The industry double girder overhead crane 20 ton is a kind of crane with the bridge on the elevated track. The bridge frame runs longitudinally along the track laid on both sides of the elevated frame, and the crane trolley runs horizontally along the track laid on the bridge frame to form a rectangular working area, which can make full use of the space under the bridge frame to lift materials. The industry double girder overhead crane 20 ton is composed of box type bridge frame, lifting trolley, crane traveling mechanism, and electrical system. http://www.sevenindustry.com