| 摘要 |
PROBLEM TO BE SOLVED: To eliminate needs of a special valve or the like for overload occurring in neutral of a selector valve and to reduce cost of whole system. SOLUTION: A first pilot check valve 6 is connected to one port 3 of a both rotation pump 2 via a first feeding passage 5. The first pilot check valve 6 is connected to a bottom side chamber 1a of a cylinder 1. A second pilot check valve 9 is connected to another port 4 via a second feeding passage 8 and the second pilot check valve 9 is connected to a rod side chamber 1b of the cylinder 1. A selector valve 22 is provided in the first feeding passage 5 or the second feeding passage 8 and a spring 23 as a switching means is provided in one pilot flow passage 22a of the selector valve 22, and leads pilot pressure of the first feeding passage 5. Only pilot pressure of the second feeding passage 8 is led to another pilot flow passage 22b. COPYRIGHT: (C)2003,JPO
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