GB602845A - Improvements in cranes or derricks - Google Patents

Abstract

602,845. Cranes. ALLARD, P. J. M. T. Dec. 13, 1945, No. 33804. Convention date, Sept. 22, 1943. [Class 78 (iv)] In a crane for handling a grab bucket of the kind which is slued automatically when the weight of the full bucket in the raised position is transferred wholly or in part to an auxiliary cable 12 distinct from the hoisting cable 8, the auxiliary cable 12 is attached to the bucket opening head 18, is guided to lie adjacent the axis of the crane post 1 by pulleys 13, 14, passes round a guide pulley 15 carried by the jib extension 16 and is secured at its end 17 to the framework 5 so that when the bucket is suspended from the head 18 a couple is developed producing rotation of the jib 6. When the hoisting cable 8 is wound on the winch 10, the bucket first closes and then is hoisted until it is hooked up to the head 18. By giving slack the bucket remains suspended on the head 18 and exerts a pull on the cable 12 which slues the jib until it reaches the discharge position and by giving slack to the hoisting cable 8 the bucket is opened. The hoisting cable 8 is then pulled, the bucket remains open, the cable 12 loses its tension and the jib returns by gravity, on account of the inclination a of the axis of the pillar to the vertical, to the collecting position. The fixed points may be 17 or 17a to allow for slueing in either direction. In a modification, the bucket is raised by a cable 8 at the same time the auxiliary cable is wound on a drum under the action of a spring or counterweight. At the required height the drum is braked the cable 8 is slacked and the weight of the bucket is transferred to the auxiliary cable. Locking the jib in any slued position may be effected by braking a loose drum carried by the jib and on which is wound a cable, the ends of which are fixed.