| 摘要 |
A hydraulic drive system includes a hose rupture control valve unit 200 having a poppet valve member 5 serving as a main valve for opening and closing communication between a cylinder connection chamber 8 and a hose connection chamber 9, a spool valve member 6 disposed in pilot passages 15a, 15b connecting a back pressure chamber 10 and the hose connection chamber 9 of the poppet valve member 5. The spool valve member is operated by a pilot pressure supplied as an external signal and operates the poppet valve member 5, and a small relief valve 7 having the function of an overload relief valve. A check valve 39 is disposed in the pilot passage 15b for cutting off a flow of the hydraulic fluid from the hose connection chamber 9 to the back pressure chamber 10.A hose rupture control valve unit 200 comprises a poppet valve member 5 serving as a main valve for opening and closing communication between a cylinder connection chamber 8 and a hose connection chamber 9, a spool valve member 6 disposed in pilot passages 15a, 15b connecting a back pressure chamber 10 and the hose connection chamber 9 of the poppet valve member 5, the spool valve member being operated by a pilot pressure supplied as an external signal and operating the poppet valve member 5, and a small relief valve 7 having the function of an overload relief valve. The valve unit further comprises a check valve 39 disposed in the pilot passage 15b for cutting off a flow of the hydraulic fluid from the hose connection chamber 9 to the back pressure chamber 10.
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