Improvements in remote hydraulic control systems

摘要

Response times for a remote hydraulic control system having control lines from a remote controller to a main control valve of 50 feet or more are reduced by providing actuator pistons which are operated at a second pilot hydraulic pressure less than a first pilot hydraulic pressure used for moving a valve spool within the main control valve. The actuator pistons open valves which allow hydraulic fluid at the higher pilot pressure to push the valve spool. "Off" times are further reduced by continuously bleeding off a portion of the hydraulic fluid applied to the actuator pistons at the second hydraulic pressure.