| 摘要 |
PURPOSE:To raise the turning controllability of an oil-pressure pump by using a system in which a turning control circuit is connected to the preference circuit of a pressure compensatory flow control valve provided to the oil-pressure pump, and the turning control valve is controlled by operating a lever. CONSTITUTION:A main control valve 4 is provided with a pressure compensatory flow control valve 42 whose preference circuit 42a is connected with a turning control valve 5. When operating a lever 61 in the direction of arrow (a), the direction control valve 51 of the turning control valve 5 is switched to a position b, the discharge oil of an oil-pressure pump P2 flows into a turning motor M3 through the pressure compensatory flow control valve 42 and the turning control valve 5, and the pressure of suction side of the turning motor M3 is gradually raised and its turning is accelerated. At this time, the secondary side pressure of a remote control valve 6 is controlled by the operating angle of the lever 61, a direction control valve 51 for turning is controlled by the secondary side pressure, and thereby the pressure and flow rate of oil coming into the turning motor M3 are controlled. |
