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A hydraulic ram, or hydram, is a cyclic water pump powered by hydropower. It takes in water at one "hydraulic head" (pressure) and flow rate, and outputs water at a higher hydraulic head and lower flow rate. The device uses the water hammer effect to develop pressure that allows a portion of the input water that powers the pump to be lifted to a point higher than where the water originally started. The hydraulic ram is sometimes used in remote areas, where there is both a source of low-head hydropower and a need for pumping water to a destination higher in elevation than the source. In this situation, the ram is often useful, since it requires no outside source of power other than the kinetic energy of flowing water. == History == In 1772, John Whitehurst of Cheshire, United Kingdom, invented a manually controlled precursor of the hydraulic ram called the "pulsation engine" and installed the first one at Oulton, Cheshire to raise water to a height of .〔 〕〔Descriptions of Whitehurst's and Montgolfier's pumps appear in: James Ferguson and David Brewster, ''Lectures on Select Subjects'' … , 3rd ed. (Edinburgh, Scotland: Stirling & Slade, etc., 1823), vol. 2, (pages 287-292 ); plates, p. 421.〕 In 1783, he installed another in Ireland. He did not patent it, and details are obscure, but it is known to have had an air vessel. The first self-acting ram pump was invented by the Frenchman Joseph Michel Montgolfier (best known as a co-inventor of the hot air balloon) in 1796 for raising water in his paper mill at Voiron. His friend Matthew Boulton took out a British patent on his behalf in 1797. The sons of Montgolfier obtained a British patent for an improved version in 1816,〔See, for example: ("New Patents: Pierre François Montgolfier," ) ''The Annals of Philosophy'', 7 (41) : 405 (May 1816).〕 and this was acquired, together with Whitehurst's design, in 1820 by Josiah Easton, a Somerset-born engineer who had just moved to London. Easton's firm, inherited by his son James (1796–1871), grew during the nineteenth century to become one of the more important engineering manufacturers in the United Kingdom, with a large works at Erith, Kent. They specialised in water supply and sewerage systems world-wide, as well as land drainage projects. Eastons had a good business supplying rams for water supply purposes to large country houses, farms, and village communities. Some of their installations still survived as of 2004. The firm closed in 1909, but the ram business was continued by James R Easton. In 1929, it was acquired by Green & Carter 〔(Green and Carter – Hydraulic Ram Pump inventors and patentees. )〕 of Winchester, Hampshire, who were engaged in the manufacturing and installation of the well-known Vulcan and Vacher Rams. The first US patent was issued to Joseph Cerneau (or Curneau) and Stephen (Étienne) S. Hallet (1755-1825) in 1809.〔See: * ''Executive Documents of the House of Representatives at the Second Session of the Twenty-first Congress'' … , vol. 2 (Washington, D.C.: Duff Green, 1831), (pages 328 and 332 ). * Letter from Stephen S. Hallet to U.S. President James Madison, September 9, 1808. Available on-line at: (U.S. National Archives ).〕〔See also Robert Fulton's hydraulic ram pump: letter to Thomas Jefferson, March 28, 1810. Available on-line at: (U.S. National Archives ).〕 US interest in hydraulic rams picked up around 1840, as further patents were issued and domestic companies started offering rams for sale. Toward the end of the 19th century, interest waned as electricity and electric pumps became widely available. By the end of the twentieth century interest in hydraulic rams has revived, due to the needs of sustainable technology in developing countries, and energy conservation in developed ones. A good example is (AID Foundation International ) in the Philippines, who won an Ashden Award for their work developing ram pumps that could be easily maintained for use in remote villages.〔(【引用サイトリンク】 date = )〕 The hydraulic ram principle has been used in some proposals for exploiting wave power, one of which was discussed as long ago as 1931 by Hanns Günther in his book ''In hundert Jahren''. Some later ram designs in the UK called compound rams were designed to pump treated water using an untreated drive water source, which overcomes some of the problems of having drinking water sourced from an open stream.〔Interpretation board at the Lost Gardens of Heligan, Cornwall〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hydraulic ram」の詳細全文を読む スポンサード リンク
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