GB379400A - Improvements in jib cranes - Google Patents

Abstract

379,400. Jib cranes ; self-sustaining gear for winding-apparatus. WEDDELL, A. H., Alpha Works, Park Street, Motherwell, Lanarkshire. June 4, 1931, No. 16149. [Classes 78 (iv) and 78 (v).] In level luffing jib cranes of the type in which the tension on the luffing rope under a given load is substantially constant in all positions of the jib, e.g. as in Specifications 207,936 and 256,781, [both in Class 78 (iv), Loading &c.], the hoisting and luffing barrels are connected by co-axial pinions and an automatic one-way friction clutch which permits relative rotation of the pinions to effect independent hoisting of the load but opposes free descent of the load, the purchase of the hoisting and luffing ropes, the diameter of the barrels and the ratios of the gearing by which the clutch is connected to the barrels being such that the torques exerted by the load on the pinions are substantially equal and opposite. As shown, the hoisting barrel B is integral with a spur wheel B<1> gearing with a pinion C which constitutes a nut engaging a thread G on a shaft F, the load torque displacing a flange H, integral with the pinion C, against a ratchet disc J freely mounted on the shaft F and abutting a collar K ; the luffing barrel D is integral with a spur wheel D<1> gearing with a pinion E which is freely mounted on the shaft F and is integral with a member L carrying pawls M engaging the disc J and gearing with a pinion Q on a clutch sleeve R slidable on a hand-operated shaft O. When the sleeve R is locked, as shown, by a fixed bearing W, the shaft F is driven through gears N, P, and rotates the pinion C to raise or lower the load, the luffing barrel being held stationary by the member L engaging the pinion Q. When the sleeve engages the pinion N, pinions C, E are rotated and the jib is luffed with the load moving horizontally. The pawls M prevent rotation of the disc J in the direction to lower the load and the friction torque between the disc and the flange H prevents the load falling when the shaft O is not driven. The pinions C, E may be mounted on separate shafts.