Double girder gantry crane has the advantage over the stronger capacity, big span, the good overall stability, and in many varieties. It consists of four main parts, namely, the bridge structure, the traveling mechanism, the trolley, and the electric equipment. According to the main girder structure, the double girder gantry crane can be divided into two forms of box beam and truss beam.

MG type frame truss structure double girder gantry crane is a kind of track rail traveling light type crane, can be used where overhead runways are not practical, or in open areas where columns cannot be accommodated. The top main girder is mounted on two shape columns which are further resting on wheel-mounted end carriages. It is widely applied to do loading and unloading work in the outdoor areas. The truss type double girder gantry crane has lightweight, strong wind resistance, and relatively cheap price.

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.