GB1355507A - Telescopic jib for a crane - Google Patents

Abstract

1355507 Telescopic jibs POTAIN 3 Aug 1971 [5 Aug 1970 12 July 1971] 36470/71 Heading B8B [Also in Division E2] A telescopic jib, Fig. 1, comprises a jib foot 1 and a jib head 2 extended to the length required for the needs of the work site. A lifting truck 5 runs on rails 3 on the jib foot 1. A dummy truck 9, fitted with rails 10 forming an extension of the rails 3 in the position shown, is arranged to run on rails 7 on the jib head 2. When the lifting truck 5 is required to distribute below the jib head 2 it is run on to the dummy truck 9 against a stop 11 and releases a latch 12 whereupon the dummy truck 9 is free to move along the jib head 2 carrying the lifting truck 5. In a modification, Fig. 14, a lifting truck 117 is traversed by an endless cable 110 driven by a winch 111. On jib head 101 the truck 117 is carried on a dummy truck 105. The trucks 105, 117 are latched together by a system comprising a stop 152 on the truck 117 which is trapped between stops 153, 154 on rockers 119, 121 on the dummy truck 105 as shown in Fig. 11. At the change between the jib foot 102 and the jib head 101 (Fig. 9) the trucks are separated, the rocker 119 contacting a roller on a stop 123 whereupon continued retraction of the dummy truck 105 raises the rocker 119 in the direction of arrow 158 so that the stop 153 is withdrawn and the truck 117 is freed, rocker 121 moving under gravity to hold the rocker 119 in its position.