Hydraulic ramping circuit for control valve - has mechanical actuator on piston rod connected to via electrical circuit to solenoid valve which can be by=passed

摘要

The hydraulically actuated control valve includes a cylinder with a piston connected through a shaft to the actuating mechanism in the control valve. Ports are provided on each side of the piston. The piston can be controlled by an electro-hydraulic servo-controlled valve which includes an electrical input, a mechanical feedback input, and two outputs. The outputs are connected to the two ports in the cylinder and a mechanical feedback is coupled to the shaft and the mechanical feedback input of the control valve. An electrical circuit is coupled to the electrical input of the servo-controlled valve to signal the hydraulic portion of the valve. A control serially connects a solenoid valve in one of the lines of the hydraulic output of the servo-controlled valve with one of the ports in the cylinder. The solenoid valve can be bypassed with a needle valve or a controllable valve. A mechanical actuator on the shaft is coupled through an electrical circuit to the solenoid valve.