuum, boosts the force of the rod and then transmits
this force into the master cylinder. This produces hydraulic pressure in the master
cylinder. On vehicles not equipped ...