| 摘要 |
This device for independently controlled motorized unfolding/folding, is applicable to a crane jib, two consecutive elements of which are articulated to one another about a horizontal axle located approximately mid-way up the jib, and which have respective cross sections which allow them to nest, in the folded position. The motorization system comprises a double-acting ram and a set of link rods. The ram is articulated to the rear jib element in the region of the upper members and to two link rods, one straight and the other cranked, which form the link rod system. One link rod is articulated to the rear part of the front jib element and the other link rod is articulated to the front part of the rear jib element in the region of the lower parts of these elements.
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