VENTILANLEGGNING FOR REGLERING AV FUNKTIONEN HOS EN HYDRAULMOTOR, SERSKILT EN HYDRAULCYLINDER

摘要

A hydraulic system comprises a hydraulic actuator (20) having opposed openings (A, B) each adapted to alternately function as inlets and outlets for moving the element (21) of the actuator in opposite directions and a variable displacement pump system (22) with load-sensing control for supplying fluid to said actuator. A meter-in valve (27) is provided to which the fluid from the pump system is supplied and a pilot controller (23) 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 service passages (32, 33) extends from the meter-in valve to the respective openings of the actuator and a meter-out valve (34, 35) is associated with each service passage to the actuator for controlling the flow out of the actuator when that service passage to the actuator does not have pressure fluid from the pump applied thereto. Each meter-out valve is pilot- operated by the pilot pressure from the controller (23).