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.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
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.