| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a simple structured hydraulic system of operating machines which improves operability and also reduces relief loss. <P>SOLUTION: The hydraulic system of operating machines includes negative control relief valves 5 and 6 interposed on center bypasses L1/L2, negative control passages L3/L4 for communicating negative control pressure to regulators 2a/3a of hydraulic pumps 2 and 3, and a main relief valve 8 specifying maximum pressures of the center bypasses L1/L2. This system interposes a low pressure relief valve 9 on the downstream side of a flow channel for hydraulic fluid relieved from the main relief valve 8, while allowing a hydraulic fluid pressure between the main relief valve 8 and the low pressure relief valve 9 to be communicated with the second negative control passages L6/L7 as the second negative control pressure. Further, it introduces the high-pressure side negative control pressure of either of the negative control passages L3/L4 or that of the second negative control passages L6/L7 into the regulators 2a/3a through shuttle valves 20 and 21. <P>COPYRIGHT: (C)2012,JPO&INPIT |
