| 摘要 |
The present invention relates to a method for supplying hydraulic jacks. According to the invention, a volume of oil at the nominal pressure of the supply source, less than the volume set by the piston, is introduced into the chamber under pressure, during at least part of the stroke in which the resisting force is small, and an additional volume of oil at a pressure less than the said nominal pressure is introduced into the said chamber, and, for example, the pressure chamber 4 opposite the chamber 5 through which the piston rod passes is made to communicate, in a manner which is controlled by a switching device 8, with the chamber 5 as long as the resisting force F is less than the pressure P multiplied by the cross-sectional area of the piston rod 3. The invention enables the volume of oil under pressure used up during the approach stroke to be greatly reduced. <IMAGE>
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