| 摘要 |
<p>PROBLEM TO BE SOLVED: To compactly and inexpensively compose a hydraulic differential gear having a differential function and a load retaining function. SOLUTION: A check valve 31 and a counterbalance valve 30 composing a differential circuit are composed as a single hydraulic valve unit 11. The hydraulic valve unit is provided with a first port connected with a cylinder rod side port, a second port connected with a cylinder tube side port, and an opening and closing spool opening and closing a passage between the ports. Pressure generated in a hydraulic cylinder acts as a pilot pressure on the opening and closing spool. The hydraulic valve unit is provided with the counterbalance valve allowing a flow from the first port to the second port in an opened state of the passage in a state of the pressure at a predetermined pressure, the check valve arranged in an oil source side and allowing a flow only from an oil pressure source to the cylinder rod side port, and an assist pilot line applying an oil pressure source pressure as the pilot pressure on the counterbalance valve in a direction closing the opening and closing spool.</p> |
