Editing Traction engine (section)

==Operation==
{{further|Steam engine}}
[[File:Ruston crawler tractor working model.JPG|thumb|right|[[Richard Hornsby & Sons|Hornsby]] chain tractor (working scale model)]]

Although the first traction engines employed a chain drive, it is more typical for large gears to be used to transfer the drive from the crankshaft to the rear axle.

The machines typically have two large powered wheels at the back and two smaller wheels for steering at the front. However, some traction engines used a four-wheel-drive variation, and some experimented with an early form of [[caterpillar track]].<ref name=HornsbyChainTractor>{{cite web | title = The Hornsby Steam Crawler | work = (or 'Chain Tractor') | url = http://hornsbycrawler.org/index.php/Main/HomePage | access-date = 2008-09-16}}</ref>
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{{Dead link|date=July 2022}} A simple animation showing the steam cycle of a traction engine, the operation of the valve gear and the reversing mechanism, may be found here:.<ref>[http://www.aonx97.dsl.pipex.com/TE-page/cycles-valves/steam-cycle.htm Animation (Flash) showing the steam cycle and reversing mechanism of a traction engine]<BR>&nbsp;&nbsp;&nbsp; &ndash; ''NB contains embedded music, which can be turned off!'' (Accessed 23 Apr 2007)</ref> -->