Windlass
- For the tool used to raise paddle gear on canal locks, see Windlass ("lock key")
The windlass is an apparatus for moving heavy weights. Typically, a windlass consists of a horizontal cylinder (barrel), which is rotated by the turn of a crank or belt. A winch is affixed to one or both ends, and a cable or rope is wound around the winch, pulling a weight attached to the opposite end.
Uses
- During the Middle Ages the windlass was used to raise materials during the construction of buildings such as in Chesterfield's crooked spire church.[1]
- By the Late Middle Ages most European crossbows employed a windlass as a cocking mechanism, which helped to pull heavier crossbows, but were used in England as early as 1215.[2]
- Windlasses are sometimes used on boats to raise the anchor as an alternative to a vertical capstan (see anchor windlass).
- The rod or stick used to tighten a tourniquet in surgical procedures is called a windlass.
- The handle used to open locks on the UK's inland waterways is called a windlass.
- Windlass can be used to raise water from a well. The oldest description of a well windlass, a rotating wooden rod installed across the mouth of a well, is found in Isidore of Seville's (c. 560–636) Origenes (XX, 15, 1-3).[3]
- Windlass have also been used in gold mining. A windlass would be constructed above a shaft which allowed heavy buckets to be hauled up to the surface.[4] This process would be used until the shaft got below 40 metres deep when the windlass would be replaced by a 'whip' or a 'whim'.[5]
Differential windlass
In a differential windlass, also called a Chinese windlass,[6][7][8] there are two coaxial drums of different radii r and r '. The rope is wound onto one drum while it unwinds from the other, with a movable pulley hanging in the bight between the drums. Since each turn of the crank raises the pulley and attached weight by only , very large mechanical advantages can be obtained.
See also
References
- ↑ "Medieval Builders' Windlass". http://www.bbc.co.uk. Retrieved September 11, 2012.
- ↑ "Engineering the Medieval Achievement-The Crossbow". http://web.mit.edu. Retrieved September 11, 2012.
- ↑ Oleson, John Peter (1984), Greek and Roman Mechanical Water-lifting Devices. The History of a Technology, Dordrecht: D. Reidel, pp. 56f., ISBN 90-277-1693-5
- ↑ "Albert Goldfields Mining Heritage" (PDF). http://outbacknsw.com.au. Retrieved September 11, 2012.
- ↑ "Searching for Gold". http://www.kidcyber.com.au. Retrieved September 11, 2012.
- ↑ "Chinese". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005. (registration required)
- ↑ Morris, Christopher, ed. (1992), Academic Press Dictionary of Science and Technology, Gulf Professional Publishing, p. 416, ISBN 978-0-12-200400-1
- ↑ Knight, Edward H. (1884), The Practical Dictionary of Mechanics, Cassell, Petter, Galpin & Co "Chinese-windlass, a differential windlass in which the cord winds off one part of the barrel and on to the other."
External links
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