GB669648A - Improvements in or relating to lifting apparatus - Google Patents

Abstract

669,648. Cranes; lever load-handling machines. BOWTELL, W. J. March 6, 1950. [March 14, 1949] No. 6912/49. Classes 78 (iii) and 78 (iv). A beam supported by a foot or pedestal at one end and suspended from a crane at its other end is provided at an intermediate point with means for supporting a load to be lifted or lowered. A load 23 exceeding the maximum safe load of the crane of Fig. 2 or lying beyond its maximum reach, is suspended by block and tackle 32, 35 from a crab 33 carried by rails 34 on an arched beam 25. The beam is supported by a trolley 30 and by ropes 27 secured to the jib 26 and is held against movement relative to the crane jib by stays 29 and an attachment 28 on the jib. The lifting rope 22 of the crane, or a permanently rigged extension releasably coupled to it, passes under a pulley 31 on the beam, is reeved about the blocks 32, 35 and is dead-ended on a post 36 on the beam : the trolley 30 may run on a track formed as an arc about the end 24 of the beam 25, or about the slueing axis of the crane, or the trolley and the crane may move on parallel tracks : where necessary pivotal movement of the beam relatively to the crane jib is prevented by guys, and the slueing or travelling motions of the crane and the trolley may be synchronized by means such as geared winches. As a further alternative the trolley may be carried on ground-engaging wheels or endless tracks. In Fig. 4 (not shown) the arch-shaped beam is replaced by a lattice girder providing a longer track for the crab 33 and supported at the end remote from the crane by a tower or by a trolley moved on an elevated track in synchronism with movement of the crane. The height of either or both ends of the jib may be varied by means which may include an auxiliarv winch and lifting rope in place of the connection of the beam to the jib. If these auxiliaries are not provided the normal lifting rope may be employed during erection to raise the end of the beam into position for connection to the jib. In a further construction the crab and its block and tackle are omitted and the load connected directly to the beam by a hook or the like, and the lifting rope is employed to raise and lower one end of the beam and thus ,the load. The beam may have several hooks, &c. from any one of which the load may be supported and is preferably formed of an aluminium alloy, and may be adjustable lengthwise relatively to its supporting foot to allow for variations in the positions of the foot or pedestal or of the crane.