Simple structure of girder gantry crane, making is easy to install, quality small Master Liang Duo to bias-rail box frame structure. Compared with the double girder gantry crane, less overall stiffness. Therefore, when lifting weight Q = s = 35m 50T, span, this form can be used. Girder gantry crane leg l-and c-type form. L-manufacture of easy installation, force good, its small, but lifted cargo through the leg space is relatively small. C-type foot shape into a sloping or bending, and aims to have more horizontal space, so that the cargo through the foot.