| 摘要 |
<p>1,146,392. Jib cranes. J. S. THOMSON. 8 Jan., 1968 [10 Feb. 1967], No. 6382/67. Heading B8B. A jib crane includes a jib 1 mounted at one end on a platform or deck 4 for luffing and slewing, a first anchorage 5 at or near the free end of the jib and extending laterally on both sides of the latter, a second anchorage 6 fixed relative to the platform or deck and disposed transversely of the latter above the mounted end of the jib, pulley means 8 . . . 14 on the anchorages 5, 6 at spaced intervals along the latter, and ropes 15, 16 operatively associated with winches 17, 18 and co-operating with the pulley means to effect the luffing and slewing, the ropes being reeved to-and-fro round and between the pulley means to form between the anchorages 5, 6 a plurality of rope reaches disposed on both sides of the vertical plane containing the jib axis and traversing in a zig-zag manner, the quadrilateral space defined by the ends of the anchorages 5, 6, the pulley means being so spaced along the anchorages that the rope reaches on opposite sides of the plane include reaches which are mutually divergent as from the first to the second anchorage. The ropes 15, 16 may pass from the winch 17 to the pulley means 14 instead of the pulley means 11 and from the winch 18 to the pulley means 11 instead of the pulley means 14. More than one pulley may be provided by each pulley means and the latter may not be arranged in a line.</p> |
