CONTROL SYSTEM FOR PRESSURE OPERATED ACTUACTOR

摘要

A control system for a fluid pressure operated actuator includes an arming valve having open and closed positions and a pilot operated selector valve having a neutral position and an extend position. The arming valve is connected to a source of fluid and the selector valve is connected to the arming valve so that two control inputs are necessary to connect the source to an operating chamber of the actuator. A solenoid actuated pilot valve is connected to the source and to a sump and has an on position in which the flow of fluid is unblocked and in an off position in which the flow of fluid is blocked. A pilot passage connects the pilot valve to a pilot chamber of the selector valve and a branch passage connects the pilot passage and the operating chamber of the actuator so that the operating chamber communicates with the sump whenever the pilot valve is off regardless of the position of the selector valve.