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Encyclopedia > Archimedes' screw
Animation of Archimedes' screw in operation.
Archimedes screw in Huseby south of Växjö Sweden.
Archimedes' screw

## Workings

The machine consists of a screw inside a hollow pipe. It was invented by Archimedes in around 250 BC or in Greece earlier. A screw can be thought of as an inclined plane (another simple machine) wrapped around a cylinder. Look up screw in Wiktionary, the free dictionary. ... The inclined plane is one of the classical simple machines; as the name suggests, it is a flat surface whose endpoints are at different heights. ... This article is about the concept in physics. ...

The screw is turned (usually by a windmill or by manual labour). As the bottom end of the tube turns, it scoops up a volume of water. This amount of water will slide up in the spiral tube as the shaft is turned, until it finally pours out from the top of the tube and feeds the irrigation syms. This article is about machines that convert wind energy into mechanical energy. ...

The contact surface between the screw and the pipe does not need to be perfectly water-tight because of the relatively large amount of water being scooped at each turn with respect to the angular speed of the screw. Also, water leaking from the top section of the screw leaks into the previous one and so on, so a sort of equilibrium is achieved while using the machine, thus preventing a decrease in efficiency. It has been suggested that this article or section be merged into Angular velocity. ... A standard definition of mechanical equilibrium is: A system is in mechanical equilibrium when the sum of the forces, and torque, on each particle of the system is zero. ... In physics, mechanical efficiency is the effectiveness of a machine and is defined as Efficiency is often indicated by a percentage, the efficiency of an ideal machine is 100%. Due to the fact that energy cannot emerge from nothing and the Second law of thermodynamics which states that the quality...

Roman screw used to dewater mines in Spain
 “ 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 a powerful 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 [1] A helix (pl: helices), from the Greek word Î­Î»Î¹ÎºÎ±Ï‚/Î­Î»Î¹Î¾, is a twisted shape like a spring, screw or a spiral (correctly termed helical) staircase. ... ”
Modern Archimedes' Screws which have replaced some of the Windmills used to drain the polders at Kinderdijk in Holland.

Archimedes' screws are used in sewage treatment plants because they cope well with varying rates of flow and with suspended solids. An auger in a snow blower or grain elevator is essentially an Archimedes' screw. Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater, both runoff and domestic. ... Study of a man using an auger, for The Seven Sorrows of the Virgin, Albrecht DÃ¼rer, ca 1496 An auger is a device for moving material or liquid by means of a rotating helical flighting. ... A heavy duty walk-behind two-stage snow blower. ... This article or section does not adequately cite its references or sources. ...

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

## Mathematics behind the screw

The slope of the outside of the screw's helical blades with respect to its sides is 2. This requires that the slope the screw makes with respect to a horizontal line be less than 2 (an angle of 63°) in order for the buckets or pockets of water to form. In the profile of the screw, the projection of each helical blade consists of two sinusoidal curves with the same periods and phases.

Main dimensions of a screwpump

One has an amplitude equal to the radius of the outer cylinder and the other has an amplitude equal to the radius of the inner cylinder. The horizontal water level of each full bucket of water is tangent to the inner sinusoidal curve. Thus, if the equation on the inner sinusoidal curve is y = sin x, then the water level is tangent to it at x = arccos(−3/4) = 138.59°.

d = diameter of centre tube
β = angle of installation
H1 = difference of medium levels, effective head
H2 = maximum difference of medium levels, delivery head
J = number of flights
L = length of helix
S = rise

## Types

### Screw conveyor

An Archimedes screw seen on a combine.

A screw conveyor is an Archimedean screw contained within a tube and turned by a motor so as to deliver material from one end of the conveyor to the other. It is particularly suitable for transport of granular materials such as plastic granules used in injection moulding, and cereal grains. It may also be used to transport liquids. In industrial control applications the conveyor may be used as a rotary feeder or variable rate feeder to deliver a measured rate or quantity of material into a process.-1... Grain redirects here. ... Primary use is for discharge from hoppers/bins, receivers and cyclones into a conveying system. ...

## Literature

J. Muysken's writings are considered very important, and his methods are still in use.[citation needed] In Germany one of the most common books are by G. Nagel: „Ritz, Handbuch der Wasserförderschnecken“, published in 1968, and „Wasserförderschnecken, Planung, Bau und Betrieb von Wasserhebeanlagen“, by G. Nagel and K.A. Radlik, from 1988. The common author G. Nagel may be a hint that the 2nd book is a revised print run without the name Ritz. Both books discuss the topic very theoretically. They are not available at this moment. At the IFAT 2008 (05th - 09th of May) a new book was introduced. It was written for planners and operators to discuss practical problems and the actual design. It is called „Manual for Archimedean Screw Pump“ by German author P.J. Kantert (Hirthammer Verlag, ISBN: 978-3-88721-202-5). It talks about new developments like energy generating screws and allows a rough calculation of existing screws and an approximately dimensioning of new ones. It is available in German and also in English.

## Also See

For other uses, see Archimedes (disambiguation). ... Marcus Vitruvius Pollio (born c. ... Screws can be used for vehicle propulsion. ...

## References

Results from FactBites:

 Archimedes (mathematician) (707 words) The lever had been used by other scientists, but it was Archimedes who demonstrated mathematically that the ratio of the effort applied to the load raised is equal to the inverse ratio of the distances of the effort and load from the pivot or fulcrum of the lever. Archimedes is credited with having claimed that if he had a sufficiently distant place to stand, he could use a lever to move the world. Archimedes had decreed that his gravestone be inscribed with a cylinder enclosing a sphere together with the formula for the ratio of their volumes – a discovery that he regarded as his greatest achievement.
 Archimedes' screw (53 words) Archimedes' screw is one of several inventions and discoveries by Archimedes. It consists of a screw inside a pipe, and is used to lift water. The lower end of the device is put in the water, and the screw is then turned (usually by a windmill or by animal labor), raising the water.
More results at FactBites »

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