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The Roman Polyspaston crane, from Ancient Greek πολύσπαστον (polúspaston, “compound pulley”), when worked by four men at both sides of the winch, could lift 3000 kg. In case the winch was replaced by a treadwheel, the maximum load even doubled to 6000 kg at only half the crew, since the treadwheel possesses a much bigger ...
A pulley may have a groove or grooves between flanges around its circumference to locate the cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain. The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991–1802 BC) [1] and Mesopotamia in the early 2nd millennium BC. [2]
The polyspastos, when worked by four men at both sides of the winch, could readily lift 3,000 kg (6,600 lb) (3 ropes x 5 pulleys x 4 men x 50 kg or 110 lb = 3,000 kg or 6,600 lb). If the winch was replaced by a treadwheel, the maximum load could be doubled to 6,000 kg (13,000 lb) at only half the crew, since the treadwheel possesses a much ...
Riggers attach loads of equipment to cranes or structures using shackles, cables, chains, clamps or straps, employing pulleys, winches, lifts or chain hoists (aka chain motors). Quick load calculations are necessary for each load and engineering principles are always in play.
The winch may be mounted to a vehicle, set into the ground by stakes, or tied to a tree. The cable may also be run through pulleys mounted offshore so that it pulls the person away from where the winch is located, and multiple pulleys may be used to multiply the force applied by a small but high revving motor instead of using a transmission.
Block (sailing) – Sailing term; single or multiple pulley; Cargo net – Net used to secure or transfer cargo; Cargo strap; Chain – Series of connected links which are typically made of metal; Chain hoist – Device used for lifting or lowering a load; Chain stopper; Come-along – Lever operated, portable ratchet winch
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