BRIDGE CRANE FOR THE EMPLACEMENT OF ELONGATE PREFABRICATED MEMBERS OF STRUCTURES SPANNING A MULTIPLICITY OF SPACED-APART SUPPORTS

摘要

ABSTRACT OF THE DISCLOSUREPrecast beams or slabs of an elongate structure suchas a bridge, viaduct or overpass are emplaced on spaced-apartpiers by a bridge crane which comprises a framework consist-ing of a pair of parallel trusses interconnected by endportals and long enough to extend across three piers. Eachtruss has a bottom stringer formed on its underside withtracks engaged above each pier by rollers mounted on a pairof rocker arms which are part of an undercarriage movable ontransverse guide rails. Top stringers of the trusses supporta trolley carrying hoists for raising and lowering the trans-ported castings. Longitudinal movement of the frameworkrelative to the piers is brought about by a motor-driven cap-stan, carried on the framework, which is engaged by cableswound about deflecting rollers at the ends of the frameworkand on an anchor frame to which the ends of the cables arefastened, the anchor frame being secured to one of the under-carriages and carrying pulleys coacting with confrontingdeflecting rollers to form a tackle with a fourfold mechani-cal advantage.