Portable engine - AbsoluteAstronomy.com

A portable engine is a small steam engine

Steam engine

A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...

, mounted on wheels or skids, which is used for driving machinery using a belt

Belt (mechanical)

A belt is a loop of flexible material used to link two or more rotating shafts mechanically. Belts may be used as a source of motion, to transmit power efficiently, or to track relative movement. Belts are looped over pulleys. In a two pulley system, the belt can either drive the pulleys in the...

from its flywheel

Flywheel

A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia, and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed...

. It is not self-propelled and is towed to the work site by horse

Draft horse

A draft horse , draught horse or dray horse , less often called a work horse or heavy horse, is a large horse bred for hard, heavy tasks such as ploughing and farm labour...

s or bullocks

Cattle

Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...

, or even a traction engine

Traction engine

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...

. Portable engines were used mainly for driving agricultural machinery

Agricultural machinery

Agricultural machinery is machinery used in the operation of an agricultural area or farm.-Hand tools:The first person to turn from the hunting and gathering lifestyle to farming probably did so by using his bare hands, and perhaps some sticks or stones. Tools such as knives, scythes, and wooden...

, such as threshing machine

Threshing machine

The thrashing machine, or, in modern spelling, threshing machine , was a machine first invented by Scottish mechanical engineer Andrew Meikle for use in agriculture. It was invented for the separation of grain from stalks and husks. For thousands of years, grain was separated by hand with flails,...

s. In industrialised countries they are no longer used for commercial purposes, but preserved examples can often be seen at steam fairs driving circular saw

Circular saw

The circular saw is a machine using a toothed metal cutting disc or blade. The term is also loosely used for the blade itself. The blade is a tool for cutting wood or other materials and may be hand-held or table-mounted. It can also be used to make narrow slots...

s or other equipment for demonstration purposes.

History

In common with many other areas of steam technology, the initial design and development of portable engines took place in England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

, with many other countries initially importing British-built equipment rather than developing their own.

Early steam engine

Steam engine

s 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

Threshing machine

was in 1799 in north Yorkshire

Yorkshire

Yorkshire is a historic county of northern England and the largest in the United Kingdom. Because of its great size in comparison to other English counties, functions have been increasingly undertaken over time by its subdivisions, which have also been subject to periodic reform...

. The next recorded application was in 1812, when Richard Trevithick

Richard Trevithick

Richard Trevithick was a British inventor and mining engineer from Cornwall. His most significant success was the high pressure steam engine and he also built the first full-scale working railway steam locomotive...

designed the first 'semi-portable' stationary steam engine

Stationary steam engine

Stationary steam engines are fixed steam engines used for pumping or driving mills and factories, and for power generation. They are distinct from locomotive engines used on railways, traction engines for heavy steam haulage on roads, steam cars , agricultural engines used for ploughing or...

for agricultural use, known as a "barn engine". This was a high-pressure, rotative engine with a Cornish boiler

Fire-tube boiler

A fire-tube boiler is a type of boiler in which hot gases from a fire pass through one or more tubes running through a sealed container of water...

, for Sir Christopher Hawkins of Probus, Cornwall

Probus, Cornwall

Probus is a civil parish and village in Cornwall, England, in the United Kingdom. It is famous for having the tallest church tower in Cornwall. The tower is high, and richly decorated with carvings...

. 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

Science museum

A science museum or a science centre is a museum devoted primarily to science. Older science museums tended to concentrate on static displays of objects related to natural history, paleontology, geology, industry and industrial machinery, etc. Modern trends in museology have broadened the range of...

. 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

Boston, Lincolnshire

Boston is a town and small port in Lincolnshire, on the east coast of England. It is the largest town of the wider Borough of Boston local government district and had a total population of 55,750 at the 2001 census...

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

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

Royal Agricultural Society

The Royal Agricultural Society of England was established in the United Kingdom in 1838 with the motto "Practice with Science". The RASE aim is to promote the scientific development of agriculture. The society received its Royal Charter from Queen Victoria in 1840.From its early days the 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
Birmingham
Birmingham is a city and metropolitan borough in the West Midlands of England. It is the most populous British city outside the capital London, with a population of 1,036,900 , and lies at the heart of the West Midlands conurbation, the second most populous urban area in the United Kingdom with a...
Ransomes
Ransomes, Sims & Jefferies
Ransomes, Sims and Jeffries was a major British agricultural machinery maker producing a wide range of products including traction engines, ploughs, lawn mowers, combine harvesters and other tilling equipment. They also manufactured aeroplanes during the First World War...

of Ipswich
Ipswich
Ipswich is a large town and a non-metropolitan district. It is the county town of Suffolk, England. Ipswich is located on the estuary of the River Orwell...
William Tuxford and Sons of Boston, Lincolnshire
Howden of Boston, Lincolnshire
Clayton & Shuttleworth
Clayton & Shuttleworth
Clayton & Shuttleworth was an engineering company located at Stamp End Works, Lincoln, Lincolnshire. The company was established in 1842 when Nathaniel Clayton formed a partnership with his brother-in-law, Joseph Shuttleworth .-History:...

of Lincoln
Lincoln, Lincolnshire
Lincoln is a cathedral city and county town of Lincolnshire, England.The non-metropolitan district of Lincoln has a population of 85,595; the 2001 census gave the entire area of Lincoln a population of 120,779....

This last manufacturer is particularly noteworthy here. 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

Vienna

Vienna is the capital and largest city of the Republic of Austria and one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.723 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre...

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

John Fowler (agricultural engineer)

John Fowler was an English agricultural engineer who was a pioneer in the use of steam engines for ploughing and digging drainage channels...

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

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 gear

Gear

A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....

ing, was markedly cheaper, and secondly, numerous applications benefitted 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.

The requirement for a small cheap source of power on farms was largely taken over by the internal combustion stationary engine

Stationary engine

A stationary engine is an engine whose framework does not move. It is normally used not to propel a vehicle but to drive a piece of immobile equipment such as a pump or power tool. They may be powered by steam; or oil-burning or internal combustion engines....

Usage

Apart from threshing work, portable engines were used to drive corn-mills, centrifugal pump

Centrifugal pump

A centrifugal pump is a rotodynamic pump that uses a rotating impeller to create flow by the addition of energy to a fluid. Centrifugal pumps are commonly used to move liquids through piping...

s, stone-crushers, dynamo

Dynamo

- Engineering :* Dynamo, a magnetic device originally used as an electric generator* Dynamo theory, a theory relating to magnetic fields of celestial bodies* Solar dynamo, the physical process that generates the Sun's magnetic field- Software :...

s, chaff

Chaff

Chaff is the dry, scaly protective casings of the seeds of cereal grain, or similar fine, dry, scaly plant material such as scaly parts of flowers, or finely chopped straw...

-cutters and hay-balers. They were even used to generate electricity for floodlighting

Floodlights (sport)

Floodlights are broad-beamed, high-intensity artificial lights often used to illuminate outdoor playing fields while an outdoor sports event is being held during low-light conditions....

at football matches, the first instance being at Bramall Lane

Bramall Lane

-Cricket at the Lane:Bramall Lane opened as a cricket ground in 1855, having been leased by Michael Ellison from the Duke of Norfolk at an annual rent of £70. The site was then away from the town's industrial area, and relatively free from smoke. It was built to host the matches of local cricket...

, Sheffield

Sheffield

Sheffield is a city and metropolitan borough of South Yorkshire, England. Its name derives from the River Sheaf, which runs through the city. Historically a part of the West Riding of Yorkshire, and with some of its southern suburbs annexed from Derbyshire, the city has grown from its largely...

in 1878.

In general, the portable engine is hauled to the work area, often a farmyard or field, and a long drive belt is fitted between the engine's flywheel and the driving wheel of the equipment to be powered.

In a number of cases, rather than being towed from site-to-site, the portable engine was semi-permanently installed in a building as a stationary steam engine

Stationary steam engine

, although the wheels were not necessarilly removed.

A more extreme use occurs where the engine is removed from the boiler and is re-used as a stationary engine. Often, the boiler is also re-used (without its wheels) to provide the steam. As of 2007, there are still examples of such dismantled portable engines working commercially in small rice mills in Burma (and, no doubt, elsewhere too). Such examples are easy to identify due to the curved saddle, below the cylinder block, that was used to mount the engine to the boiler.

General layout

The most common arrangement follows the original Tuxford design. Although this closely resembles the common layout of a traction engine, the engine of a portable is usually reversed, with the cylinders

Cylinder (engine)

A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...

at the firebox end and the crankshaft

Crankshaft

The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...

at the smokebox

Smokebox

A smokebox is one of the major basic parts of a Steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the chimney .To assist...

end. This layout was designed to position the regulator close to the firebox, making it easier for the engineman to maintain the fire and control the engine speed from the one location. An added bonus is that the flywheel

Flywheel

is clear of the rear road wheels so the latter can be set on a narrower track, making the engine easier to manoeuvre through field gates.

A few makers (e.g. Fowler

John Fowler & Co.

thumb|right|John Fowler & Co. [[steam roller]] of 1923John Fowler & Co Engineers of Leathley Road, Hunslet, Leeds, West Yorkshire, England produced traction engines and ploughing implements and equipment, as well as railway equipment. Fowler also produced the Track Marshall tractor which was a...

) made their portable engines in the same style as traction engines, with the cylinder at the smokebox end. This was probably to reduce manufacturing costs, as there is no other obvious benefit of doing this. (Thomas Aveling realised that, for a traction engine, it would be better to position the flywheel within reach of the driver in case he carelessly allowed the crank to stop on top dead centre (where it could not self-start) and most other traction engine manufacturers followed this same idea.)

Boiler

This is usually a fire-tube boiler

Fire-tube boiler

A fire-tube boiler is a type of boiler in which hot gases from a fire pass through one or more tubes running through a sealed container of water...

with a locomotive

Steam locomotive

A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

-type firebox. However, some designs (e.g. the Marshall

Marshall, Sons & Co.

-External links:* – at the Powerhouse Museum, Sydney, Australia...

"Britannia" (pictured)) have circular, marine-type, fireboxes. This latter type were also known by British manufacturers as 'colonial' boilers, as they were mainly intended for export to 'the Colonies'

Crown colony

A Crown colony, also known in the 17th century as royal colony, was a type of colonial administration of the English and later British Empire....

, and had a high ground clearance for travelling along rough tracks.

Fuel is usually coal

Coal

Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

but the engine may be designed to use wood fuel

Wood fuel

Wood fuel is wood used as fuel. The burning of wood is currently the largest use of energy derived from a solid fuel biomass. Wood fuel can be used for cooking and heating, and occasionally for fueling steam engines and steam turbines that generate electricity. Wood fuel may be available as...

, straw or bagasse

Bagasse

Bagasse is the fibrous matter that remains after sugarcane or sorghum stalks are crushed to extract their juice. It is currently used as a biofuel and as a renewable resource in the manufacture of pulp and paper products and building materials....

(sugar cane residue) instead. A longer, circular firebox is particularly suitable for burning logs rather than shorter wood billets. Machines designed for wood-burning may be fitted with spark arrestors.

Engine

Most portable engines are single-cylinder but two-cylinder engines were also built. The slide valve

D slide valve

The slide valve is a rectilinear valve used to control the admission of steam into, and emission of exhaust from, the cylinder of a steam engine.-Use:...

is usually driven by a single eccentric

Eccentric (mechanism)

In mechanical engineering, an eccentric is a circular disk solidly fixed to a rotating axle with its centre offset from that of the axle ....

and no reversing gear

Valve gear

The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in the cycle...

is fitted. There is usually a belt-driven governor

Governor (device)

A governor, or speed limiter, is a device used to measure and regulate the speed of a machine, such as an engine. A classic example is the centrifugal governor, also known as the Watt or fly-ball governor, which uses a rotating assembly of weights mounted on arms to determine how fast the engine...

to keep the engine running at constant speed, even if the load fluctuates.

The engine may have one or two flywheels mounted on the same crankshaft. Where two are provided, they are mounted either side of the engine and may be of different diameters. A smaller flywheel provides a slower speed for farmyard work (e.g. chopping feedstuffs) than is required for driving a threshing machine

Threshing machine

(for example).

Auxiliaries

The crankshaft drives a boiler feedwater pump

Boiler feedwater pump

A boiler feedwater pump is a specific type of pump used to pump feedwater into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler...

which draws water from a barrel placed alongside the engine. Many engines have a simple, but effective, feedwater heater

Feedwater heater

A feedwater heater is a power plant component used to pre-heat water delivered to a steam generating boiler. Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency of the system...

which works by blowing a small portion of the exhaust steam into the water barrel. The barrel also acts as an oil separator. Oil in the exhaust steam rises to the top of the barrel and can be skimmed off.

Chimney

A tall chimney is provided to ensure a good draught for the fire. To permit negotiation of overhead obstacles, the chimney is hinged at its base, and is folded down for transport and storage. A suitably shaped bracket is usually provided towards the firebox end to support the chimney when folded.

Wheels

Most designs are fitted with four wheels and no suspension of any kind. The first portables had wooden wheels, but as the engines became more powerful (and heavier), fabricated steel wheels were fitted instead.

The 'front' wheels are normally smaller than those at the back. This is because they are mounted on the swivelling fore-carriage, under the smokebox, and large wheels would be liable to hit the boiler when the engine was turned around a corner. An added bonus is that a larger diameter flywheel may be fitted, providing a more steady power output.

Preservation

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

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

Great Dorset Steam Fair

The Great Dorset Steam Fair is an annual show featuring steam-powered vehicles and machinery. It now covers and runs for five days from the Wednesday after the UK August bank holiday...

, 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

Marshall, Sons & Co.

-External links:* – at the Powerhouse Museum, Sydney, Australia...

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

New South Wales

New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

. This engine is also the oldest documented portable in Australia.

External links

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.

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

History

Usage

General layout

Boiler

Engine

Auxiliaries

Chimney

Wheels

Preservation

See also

Further reading

External links