Overhead cranes

Claim 1

In a crane comprising a transverse overhead beam, a pair of carriages supporting the ends of the beam and forming with the beam a longitudinally movable structure, a trolley carried by the beam for traversing movement along the beam, traverse means for moving the trolley along the beam and hoisting means for a hoist rope depending from the trolley; the improvement comprising mounting means for the trolley alongside a sidewall of the beam and externally thereof to load the beam torsionally, power operable driving means for said traverse and hoisting means mounted on said structure, said hoisting means comprising a winding device mounted on one end carriage, a pulley wheel mounted on the other end carriage, a pair of side-by-side pulley wheels mounted on the trolley, a load receiving pulley wheel located under the trolley, and a hoist rope extending alongside the beam from the winding device, around the pulley wheel on said other carriage alongside the beam, over the pulley wheels on the trolley in a U-loop which carries the load receiving pulley wheel, and alongside the beam to the second end carriage, the arrangement being such that the height of the load-receiving pulley wheel is unaffected by the traversing movement of the trolley, said sidewall of the beam having upper and lower tracks on which said trolley is mounted, the lower track being of box section having horizontally and vertically disposed bearing surfaces, and the upper track depending from cantilevers secured to the beam and having a vertically disposed bearing surface spaced from and confronting said sidewall of the beam, said trolley having load bearing wheels arranged to run on said bearing surfaces on said upper and lower tracks, said trolleydriving means and hoisting means being so arranged that no substantial portion thereof extends above or below the beam.