| 摘要 |
PURPOSE:To raise the efficiency of working by enabling the speeds of threwing, a boom, and an arm to be controlled smoothly and freely from low to high speeds without any practical interference for concurrent working by two variable pumps. CONSTITUTION:In valve units 31 and 32 by which a fluid from variable pumps 131a and 131b is directed to each actuator, the valve unit 31 is provided with a decompression type pressure compensatory valve 36 and the first and second flow direction control valves 37a, 37b, 38a, and 38b, and also the valve unit 32 is provided with a preference type pressure compensatory valve 81 and the third and fourth flow direction control valves 82a-82c and 83. The maximum pressure of the fluid pressure of the spring chamber of the said compensatory valve 36 and the fluid pressure of the load pressure sensing port of the valve 38b is selected by a shuttle valve 52 and transmitted to the first power matching valve 132a, and also pressure before and behind the valve 83 is transmitted to the second power matching valve 132b to control the discharge controller for the pumps 131a and 131b. |
