| 摘要 |
The system comprises a hydraulic actuator having opposed openings adapted to alternately function as inlets and outlets for moving the element of the actuator in opposite directions. There is a pump for supplying fluid to the actuator. There is also a directional valve comprising pilot operated meter-in valves to which the fluid from the pump is supplied through first lines for controlling the direction of movement of the actuator and a pilot operated meter-out valve associated with each opening of the actuator for controlling the flow out of the actuator. The pressure of fluid supplied to the actuator by the meter-in valve is sensed and supplied to a line extending from the output of the meter-in valve. A valve is provided in this line to provide a force selectively on the meter-in valve opposing the movement of the meter-in valve by the pilot pressure. The valve may comprise either a modulating valve or a shut-off valve. |
