The single girder cantilever gantry crane has the advantages of simple structure, convenient manufacture and installation, small self quality, and more than 100 main girders are skew rail box structure. Compared with the double main girder gantry crane, the overall stiffness is weaker. Therefore, when the lifting capacity Q ≤ 50t and the span s ≤ 35m, this form can be used. There are two types of legs of single main portal beam crane, i.e. L-type and C-type. L-type is easy to manufacture and install, with good stress condition and small self weight. However, the space of lifting goods through the legs is relatively small. C-type legs are made into inclined or curved shape, so as to have a large special transverse space, So that the goods can pass through the feet smoothly.
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