DIRECT-ACTING VACUUM SERVO

摘要

A direct-acting vacuum servo incorporates a casing formed by front and rear pressings (11 and 12) and a body (15) forming a movable wall in the casing sealed by a diaphragm (13). A front chamber (24) is connected to a vacuum source. A valve assembly constitutied by valve body (15), valve member (19) and valve seat (21) controls the pressure in a rear chamber (25) by sealing it off (as shown) or connecting it to atmosphere or to the front chamber (24). A reaction member (34) relates relative movement between valve member and valve body to an input load and servo load applied to the valve member and valve body respectively. Axial transfer passages (23) and inlet passages (26) communicate with transfer ports (29) and inlet ports (28) which are arranged to occupy alternating discrete sectors within an annular area covered by the valve seat (21).