Multi-fall safety rope hoist - has four hoist drums in coaxial pairs and two sizes of pulley

摘要

The multi-fall safety rope hoist has pulleys arranged in single rows, one end of each rope being wound on the hoist drum while the other is secured to a resilient anchor point on a compensator drum common to the two. There are two sets of pulley blocks, an outer one enclosing an inner one. The pulleys in the upper and lower blocks are on common spindles and of alternately large and small diameter, the large ones in the upper blocks lying opposite the small ones in the lower. The rope falls cross each other, one being reeved round the smaller pulleys and the other round the larger ones. There are four hoist drums (1-4) arranged in coaxial pairs. The rope (10) from one pair (1, 2) is reeved, in the opposite direction to that in which it passes round them, round the smaller diameter pulleys (8), and that (12) from the other pair (3, 4) round the larger ones (9) in the upper and lower blocks (6, 5) to the compensation pulleys between the blocks and the drums.