| 摘要 |
PURPOSE:To prevent the generation of negative pressure and cavitation by installing a resisting means into a tank line and connecting the return line of a relief valve for a pilot hydraulic pressure source onto the upstream side and supplying working oil into a load line from the tank line. CONSTITUTION:A hydraulic pilot operation type selector valve 3 is connected between a variable-capacity type pump 1 and an actuator 2. The pilot chambers 3a and 3b of the selector valve 3 are connected through a variable reducing valve 11 onto the pilot hydraulic pressure source 8 constituted of a fixed-capacity type pump 6 and a relief valve 7, and the selector valve 3 is remote-controlled by the pilot hydraulic pressure source 8 and the variable reducing valve 11. In the above-described hydraulic circuit, a check valve 21 as resisting means is installed into the tank line 16 for connecting the selector valve 3 and a tank 15, and the return line 27 of the relief valve 7 is connected to the upstream side of the check valve 21, Therefore, working oil is supplied into a load line 12 by positively applying a back pressure into the tank line 16. |
