DUAL VALVE OPERATED PRESSURE DIFFERENTIAL SERVOMOTOR

摘要

A servomotor having a first valve for controlling the communication of vacuum and air at atmospheric pressure and a second valve for controlling the communication of air above atmospheric pressure to move a wall in response to a created pressure differential. A plunger moved by a push rod will progressively operate the first and second valves to provide a substantially uniform force for operating a brake actuator. A check valve located in the flow path of the air at atmospheric pressure will prevent the air above atmospheric pressure from being diverted to the atmosphere upon operation of the second valve.