
436 LIGHT AND HEAVY VEHICLE TECHNOLOGY
25.6 VACUUM SERVO-ASSISTED BRAKING
General background
Until the increasing weight and speed of commercial
vehicles dictated the use of power-operated com-
pressed air brakes, as opposed to power-assisted vac-
uum brakes, the latter proved to be a competent and
reliable system of braking. In
brief,
the installation
comprised a master servo, two front wheel servos and a
vacuum reservoir. The piston-operated master servo
converted vacuum, created by either manifold de-
pression or exhauster pump according to whether the
vehicle was petrol or diesel engined, into power for
assisting brake application. It was