The most commonly referred to type of overhead crane is a bridge crane. Perfect for medium to heavy lifting, a bridge crane has an elevated parallel runway system with a traveling bridge to move the load forward and backward. The hoist lifts the load up and down, so overall the bridge crane offers four-way maneuverability. It also runs overhead, providing the ability to move loads over aisles and other obstacles.
A Top Running bridge crane runs on a rail installed on top of the runway system, while a Top Runner bridge crane uses a pair of single flange wheels to run right along the top of the runway beam itself, eliminating the need and expense of a rail. An underhung bridge crane runs on the bottom of the runway beam. Underhung, or under-running bridge cranes are used for lighter capacities since they are frequently suspended from the roof and eliminate the need for additional floor column support.
In comparing single girder and double girder bridge cranes, the primary difference is the height that the hoist will lift. Single girder cranes have a lower height, but may be less expensive due to a simpler trolley, quicker installation, lighter runway beams and the need for only one girder.
Below is a general guideline for single girder crane use:
- Up to 7.5
- Up to 10
- Up to 15
- Up to 20
- Up to 25
- Up to 30
- Up to 35
In a monorail system, a hoist and trolley runs along one beam, allowing for only up and down movement with the hook and forward and back movement along the beam. For this reason, monorail systems are highly effective in moving loads from one point to another with great speed and efficiency. Monorail systems can be customized with a curved track and to integrate with other crane systems.