trolley beam

trolley beam

An exposed steel beam, attached to the underside of the structure above; provides support for and acts as a track for a trolley crane.
References in periodicals archive ?
A 3-ton hoist attached to a trolley beam bolted to the mine roof was used to place pallets of block on the platform.
Contractors are scheduled to build a launch track with trolley beams to place the eight separate spans as they're built.
It is made of a steel deck with plywood floor, four trolley beams, four main beams, seven bar joists, and seven rows of hangers consisting of bean clamps, threaded rods, and trolley wheels.