Pressure control for vacuum servo pump - has pressure limiter on suction line to allow pump to idle when servo not used

摘要

The vacuum servo line pressure control has a valve (9) which vents the line above a set vacuum level to allow the vacuum pump to idle. This relieves the pump (1) of drag and wear and provides a consistent servo level. The vacuum servo drives ancillary gear while the control valve has a single membrane (10) which lifts the venting valve element (18) against a return soring (19). One side of the membrane is subjected to the vacuum-level in the ancillary line (4) and when this reaches a set value the pump is vented.