| 摘要 |
<p>HOIST OR WINCH MECHANISM ADAPTED FOR MULTIPLE VARIABLE RIGGING Portable hoist or winch apparatus comprises such mechanism having a frame carrying a drum for a cable or other flexible member, and load-carrying means which includes first and second pulley block assemblies. A hook-bearing first assembly, in normal use, depends from a loop of cable extending from the drum back into securement with the winch frame; a second assembly is disposed in the cable rigging intermediate the drum and the first assembly. The first pulley block assembly has at least two pulleys; the second pulley block assembly has at least one pulley. The cable extends serially from the drum to a pulley of the first assembly, thence to the pulley of the second, back to the second pulley of the first assembly, and thence to the frame. Movement of the second assembly between a position in which it is coupled to the first assembly, and a position in which it is coupled to the winch frame, converts the rigging so that the ideal mechanical advantage of the apparatus is varied from a predetermined value to a value which is a multiple thereof.</p> |
