| 摘要 |
A portable hydraulic tool, such as a hydraulic secateurs, is of the kind having a single acting ram including a driving piston with its piston rod connected to at least one movable operating member such as a cutting element of the tool, the piston being movable in fluid tight manner in a bore under the thrust of hydraulic fluid acting on a working face of the piston, the improvement being that there is provided a return chamber the volume of which decreases when the driving piston is displaced in its working stroke, the return chamber containing a compressible fluid under pressure such that, when the thrust exerted on the piston by the hydraulic fluid becomes less than the thrust exerted on the piston by the compressible fluid, the piston is caused to carry out a return stroke by the expansion of the compressible fluid.
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