50 ton overhead crane can be double girder bridge crane while single girder overhead crane is suitable for lifting relatively lighter materials like 10 ton.
Below are examples of different overhead traveling bridge crane 7 ton capacity top running double box girder hydraulic lift stacker crane with 48" load
China Dy Factory Electric Single Girder 50 Ton Overhead Bridge Crane, Find details about China Overhead Crane, Eot Crane from Dy Factory Electric Single
MOBILE GANTRY TYPE CRANES: (2) 40 Ton Drott Straddle Mobile Gantry Crane • 40 Ton Drott/Mi-Jack Straddle Mobile Gantry Crane. HOISTS *(3) 50 Ton Kone Hoists