| 摘要 |
PURPOSE:To regulate a quantity of oil supplied to a downstream side actuator for effective usage thereof by providing a priority control valve containing a spool whose travel is increased with increase of loading on an upstream side actuator and providing the spool with an orifice whose opening degree is in proportion to the traveling distance of the spool. CONSTITUTION:The most downstream one 31 of directional control valves 28 to 31 which are incorporated into a circuit system 26 controls an arm cylinder 38, while the directional control valve 30 more upstream than the latter controls a turning motor 39. A priority control valve V is mounted in the way of a parallel passage 43 in such configuration as it makes changeover, utilizing the pressure in the passage 43 as a pilot pressure. Since a spool inserted in the body of the valve has an orifice whose opening area is varied in proportion to travel of the spool, an opening area of the orifice is increased with increase of loading on the more upstream actuators an unnecessary oil is supplied to the more downstream actuators. |
