| 摘要 |
A double-acting jack having a working chamber is fitted with an adjustable stop against which its piston comes to rest. The stop is constituted by a nonrotatable nut, which is axially displaceable by an axially nondisplaceable lead screw with which it meshes. The stop includes means for controlling the supply of pressurized fluid from a supply line to the working chamber, the supply line being opened whenever the piston and its associated rod are not in the end-of-stroke position and closed whenever the piston and its rod are in the end-of-stroke position. The lead screw is mounted to have a slight amount of axial play. The supply line terminates in an annular opening provided on a shoulder of the lead screw, which defines a valve, or in it seat.
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