| 摘要 |
This invention relates to a multiple jack incorporating at least three elements, viz. two pistons and two cylinders which define large and small chambers of a first cylinder, and large and small chambers of a second cylinder. According to the invention: a) a first inner conduit connects the large chamber of the first cylinder to a first outer conduit; b) a second inner conduit connects the small chamber of the first cylinder to a second outer conduit; c) a third inner conduit connects the large chamber of the second cylinder to a third outer conduit; and d) a fourth inner conduit connects the small chamber of the second cylinder to a fourth outer conduit. One application is the production of a telescopic jib presenting a satisfactory flexibility of use.
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