Editing Connecting rod (section)

== Steam engines ==
{{multiple image
| align             = right
| direction         = vertical
| width             = 220
| image1            = Twin Beam Engine.jpg
| caption1          = [[Beam engine]] with twin connecting rods (almost vertical) between the horizontal beam and the flywheel
| image2            = Walschaerts valve gear.jpg
| caption2          = Steam locomotive connecting rod (between the piston and the rear wheel; the largest rod visible)
}}

The 1712 [[Newcomen atmospheric engine]] (the first steam engine) used chain drive instead of a connecting rod, since the piston only produced force in one direction.<ref>{{cite web|title = Steam Locomotive Glossary|url = http://www.railway-technical.com/st-glos.shtml|website = www.railway-technical.com|access-date = 2016-02-05|archive-url = https://web.archive.org/web/20080128230325/http://www.railway-technical.com/st-glos.shtml|archive-date = 2008-01-28|url-status = dead}}</ref> However, most steam engines after this are [[double-acting cylinder|double-acting]], therefore the force is produced in both directions, leading to the use of a connecting rod. The typical arrangement uses a large sliding bearing block called a [[crosshead]] with the hinge between the piston and connecting rod placed outside the cylinder, requiring a seal around the [[piston rod]].<ref>{{cite book| url=https://books.google.com/books?id=4iYeCgAAQBAJ| title=The Victorian Steam Locomotive: Its Design & Development 1804-1879| pages=27–28| first1=G.D.| last1=Dempsey| first2=D. Kinnear| last2=Clark| publisher=Pen & Sword Transport| year=2015| location=Barnsley, England| isbn=978-1-47382-323-5| via=Google Books}}</ref>
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Expansion on crossheads, maybe Watt parallel motion
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In a [[steam locomotive]], the cranks are usually mounted directly on the [[driving wheel]]s. The connecting rod is used between the crank pin on the wheel and the crosshead (where it connects to the [[piston rod]]).<ref>{{cite book| url=https://books.google.com/books?id=_7lJAAAAIAAJ| pages=74–78| title=Steam Locomotive Construction and Maintenance| publisher=The Locomotive Publishing Co. Ltd.| location=London| series=Pitman's Technical Primer Series| editor-first=R.E.| editor-last=Neale| first=E.L.| last=Ahrons| year=1921| via=Google Books}}</ref> On smaller steam locomotives, the connecting rods are usually of rectangular cross-section;<ref>{{cite book| url=https://books.google.com/books?id=1A4iiGAz628C&q=steam+locomotive+connecting+rod&pg=PA185| page=185| title=A History of the American Locomotive: Its Development, 1830-1880| first=John H. Jr.| last=White| publisher=Dover Publications| location=New York| year=1979| isbn=9780486238180| via=Google books}}</ref> however, marine-type rods of circular cross-section have occasionally been used.

On [[paddle steamer]]s, the connecting rods are called 'pitmans' (not to be mistaken for [[pitman arm]]s).

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