GB722703A - Improvements in and relating to cranes - Google Patents

Abstract

722,703. Mobile jib cranes; overhead travellers. BRITISH HOIST & CRANE CO., Ltd., and EVANS, P. N. Nov. 23, 1951 (Nov. 24, 1950], No. 28797/50. Class 78 (4). Mounting and supporting.-Outriggers 18, Fig. 2, for extending the ground engaging base of a crane are moved to a stowed position on the crane chassis when the crane is to be moved on its road wheels 14, Fig. 1. The outriggers are carried by vertical pivots from lugs 12a, Fig. 2, and carry at their ends screw jacks 19 formed either with feet 49 (as shown at the left of Fig. 2) for engaging the ground or bogies 50 (as shown at the right of Fig. 2) for engaging a narrow gauge rail track. The rear of the trailer chassis shown is then supported either by jacks 20, Fig. 1, or by one of the road wheels 14 placed on a stub axle 15, Fig. 1. The trailer chassis is also provided with jockey wheels 16. Jib cranes: folding and collapsible, luffing and slewing. Overhead travellers : supporting booms.-The mast of the crane illustrated is formed in two parts, a lower part 22 pivoted about a horizontal axis 39 to fold on top of the chassis and an upper part 21 supported by a slewing bearing from the lower part. The jib 28 comprises two box girders bolted together at 29 and is detachable from the mast. When the crane is to be assembled the mast 22, 21 is first raised about its heel pivot 39 by securing the block 33 of the backstay to the mast and winding a hand winch 41 controlling the backstay. The rope from the hand winch 41 is then reeved to cause plates 30 at the heel of the jib to slide up rails on the mast until they can be secured in position on a collar 31. The jib is then pivoted into the position illustrated in Fig. 1 by reeving the backstay cable 32 about the hand winch 41. The jib 28 and the upper part 21 of the mast are slewed by a cable 42 passed around a sheave 27 on the mast and around a winch driven by an engine 17 on the chassis. The backstay cable 32 may also be operated from a winch driven by the engine 17 in which case the cable passes over one of several pulleys 23 at the lower end of the mast. In a construction described in the Provisional Specification the mast is raised by a screw-and-nut device on the chassis. Overhead travellers: horizontal travel of load. Lifting gear.-The jib 28 is formed with a track on which runs a trolley 35 traversed by a cable 46 passing around a jib-end pulley 47, a pulley 25 on the mast, one of the pulleys 23 at the foot of the mast and a winch 44 driven by the engine 17. A hoisting cable 45 passes from a further winch 43 driven by the engine 17 over one of the pulleys 23, over a pulley 26 on the mast, over a pulley 36 on the trolley 35, under a load block pulley 37, and over a further pulley 36 on the trolley to be dead-ended on the jib.