1) Bridge Crane
A lifting and horizontal movement device mounted on a "bridge" of one or more horizontal girders (bridge girders) which are supported at either end by trucks (end trucks). These trucks are attached at right angles to the girders and move on runways which are attached to a building's columns, overhead trusses, frames, or via a free standing system of columns.
2) Double girder crane
An overhead traveling bridge crane that utilizes two bridge beams set atop the runway (end) trucks. Generally this type of crane utilizes a top running trolley hoist which moves along the top of the two bridge beams on its own set of trucks/trolley wheels. The hook from the hoist "falls" between the two bridge beams. Headroom under the crane is increased by utilizing this hoist/crane configuration.
3) I-beam crane
An overhead traveling bridge crane that utilizes standard I-beam (S beams) as the bridge girder and at times also utilizes I beams as the runway beams. Cranes that utilize H-beams (structural beams) as girder and runways are sometimes referred to as I-beam cranes as opposed to patented track cranes.
4) Stacker crane
The stacker crane in appearance looks like a conventional bridge crane except that in place of a hoist, a rotating ridged or telescoping mast is suspended from the bridge trolley with the mast equipped with a load handling device such as single or double forks or a grab.
These cranes can be manually operated or powered and are used where the carne spans multiple aisles allowing for the storage and retrieval within any aisle of items such as coils of steel.