| 摘要 |
A hydraulic control system comprising a hydraulic actuator having opposed openings adapted to alternately function as inlets and outlets for moving the element of the actuator in opposite directions and a variable displacement pump with loading sensing control for supplying fluid to said actuator. A pilot operated spool type meter-in valve is provided to which the fluid from the pump is supplied and a pilot controller alternately supplies fluid at pilot pressure to the meter-in valve for controlling the direction and displacement of movement of the meter-in valve and the direction and velocity of the actuator. A pair of lines extends from the meter-in valve to the respective openings of the actuator and a pilot operated meter-out valve is associated with each line of the actuator for controlling the flow out of the actuator when that line to the actuator does not have pressure fluid from the pump applied thereto. Pressure of fluid in the line to the actuator, which does not have pressure fluid from the pump, is applied to the meter-in valve to apply a centering force which aids the pressure compensating flow forces to keep the flow constant.
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