Word forms: (regular plural) vacuum servos
( Automotive engineering : Vehicle components , Bodywork, controls, and accessories )
A vacuum servo
is a servo-mechanism using atmospheric pressure acting on a piston
in a vacuum cylinder
to operate a system such as a brake
To adjust the speed, the vacuum servo controls the position of the throttle.
The vacuum servo is mounted between the brake pedal and the master cylinder.
If the vacuum servo stops working the brakes will still operate, but extra force will be required.
Collins English Dictionary. Copyright © HarperCollins Publishers