Vacuum servo

A vacuum servo (also called a brake booster, power booster, or power brake unit) is a component used on motor vehicles in their braking system, to provide assistance to the driver by decreasing the braking effort. It uses a vacuum, usually supplied by the engine, to multiply the driver's pedal effort and apply that effort to the master cylinder.^[1]

Brake booster from a Geo Storm.

Brake vacuum servo section

Because the servo depends on the vacuum supplied by a running engine, a check valve is typically used in the vacuum line to maintain residual vacuum without engine support, allowing limited use even after parking.

See also

• List of auto parts