A portable engine is a small steam engine, mounted on wheels or skids, which is used for driving machinery using a belt from its flywheel. It is not self-propelled and is towed to the work site by horses or bullocks, or even a traction engine. Portable engines were used mainly for driving agricultural machinery, such as threshing machines. In industrialised countries they are no longer used for commercial purposes, but preserved examples can often be seen at steam fairs driving circular saws or other equipment for demonstration purposes.
In common with many other areas of steam technology, the initial design and development of portable engines mainly took place in England, with many other countries initially importing British-built equipment rather than developing their own.
Early steam engines were too large and expensive for use on the average farm; however, the first positive evidence of steam power being used to drive a threshing machine was in 1799 in North Yorkshire. The next recorded application was in 1812, when Richard Trevithick designed the first 'semi-portable' stationary steam engine for agricultural use, known as a "barn engine". This was a high-pressure, rotative engine with a Cornish boiler, for Sir Christopher Hawkins of Probus, Cornwall. It was used to drive a corn threshing machine and was much cheaper to run than the horses it replaced. Indeed, it was so successful that it remained in use for nearly 70 years, and has been preserved by the Science Museum. Although termed 'semi-portable', as they could be transported and installed without being dismantled, these engines were essentially stationary. They were used to drive such barn machinery as pumps and hammer mills, bone-crushers, chaff and turnip cutters, and fixed and mobile threshing drums.
It was not until about 1839 that the truly portable engine appeared, allowing the application of steam power beyond the confines of the farmyard. William Tuxford of Boston, Lincolnshire started manufacture of an engine built around a locomotive-style boiler with horizontal smoke tubes. A single cylinder and the crankshaft were mounted on top of the boiler, and the whole assembly was mounted on four wheels: the front pair being steerable and fitted with shafts for horse-haulage between jobs. A large flywheel was mounted on the crankshaft, and a stout leather belt was used to transfer the drive to the equipment being driven.
Several Tuxford engines were displayed at the Royal Agricultural Society's Show at Bristol in 1842, and other manufacturers soon joined in, using the basic design of the Tuxford engine as a pattern for the majority of portable engines produced thereafter.
Early manufacturers in the UK included:
- Alexander Dean of Birmingham
- Clayton & Shuttleworth of Lincoln
- Ransomes, Sims & Jefferies of Ipswich
- William Tuxford and Sons of Boston, Lincolnshire
- Howden of Boston, Lincolnshire
- Marshall, Sons & Co. of Gainsborough, Lincolnshire
The first Clayton & Shuttleworth portable was built in 1845, a two-cylinder engine. In 1852, the company won a gold medal for a portable engine at the Royal Agricultural Society's Gloucester show, and thereafter the business expanded rapidly: they established a second works, in Vienna in 1857, to target the European market, and by 1890 the company had manufactured over 26,000 portable engines, many being exported all over the world.
In the 1850s, John Fowler used a Clayton & Shuttleworth portable engine to drive apparatus in the first public demonstrations of the application of cable haulage to cultivation.
In parallel with the early portable engine development, many engineers attempted to make them self-propelled – the fore-runners of the traction engine. In most cases this was achieved by fitting an additional pinion on the end of the crankshaft, and running a chain from this to another pinion on the rear axle. These experiments met with mixed success.
As noted early on by Thomas Aveling (later of Aveling & Porter fame), it was absurd to use four horses to pull a steam engine from job-to-job, when the engine possessed ten times the strength of the horses. It was therefore inevitable, once self-propelled traction engines had become sufficiently reliable, that they would take over the roles of many portable engines, and this indeed started to happen from the late 1860s.
However, the portable engine was never completely replaced by the traction engine. Firstly, the portable, having no gearing, was markedly cheaper, and secondly, numerous applications benefited from a simple steam engine that could be moved, but did not require the additional complexity of one that could move itself.
Small numbers of portables continued to be built even after traction engine production ceased. Robey and Company of Lincoln were still offering portables for sale into the 1960s.
Many portable engines still survive, as they were built in large quantities and were shipped to many remote corners of the Earth. A substantial number of them have been preserved, with many restored to full working order: their relatively small size and simpler construction, compared to a traction engine, makes them a much more viable proposition for restoration by the average enthusiast. (That is, provided the boiler is in reasonable condition: boiler repairs can be very expensive; replacement boilers even more so.)
It is usually possible to see portable engines working at traction engine rallies and steam festivals. At the Great Dorset Steam Fair, for example, portable engines may be found in the relevant demonstration areas driving saw benches, threshing machines, rock crushers and other contemporary equipment.
Numerous agricultural and industrial museums include portable engines within their collections.
What is thought to be the oldest surviving Marshall product, works no. 415, a 2.5 nhp portable from 1866, may be seen at the Turon Technology Museum (Museum of Power), in New South Wales, Australia. This engine is also the oldest documented portable in Australia.
Several firms are re-importing machines into the UK from places like South America, were large No. were exported to and the dry climate has resulted in old abandoned engines being preserved in good condition without the Rust (Rot) that occurs in the UKs damp climate.
- Agricultural Machinery
- List of Steam Machinery Manufacturers – many traction engine manufacturers also built portable engines
- Extract from wikipedia article
- Old Glory Magazine -For Steam and machinery preservation enthusiasts
- ↑ name=MERL
- "Portable Steam Engines" (Shire Album 163) by Lyndon R. Shearman, published by Shire Publications Ltd, ISBN 0 85263 783 7
- "The Portable Steam Engine: Its Construction and Management – A Practical Manual for Owners and Users of Steam Engines Generally" by W. D. Wansbrough, 168 pages, published by TEE Publishing Ltd (1994), ISBN 1857610679 - (This is a modern reprint of a book originally published in 1887 or 1911, depending on which online bookseller you refer to!.)
- Steam Scenes – extensive searchable photo library – preserved portable engines in the UK, Europe, Australia and New Zealand
- List (and details) of surviving Paxman portable engines
- Scale model built from Meccano, with close-up pictures showing the components of a typical portable engine.
- Restoration of a derelict 1904 Ruston Proctor portable (in Australia) – Employed some unusual solutions, including design of a new pressure vessel to fit inside the original, unrepairable, boiler shell.
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