| 摘要 |
PROBLEM TO BE SOLVED: To prevent excessive retraction of a cylinder and a rod by adequately setting the load of a return spring and a leak down time. SOLUTION: The rod 21 is inserted into the cylinder 17 in which operating oil is filled, and a plunger 22 provided at the lower end of the rod 21 is freely slidably fitted in the inner diameter face of the cylinder at a leak clearance 24 to form a pressure chamber 25 and a reservoir chamber 26 under and above the plunger 22, respectively. A passage 28 is formed in the plunger 22 to communicate the pressure chamber 25 with the reservoir chamber 26. A check valve is provided in the passage 28 for closing the passage 28 when pressure in the pressure chamber 25 is higher than pressure in the reservoir chamber 26, and the return spring 31 is provided outside the cylinder 17 for energizing the cylinder 17 and the rod 21 in the elongating direction. A lower limit set value for a leak down time in the leak clearance 24 is 0.65 s/mm or greater. COPYRIGHT: (C)2010,JPO&INPIT
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