Editing Two-stroke engine (section)

== History ==
The first commercial two-stroke engine involving cylinder compression is attributed to [[Scotland|Scottish]] engineer [[Dugald Clerk]], who patented his design in 1881.<ref>See:
*  Clerk, Dugald; English patent no. 1,089 (issued:  March 14, 1881).
*  Clerk, Dugald [https://pdfpiw.uspto.gov/.piw?Docid=00249307 "Motor worked by combustible gas or vapor,"] U.S. patent no. 249,307 (filed:  September 2, 1881; issued:  November 8, 1881).</ref> However, unlike most later two-stroke engines, his had a separate charging cylinder. The [[crankcase]]-scavenged engine, employing the area below the piston as a charging pump, is generally credited to Englishman [[Joseph Day (inventor)|Joseph Day]].<ref>See:
*  Day, Joseph; British patent no. 6,410 (issued: April 14, 1891).
*  Day, Joseph; British patent no. 9,247 (issued: July 1, 1891).
*  Day, Joseph [https://pdfpiw.uspto.gov/.piw?docid=00543614 "Gas-engine"] US patent no. 543,614 (filed:  May 21, 1892; issued:  July 30, 1895).
*  {{cite journal |last1=Torrens |first1=Hugh S. |title=A study of 'failure' with a 'successful innovation': Joseph Day and the two-stroke internal combustion engine |journal=Social Studies of Science |date=May 1992 |volume=22 |issue=2 |pages=245–262|doi=10.1177/030631292022002004 |s2cid=110285769 }}</ref><ref>Joseph Day's engine used a reed valve.  One of Day's employees, Frederic Cock (1863–1944), found a way to render the engine completely valve-less. See:
*  Cock, Frederic William Caswell; British patent no. 18,513 (issued:  October 15, 1892).
*  Cock, Frederic William Caswell [https://pdfpiw.uspto.gov/.piw?docid=00544210 "Gas-engine"] US patent no. 544,210 (filed:  March 10, 1894; issued: August 6, 1895).
*  The Day-Cock engine is illustrated in: {{cite journal |last1=Dowson |first1=Joseph Emerson |title=Gas-power for electric lighting: Discussion |journal=Minutes of Proceedings of the Institution of Civil Engineers |date=1893 |volume=112 |pages=2–110 |doi=10.1680/imotp.1893.20024 |url=https://babel.hathitrust.org/cgi/pt?id=hvd.hxgrpu&view=1up&seq=60|url-access=subscription }}; see p. 48.</ref> On 31 December 1879, [[Germany|German]] [[inventor]] [[Karl Benz]] produced a two-stroke gas engine, for which he received a patent in 1880 in Germany. The first truly practical two-stroke engine is attributed to Yorkshireman [[Alfred Angas Scott]], who started producing [[two cylinder|twin-cylinder]] [[water cooled|water-cooled]] [[motorcycle]]s in 1908.<ref>{{cite book|last1=Clew|first1=Jeff|title=The Scott Motorcycle: The Yowling Two-Stroke|date=2004|publisher=Haynes Publishing|isbn=0854291644|pages=240}}</ref>

Two-stroke [[gasoline]] engines with electrical [[spark ignition]] are particularly useful in lightweight or portable applications such as [[chainsaws]] and motorcycles. However, when weight and size are not an issue, the cycle's potential for high [[thermodynamic efficiency]] makes it ideal for [[diesel fuel|diesel]] [[compression ignition]] engines operating in large, weight-insensitive applications, such as [[marine propulsion]], [[locomotive|railway locomotives]], and [[Diesel generator|electricity generation]]. In a two-stroke engine, the exhaust gases transfer less heat to the cooling system than a four-stroke, which means more energy to drive the piston, and if present, a turbocharger.