page_title: History of the steam engine
section_title: Porter-Allen high speed steam engine
hierarchical_section_title: History of the steam engine / Porter-Allen high speed steam engine
caption_attribution_description: Porter-Allen high-speed engine (New Catechism of the Steam Engine, 1904).jpg
context_page_description: The first recorded rudimentary steam engine was the aeolipile described by Heron of Alexandria in 1st-century Roman Egypt. Several steam-powered devices were later experimented with or proposed, such as Taqi al-Din's steam jack, a steam turbine in 16th-century Ottoman Egypt, and Thomas Savery's steam pump in 17th-century England. In 1712, Thomas Newcomen's atmospheric engine became the first commercially successful engine using the principle of the piston and cylinder, which was the fundamental type of steam engine used until the early 20th century. The steam engine was used to pump water out of coal mines.
  During the Industrial Revolution, steam engines started to replace water and wind power, and eventually became the dominant source of power in the late 19th century and remaining so into the early decades of the 20th century, when the more efficient steam turbine and the internal combustion engine resulted in the rapid replacement of the steam engines. The steam turbine has become the most common method by which electrical power generators are driven.
context_section_description: The Porter-Allen engine, introduced in 1862, used an advanced valve gear mechanism developed for Porter by Allen, a mechanic of exceptional ability, and was at first generally known as the Allen engine.  The high speed engine was a precision machine that was well balanced, achievements made possible by advancements in machine tools and manufacturing technology.
  The high speed engine ran at piston speeds from three to five times the speed of ordinary engines.  It also had low speed variability. The high speed engine was  widely used in sawmills to power circular saws.  Later it was used for electrical generation.
  The engine had several advantages. It could, in some cases, be directly coupled.  If gears or belts and drums were used, they could be much smaller sizes.  The engine itself was also small for the amount of power it developed.
  Porter greatly improved the fly-ball governor by reducing the rotating weight and adding a weight around the shaft.  This significantly improved speed control. Porter's governor became the leading type by 1880.
  The efficiency of the Porter-Allen engine was good, but not equal to the Corliss engine.
caption: Porter-Allen high speed engine.  Enlarge to see the Porter governor at left front of flywheel
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