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The Willans engine was a high-speed stationary steam engine used for electricity generation around the start of the 20th century. Willans' engine was one of the best-known examples of the steeple compound engine. These were double- or triple-expansion compound engines, with the unusual features of single-acting cylinders and a central spindle valve shared between all the cylinders of that spindle. The cylinders are arranged as tandem compounds, with high- and low-pressure cylinders mounted on the same vertical shaft. This vertical arrangement of the steeple compound gives a compact floor layout for an engine of such power. Willans engines were not the first high-speed engines for electricity generation, but they were soon adopted to become the predominant type in service. == Application == The engines were developed by Peter W. Willans and Mark Robinson at Thames Ditton, primarily for the increasing market in electrical generation.In 1884 they were granted a patent for the central valve principle.〔 By the 1890s, more of the Willans type were in service for electricity generation than any other type.〔 As with other high-speed steam engines, the need was for a steam engine that ran at sufficiently high speeds to drive dynamos directly and also that had accurate speed regulation under changing load, so as to maintain the correct voltage. Maintaining the correct frequency for AC systems was even more important, but AC systems tended to favour slow-speed engines with large flywheels, rather than the high-speed engines used for DC. Willans engines were also used for powering textile mills, although as many mills had been built by this date, the longer-established cross-compound Corliss and drop-valve engines are better known in this application. The Willans engine, its low inertia and accurate speed control made it highly suitable for mill work. The constant shaft speed it delivered, even under a varying load, was considered to improve spinning quality and reduced the number of ends broken by shock loads. 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「Willans engine」の詳細全文を読む スポンサード リンク
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