The next option is the under-slung crane, which runs on the bottom flanges of rolled steel beams which form the crane tracks. These are usually indoor cranes and the crane tracks are suspended from the building structure. They have the advantage of being able to cover part of the building span without obstructing the floor below. Latest in this type are light weight crane systems wherein hollow sections are used as track sections inside which the travel trolley wheels move. These track sections can be used for the long travel tracks and also for the crane bridge.
The under-slung arrangement allows the bridge of this type of crane to be designed with a cantilever at one or both ends.

The next option is the under-slung crane, which runs on the bottom flanges of rolled steel beams which form the crane tracks. These are usually indoor cranes and the crane tracks are suspended from the building structure. They have the advantage of being able to cover part of the building span without obstructing the floor below. Latest in this type are light weight crane systems wherein hollow sections are used as track sections inside which the travel trolley wheels move. These track sections can be used for the long travel tracks and also for the crane bridge.
The under-slung arrangement allows the bridge of this type of crane to be designed with a cantilever at one or both ends.