Power brakes

Power brakes consist of a system of hydraulics used to slow down or stop a motor vehicle.

These are pushed by the output rod of the vacuum booster to compress fluid within its primary and secondary chambers (hydraulic pressure).

The job of the caliper is to slow the vehicle's wheels using the friction they create against metal discs (rotors).

The first caliper-type automobile disc brake was patented by Frederick William Lanchester in his Birmingham factory in 1902.

When the driver pushes the brake pedal with his/her foot, the pistons inside the cylinder will activate.

There, the fluid compresses the caliper pistons, which causes the brake pads to move inboard and contact the rotors.

This process is largely the same as a manual braking system; the primary difference is the addition of the vacuum booster.

A cutaway view of the inside of the vacuum booster assembly
An animation of how the master cylinder works along with how the force is transferred to the brake calipers
The inside of a drum brake with the drum removed to show the internal mechanisms