| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic drive device capable of simplifying the structure of an unload valve, facilitating machining on a body side into which the unload valve is assembled, and reducing troublesome work of a pipeline.SOLUTION: For an unload valve 21B, a stepped shaft-like spool 31 is slidably inserted into a valve body 30, and both ends of the valve body 30 is sealed in a liquid tight manner by a plug 32 and a closing plug 33. For the spool 31, a large-diameter part 31a is connected to a tank line 29, and a large-diameter part 31b is connected to a pressure oil supply passage 4. On the end surface of the large-diameter part 31b of the spool 31, formed an opening 34 whose cross section is a circular shape, and a piston 35 is slidably inserted into the opening 34.SELECTED DRAWING: Figure 2 |
