Single girder crane beam chart

Single girder crane beam chart advantages

Many people mistakenly think that a double girder crane is heavier duty than a single girder or that they will last longer.  That assumption is incorrect because the components (End Trucks and Hoist with trolleys) can be of exactly the same duty and be configured into a single girder design or a double girder design.  A double girder crane is generally used when the duty requirement is D+ (Very Heavy Duty) or E (Severe Duty) because the special hoisting equipment often includes an open winch with a separate split gearcase, heavy-duty motor and a brake that are mounted on a deck frame.  Also, heavy-duty or critical applications often include a bridge-mounted footwalk or maintenance platform for the safety and convenience of technician service and repair access to the hoist and crane components.  It is not typically practical to mount an effective service platform to a single girder crane.

In many existing runways, there is insufficient clearance above the runway girders to fit a standard double girder crane, and therefore a single girder design is most practical.  In cases where there is excessive clearance, the crane girder can be stooled up to increase available hoist hook height.  Single girder cranes have the hoist trolley traversing on the lower flange of the girder.  Also, the beam will likely to be deeper than a double girder.  So the available hook height of a single girder crane will likely be less than a comparable double girder.