| 摘要 |
PROBLEM TO BE SOLVED: To provide a single unload valve provided on a first circulation line and a second circulation line.SOLUTION: An unload valve 7 provided on a first circulation line and a second circulation line in a hydraulic drive system of a building machine, includes: a housing 8 which has a first pump port 81 on a pump side of the first circulation line, a first output port 82 on a throttle side of the first circulation line, a second pump port 85 on a pump side of the second circulation line, a second output port 86 on a throttle side of the second circulation line, and a tank port; and a spool 9 held by the housing, and moved between a normal position communicating the first pump port to the first output port and communicating the second pump port to the second output port, and an unload position communicating the first pump port and the second pump port to the tank port.SELECTED DRAWING: Figure 1 |
