| 摘要 |
PROBLEM TO BE SOLVED: To provide a rising and falling hydraulic circuit capable of obtaining rising and falling force for two upper and lower working devices. SOLUTION: When both up and down two working devices are put on a rising and falling hydraulic circuit in a liftable manner, in the rising and falling hydraulic circuit for lifting and lowering the working device by feeding an operating fluid from a hydraulic pump 4 to hydraulic motors 61 and 71 of an optionally selected rising and falling device, three control valves 21, 22 and 23 for supplying the operating fluid from the hydraulic pump 4 to the hydraulic motors 61 and 71 by selecting one or both of the upper side rising and falling device and the lower side rising and falling device are included, and when the upper side rising and lowering device and the lower side rising and falling device are simultaneously raised and lowered, two control valves 21 and 23/22 and 23 of three control valves are used, and oil lines supplying the operating fluid of the hydraulic pump 4 to the hydraulic motors 61 and 71 of the upper side rising and falling device and the lower side rising and falling device are connected in series or in parallel. COPYRIGHT: (C)2004,JPO
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