A traction engine is a self-propelled steam engine 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', 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 locomotives – that is, steam engines that run on rails.
Traction engines tend to be large, robust and powerful, but heavy, slow, and difficult to manoeuvre. Nevertheless, they revolutionized agriculture and road haulage at a time when the only alternative prime mover was the draught horse.
- spud or lug – strip of angled metal that could be bolted to the driving wheels to provide greater traction on soft or heavy ground. Spuds were often required on ploughing engines when moving across farmland.
- strake – name for the diagonal strips cast into or rivetted onto the wheel rims to provide traction on unmade ground (similar to the tread on a pneumatic tyre).
- Nominal horse power– nhp is the typical way that traction engines are rated. However, it has long been accepted that nominal horse power greatly understates the actual power of the engine. There are many ways to estimate the actual horse power but none of them gives an accurate answer, for example, a 4 nhp engine is said to be approximately 36 hp (27 kW); however a 4 nhp engine can happily[weasel words] pull a laden 8-wheeler lorry while a diesel engine of 36 hp (27 kW) cannot. Thus, many[who?] have resigned themselves that this debate will never be settled and, while nominal horsepower gives a convenient way of rating traction engines, it may never be converted accurately into diesel HP.
Although no longer used commercially, traction engines of all types continue to be maintained and preserved by enthusiastic individuals and are frequently
Model traction engines, powered by steam, are manufactured by several companies, notably Mamod and Wilesco. Larger scale model engines are popular subjects for model engineers to construct, either as a supplied kit of parts, or machined from raw materials.
Traction engines in popular culture
See also Steamrollers in popular culture
- On film
- The 1962 film The Iron Maiden featured a showman's engine as the film's star, along with many others, at the annual rally at Woburn Abbey.
- In the 2004 film Tremors 4: The Legend Begins, the people of Rejection, Nevada had a traction engine and were proud of it. When they were forced to abandon their town, the engine was going to be used to pull two wagons. During the final battle, two of the characters fired their guns from on the traction engine; and the traction engine was used to kill the last Grabiod by ramming it with such force against the front of the engine, it was decapitated.
- In literature
- Trevor the Traction Engine is one of the non-railway characters featured in The Railway Series of children's books by the Rev. W. Awdry. Appearing in several of the books, the traction engine was originally 'saved from scrap' by The Vicar of Wellsworth with the help of Edward the Blue Engine. Trevor has also appeared in a number of episodes in the TV spin-off Thomas the Tank Engine and Friends. Another traction engine, Fergus the Railway Traction Engine also appears in Thomas & Friends, but unlike Trevor, Fergus runs on rails instead of roads.
- In the book Gumdrop and The Farmer's Friend, by Val Biro, the vintage motor-car Gumdrop is rescued from a snowy ditch by "The Farmer's Friend", a traction engine belonging to a local farmer. Some months later, the two vehicles are instrumental in thwarting a pair of car thieves.
The end-papers of the book include a simplified cut-away drawing of the traction engine: a single-cylinder, 6 nhp Fowler light tractor, built in 1903.
- Traction engines for road haulage feature prominently in Keith Roberts' alternate-history novel Pavane.
- On television
- Fred Dibnah of Bolton, England was known as a National Institution in Great Britain for the conservation of old traction engines and other steam engines. His television series, Fred Dibnah's Made in Britain, shows him touring the United Kingdom in his rebuilt, 10 ton traction engine.
- In the television play Threads, depicting the consequences of nuclear war in the United Kingdom, traction engines come back into use as petrol becomes unavailable.
- History of steam road vehicles
- Live steam
- Steam car
- Steam roller
- Steam shovel
- Steam tractor
- Museum of English Rural Life (MERL) – UK national collection of history of farming
- List of steam fairs – where preserved traction engines may be seen in action
- Bonnett, Harold (1975). Discovering Traction Engines. Shire Publications Ltd. p. 5. ISBN 0-85263-318-1.
- "Motor Transport. County Council Haulage II Petrol V. Horse". The Times. 12 February 1921.
- "Motor Transport. The New Legislation". The Times. 6 April 1922.
- "Motor Taxation. Vehicles Using Fuel Oil (Letters)". The Times. 24 March 1933.
- "Tax On Heavy Oils". The Times. 9 March 1934.
- "The Hornsby Steam Crawler". (or 'Chain Tractor'). Retrieved 2008-09-16.
- Garrett Steam Tractors & Rollers, R A Whitehead, 1999
- William Fletcher (1891). "Charles Burrell and Sons: Road Locomotive". Extract from Steam Locomotion on Common Roads by William Fletcher. Published 1891.