8/15/13 Archimedes' screw - Wikipedia, the free encyclopedia

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Archimedes' screw was operated

by hand and could raise water

efficiently

An Archimedes screw in Huseby

south of Växjö Sweden

Archimedes' screw

Archimedes' screwFrom Wikipedia, the free encyclopedia

Archimedes' screw, also called the Archimedean screw orscrewpump, is a machine historically used for transferring water from alow-lying body of water into irrigation ditches. The screw pump iscommonly attributed to Archimedes on the occasion of his visit to Egypt,but this tradition may reflect only that the apparatus was unknown to theGreeks before Hellenistic times and introduced in his lifetime by

unknown Greek engineers.[1]

Contents

1 Design

2 Uses

3 History4 Variants

4.1 Reverse action

5 See also

6 Footnotes

7 Sources8 External links

Design

Archimedes' screw consists of a screw (a helical surface surrounding acentral cylindrical shaft) inside a hollow pipe. The screw is turned usuallyby a windmill or by manual labour. As the shaft turns, the bottom endscoops up a volume of water. This water will slide up in the spiral tube,until it finally pours out from the top of the tube and feeds the irrigationsystems. The screw was used mostly for draining water out of mines orother areas of low lying water.

The contact surface between the screw and the pipe does not need to beperfectly watertight, as long as the amount of water being scooped ateach turn is large compared to the amount of water leaking out of eachsection of the screw per turn. Water leaking from one section leaks intothe next lower one, so that a sort of mechanical equilibrium is achieved inuse.

In some designs, the screw is fixed to the casing and they rotate togetherinstead of the screw turning within a stationary casing. A screw could besealed with pitch resin or some other adhesive to its casing, or cast as a

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Roman screw used to dewater mines

in Spain

Modern Archimedes screws which

have replaced some of the windmills

used to drain the polders at Kinderdijk

in the Netherlands

single piece in bronze. Some researchers have postulated this as beingthe device used to irrigate the Hanging Gardens of Babylon, one of theSeven Wonders of the Ancient World. Depictions of Greek and Romanwater screws show them being powered by a human treading on theouter casing to turn the entire apparatus as one piece, which wouldrequire that the casing be rigidly attached to the screw.

“The design of the everyday Greek and Roman water

screw, in contrast to the heavy bronze device of

Sennacherib, with its problematic drive chains, has apowerful simplicity. A double or triple helix was built of

wood strips (or occasionally bronze sheeting) around a

heavy wooden pole. A cylinder was built around the

helices using long, narrow boards fastened to their

periphery and waterproofed with pitch[2] ”

Uses

Along with transferring water to irrigation ditches, the device was alsoused for draining land that was underneath the sea in the Netherlands andother places in the creation of polders. A part of the sea would beenclosed and the water would be pumped out of the enclosed area,starting the process of draining the land for use in agriculture. Dependingon the length and diameter of the screws, more than one machine couldbe used successively to lift the same water.

An Archimedes' screw was used by British soils engineer John Burlandin the successful 2001 stabilization of the Leaning Tower of Pisa. Smallamounts of subsoil saturated by groundwater were removed from farbelow the north side of the Tower, and the weight of the tower itselfcorrected the lean.

Archimedes' screws are used in sewage treatment plants because theycope well with varying rates of flow and with suspended solids. An augerin a snow blower or grain elevator is essentially an Archimedes' screw.Many forms of axial flow pump basically contain an Archimedes' screw.

The principle is also found in pescalators, which are Archimedes screwsdesigned to lift fish safely from ponds and transport them to anotherlocation. This technology is used primarily at fish hatcheries, where it isdesirable to minimize the physical handling of fish.

It is also used in chocolate fountains.

History

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Archimedes' screw as a form of art

by Tony Cragg at 's-Hertogenbosch

in the Netherlands

An Archimedes screw seen on a

combine harvester

The invention of the water screw is credited to the Greek polymath

Archimedes of Syracuse in the 3rd century BC.[1] A cuneiforminscription of the Assyrian king Sennacherib (704 - 681BC) has been

interpreted by Dalley[3] to describe the casting of water screws in bronzesome 350 years earlier. This is consistent with the classical author Strabowho describes the Hanging Garden as watered by screws. A contrary

view is expressed by Oleson in an earlier review.[4] The Germanengineer Konrad Kyeser, in his Bellifortis (1405), equips theArchimedes screw with a crank mechanism. This mechanism soon

replaced the ancient practice of working the pipe by treading.[5]

Variants

Main article: Screw conveyor

A screw conveyor is an Archimedes' screw contained within a tube andturned by a motor so as to deliver material from one end of the conveyorto the other. It is particularly suitable for transport of granular materialssuch as plastic granules used in injection molding, and cereal grains. Itmay also be used to transport liquids. In industrial control applicationsthe conveyor may be used as a rotary feeder or variable rate feeder todeliver a measured rate or quantity of material into a process.

A variant of the Archimedes' screw can also be found in some injectionmolding machines, die casting machines and extrusion of plastics, whichemploy a screw of decreasing pitch to compress and melt the material.Finally, it is also used in a specific type of positive displacement aircompressor: the rotary-screw air compressor. On a much larger scale,Archimedes' screws of decreasing pitch are used for the compaction ofwaste material.

Reverse action

If water is poured into the top of an Archimedes' screw, it will force the screw to rotate. The rotating shaft can thenbe used to drive an electric generator. Such an installation has the same benefits as using the screw for pumping: theability to handle very dirty water and widely varying rates of flow at high efficiency. Settle Hydro and Torrs Hydroare two reverse screw micro hydro schemes operating in England. As a generator the screw is good at low heads,

commonly found in English rivers, including the Thames powering Windsor Castle.[6][7]

See also

ArchimedesMachine

Screw-propelled vehicle

SS Archimedes – the first steamship driven by a screw propeller.

Screw (simple machine)

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Spiral pump

Turbine

Vitruvius

Footnotes

1. ̂a b Oleson 2000, pp. 242–251

2. ^ Online copy of Dalley/Oleson article (http://muse.jhu.edu/journals/technology_and_culture/v044/44.1dalley.pdf)

3. ^ Stephanie Dalley, The Mystery of the Hanging Garden of Babylon: an elusive World Wonder traced, (2013),OUP ISBN 978-0-19-966226-5

4. ^ Dalley S and Oleson JP, (2003), "Sennacherib, Archimedes and the water screw: the context of invention in the

ancient world" Technology and Culture 44

5. ^ White, Jr. 1962, pp. 105, 111, 168

6. ^ Shankleman, Jessica. "Queen Elizabeth joins the hydropower revolution"(http://www.businessgreen.com/bg/news/2108103/queen-elizabeth-joins-hydropower-revolution) BusinessGreen, 9September 2011. Retrieved: 21 July 2012.

7. ^ Shankleman, Jessica. "The Queen's hydro energy scheme slots into place"(http://www.businessgreen.com/bg/news/2133972/queens-hydro-energy-scheme-slots) BusinessGreen, 21December 2011. Retrieved: 21 July 2012.

Sources

Oleson, John Peter (1984), Greek and Roman mechanical water-lifting devices. The History of a

Technology, Dordrecht: D. Reidel, ISBN 90-277-1693-5

Oleson, John Peter (2000), "Water-Lifting", in Wikander, Örjan, Handbook of Ancient Water

Technology, Technology and Change in History 2, Leiden, pp. 217–302 (242–251), ISBN 90-04-11123-9

P. J. Kantert: „Manual for Archimedean Screw Pump“, Hirthammer Verlag 2008, ISBN 978-3-88721-

896-6.P. J. Kantert: „Praxishandbuch Schneckenpumpe“, Hirthammer Verlag 2008, ISBN 978-3-88721-202-5.

Nuernbergk, D. and Rorres C.: „An Analytical Model for the Water Inflow of an Archimedes Screw Used

in Hydropower Generation", ASCE Journal of Hydraulic Engineering, Published: 23 July 2012

Nuernbergk D. M.: „Wasserkraftschnecken – Berechnung und optimaler Entwurf von archimedischenSchnecken als Wasserkraftmaschine", Verlag Moritz Schäfer, Detmold, 1. Edition. 2012, 272 papes, ISBN

978-3-87696-136-1

Rorres C.: The turn of the Screw: Optimum design of an Archimedes Screw", ASCE Journal of Hydraulic

Engineering, Volume 126, Number 1, Jan.2000, pp. 72–80Nagel, G.; Radlik, K.: Wasserförderschnecken – Planung, Bau und Betrieb von Wasserhebeanlagen; Udo

Pfriemer Buchverlag in der Bauverlag GmbH, Wiesbaden, Berlin (1988)

White, Jr., Lynn (1962), Medieval Technology and Social Change, Oxford: At the Clarendon Press

External links

Technology and Culture Volume 44, Number 1, January 2003 (PDF)(http://muse.jhu.edu/journals/technology_and_culture/toc/tech44.1.html) Dalley, Stephanie. Oleson, John

Peter. "Sennacherib, Archimedes, and the Water Screw: The Context of Invention in the Ancient World"

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The Turn of the Screw: Optimal Design of an Archimedes Screw, by Chris Rorres, PhD.

(http://www.mcs.drexel.edu/~crorres/screw/screw.pdf)

PVC archimedean screw pump, how to build a functioning Archimedes screw pump from modernmaterials (http://www.redstoneprojects.com/trebuchetstore/archimedeswaterscrewplans.html)

"Archimedean Screw" (http://demonstrations.wolfram.com/ArchimedeanScrew/) by Sándor Kabai, Wolfram

Demonstrations Project, 2007.

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