According to the difference of the door frame, we divide the double girder gantry crane into two categories:
- U-Type Double Girder Gantry Crane: This type gantry crane adopts U type door frame, it consists of main parts, namely, the bridge structure, the traveling mechanism, the cart and the electric equipment.
- A-Type Double Girder Gantry Crane: This type Gantry Crane adopts A-type door frame. The bridge is welded structure of box-type; individual drives are adopted for traveling mechanism on each end of the crane. All movements of the crane are controlled in the cabin.