The double beam semi gantry crane consists of 5 main parts, namely, the bridge structure, A-frame support legs, the traveling mechanism, the trolley, and the electric equipment. It has box type and truss type. Box type has characteristics of a slim body and strong lifting capacity; the trussed type has characteristics of small windward surface, small deadweight, and strong lifting capacity.
The double girder semi gantry crane is for heavy-duty applications, where a suitable track is provided on top of the girders for travel of crab wheels.