Editing Traction engine (section)

{{short description|Steam-powered haulage engine}}
{{For|similar terms|Traction motor||}}
{{Use dmy dates|date=October 2020}}
[[File:General Purpose Engine BJ 7155 GDSF.JPG|thumb|upright=1.3|1909 [[Charles Burrell & Sons]] 6 [[Horsepower#Nominal horsepower|nominal horsepower]] general purpose engine, at [[Great Dorset Steam Fair]] in 2018]]

A '''traction engine''' is a [[steam engine|steam-powered]] [[tractor]] used to move heavy loads on roads, plough ground or to provide power at a chosen location. The name derives from the Latin ''tractus'', meaning 'drawn',<ref>{{cite book |last1=Ainsworth |first1=Robert |title=Thesaurus Linguæ Latinæ Compendiarus, Or A Compendious Dictionary of the Latin Tongue ... By Mr. Robert Ainsworth |date=1808 |publisher=J. Johnson, J. Nichols and son, R. Baldwin [...] |url=https://www.google.com/books/edition/Thesaurus_Lingu%C3%A6_Latin%C3%A6_Compendiarus_O/fNEdn7WM7jsC?hl=en&gbpv=1&dq=latin%20traho%20tractor&pg=PA14-IA126&printsec=frontcover |language=en |quote='''Tractus''' part. (à traho) 1. Drawn, pulled; dragged.}}</ref> since the prime function of any traction engine is to draw a load behind it. They are sometimes called '''road locomotives''' to distinguish them from railway [[steam locomotive|locomotives]] &ndash; that is, steam engines that run on rails.

Traction engines tend to be large, robust and powerful, but also heavy, slow, and difficult to manoeuvre. Nevertheless, they revolutionized agriculture and road haulage at a time when the only alternative [[Prime mover (tractor unit)|prime mover]] was the [[draught horse]].

They became popular in industrialised countries from around 1850, when the first self-propelled portable steam engines for agricultural use were developed. Production continued well into the early part of the 20th century, when competition from [[internal combustion engine]]-powered [[tractor]]s saw them fall out of favour, although some continued in commercial use in the [[United Kingdom]] well into the 1950s and later. All types of traction engines have now been superseded in commercial use. However, several thousand examples have been preserved worldwide, many in working order. Steam fairs are held throughout the year in the United Kingdom and in other countries, where visitors can experience working traction engines at close hand.

Traction engines were cumbersome and ill-suited for crossing soft or heavy ground, so their agricultural use was usually either "on the belt" &ndash;&nbsp;powering farm machinery by means of a continuous leather belt driven by the flywheel, a form of [[power take-off]] &ndash;&nbsp;or in pairs, dragging an implement on a cable from one side of a field to another. However, where soil conditions permitted, direct hauling of implements ("off the [[Drawbar (haulage)|drawbar]]") was preferred; in America, this led to the divergent development of the [[steam tractor]]. 
This aside, American designs were far more varied than those of the British with different boiler positions, wheel numbers and piston placements being used.<ref name=Burton29 /> Additionally American engines often had higher top speeds than those of Britain as well as the ability to run on straw.<ref name=Burton35>{{cite book |last=Burton |first=Anthony |date=2000 |title=Traction Engines Two Centuries of Steam Power| publisher=Silverdale Books |page=35 |isbn=1856055337}}</ref>

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