| 摘要 |
PURPOSE:To decrease energy loss in a two-pump system, by unloading pressurized oil of the other pump from a pressure compensating valve when a sufficient amount of the oil is delivered from one pump at an operation with fine adjustment of a direction control valve. CONSTITUTION:If a direction control valve 3 is moved leftward from a neutral position, ports 8, 10 are communicated to conduct load pressure of a cylinder 19 to a spring chamber 28 of a pressure compensating valve 2, and the valve 2 is moved rightward to shut off communication of ports 22, 23 to ports 24, 25, if the valve 3 is further moved leftward, pressurized oil flows in through a notch 14a to the port 8. However, a small opening of this circulation increases pressure of a port 20, if pressure in a pressure chamber 29 rises, the valve 3 is moved leftward to open the ports 23, 25, and the second pump P2 is unloaded to fixedly hold a flow rate to the port 8. When the valve 3 is fully selected leftward, the valve 2 is stopped for the right to close the ports 24, 25. |
