Main beam form can be divided into single master volume and double main beam cranes

1. The single girder
single girder overhead crane structure is simple, easy manufacture and installation, small quality of their main beam much for the partial rail box-shaped frame structure. Compared with double girder gantry crane, the overall stiffness weaker. Therefore, when the starting weight Q≤50t, when the span S≤35m, can this form. Single girder gantry crane doors leg has L and C forms. L type of manufacture and installation convenience, the force was better, the smaller their own quality, but, lifting goods through space at the relatively small number of legs. C-type legs made of sloped or curved shape, aimed at a greater horizontal space, so that goods pass foot.
2. The double main beam
double girder gantry crane carrying capacity, span, the overall stability, variety, but the quality of their starting weight compared with the same single-girder gantry crane to be bigger, the cost is higher. Depending on the main beam structure, it can be divided into box beams and trusses in two forms. More commonly used box structure.