Editing Traction engine (section)

==Relatives of the traction engine==
[[File:Kuernbach-lokomobil.jpg|thumb|upright=0.75|Portable engine showing the lack of self-driven wheels]]

A number of other steam-powered vehicles share design features with the traction engine, usually because the same technology was re-used in a new application.

===Portable engine===
{{main|Portable engine}}

A '''portable engine''' is a type of self-contained steam engine and boiler combination that may be moved from site to site. Although bearing a strong family resemblance, in both appearance and (stationary) operation, the portable engine is ''not'' classed as a traction engine as it is not self-propelled.  However, it is included in this list because the traction engine is a direct descendant.

===Steam wagon===
{{main|Steam wagon}}
[[File:Foden 5 ton steam lorry registration WX 2682.jpg|left|thumb|1930 [[Edwin Foden, Sons & Co.|Foden]] C-Type 5 ton 'overtype' steam wagon]]
A steam wagon is a [[steam]]-powered road vehicle for carrying [[freight]]. It was the earliest form of [[lorry]] (truck) and came in two basic forms: ''overtype'' and ''undertype'' – the distinction being the position of the [[steam engine|engine]] relative to the [[boiler]]. Among the firms that specialized in them in the 1900s was the short-lived Invicta Works of Maidstone, owned by [[Jesse Ellis]].

The overtype had a steam engine mounted on top of a [[fire-tube boiler]], in a similar manner to a traction engine. The front of an overtype steam wagon bears a close family resemblance to traction engines, and manufacturers who made both may well have been able to use some common parts.

The undertype had the steam engine mounted under the boiler, usually between the frames of the chassis. The boiler was usually mounted well forward and was often a vertical and/or water tube type.

Steam wagons were the dominant form of powered road traction for commercial haulage in the early part of the twentieth century, although they were a largely British phenomenon, with few manufacturers outside Great Britain. Competition from [[internal-combustion engine|internal-combustion]]-powered vehicles and adverse legislation meant that few remained in commercial use beyond the [[Second World War]].

===Traction engines as railway locomotives===
[[File:Aveling and Porter the blue circle.JPG|right|thumb|upright=0.75|An [[Aveling and Porter]] traction engine-based railway locomotive, as used by [[Holborough Cement Co]].]]
Several traction engine builders (such as [[Aveling and Porter]]<ref>{{Cite book |last=Preston |first=James |url=https://www.google.com/books/edition/Aveling_Porter_An_Illustrated_History/QVe-DwAAQBAJ?hl=en&gbpv=1&dq=Aveling%20&%20Porter%20traction%20company%20No.807%20has%20a%20Single%20Cylinder%20mounted%20on%20top%20of%20the%20Boiler&pg=PT25&printsec=frontcover |title=Aveling & Porter: An Illustrated History |date=2019-11-15 |publisher=Amberley Publishing Limited |isbn=978-1-4456-8883-1 |language=en}}</ref> and [[John Fowler & Co.|Fowler]]) built light [[railway locomotive]]s based on their traction engines. In their crudest form these simply had flanged steel wheels to enable them to run on rails. More sophisticated models had the boiler and engine mounted on a [[chassis]] which carried railway-wagon style axles. The rear axle was driven from the engine by gear or chain-drive. These unusual locomotives were sold to small industries for use in shunting and marshalling duties, although they also found favour with engineering firms engaged in the construction of mainline railways for hauling men, equipment and materials over the partly constructed line.