steam locomotive

TheInfoList

A steam locomotive is a
rail vehicle A railroad car, railcar (American English, American and Canadian English), railway wagon, railway carriage, railway truck, railwagon, railcarriage or railtruck (British English and International Union of Railways, UIC), also called a train car, ...
that provides the
force In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space and time, and the related entities of energy and force ...
to move itself and other vehicles by means of the expansion of
steam Steam is water Water (chemical formula H2O) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organism ...

. It is fuelled by burning combustible material (usually
coal Coal is a black or brownish-black , formed as called . Coal is mostly with variable amounts of other , chiefly , , , and . Coal is formed when dead decays into and is converted into coal by the heat and pressure of deep burial over mill ...

,
oil An oil is any nonpolar chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can b ...
or – now rare –
wood Wood is a porous and fibrous structural tissue found in the stems and roots of tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. ...
) to heat water in the locomotive's
boiler Poland Poland ( pl, Polska ), officially the Republic of Poland ( pl, Rzeczpospolita Polska, links=no ), is a country located in Central Europe. It is divided into 16 Voivodeships of Poland, administrative provinces, covering an area of , ...
to the point when it becomes gaseous and its volume increases 1,700 times. Functionally, it is a
steam engine from Stott Park Bobbin Mill, Cumbria, England A steam engine is a heat engine In thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energ ...

on wheels. In most locomotives, the steam is admitted alternately to each end of its
cylinders A cylinder (from Greek language, Greek κύλινδρος – ''kulindros'', "roller", "tumbler") has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. It is the idealized version of a solid physi ...
, in which
piston A piston is a component of reciprocating engine , internal combustion piston engine. A reciprocating engine, also often known as a piston engine, is typically a heat engine (although there are also pneumatic Pneumatics (from Greek ‘wind, ...

s are mechanically connected to the locomotive's main wheels. Fuel and water supplies are usually carried with the locomotive, either on the locomotive itself or in a tender coupled to it.
Variations Variation or Variations may refer to: Science and mathematics * Variation (astronomy), any perturbation of the mean motion or orbit of a planet or satellite, particularly of the moon * Genetic variation, the difference in DNA among individuals ...

in this general design include electrically-powered boilers, turbines in place of pistons, and using steam generated externally. Steam locomotives were first developed in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use Britain as a synonym for the United Kingdom. Some prefer to use Britain as shorth ...

during the early 19th century and used for railway transport until the middle of the 20th century.
Richard Trevithick Richard Trevithick (13 April 1771 – 22 April 1833) was a British inventor and mining engineer from Cornwall Cornwall (; kw, Kernow ) is a Ceremonial counties of England, ceremonial county in South West England. It is recognised as one ...

built the first steam locomotive known to have hauled a load over a distance at
Pen-y-darren : ''For Trevithick's Pen-y-darren locomotive, see Richard Trevithick Richard Trevithick (13 April 1771 – 22 April 1833) was a British inventor and mining engineer from Cornwall Cornwall (; kw, Kernow ) is a Ceremonial counties of Engla ...

in 1804, although he produced an earlier locomotive for trial at
Coalbrookdale Coalbrookdale is a village in the Ironbridge Gorge in Shropshire Shropshire (; alternatively Salop; abbreviated, in print only, Shrops; demonym Salopian ,) is a landlocked county A county is a geographical region of a country used f ...
in 1802. ''
Salamanca Salamanca ( , ) is a city situated in western Spain and is the capital of the Province of Salamanca in the Autonomous communities of Spain, autonomous community of Castile and León. The city lies on several rolling hills by the Tormes River. Its ...
'', built in 1812 by
Matthew Murray Matthew Murray (1765 – 20 February 1826) was an English steam engine from Stott Park Bobbin Mill, Cumbria, England A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses ...

for the
Middleton Railway The Middleton Railway is the world's oldest continuously working railway, situated in the English city of Leeds Leeds is the largest city in the Ceremonial counties of England, county of West Yorkshire, England and the most populous in ...

, was the first commercially successful steam locomotive. ''Locomotion'' No. 1, built by
George Stephenson George Stephenson (9 June 1781 – 12 August 1848) was an English civil engineer A civil engineer is a person who practices civil engineering Civil engineering is a Regulation and licensure in engineering, professional engineering disci ...

and his son company
Robert Stephenson and Company Robert Stephenson and Company was a locomotive manufacturing company founded in 1823 in Forth Street, Newcastle upon Tyne in England. It was the first company in the world created specifically to build Steam locomotive, railway engines. Famous ...
, was the first steam locomotive to haul passengers on a public railway, the
Stockton and Darlington Railway The Stockton and Darlington Railway (S&DR) was a railway company that operated in north-east England from 1825 to 1863. The world's first public railway to use steam locomotives, its first line connected coal mining, collieries near Shildon ...
, in 1825. Rapid development ensued; in 1830 George Stephenson opened the first public inter-city railway, the
Liverpool and Manchester Railway The Liverpool and Manchester Railway (L&MR) was the first inter-city railway in the world. It opened on 15 September 1830 between the Lancashire Lancashire ( ; abbreviated Lancs.) is a ceremonial county and geographical area in North W ...
, after the success of
Rocket A rocket (from it, rocchetto, , bobbin/spool) is a spacecraft File:Space Shuttle Columbia launching.jpg, 275px, The US Space Shuttle flew 135 times from 1981 to 2011, supporting Spacelab, ''Mir'', the Hubble Space Telescope, and the ISS. (' ...

at the 1829
Rainhill Trials The Rainhill Trials was an important competition run in October 1829, to test George Stephenson's argument that locomotive File:R707-loco-victorian-railways.jpg, upright=1.2, An Victorian Railways R class, R class steam locomotive number R70 ...
had proved that steam locomotives could perform such duties. Robert Stephenson and Company was the pre-eminent builder of steam locomotives in the first decades of steam for railways in the United Kingdom, the United States, and much of Europe. Towards the end of the steam era, a longstanding British emphasis on speed culminated in a record, still unbroken, of by . In the United States, larger loading gauges allowed the development of very large, heavy locomotives such as the
Union Pacific Big Boy The Union Pacific Big Boy is a type of simple articulated locomotive, articulated 4-8-8-4 steam locomotive manufactured by the American Locomotive Company (ALCO) between 1941 and 1944 and operated by the Union Pacific Railroad in revenue service u ...
, which weighed and had a tractive effort of .Comparable figures for the last-built British Railways freight locomotive, the Class 9F, were and . From the early 1900s, steam locomotives were gradually superseded by
electric Electricity is the set of physics, physical Phenomenon, phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnet ...

and
diesel locomotive -operated locos show three styles of diesel locomotive body: box cab (rear), hood unit running long hood forward. Image:BNSF GP60B 346.jpg, 200px, BNSF Railway, BNSF EMD GP60B, GP60B #346, a cabless hood unit A hood unit, in North American rai ...
s, with railways fully converting to electric and diesel power beginning in the late 1930s. The majority of steam locomotives were retired from regular service by the 1980s, although several continue to run on tourist and heritage lines.

# History

## Britain

The earliest railways employed horses to draw carts along
rail tracks A railway track (British English and International Union of Railways, UIC terminology) or railroad track (American English), also known as permanent way or simply track, is the structure on a Rail transport, railway or railroad consisting of ...

. In 1784,
William Murdoch William Murdoch (sometimes spelled Murdock) (21 August 1754 – 15 November 1839) was a Scottish engineer and inventor. Murdoch was employed by the firm of Boulton & Watt and worked for them in Cornwall Cornwall (; kw, Kernow ) is a ...

, a
Scottish Scottish usually refers to something of, from, or related to Scotland, including: *Scottish Gaelic, a Celtic Goidelic language of the Indo-European language family native to Scotland *Scottish English *Scottish national identity, the Scottish iden ...

inventor, built a small-scale prototype of a steam road locomotive in
Birmingham Birmingham ( ) is a City status in the United Kingdom, city and metropolitan borough in the West Midlands (county), West Midlands, England. It is the second-largest city, urban area and ESPON metropolitan areas in the United Kingdom, metropol ...

. A full-scale rail steam locomotive was proposed by William Reynolds around 1787. An early working model of a steam rail locomotive was designed and constructed by steamboat pioneer in the US during 1794. His steam locomotive used interior bladed wheels guided by rails or tracks. The model still exists at the
Ohio Historical Society Ohio History Connection, formerly The Ohio State Archaeological and Historical Society and Ohio Historical Society, is a nonprofit organization incorporated in 1885. Headquartered at the Ohio History Center in Columbus, Ohio, Ohio History Connecti ...
Museum in Columbus. The authenticity and date of this locomotive is disputed by some experts and a workable steam train would have to await the invention of the high-pressure steam engine by
Richard Trevithick Richard Trevithick (13 April 1771 – 22 April 1833) was a British inventor and mining engineer from Cornwall Cornwall (; kw, Kernow ) is a Ceremonial counties of England, ceremonial county in South West England. It is recognised as one ...

, who pioneered the use of steam locomotives. The first full-scale working railway steam locomotive, was the gauge ''Coalbrookdale Locomotive'', built by Trevithick in 1802. It was constructed for the
Coalbrookdale Coalbrookdale is a village in the Ironbridge Gorge in Shropshire Shropshire (; alternatively Salop; abbreviated, in print only, Shrops; demonym Salopian ,) is a landlocked county A county is a geographical region of a country used f ...
ironworks in
Shropshire Shropshire (; alternatively Salop; abbreviated in print only as Shrops; demonym Salopian ) is a landlocked historic county A county is a geographical region of a country used for administrative or other purposesChambers Dictionary Th ...

in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use Britain as a synonym for the United Kingdom. Some prefer to use Britain as shorth ...

though no record of it working there has survived. On 21 February 1804, the first recorded steam-hauled railway journey took place as another of Trevithick's locomotives hauled a train along the from the
Pen-y-darren : ''For Trevithick's Pen-y-darren locomotive, see Richard Trevithick Richard Trevithick (13 April 1771 – 22 April 1833) was a British inventor and mining engineer from Cornwall Cornwall (; kw, Kernow ) is a Ceremonial counties of Engla ...

ironworks, near
Merthyr Tydfil Merthyr Tydfil (; cy, Merthyr Tudful ) is the main town in Merthyr Tydfil County Borough Merthyr Tydfil County Borough (; cy, Merthyr Tudful ) has been one of the 22 Local government in Wales, unitary authorities in Wales since 1 April 1996 ...
, to
Abercynon Abercynon (), is both a village and a community (Wales), community (and electoral ward) in the Cynon Valley within the unitary authority of Rhondda Cynon Taf, Wales. The community comprises the village and the districts of Carnetown and Grovers Fie ...

in South Wales. Accompanied by
Andrew Vivian Andrew Vivian (1759–1842) was an Cornish mechanical engineer, inventor, and mine captain of the Dolcoath mine in Cornwall Cornwall (; kw, Kernow ) is a Ceremonial counties of England, ceremonial county in South West England. It is reco ...
, it ran with mixed success. The design incorporated a number of important innovations that included using high-pressure steam which reduced the weight of the engine and increased its efficiency. Trevithick visited the
NewcastleNewcastle usually refers to either: *Newcastle upon Tyne Newcastle upon Tyne (, ), often simply Newcastle, is the most populous City status in the United Kingdom, city and metropolitan borough in North East England. It forms the Tyneside conurbati ...

area in 1804 and had a ready audience of colliery (coal mine) owners and engineers. The visit was so successful that the colliery railways in north-east England became the leading centre for experimentation and development of the steam locomotive. Trevithick continued his own steam propulsion experiments through another trio of locomotives, concluding with the ''
Catch Me Who Can ''Catch Me Who Can'' was the fourth and last steam railway locomotive created by the inventor and mining engineer Richard Trevithick. It was an evolution of three earlier locomotives which had been built for Coalbrookdale Coalbrookdale is ...

'' in 1808. In 1812,
Matthew Murray Matthew Murray (1765 – 20 February 1826) was an English steam engine from Stott Park Bobbin Mill, Cumbria, England A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses ...

's successful twin-cylinder locomotive ''
Salamanca Salamanca ( , ) is a city situated in western Spain and is the capital of the Province of Salamanca in the Autonomous communities of Spain, autonomous community of Castile and León. The city lies on several rolling hills by the Tormes River. It ...
'' first ran on the edge-railed
Middleton Railway The Middleton Railway is the world's oldest continuously working railway, situated in the English city of Leeds Leeds is the largest city in the Ceremonial counties of England, county of West Yorkshire, England and the most populous in ...

. Another well-known early locomotive was '' Puffing Billy'', built 1813–14 by engineer
William Hedley William Hedley (13 July 1779 – 9 January 1843) was born in Newburn Newburn is a semi rural parish A parish is a territorial entity in many Christianity, Christian denominations, constituting a division within a diocese. A parish is u ...

. It was intended to work on the Wylam Colliery near Newcastle upon Tyne. This locomotive is the oldest preserved, and is on static display at the
Science Museum, London The Science Museum is a major museum on Exhibition Road Exhibition Road is a street in South Kensington South Kensington is a district just west of Central London Central London (also known less commonly as London city centre) is the ...
.

### George Stephenson

George Stephenson George Stephenson (9 June 1781 – 12 August 1848) was an English civil engineer A civil engineer is a person who practices civil engineering Civil engineering is a Regulation and licensure in engineering, professional engineering disci ...

, a former miner working as an engine-wright at Killingworth Colliery, developed up to sixteen
Killingworth locomotives George Stephenson built a number of experimental steam locomotives to work in the Killingworth Colliery between 1814 and 1826. Background George Stephenson was appointed as engine-wright at Killingworth Colliery in 1812 and immediately impro ...
, including '' Blücher'' in 1814, another in 1815, and a (newly identified) ''Killingworth Billy'' in 1816. He also constructed ''The Duke'' in 1817 for the
Kilmarnock and Troon Railway The Kilmarnock and Troon Railway was an early railway line in Ayrshire, Scotland. It was constructed to bring coal from pits around Kilmarnock to coastal shipping at Troon, Troon Harbour, and passengers were carried. It opened in 1812, and was ...

, which was the first steam locomotive to work in Scotland. In 1825, Stephenson built Locomotion No. 1 for the
Stockton and Darlington Railway The Stockton and Darlington Railway (S&DR) was a railway company that operated in north-east England from 1825 to 1863. The world's first public railway to use steam locomotives, its first line connected coal mining, collieries near Shildon ...
, north-east England, which was the first public steam railway in the world. In 1829, his son
Robert The name Robert is an ancient Germanic given nameGermanic given names are traditionally dithematic; that is, they are formed from two elements, by joining a prefix A prefix is an affix which is placed before the stem of a word. Adding it ...

built in Newcastle '' The Rocket'', which was entered in and won the
Rainhill Trials The Rainhill Trials was an important competition run in October 1829, to test George Stephenson's argument that locomotive File:R707-loco-victorian-railways.jpg, upright=1.2, An Victorian Railways R class, R class steam locomotive number R70 ...
. This success led to the company emerging as the pre-eminent builder of steam locomotives used on railways in the UK, US and much of Europe. The
Liverpool and Manchester Railway The Liverpool and Manchester Railway (L&MR) was the first inter-city railway in the world. It opened on 15 September 1830 between the Lancashire Lancashire ( ; abbreviated Lancs.) is a ceremonial county and geographical area in North W ...
opened a year later making exclusive use of steam power for passenger and
goods trains hauled container freight train on the West Coast Main Line The West Coast Main Line (WCML) is one of the most important railway corridors in the United Kingdom, connecting the major cities of London and Glasgow with branches to Birmingham, Liv ...

.

## United States

Prior to the arrival of British imports, some domestic steam locomotive prototypes were built and tested in the United States. An early miniature prototype was built by , who demonstrated his miniature engine to
George Washington George Washington (February 22, 1732, 1799) was an American soldier, statesman, and Founding Fathers of the United States, Founding Father who served as the first President of the United States from 1789 to 1797. Appointed by the Continenta ...

during the 1780s. A prominent large example was Col. John Steven's "steam wagon" which was demonstrated on a loop of track in
Hoboken, New Jersey Hoboken ( ; Unami: ') is a city A city is a large human settlement.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The Social Science Encyclopedia''. 2nd edition. London: ...

in 1825. Many of the earliest locomotives for commercial use on American railroads were imported from Great Britain, including first the ''
Stourbridge Lion The ''Stourbridge Lion'' was a railroad Rail transport (also known as train transport) is a means of transferring passengers and goods on wheeled vehicles running on rails, which are located on tracks. In contrast to road transport, wher ...

'' and later the ''
John Bull recruiting poster in an 1803 caricature by James Gillray. Image:Germany GB France.gif, A 1904 British cartoon commenting on the Entente Cordiale: John Bull walking off with Marianne, turning his back on the Wilhelm II, German Emperor, Kaiser ...
''. However, a domestic locomotive-manufacturing industry was soon established. In 1830, the
Baltimore and Ohio Railroad The Baltimore and Ohio Railroad was the first common carrier A common carrier in common law countries (corresponding to a public carrier in some civil law (legal system), civil law systems,Encyclopædia Britannica CD 2000 "Civil-law public ca ...
's ''
Tom Thumb Tom Thumb ( cy, Bawd Tom) is a character of English folklore English folklore consists of the myths and legends of England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It shares land borders ...
'', designed by
Peter Cooper Peter Cooper (February 12, 1791April 4, 1883) was an American industrialist A business magnate is someone who has achieved great success and enormous wealth through the ownership of multiple lines of enterprise. The term characteristically refe ...

, was the first commercial US-built locomotive to run in America; it was intended as a demonstration of the potential of steam traction rather than as a revenue-earning locomotive. The ''
DeWitt Clinton DeWitt Clinton (March 2, 1769February 11, 1828), whose name was almost always spelled De Witt during his lifetime and until the late 20th century, was an American politician and naturalist Natural history is a domain of inquiry involving org ...

'', built in 1831 for the
Mohawk and Hudson RailroadMohawk may refer to: Related to Native Americans * Mohawk people, an indigenous people of North America (Canada and New York) *Mohawk language Mohawk (; ''Kanienʼkéha'', " anguageof the Flint Place") is an Iroquoian language currently spoken ...
, was a notable early locomotive. , the original ''John Bull'' was on static display in the
National Museum of American History The National Museum of American History: Kenneth E. Behring Center collects, preserves, and displays the heritage of the United States The United States of America (USA), commonly known as the United States (U.S. or US), or America, is a ...

in
Washington, D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument The Washington Monument is an obelisk within the National Mall The National Mall is a Landscape architecture, landscaped ...
The replica is preserved at the
Railroad Museum of Pennsylvania The Railroad Museum of Pennsylvania is a railroad museum in Strasburg, Lancaster County, Pennsylvania. The museum is located on the east side of Strasburg along Pennsylvania Route 741. It is administered by the Pennsylvania Historical and Mus ...
.

## Continental Europe

The first railway service outside the United Kingdom and North America was opened in 1829 in
France France (), officially the French Republic (french: link=no, République française), is a spanning and in the and the , and s. Its extends from the to the and from the to the and the ; overseas territories include in , in the N ...

between and
Lyon Lyon or Lyons (, , ; frp, Liyon, ) is the third-largest city and second-largest urban area of France. It is located at the confluence of the rivers Rhône The Rhône ( , ; german: Rhone ; wae, Rotten ; it, Rodano ; frp, Rôno ; oc, ...

; it was initially limited to animal traction. The first steam locomotive in service in Europe was named ''The Elephant'', which on 5 May 1835 hauled a train on the first line in Belgium, linking
Mechelen Mechelen (; french: Malines ; traditional English name: MechlinMechelen has been known in English as ''Mechlin'', from where the adjective ''Mechlinian'' is derived. This name may still be used, especially in a traditional or historical contex ...
and Brussels. In Germany, the first working steam locomotive was a rack-and-pinion engine, similar to the ''Salamanca'', designed by the British locomotive pioneer
John Blenkinsop John Blenkinsop (1783 – 22 January 1831) was an English mining engineer and an inventor of steam locomotive climbing the ''Schiefe Ebene'' with DRG Class 01.10, 01 1066 as bank engine, pusher locomotive (video 34.4 MB) A steam ...
. Built in June 1816 by Johann Friedrich Krigar in the Royal Berlin Iron Foundry (''Königliche Eisengießerei'' zu Berlin), the locomotive ran on a circular track in the factory yard. It was the first locomotive to be built on the European mainland and the first steam-powered passenger service; curious onlookers could ride in the attached coaches for a fee. It is portrayed on a New Year's badge for the Royal Foundry dated 1816. Another locomotive was built using the same system in 1817. They were to be used on pit railways in Königshütte (Oberschlesien), Königshütte and in Luisenthal on the Saar (today part of Völklingen), but neither could be returned to working order after being dismantled, moved and reassembled. On 7 December 1835, the ''Adler (locomotive), Adler'' ran for the first time between Nuremberg and Fürth on the Bavarian Ludwig Railway. It was the 118th engine from the locomotive works of Robert Stephenson and stood under patent protection. In Russia, the first steam locomotive was built in 1834 by Yefim and Miron Cherepanov, Cherepanovs. The first Russian Tsarskoye Selo Railway, Tsarskoye Selo steam railway started in 1837. In 1837, the first steam railway started in Austria on the Austrian Northern Railway, Emperor Ferdinand Northern Railway between Floridsdorf, Vienna-Floridsdorf and Deutsch-Wagram. The oldest continually working steam engine in the world also runs in Austria: the Südbahn Class 23 (old), GKB 671 built in 1860, has never been taken out of service, and is still used for special excursions. In 1838, the third steam locomotive to be built in Germany, the ''Saxonia (locomotive), Saxonia'', was manufactured by the ''Maschinenbaufirma Übigau'' near Dresden, built by Prof. Johann Andreas Schubert. The first independently designed locomotive in Germany was the ''Beuth (locomotive), Beuth'', built by August Borsig in 1841. The first locomotive produced by Henschel-Werke in Kassel, the ''Drache'', was delivered in 1848. The first steam locomotives operating in Italy were the ''Bayard'' and the ''Vesuvio'', running on the Napoli-Portici line, in the Kingdom of the Two Sicilies. The first railway line over Swiss territory was the Strasbourg–Basle line opened in 1844. Three years later, in 1847, the first fully Swiss railway line, the Swiss Northern Railway, ''Spanisch Brötli Bahn'', from Zürich to Baden was opened.

# Components

## Boiler

The fire-tube boiler was standard practice for steam locomotive. Although other types of boiler were evaluated they were not widely used, except for some 1,000 locomotives in Hungary which used the water-tube Brotan boiler. A boiler consists of a firebox where the fuel is burned, a barrel where water is turned into steam and a smokebox which is kept at a slightly lower pressure than outside the firebox. Solid fuel, such as wood, coal or coke, is thrown into the firebox through a door by a fireman (steam engine), fireman, onto a set of Glossary of steam locomotive components, grates which hold the fuel in a bed as it burns. Ash falls through the grate into an ashpan. If oil is used as the fuel, a door is needed for adjusting the air flow, maintaining the firebox, and cleaning the oil jets. The fire-tube boiler has internal tubes connecting the firebox to the smokebox through which the combustion gases flow transferring heat to the water. All the tubes together provide a large contact area, called the tube heating surface, between the gas and water in the boiler. Boiler water surrounds the firebox to stop the metal from becoming too hot. This is another area where the gas transfers heat to the water and is called the firebox heating surface. Ash and char collect in the smokebox as the gas gets drawn up the chimney (''stack'' or ''smokestack'' in the US) by the exhaust steam from the cylinders. The pressure in the boiler has to be monitored using a gauge mounted in the cab. Steam pressure can be released manually by the driver or fireman. If the pressure reaches the boiler's design working limit, a safety valve opens automatically to reduce the pressure and avoid a catastrophic accident. The exhaust steam from the engine cylinders shoots out of a nozzle pointing up the chimney in the smokebox. The steam entrains or drags the smokebox gases with it which maintains a lower pressure in the smokebox than that under the firebox grate. This pressure difference causes air to flow up through the coal bed and keeps the fire burning. The search for thermal efficiency greater than that of a typical fire-tube boiler led engineers, such as Nigel Gresley, to consider the water-tube boiler. Although he tested the concept on the LNER Class W1, the difficulties during development exceeded the will to increase efficiency by that route. The steam generated in the boiler not only moves the locomotive, but is also used to operate other devices such as the whistle, the air compressor for the brakes, the pump for replenishing the water in the boiler and the passenger car heating system. The constant demand for steam requires a periodic replacement of water in the boiler. The water is kept in a tank in the locomotive tender or wrapped around the boiler in the case of a tank locomotive. Periodic stops are required to refill the tanks; an alternative was a scoop installed under the tender that collected water as the train passed over a track pan located between the rails. While the locomotive is producing steam, the amount of water in the boiler is constantly monitored by looking at the water level in a transparent tube, or sight glass. Efficient and safe operation of the boiler requires keeping the level in between lines marked on the sight glass. If the water level is too high, steam production falls, efficiency is lost and water is carried out with the steam into the cylinders, possibly causing mechanical damage. More seriously, if the water level gets too low, the crown(top)sheet of the firebox becomes exposed. Without water on top of the sheet to transfer away the heat of combustion, it softens and fails, letting high-pressure steam into the firebox and the cab. The development of the fusible plug, a temperature-sensitive device, ensured a controlled venting of steam into the firebox to warn the fireman to add water. Scale builds up in the boiler and prevents adequate heat transfer, and corrosion eventually degrades the boiler materials to the point where it needs to be rebuilt or replaced. Start-up on a large engine may take hours of preliminary heating of the boiler water before sufficient steam is available. Although the boiler is typically placed horizontally, for locomotives designed to work in locations with steep slopes it may be more appropriate to consider a vertical boiler or one mounted such that the boiler remains horizontal but the wheels are inclined to suit the slope of the rails.

## Steam circuit

The steam generated in the boiler fills the space above the water in the partially filled boiler. Its maximum working pressure is limited by spring-loaded safety valves. It is then collected either in a perforated tube fitted above the water level or by a dome that often houses the regulator valve, or throttle, the purpose of which is to control the amount of steam leaving the boiler. The steam then either travels directly along and down a steam pipe to the engine unit or may first pass into the wet header of a superheater, the role of the latter being to improve thermal efficiency and eliminate water droplets suspended in the "saturated steam", the state in which it leaves the boiler. On leaving the superheater, the steam exits the dry header of the superheater and passes down a steam pipe, entering the steam chests adjacent to the cylinders of a reciprocating engine. Inside each steam chest is a sliding valve that distributes the steam via ports that connect the steam chest to the ends of the cylinder space. The role of the valves is twofold: admission of each fresh dose of steam, and exhaust of the used steam once it has done its work. The cylinders are double-acting, with steam admitted to each side of the piston in turn. In a two-cylinder locomotive, one cylinder is located on each side of the vehicle. The cranks are set 90° out of phase. During a full rotation of the driving wheel, steam provides four power strokes; each cylinder receives two injections of steam per revolution. The first stroke is to the front of the piston and the second stroke to the rear of the piston; hence two working strokes. Consequently, two deliveries of steam onto each piston face in the two cylinders generates a full revolution of the driving wheel. Each piston is attached to the driving axle on each side by a connecting rod, and the driving wheels are connected together by coupling rods to transmit power from the main driver to the other wheels. Note that at the two "dead centres", when the connecting rod is on the same axis as the crankpin on the driving wheel, the connecting rod applies no torque to the wheel. Therefore, if both cranksets could be at "dead centre" at the same time, and the wheels should happen to stop in this position, the locomotive could not start moving. Therefore, the crankpins are attached to the wheels at a 90° angle to each other, so only one side can be at dead centre at a time. Each
piston A piston is a component of reciprocating engine , internal combustion piston engine. A reciprocating engine, also often known as a piston engine, is typically a heat engine (although there are also pneumatic Pneumatics (from Greek ‘wind, ...

## Chassis

The chassis, or locomotive frame, is the principal structure onto which the boiler is mounted and which incorporates the various elements of the running gear. The boiler is rigidly mounted on a "saddle" beneath the smokebox and in front of the boiler barrel, but the firebox at the rear is allowed to slide forward and backwards, to allow for expansion when hot. European locomotives usually use "plate frames", where two vertical flat plates form the main chassis, with a variety of spacers and a buffer beam at each end to form a rigid structure. When inside cylinders are mounted between the frames, the plate frames are a single large casting that forms a major support element. The axleboxes slide up and down to give some sprung suspension, against thickened webs attached to the frame, called "hornblocks". American practice for many years was to use built-up bar frames, with the smokebox saddle/cylinder structure and drag beam integrated therein. In the 1920s, with the introduction of "superpower", the cast-steel locomotive bed became the norm, incorporating frames, spring hangers, motion brackets, smokebox saddle and cylinder blocks into a single complex, sturdy but heavy casting. A SNCF design study using welded tubular frames gave a rigid frame with a 30% weight reduction.

## Crew

A steam locomotive is normally controlled from the boiler's backhead, and the crew is usually protected from the elements by a cab. A crew of at least two people is normally required to operate a steam locomotive. One, the Railroad engineer, train driver or engineer (North America), is responsible for controlling the locomotive's starting, stopping, and speed, and the fireman is responsible for maintaining the fire, regulating steam pressure and monitoring boiler and tender water levels. Due to the historical loss of operational infrastructure and staffing, preserved steam locomotives operating on the mainline will often have a support crew (UK steam locomotive), support crew travelling with the train.

# Fittings and appliances

All locomotives are fitted with a variety of appliances. Some of these relate directly to the operation of the steam engine; others are for signalling, train control or other purposes. In the United States, the Federal Railroad Administration mandated the use of certain appliances over the years in response to safety concerns. The most typical appliances are as follows:

## Steam pumps and injectors

Water (feedwater) must be delivered to the boiler to replace that which is exhausted as steam after delivering a working stroke to the pistons. As the boiler is under pressure during operation, feedwater must be forced into the boiler at a pressure that is greater than the steam pressure, necessitating the use of some sort of pump. Hand-operated pumps sufficed for the very earliest locomotives. Later engines used pumps driven by the motion of the pistons (axle pumps), which were simple to operate, reliable and could handle large quantities of water but only operated when the locomotive was moving and could overload the valve gear and piston rods at high speeds. Steam injectors later replaced the pump, while some engines transitioned to turbopumps. Standard practice evolved to use two independent systems for feeding water to the boiler; either two steam injectors or, on more conservative designs, axle pumps when running at service speed and a steam injector for filling the boiler when stationary or at low speeds. By the 20th century virtually all new-built locomotives used only steam injectors – often one injector was supplied with "live" steam straight from the boiler itself and the other used exhaust steam from the locomotive's cylinders, which was more efficient (since it made use of otherwise wasted steam) but could only be used when the locomotive was in motion and the regulator was open. Injectors became unreliable if the feedwater was at a high temperature, so locomotives with feedwater heaters, tank locomotives with the tanks in contact with the boiler and condensing locomotives sometimes used reciprocating steam pumps or turbopumps. Vertical glass tubes, known as Sight glass, water gauges or water glasses, show the level of water in the boiler and are carefully monitored at all times while the boiler is being fired. Before the 1870s it was more common to have a series of try-cocks fitted to the boiler within reach of the crew; each try cock (at least two and usually three were fitted) was mounted at a different level. By opening each try-cock and seeing if steam or water vented through it, the level of water in the boiler could be estimated with limited accuracy. As boiler pressures increased the use of try-cocks became increasingly dangerous and the valves were prone to blockage with scale or sediment, giving false readings. This led to their replacement with the sight glass. As with the injectors, two glasses with separate fittings were usually installed to provide independent readings.

## Boiler insulation

The term for pipe and boiler insulation is "lagging" which derives from the Cooper (profession), cooper's term for a wooden Stave (wood), barrel stave. Two of the earliest steam locomotives used wooden lagging to insulate their boilers: the
Salamanca Salamanca ( , ) is a city situated in western Spain and is the capital of the Province of Salamanca in the Autonomous communities of Spain, autonomous community of Castile and León. The city lies on several rolling hills by the Tormes River. Its ...
, the first commercially successful steam locomotive, built in 1812, and the Locomotion No. 1, the first steam locomotive to carry passengers on a public rail line. Large amounts of heat are wasted if a boiler is not insulated. Early locomotives used lags, shaped wooden staves, fitted lengthways along the boiler barrel, and held in place by hoops, metal bands, the terms and methods are from Cooper (profession), cooperage. Improved insulating methods included applying a thick paste containing a porous mineral such as kieselgur, or attaching shaped blocks of insulating compound such as Magnesium oxide, magnesia blocks. In the latter days of steam, "mattresses" of stitched asbestos cloth stuffed with asbestos fibre were fixed to the boiler, on separators so as not quite to touch the boiler. However, asbestos is currently banned in most countries for health reasons. The most common modern-day material is glass wool, or wrappings of aluminium foil. The lagging is protected by a close-fitted sheet-metal casing known as boiler clothing or cleading. Effective lagging is particularly important for fireless locomotives; however, in recent times under the influence of L.D. Porta, "exaggerated" insulation has been practised for all types of locomotive on all surfaces liable to dissipate heat, such as cylinder ends and facings between the cylinders and the mainframes. This considerably reduces engine warmup time with a marked increase in overall efficiency.

## Safety valves

Early locomotives were fitted with a valve controlled by a weight suspended from the end of a lever, with the steam outlet being stopped by a cone-shaped valve. As there was nothing to prevent the weighted lever from bouncing when the locomotive ran over irregularities in the track, thus wasting steam, the weight was later replaced by a more stable spring-loaded column, often supplied by Salter, a well-known spring scale manufacturer. The danger of these devices was that the driving crew could be tempted to add weight to the arm to increase pressure. Most early boilers were fitted with a tamper-proof "lockup" direct-loaded ball valve protected by a cowl. In the late 1850s, John Ramsbottom (engineer), John Ramsbottom introduced a safety valve that became popular in Britain during the latter part of the 19th century. Not only was this valve tamper-proof, but tampering by the driver could only have the effect of easing pressure. George Richardson's safety valve was an American invention introduced in 1875, and was designed to release the steam only at the moment when the pressure attained the maximum permitted. This type of valve is in almost universal use at present. Britain's Great Western Railway was a notable exception to this rule, retaining the direct-loaded type until the end of its separate existence, because it was considered that such a valve lost less pressure between opening and closing.

## Pressure gauge

The earliest locomotives did not show the pressure of steam in the boiler, but it was possible to estimate this by the position of the safety valve arm which often extended onto the firebox back plate; gradations marked on the spring column gave a rough indication of the actual pressure. The promoters of the Rainhill trials urged that each contender have a proper mechanism for reading the boiler pressure, and Stephenson devised a nine-foot vertical tube of mercury with a sight-glass at the top, mounted alongside the chimney, for his ''Rocket''. The Bourdon tube gauge, in which the pressure straightens an oval-section coiled tube of brass or bronze connected to a pointer, was introduced in 1849 and quickly gained acceptance, and is still used today. Some locomotives have an additional pressure gauge in the steam chest. This helps the driver avoid wheel-slip at startup, by warning if the regulator opening is too great.

## Spark arrestors and smokeboxes

;Spark arrestor and self-cleaning smokebox Wood-burners emit large quantities of flying sparks which necessitate an efficient spark-arresting device generally housed in the smokestack. Many different types were fitted, the most common early type being the Bonnet stack that incorporated a cone-shaped deflector placed before the mouth of the chimney pipe, and a wire screen covering the wide stack exit. A more-efficient design was the Radley and Hunter centrifugal stack patented in 1850 (commonly known as the diamond stack), incorporating baffles so oriented as to induce a swirl effect in the chamber that encouraged the embers to burn out and fall to the bottom as ash. In the self-cleaning smokebox the opposite effect was achieved: by allowing the flue gasses to strike a series of deflector plates, angled in such a way that the blast was not impaired, the larger particles were broken into small pieces that would be ejected with the blast, rather than settle in the bottom of the smokebox to be removed by hand at the end of the run. As with the arrestor, a screen was incorporated to retain any large embers. Locomotives of the BR standard classes, British Railways standard classes fitted with self-cleaning smokeboxes were identified by a small cast oval plate marked "S.C.", fitted at the bottom of the smokebox door. These engines required different disposal procedures and the plate highlighted this need to depot staff.

## Stokers

A factor that limits locomotive performance is the rate at which fuel is fed into the fire. In the early 20th century some locomotives became so large that the fireman could not shovel coal fast enough. In the United States, various steam-powered mechanical stokers became standard equipment and were adopted and used elsewhere including Australia and South Africa.

## Feedwater heating

Introducing cold water into a boiler reduces power, and from the 1920s a variety of Feedwater heater, heaters were incorporated. The most common type for locomotives was the exhaust steam feedwater heater that piped some of the exhaust through small tanks mounted on top of the boiler or smokebox or into the tender tank; the warm water then had to be delivered to the boiler by a small auxiliary steam pump. The rare economiser type differed in that it extracted residual heat from the exhaust gases. An example of this is the pre-heater drum(s) found on the Franco-Crosti boiler. The use of live steam and exhaust steam injectors also assists in the pre-heating of boiler feedwater to a small degree, though there is no efficiency advantage to live steam injectors. Such pre-heating also reduces the thermal shock that a boiler might experience when cold water is introduced directly. This is further helped by the top feed, where water is introduced to the highest part of the boiler and made to trickle over a series of trays. George Jackson Churchward fitted this arrangement to the high end of his domeless coned boilers. Other British lines such as the London, Brighton & South Coast Railway fitted some locomotives with the top feed inside a separate dome forward of the main one.

## Condensers and water re-supply

Steam locomotives consume vast quantities of water because they operate on an open cycle, expelling their steam immediately after a single use rather than recycling it in a closed loop as stationary and marine steam engines do. Water was a constant logistical problem, and condensing engines were devised for use in desert areas. These engines had huge radiators in their tenders and instead of exhausting steam out of the funnel it was captured, passed back to the tender and condensed. The cylinder lubricating oil was removed from the exhausted steam to avoid a phenomenon known as priming, a condition caused by foaming in the boiler which would allow water to be carried into the cylinders causing damage because of its incompressibility. The most notable engines employing condensers (Class 25, the "puffers which never puff") worked across the Karoo desert of South Africa from the 1950s until the 1980s. Some British and American locomotives were equipped with scoops which collected water from "water troughs" (track pan, ''track pans'' in the US) while in motion, thus avoiding stops for water. In the US, small communities often did not have refilling facilities. During the early days of railroading, the crew simply stopped next to a stream and filled the tender using leather buckets. This was known as "jerking water" and led to the term "jerkwater towns" (meaning a small town, a term which today is considered derisive). In Australia and South Africa, locomotives in drier regions operated with large oversized tenders and some even had an additional water wagon, sometimes called a "canteen" or in Australia (particularly in New South Wales) a "water gin". Steam locomotives working on underground railways (such as London's Metropolitan Railway) were fitted with condensing apparatus to prevent steam from escaping into the railway tunnels. These were still being used between London King's Cross railway station, King's Cross and Moorgate station, Moorgate into the early 1960s.

## Braking

Locomotives have their own braking system, independent from the rest of the train. Locomotive brakes employ large shoes which press against the driving wheel treads. With the advent of compressed air brake (rail), air brakes, a separate system allowed the driver to control the brakes on all cars. A single-stage, steam-driven, air compressor was mounted on the side of the boiler. Long freight trains needed more air and a two-stage compressor with LP and HP cylinders, driven by cross-compound HP and LP steam cylinders, was introduced. It had three and a half times the capacity of the single stage. Most were made by Westinghouse Air Brake Company, Westinghouse. Two were fitted in front of the smokebox on big articulated locomotives. Westinghouse systems were used in the United States, Canada, Australia and New Zealand. An alternative to the air brake is the vacuum brake, in which a steam-operated steam ejector, ejector is mounted on the engine instead of the air pump, to create a vacuum and release the brakes. A secondary ejector or crosshead vacuum pump is used to maintain the vacuum in the system against the small leaks in the pipe connections between carriages and wagons. Vacuum systems existed on British, Indian, West Australian and South African railway networks. Steam locomotives are fitted with sandbox (railways), sandboxes from which sand can be deposited on top of the rail to improve traction (engineering), traction and braking in wet or icy weather. On American locomotives, the sandboxes, or sand domes, are usually mounted on top of the boiler. In Britain, the limited loading gauge precludes this, so the sandboxes are mounted just above, or just below, the running plate.

## Lubrication

The pistons and valves on the earliest locomotives were lubrication, lubricated by the enginemen dropping a lump of tallow down the blast pipe. More sophisticated methods of delivering the substance were soon developed. Tallow adheres well to cylinder walls and is more effective than mineral oil in resisting the action of water. It remains a constituent of modern steam cylinder oil formulation. As speeds and distances increased, mechanisms were developed that injected thick mineral oil into the steam supply. The first, a automatic lubricator, displacement lubricator, mounted in the cab, uses a controlled stream of steam condensing into a sealed container of oil. Water from the condensed steam displaces the oil into pipes. The apparatus is usually fitted with sight-glasses to confirm the rate of supply. A later method uses a mechanical pump worked from one of the crossheads. In both cases, the supply of oil is proportional to the speed of the locomotive. Lubricating the frame components (axle bearings, Rail terminology#H, horn blocks and bogie pivots) depends on capillary action: trimmings of worsted yarn are trailed from oil reservoirs into pipes leading to the respective component. The rate of oil supplied is controlled by the size of the bundle of yarn and not the speed of the locomotive, so it is necessary to remove the trimmings (which are mounted on wire) when stationary. However, at regular stops (such as a terminating station platform), oil finding its way onto the track can still be a problem. Crankpin and crosshead bearings carry small cup-shaped reservoirs for oil. These have feed pipes to the bearing surface that start above the normal fill level, or are kept closed by a loose-fitting pin, so that only when the locomotive is in motion does oil enter. In United Kingdom practice, the cups are closed with simple corks, but these have a piece of porous cane pushed through them to admit air. It is customary for a small capsule of pungent oil (aniseed or garlic) to be incorporated in the bearing metal to warn if the lubrication fails and excess heating or wear occurs.

## Blower

When the locomotive is running under power, a draught on the fire is created by the exhaust steam directed up the chimney by the blastpipe. Without draught, the fire will quickly die down and steam pressure will fall. When the locomotive is stopped, or coasting with the regulator closed, there is no exhaust steam to create a draught, so the draught is maintained by means of a blower. This is a ring placed either around the base of the chimney, or around the blast pipe orifice, containing several small steam nozzles directed up the chimney. These nozzles are fed with steam directly from the boiler, controlled by the blower valve. When the regulator is open, the blower valve is closed; when the driver intends to close the regulator, he will first open the blower valve. It is important that the blower be opened before the regulator is closed, since without draught on the fire, there may be Backdraft, backdraught – where atmospheric air blows down the chimney, causing the flow of hot gases through the boiler tubes to be reversed, with the fire itself being blown through the firehole onto the footplate, with serious consequences for the crew. The risk of backdraught is higher when the locomotive enters a tunnel because of the pressure shock. The blower is also used to create draught when steam is being raised at the start of the locomotive's duty, at any time when the driver needs to increase the draught on the fire, and to clear smoke from the driver's line of vision. Blowbacks were fairly common. In a 1955 report on an accident near Dunstable, the Inspector wrote, "In 1953 twenty-three cases, which were not caused by an engine defect, were reported and they resulted in 26 enginemen receiving injuries. In 1954, the number of occurrences and of injuries were the same and there was also one fatal casualty." They remain a problem, as evidenced by the 2012 incident with BR Standard Class 7 70013 Oliver Cromwell#Preservation, BR Standard Class 7 70013 ''Oliver Cromwell''.

## Buffers

In British and European (except former Soviet Union countries) practice, locomotives usually have buffer (rail transport), buffers at each end to absorb compressive loads ("buffets"''Oxford English Dictionary'': Buff 1). The tensional load of drawing the train (draft force) is carried by the Railway coupling, coupling system. Together these control slack between the locomotive and train, absorb minor impacts and provide a bearing point for pushing movements. In Canadian and American practice, all of the forces between the locomotive and cars are handled through the coupler – particularly the Janney coupler, long standard on American railroad rolling stock – and its associated draft gear, which allows some limited slack movement. Small dimples called "poling pockets" at the front and rear corners of the locomotive allowed cars to be pushed onto an adjacent track using a pole braced between the locomotive and the cars. In Britain and Europe, North American style "buckeye" and other couplers that handle forces between items of rolling stock have become increasingly popular.

## Pilots

A pilot (locomotive), pilot was usually fixed to the front end of locomotives, although in European and a few other railway systems including rail transport in New South Wales, New South Wales, they were considered unnecessary. Plough-shaped, sometimes called "cow catchers", they were quite large and were designed to remove obstacles from the track such as cattle, bison, other animals or tree limbs. Though unable to "catch" stray cattle, these distinctive items remained on locomotives until the end of steam. Switching engines usually replaced the pilot with small steps, known as ''footboards''. Many systems used the pilot and other design features to produce a distinctive appearance.

When night operations began, railway companies in some countries equipped their locomotives with lights to allow the driver to see what lay ahead of the train, or to enable others to see the locomotive. Headlights were originally oil or acetylene lamps, but when electric arc lamps became available in the late 1880s, they quickly replaced the older types. Britain did not adopt bright headlights as they would affect night vision and so could mask the low-intensity oil lamps used in the Railway semaphore signal, semaphore signals and at each end of trains, increasing the danger of missing signals, especially on busy tracks. Locomotive stopping distances were also normally much greater than the range of headlights, and the railways were well-signalled and fully fenced to prevent livestock and people from straying onto them, largely negating the need for bright lamps. Thus low-intensity oil lamps continued to be used, positioned on the front of locomotives to indicate the class of each train. Four "lamp irons" (brackets on which to place the lamps) were provided: one below the chimney and three evenly spaced across the top of the buffer beam. The exception to this was the Southern Railway (England), Southern Railway and its constituents, who added an extra lamp iron each side of the smokebox, and the arrangement of lamps (or in daylight, white circular plates) told railway staff the origin and destination of the train. On all vehicles, equivalent lamp irons were also provided on the rear of the locomotive or tender for when the locomotive was running tender- or bunker-first. In some countries, heritage steam operation continues on the national network. Some railway authorities have mandated powerful headlights on at all times, including during daylight. This was to further inform the public or track workers of any active trains.

## Bells and whistles

Locomotives used bells and steam whistles from earliest days of steam locomotion. In the United States, India and Canada, bells warned of a train in motion. In Britain, where all lines are by law fenced throughout, bells were only a requirement on railways running on a road (i.e. not fenced off), for example a tramway along the side of the road or in a dockyard. Consequently, only a minority of locomotives in the UK carried bells. Whistles are used to signal personnel and give warnings. Depending on the terrain the locomotive was being used in, the whistle could be designed for long-distance warning of impending arrival, or for more localised use. Early bells and whistles were sounded through pull-string cords and levers. Automatic bell ringers came into widespread use in the US after 1910.

## Automatic control

From the early 20th century operating companies in such countries as Germany and Britain began to fit locomotives with Automatic Warning System (AWS) in-cab signalling, which automatically applied the brakes when a signal was passed at "caution". In Britain, these became mandatory in 1956. In the United States, the Pennsylvania Railroad also fitted their locomotives with such devices.

## Booster engines

The booster engine was an auxiliary steam engine which provided extra tractive effort for starting. It was a low-speed device, usually mounted on the trailing truck. It was dis-engaged via an idler gear at a low speed, e.g. 30 km/hr. Boosters were widely used in the US and tried experimentally in Britain and France. On the narrow-gauged New Zealand railway system, six NZR KB class, Kb 4-8-4 locomotives were fitted with boosters, the only gauge engines in the world to have such equipment. Booster engines were also fitted to tender trucks in the US and known as auxiliary locomotives. Two and even three truck axles were connected together using side rods which limited them to slow-speed service.

## Firedoor

The firedoor is used to cover the firehole when coal is not being added. It serves two purposes, first, it prevents air being drawn over the top of the fire, rather forcing it to be drawn through it. The second purpose is to safeguard the train crew against blowbacks. It does, however, have a means to allow some air to pass over the top of the fire (referred to as "secondary air") to complete the combustion of gases produced by the fire. Firedoors come in multiple designs, the most basic of which is a single piece which is hinged on one side and can swing open onto the footplate. This design has two issues. First, it takes up much room on the footplate, and second, the draught will tend to pull it completely shut, thus cutting off any secondary air. To compensate for this some locomotives are fitted with a latch that prevents the firedoor from closing completely whereas others have a small vent on the door that may be opened to allow secondary air to flow through. Though it was considered to design a firedoor that opens inwards into the firebox thus preventing the inconvenience caused on the footplate, such a door would be exposed to the full heat of the fire and would likely deform, thus becoming useless. A more popular type of firedoor consists of a two-piece sliding door operated by a single lever. There are tracks above and below the firedoor which the door runs along. These tracks are prone to becoming jammed by debris and the doors required more effort to open than the aforementioned swinging door. In order to address this some firedoors use powered operation which utilized a steam or air cylinder to open the door. Among these are the butterfly doors which pivot at the upper corner, the pivoting action offers low resistance to the cylinder that opens the door.

# Variations

Numerous variations on the basic locomotive occurred as railways attempted to improve efficiency and performance.

## Cylinders

Early steam locomotives had two cylinders, one either side, and this practice persisted as the simplest arrangement. The cylinders could be mounted between the mainframes (known as "inside" cylinders), or mounted outside the frames and driving wheels ("outside" cylinders). Inside cylinders are driven by cranks built into the driving axle; outside cylinders are driven by cranks on extensions to the driving axles. Later designs employed three or four cylinders, mounted both inside and outside the frames, for a more even power cycle and greater power output. This was at the expense of more complicated valve gear and increased maintenance requirements. In some cases the third cylinder was added inside simply to allow for smaller diameter outside cylinders, and hence reduce the width of the locomotive for use on lines with a restricted loading gauge, for example the SR K1 class, SR K1 and SR U1 class, U1 classes. Most British express-passenger locomotives built between 1930 and 1950 were or types with three or four cylinders (e.g. GWR 6000 Class, LMS Coronation Class, SR Merchant Navy Class, LNER Gresley Classes A1 and A3, LNER Gresley Class A3). From 1951, all BR Standard Class 8, but one of the 999 new British Rail standard class steam locomotives across all types used 2-cylinder configurations for easier maintenance.

## Valve gear

Early locomotives used a simple valve gear that gave full power in either forward or reverse. Soon the Stephenson valve gear allowed the driver to control cut-off; this was largely superseded by Walschaerts valve gear and similar patterns. Early locomotive designs using slide valves and outside admission were relatively easy to construct, but inefficient and prone to wear. Eventually, slide valves were superseded by inside admission piston valve (steam engine), piston valves, though there were attempts to apply poppet valves (commonly used in stationary engines) in the 20th century. Stephenson valve gear was generally placed within the frame and was difficult to access for maintenance; later patterns applied outside the frame were more readily visible and maintained.

## Compounding

Compound locomotives were used from 1876, expanding the steam twice or more through separate cylinders – reducing thermal losses caused by cylinder cooling. Compound locomotives were especially useful in trains where long periods of continuous efforts were needed. Compounding contributed to the dramatic increase in power achieved by André Chapelon's rebuilds from 1929. A common application was in articulated locomotives, the most common being that designed by Anatole Mallet, in which the high-pressure stage was attached directly to the boiler frame; in front of this was pivoted a low-pressure engine on its own frame, which takes the exhaust from the rear engine.

## Articulated locomotives

Very powerful locomotives tend to be longer than those with lower power output, but long rigid-framed designs are impracticable for the tight curves frequently found on narrow-gauge railways. Various designs for articulated locomotives were developed to overcome this problem. The Mallet locomotive, Mallet and the Garratt were the two most popular. They had a single boiler and two engine units (sets of cylinders and driving wheels): both of the Garratt's engine units were on swivelling frames, whereas one of the Mallet's was on a swivelling frame and the other was fixed under the boiler unit. A few triplex (locomotive), triplex locomotives were also designed, with a third engine unit under the tender. Other less common variations included the Fairlie locomotive, which had two boilers back-to-back on a common frame, with two separate engine units.

## Duplex types

Duplex locomotives, containing two engines in one rigid frame, were also tried, but were not notably successful. For example, the Pennsylvania Railroad class T1, designed for very fast running, suffered recurring and ultimately unfixable slippage problems throughout their careers.

## Geared locomotives

For locomotives where a high starting torque and low speed were required, the conventional direct drive approach was inadequate. "Geared" steam locomotives, such as the Shay locomotive, Shay, the Climax locomotive, Climax and the Heisler locomotive, Heisler, were developed to meet this need on industrial, logging, mine and quarry railways. The common feature of these three types was the provision of reduction gearing and a drive shaft between the crankshaft and the driving axles. This arrangement allowed the engine to run at a much higher speed than the driving wheels compared to the conventional design, where the ratio is 1:1.

## Cab forward

In the United States on the Southern Pacific Railroad, a series of cab forward locomotives were produced with the cab and the firebox at the front of the locomotive and the tender behind the smokebox, so that the engine appeared to run backwards. This was only possible by using oil-firing. Southern Pacific selected this design to provide air free of smoke for the engine driver to breathe as the locomotive passed through mountain tunnels and snow sheds. Another variation was the Camelback locomotive, with the cab situated halfway along the boiler. In England, Oliver Bulleid developed the SR Leader class locomotive during the nationalisation process in the late 1940s. The locomotive was heavily tested but several design faults (such as coal firing and sleeve valves) meant that this locomotive and the other part-built locomotives were scrapped. The cab-forward design was taken by Bulleid to Ireland, where he moved after nationalisation, where he developed the "turfburner". This locomotive was more successful, but was scrapped due to the dieselisation of the Irish railways. The only preserved cab forward locomotive is Southern Pacific 4294 in Sacramento, California. In France, the three Heilmann locomotives were built with a cab forward design.

## Steam turbines

Steam turbines were created as an attempt to improve the operation and efficiency of steam locomotives. Experiments with steam turbine locomotive, steam turbines using direct-drive and electrical transmissions in various countries proved mostly unsuccessful. The London, Midland & Scottish Railway built the LMS Turbomotive, Turbomotive, a largely successful attempt to prove the efficiency of steam turbines. Had it not been for the outbreak of World War II, more may have been built. The Turbomotive ran from 1935 to 1949, when it was rebuilt into a conventional locomotive because many parts required replacement, an uneconomical proposition for a "one-off" locomotive. In the United States, Union Pacific, Chesapeake & Ohio Railway, Chesapeake & Ohio and Norfolk & Western (N&W) railways all built turbine-electric locomotives. The Pennsylvania Railroad (PRR) also built turbine locomotives, but with a direct-drive gearbox. However, all designs failed due to dust, vibration, design flaws or inefficiency at lower speeds. The final one remaining in service was the N&W's, retired in January 1958. The only truly successful design was the TGOJ MT3, used for hauling iron ore from Grängesberg in Sweden to the ports of Oxelösund. Despite functioning correctly, only three were built. Two of them are preserved in working order in museums in Sweden.

## Fireless locomotive

In a fireless locomotive the boiler is replaced by a steam accumulator, which is charged with steam (actually water at a temperature well above boiling point, () from a stationary boiler. Fireless locomotives were used where there was a high fire risk (e.g. oil refineries), where cleanliness was important (e.g. food-production plants) or where steam is readily available (e.g. paper mills and power stations where steam is either a by-product or is cheaply available). The water vessel ("boiler") is heavily insulated, the same as with a fired locomotive. Until all the water has boiled away, the steam pressure does not drop except as the temperature drops. Another class of fireless locomotive is a compressed-air locomotive.

## Mixed power

### Steam diesel hybrid locomotive

Mixed power locomotives, utilising both steam and diesel propulsion, have been produced in Russia, Britain and Italy.

### Electric-steam locomotive

Under unusual conditions (lack of coal, abundant hydroelectricity) some locomotives in Switzerland were modified to use electricity to heat the boiler, making them electric-steam locomotives.

### Steam-electric locomotive

A steam-electric locomotive uses electric transmission (mechanical), electric transmission, like diesel-electric locomotives, except that a steam engine instead of a diesel engine is used to drive a generator. Three such locomotives were built by the French engineer in the 1890s.

# Categorisation

Steam locomotives are categorised by their wheel arrangement. The two dominant systems for this are the Whyte notation and UIC classification. The Whyte notation, used in most English-speaking and Commonwealth countries, represents each set of wheels with a number. These numbers typically represented the number of unpowered leading wheels, followed by the number of driving wheels (sometimes in several groups), followed by the number of un-powered trailing wheels. For example, a yard engine with only 4 driven wheels would be categorised as a wheel arrangement. A locomotive with a 4-wheel leading truck, followed by 6 drive wheels, and a 2-wheel trailing truck, would be classed as a . Different arrangements were given names which usually reflect the first usage of the arrangement; for instance, the "Santa Fe" type () is so called because the first examples were built for the Atchison, Topeka and Santa Fe Railway. These names were informally given and varied according to region and even politics. The UIC classification is used mostly in European countries apart from the United Kingdom. It designates consecutive pairs of wheels (informally "axles") with a number for non-driving wheels and a capital letter for driving wheels (A=1, B=2, etc.) So a Whyte designation would be an equivalent to a 2-C-1 UIC designation. On many railroads, locomotives were organised into class (locomotive), classes. These broadly represented locomotives which could be substituted for each other in service, but most commonly a class represented a single design. As a rule classes were assigned some sort of code, generally based on the wheel arrangement. Classes also commonly acquired nicknames, such as ''Pug (steam locomotive), Pug'' (a small shunting locomotive), representing notable (and sometimes uncomplimentary) features of the locomotives.

# Performance

## Measurement

In the steam locomotive era, two measures of locomotive performance were generally applied. At first, locomotives were rated by tractive effort, defined as the average force developed during one revolution of the driving wheels at the railhead. This can be roughly calculated by multiplying the total piston area by 85% of the boiler pressure (a rule of thumb reflecting the slightly lower pressure in the steam chest above the cylinder), and dividing by the ratio of the driver diameter over the piston stroke. However, the precise formula is: :$t = \frac$. where is the bore of the cylinder (diameter) in inches, is the cylinder stroke, in inches, is boiler pressure in pounds per square inch, is the diameter of the driving wheel in inches, and is a factor that depends on the effective cut-off. In the US, is usually set at 0.85, but lower on engines that have maximum cutoff limited to 50–75%. The tractive effort is only the "average" force, as not all effort is constant during the one revolution of the drivers. At some points of the cycle, only one piston is exerting turning moment and at other points, both pistons are working. Not all boilers deliver full power at starting, and the tractive effort also decreases as the rotating speed increases. Tractive effort is a measure of the heaviest load a locomotive can start or haul at very low speed over the ruling grade in a given territory. However, as the pressure grew to run faster goods and heavier passenger trains, tractive effort was seen to be an inadequate measure of performance because it did not take into account speed. Therefore, in the 20th century, locomotives began to be rated by power output. A variety of calculations and formulas were applied, but in general railways used dynamometer cars to measure tractive force at speed in actual road testing. British railway companies have been reluctant to disclose figures for drawbar horsepower and have usually relied on continuous tractive effort instead.

# Manufacture

## Most manufactured classes

The most-manufactured single class of steam locomotive in the world is the Russian locomotive class E steam locomotive with around 11,000 produced both in Russia and other countries such as Czechoslovakia, Germany, Sweden, Hungary and Poland. The Russian locomotive class O numbered 9,129 locomotives, built between 1890 and 1928. Around 7,000 units were produced of the German DRB Class 52 Kriegslok. In Britain, 863 of the GWR 5700 Class were built, and 943 of the LNWR DX Goods class, DX class of the London and North Western Railway - including 86 engines built for the Lancashire and Yorkshire Railway.

## United Kingdom

Before the Railway Act 1921, 1923 Grouping Act, production in the UK was mixed. The larger railway companies built locomotives in their own workshops, with the smaller ones and industrial concerns ordering them from outside builders. A large market for outside builders existed due to the home-build policy exercised by the main railway companies. An example of a pre-grouping works was the one at Melton Constable, which maintained and built some of the locomotives for the Midland and Great Northern Joint Railway. Other works included one at Boston (an early GNR building) and Horwich Works. Between 1923 and 1947, the Big Four railway companies (the Great Western Railway, the London, Midland & Scottish Railway, the London & North Eastern Railway and the Southern Railway) all built most of their own locomotives, only buying locomotives from outside builders when their own works were fully occupied (or as a result of government-mandated standardisation during wartime). From 1948, British Railways (BR) allowed the former Big Four companies (now designated as "Regions") to continue to produce their own designs, but also created a range of Steam locomotives of British Railways#BR standard classes, standard locomotives which supposedly combined the best features from each region. Although a policy of dieselisation was adopted in 1955, BR continued to build new steam locomotives until 1960, with the final engine being named ''BR Standard Class 9F 92220 Evening Star, Evening Star''.British Railways' Last Steam Locomotive ''Railway Gazette International, Railway Gazette'' 23 March 1960 page 355 Some independent manufacturers produced steam locomotives for a few more years, with the last British-built industrial steam locomotive being constructed by Hunslet Engine Company, Hunslet in 1971. Since then, a few specialised manufacturers have continued to produce small locomotives for narrow gauge and miniature railways, but as the prime market for these is the tourist and heritage railway sector, the demand for such locomotives is limited. In November 2008, a new build main line steam locomotive, LNER Peppercorn Class A1 60163 Tornado, 60163 ''Tornado'', was tested on UK mainlines for eventual charter and tour use.

## Sweden

In the 19th and early 20th centuries, most Swedish steam locomotives were manufactured in Britain. Later, however, most steam locomotives were built by local factories including NOHAB in Trollhättan and ASJ in Falun. One of the most successful types was the class "B" (), inspired by the Prussian class P8. Many of the Swedish steam locomotives were preserved during the Cold War in case of war. During the 1990s, these steam locomotives were sold to non-profit associations or abroad, which is why the Swedish class B, class S () and class E2 () locomotives can now be seen in Britain, the Netherlands, Germany and Canada.

## Australia

In Sydney, Clyde Engineering and the Eveleigh Railway Workshops both built steam locomotives for the New South Wales Government Railways. These include the New South Wales 38 class locomotive, C38 class ; the first five were built at Clyde with streamliner, streamlining, the other 25 locomotives were built at Eveleigh (13) and Cardiff Locomotive Workshops, Cardiff Workshops (12) near Newcastle. In Queensland, steam locomotives were locally constructed by Walkers Limited, Walkers. Similarly, the South Australian Railways also manufactured steam locomotives locally at Islington Railway Workshops in Adelaide. Victorian Railways constructed most of their locomotives at its Newport Workshops and in Bendigo, while in the early days locomotives were built at the Phoenix Foundry in Ballarat. Locomotives constructed at the Newport shops ranged from the nA class built for the Narrow gauge lines of the Victorian Railways, narrow gauge, up to the H class – the largest conventional locomotive ever to operate in Australia, weighing 260 tons. However, the title of largest locomotive ever used in Australia goes to the 263-ton New South Wales AD60 class locomotive Garratt, built by Beyer, Peacock & Company in England. Most steam locomotives used in Western Australia were built in the United Kingdom, though some examples were designed and built locally at the Western Australian Government Railways' Midland Railway Workshops. The 10 WAGR S class locomotives (introduced in 1943) were the only class of steam locomotive to be wholly conceived, designed and built in Western Australia, while the Midland workshops notably participated in the Australia-wide construction program of Australian Standard Garratts – these wartime locomotives were built at Midland in Western Australia, Clyde Engineering in New South Wales, Newport in Victoria and Islington in South Australia and saw varying degrees of service in all Australian states.

# The end of steam in general use

The introduction of electric locomotives around the turn of the 20th century and later diesel-electric locomotives spelled the beginning of a decline in the use of steam locomotives, although it was some time before they were phased out of general use. As diesel power (especially with electric transmission) became more reliable in the 1930s, it gained a foothold in North America. The full transition away from steam power in North America took place during the 1950s. In continental Europe, large-scale electrification had replaced steam power by the 1970s. Steam was a familiar technology, adapted well to local facilities, and also consumed a wide variety of fuels; this led to its continued use in many countries until the end of the 20th century. Steam engines have considerably less thermal efficiency than modern diesels, requiring constant maintenance and labour to keep them operational. Water is required at many points throughout a rail network, making it a major problem in desert areas, as are found in some regions of the United States, Australia and South Africa. In places where water is available, it may be Hard water, hard, which can cause "Fouling, scale" to form, composed mainly of calcium carbonate, magnesium hydroxide and calcium sulfate. Calcium and magnesium carbonates tend to be deposited as off-white solids on the inside the surfaces of pipes and heat exchangers. This precipitation is principally caused by thermal decomposition of bicarbonate ions but also happens in cases where the carbonate ion is at saturation concentration. The resulting build-up of scale restricts the flow of water in pipes. In boilers, the deposits impair the flow of heat into the water, reducing the heating efficiency and allowing the metal boiler components to overheat. The reciprocating mechanism on the driving wheels of a two-cylinder single expansion steam locomotive tended to pound the rails (see hammer blow), thus requiring more maintenance of way, maintenance. Raising steam from coal took a matter of hours, and created serious pollution problems. Coal-burning locomotives required fire cleaning and ash removal between turns of duty. Diesel or electric locomotives, by comparison, drew benefit from new custom-built servicing facilities. The smoke from steam locomotives was also deemed objectionable; the first electric and diesel locomotives were developed in response to smoke abatement requirements, although this did not take into account the high level of less-visible pollution in diesel exhaust smoke, especially when idling. In some countries, however, power for electric locomotives is derived from steam generated in power stations, which are often run by coal.

## Britain

Trials of diesel locomotives and railcars began in Britain in the 1930s but made only limited progress. One problem was that British diesel locomotives were often seriously under-powered compared with the steam locomotives against which they were competing. Moreover, labour and coal were relatively cheap. After 1945, problems associated with post-war reconstruction and the availability of cheap domestic-produced coal kept steam in widespread use throughout the two following decades. However the ready availability of cheap oil led to new dieselisation programmes from 1955, and these began to take full effect from around 1962. By then it was apparent that steam locomotives had reached their limit in terms of power within the restrictive British loading gauge, with no scope for larger boilers or cylinders even if mechanical firing were to be employed. Towards the end of the steam era, steam motive power fell into a state of disrepair. The last steam locomotive built for mainline British Railways was BR Standard Class 9F 92220 Evening Star, 92220 ''Evening Star'', which was completed in March 1960. The last steam-hauled service trains on the British Railways network ran in 1968, but the use of steam locomotives in British industrial railway, industry continued into the 1980s. In June 1975, there were still 41 locations where steam was in regular use, and many more where engines were maintained in reserve in case of diesel failures. Gradually, the decline of the ironstone quarries, steel, coal mining and shipbuilding industries – and the plentiful supply of redundant British Rail diesel shunters as replacements – led to the end of steam power for commercial uses. Several hundred rebuilt and preserved steam locomotives are still used on preserved volunteer-run 'heritage' railway lines in the UK. A proportion of the locomotives are Mainline steam trains in Great Britain, regularly used on the national rail network by private operators where they run special excursions and touring trains. A new steam locomotive, the LNER Peppercorn Class A1 60163 ''Tornado'' has been built (began service in 2009), and more are in the planning stage.

## Russia

In the USSR, although the first mainline diesel-electric locomotive was built in USSR in 1924, the last steam locomotive (:ru:П36, model П36, serial number 251) was built in 1956; it is now in the Museum of Railway Machinery at the former Warsaw Rail Terminal, Saint Petersburg. In the European part of the USSR, almost all steam locomotives were replaced by diesel and electric locomotives in the 1960s; in Siberia and Central Asia, state records verify that L-class s and LV-class s were not retired until 1985. Until 1994, Russia had at least 1,000 steam locomotives stored in operable condition in case of "national emergencies".

## China

China continued to build mainline steam locomotives until the late 20th century, even building a few examples for American tourist operations. China was the last main-line user of steam locomotives, with use ending officially on the Jitong railway, Jitong line at the end of 2005. Some steam locomotives are still in use in industrial operations in China. Some coal and other mineral operations maintain an active roster of China Railways JS (建设, "Jiànshè") or China Railways SY (上游, "Shàngyóu") steam locomotives bought secondhand from China Railway. The last steam locomotive built in China was SY 1772, finished in 1999. at least six Chinese steam locomotives exist in the United States – 3 QJs bought by the Rail Development Corporation (Nos. 6988 and 7081 for Iowa Interstate Railroad, IAIS and No. 7040 for R.J. Corman), a JS bought by the Boone and Scenic Valley Railroad, and two SYs. No. 142 (formerly No. 1647) is owned by the New York, Susquehanna and Western Railway, NYSW for tourist operations, re-painted and modified to represent a 1920s-era US locomotive; Knox & Kane 58, No. 58 is operated by the Valley Railroad (Connecticut), Valley Railroad and has been modified to represent New York, New Haven and Hartford Railroad, New Haven Railroad number 3025.

## Japan

Owing to the destruction of much of the nation's infrastructure during the Second World War, and the cost of electrification and dieselisation, new steam locomotives were built in Japan until 1960. The number of Japanese steam locomotives reached a peak of 5,958 in 1946. With the booming post-war Japanese economy, steam locomotives were gradually withdrawn from main line service beginning in the early 1960s, and were replaced with diesel and electric locomotives. They were relegated to branch line and sub-main line services for several more years until the late 1960s, when electrification and dieselisation began to increase. From 1970 onwards, steam locomotion was gradually abolished on the Japanese National Railways, JNR: * Shikoku (April 1970) * Kanto area (Tokyo) (October 1970), * Kinki (Osaka, Kyoto area) (September 1973) * Chubu (Nagoya, Nagano area) (April 1974), * Tohoku (November 1974), * Chugoku (Yamaguchi area) (December 1974) * Kyushu (January 1975) * Hokkaido (March 1976) The last regular steam passenger train, pulled by a JNR Class C57, C57-class locomotive built in 1940, departed from Muroran railway station to Iwamizawa on 14 December 1975. It was then officially retired from service, dismantled and sent to the Tokyo Transportation Museum, where it was inaugurated as an exhibit on 14 May 1976. It was moved to the Saitama Railway Museum in early 2007. The last Japanese main line steam train, D51-241, a JNR Class D51, D51-class locomotive built in 1939, left Yubari, Hokkaido, Yubari railway station on 24 December 1975. That same day, all steam main line service ended. D51-241 was retired on 10 March 1976, and destroyed in a depot fire a month later, though some parts were preserved. On 2 March 1976, the only steam locomotive still operating on the JNR, 9600–39679, a 9600-class locomotive built in 1920, made its final journey from Oiwake railway station, ending 104 years of steam locomotion in Japan. Today steam passenger trains are operated by JR Group, JR companies on an infrequent excursion/nostalgia basis, their services always prefixed with the letters ''SL'' (for ''steam liner''). Examples are ''SL Hitoyoshi'' and ''SL Ginga''.

## South Korea

The first steam locomotive in South Korea (Korea at the time) was the Moga (Mogul) 2-6-0, which first ran on 9 September 1899 on the Gyeong-In Line. Other South Korean steam locomotive classes include the Sata, Pureo, Ame, Sig, Mika (USRA Heavy Mikado), Pasi (USRA Light Pacific), Hyeogi (Narrow gauge), Class 901, Mateo, Sori and Tou. Used until 1967, the Pasi 23 is now in the Railroad Museum.

## India

New steam locomotives were built in India well into the early 1970s; the last broad-gauge steam locomotive to be manufactured, ''Last Star'', a WG-class locomotive (No. 10560) was built in June 1970, followed by the last meter-gauge locomotive in February 1972. Steam locomotion continued to predominate on Indian Railways through the early 1980s; in fiscal year 1980–81, there were 7,469 steam locomotives in regular service, compared to 2,403 diesels and 1,036 electrics. Subsequently, steam locomotion was gradually phased out from regular service, beginning with the Southern Railway Zone in 1985; the number of diesel and electric locomotives in regular service surpassed the number of steam locomotives in service in 1987–88. The first electric trains were introduced in India as part of the Bombay suburban railway system on 3 February 1925. The first metre gauge diesel locomotives were introduced in 1955 and broad gaue in 1957. All regular broad-gauge steam service in India ended in 1995, with the final run made from Jalandhar to Ferozpur on 6 December. The last meter-gauge and narrow-gauge steam locomotives in regular service were retired in 2000. After being withdrawn from service, most steam locomotives were scrapped, though some have been preserved in various railway museums. The only steam locomotives remaining in regular service are on India's heritage lines.

## South Africa

In South Africa, the last new steam locomotives purchased were Garratts from Hunslet Taylor for the gauge lines in 1968. Another class 25NC locomotive, No. 3450, nicknamed the "Red Devil" because of its colour scheme, received modifications including a prominent set of double side-by-side exhaust stacks. In southern Natal, two former South African Railway gauge NGG16 Garratts operating on the privatised Alfred County Railway, Port Shepstone and Alfred County Railway (ACR) received some L.D. Porta modifications in 1990, becoming a new NGG16A class.VidRail Productions, South African end of Steam: ''Orange Free State, Part 4, Vols. 3, 4 and 5'' and ''Natal, Part 3, Vol. 1'', in ''The Best of Southern African Steam, 1983–1990'' By 1994 almost all commercial steam locomotives were put out of service, although many of them are preserved in museums or at railway stations for public viewing. Today only a few privately owned steam locomotives are still operating in South Africa, including the ones being used by the 5-star luxury train Rovos Rail, and the tourist trains ''Outeniqua Tjoe Choo'', ''Apple Express'' and (until 2008) ''Banana Express''.

## Other countries

In other countries, the dates for conversion from steam to diesel and electric power varied. On the contiguous North American standard gauge network across Canada, Mexico and the United States, the use of standard gauge main line steam locomotion using s built in 1946 for handling freight between Mexico City and Irapuato lasted until 1968. The Mexican Pacific line, a standard gauge short line in the state of Sinaloa, was reported in August 1987 to still be using steam, with a roster of one , two s and one . By March 1973 in Australia, steam was no longer used for industrial purposes. Diesel locomotives were more efficient and the demand for manual labour for service and repairs was less than for steam. Cheap oil also had cost advantages over coal. Regular scheduled steam services operated from 1998 until 2004 on the West Coast Railway (Victoria), West Coast Railway. In New Zealand's North Island, steam traction ended in 1968 when AB 832 (now stored at the Glenbrook Vintage Railway, Auckland, but owned by the Museum of Transport & Technology) hauled a Farmers Trading Company "Santa Special" from Hamilton railway station, New Zealand, Frankton Junction to Claudelands. In the South Island, due to the inability of the new DJ class diesel locomotives to provide in-train steam heating, steam operations continued using the J and JA class tender locomotives on the overnight Christchurch-Invercargill expresses, Trains 189/190, until 1971. By this time sufficient FS steam-heating vans were available, thus allowing the last steam locomotives to be withdrawn. Two NZR AB class, AB class tender locomotives, AB 778 and AB 795, were retained at Lyttelton, New Zealand, Lyttelton to steam-heat the coaches for the Boat Trains between Christchurch and Lyttelton, until they were restored for the ''Kingston Flyer'' tourist train in 1972. In Finland, the first diesels were introduced in the mid-1950s, superseding steam locomotives by the early 1960s. State railways (VR Group, VR) operated steam locomotives until 1975. In the Netherlands, the first electric trains appeared in 1908, making the trip from Rotterdam to The Hague. The first diesels were introduced in 1934. As electric and diesel trains performed so well, the decline of steam started just after World War II, with steam traction ending in 1958. In Poland, on non-electrified tracks, steam locomotives were superseded almost entirely by diesels by the 1990s. A few steam locomotives, however, operate in the regularly scheduled service from Wolsztyn. After ceasing on 31 March 2014, regular service resumed out of Wolsztyn on 15 May 2017 with weekday runs to Leszno. This operation is maintained as a means of preserving railway heritage and as a tourist attraction. Apart from that, numerous railway museums and heritage railways (mostly narrow gauge) own steam locomotives in working condition. In France, steam locomotives have not been used for commercial services since 24 September 1975. In Spain, the first electric trains were introduced en 1911, and the first diesels in 1935, just one year before the Spanish Civil War. National railway company (Renfe) operated steam locomotives until 9 June 1975. In Bosnia and Herzegovina, some steam locomotives are still used for industrial purposes, for example at the coal mine in Banovići and ArcelorMittal factory in Zenica. History of rail transport in Paraguay, In Paraguay, wood-burning steam locomotives operated until 1999. In Thailand, all steam locomotives were withdrawn from service between the late 1960s and early 1970s. Most were scrapped in 1980. However, there are about 20 to 30 locomotives preserved for exhibit in important or end-of-the-line stations throughout the country. During the late 1980s, six locomotives were restored to running condition. Most are JNR-built steam locomotives with the exception of a single . Indonesia has also used steam locomotives since 1876. The last batch of E10 rack tank locomotives were purchased in 1967 (Kautzor, 2010) from Nippon Sharyo. The last locomotives – the D 52 class, manufactured by the German firm Krupp in 1954 – operated until 1994, when they were replaced by diesel locomotives. Indonesia also purchased the last batch of mallet locomotives from Nippon Sharyo, to be used on the Aceh Railway. In Sumatra Barat (West Sumatra) and Ambarawa some rack railways (with a maximum gradient of 6% in mountainous areas) are now operated for tourism only. There are two rail museums in Indonesia, Taman Mini and Ambarawa (Ambarawa Railway Museum). In the Philippines, the Manila Railroad retired its entire steam locomotive fleet from mainline service by August 1956 as part of the agency's efforts towards dieselisation. All but three tank locomotives were scrapped by its successor, the Philippine National Railways. The last of such engines ordered were ten JNR Class D51, Manila Railroad 300 class locomotives in 1951. However, steam locomotives continue to operate in Negros Island for much of the later 20th and the 21st centuries. One sugar mill operates two 0-6-0 steam locomotives as of 2020. Pakistan Railways still has a regular steam locomotive service; a line operates in the North-West Frontier Province, Pakistan, North-West Frontier Province and in Sindh. It has been preserved as a "nostalgia" service for tourism in exotic locales, and is specifically advertised as being for "steam buffs". In Sri Lanka, one steam locomotive is maintained for private service to power the ''Viceroy Special''.

# Climate change

The future use of steam locomotives in the United Kingdom is in doubt because of government policy on climate change. The Heritage Railway Association is working with the All-Party Parliamentary Group on Heritage Rail in an effort to continue running steam locomotives on coal. Many tourist railroads use oil-fired steam locomotives (or have converted their locomotives to run on oil) to reduce their environmental footprint, and because fuel oil can be easier to obtain than coal of the proper type and sizing for locomotives. For example, the Grand Canyon Railway runs its steam locomotives on used vegetable oil. An organization called the Coalition for Sustainable Rail (CSR) is developing an environmentally friendly coal substitute made from torrefied biomass. In early 2019, they performed a series of tests using Everett Railroad to evaluate the performance of the biofuel, with positive results. The biofuel was found to burn slightly faster and hotter than coal. The goal of the project is primarily to find a sustainable fuel for historic steam locomotives on tourist railroads, but CSR has also suggested that, in the future, steam locomotives powered by torrefied biomass could be an environmentally and economically superior alternative to diesel locomotives.

# Steam locomotives in popular culture

Steam locomotives have been present in popular culture since the 19th century. Folk songs from that period including "I've Been Working on the Railroad" and the "John Henry (folklore), Ballad of John Henry" are a mainstay of American music and culture. Many steam locomotive toys have been made, and Rail transport modelling, railway modelling is a popular hobby. Steam locomotives are often portrayed in fictional works, notably ''The Railway Series'' by the Wilbert Awdry, Rev W. V. Awdry, ''The Little Engine That Could'' by Watty Piper, ''The Polar Express'' by Chris Van Allsburg, and the Hogwarts Express from J.K. Rowling's Harry Potter series. They have also been featured in many children's television shows, such as ''Thomas the Tank Engine and Friends'', based on characters from the books by Awdry, and ''Ivor the Engine'' created by Oliver Postgate. The Hogwarts Express also appears in the Harry Potter series of films, portrayed by GWR 4900 Class 5972 Olton Hall in a special Hogwarts livery. The Polar Express appears in the The Polar Express (film), animated movie of the same name. An elaborate, themed funicular Hogwarts Express (Universal Orlando Resort), Hogwarts Express ride is featured in the Universal Orlando Resort in Florida, connecting the Harry Potter section of Universal Studios with the Islands of Adventure theme park. The Polar Express is recreated on many heritage railroads in the United States, including the North Pole Express pulled by the Pere Marquette 1225 locomotive, which is operated by the Steam Railroading Institute in Owosso, Michigan. According to author Van Allsburg, this locomotive was the inspiration for the story and it was used in the production of the movie. A number of computer and video games feature steam locomotives. ''Sid Meier's Railroad Tycoon, Railroad Tycoon'', produced in 1990, was named "one of the best computer games of the year". There are two notable examples of steam locomotives used as Charge (heraldry), charges on heraldic Coat of arms, coats of arms. One is that of Darlington, which displays '' Locomotion No. 1''. The other is the original coat of arms of Swindon, not currently in use, which displays a basic steam locomotive. Steam locomotives are a popular topic for coin collectors. The 1950 Silver 5 Peso coin of Mexico has a steam locomotive on its reverse as the prominent feature. The 20 euro Euro gold and silver commemorative coins (Austria)#2003 coinage, Biedermeier Period coin, minted 11 June 2003, shows on the obverse an early model steam locomotive (the ''KFNB Minotaurus and Ajax, Ajax'') on Austria's first railway line, the Emperor Ferdinand Northern Railway, Kaiser Ferdinands-Nordbahn. The ''Ajax'' can still be seen today in the Technisches Museum Wien. As part of the 50 State Quarters program, the quarter representing the US state of Utah depicts the ceremony where the two halves of the First Transcontinental Railroad met at Promontory Summit, Utah, Promontory Summit in 1869. The coin recreates a popular image from the ceremony with steam locomotives from each company facing each other while the golden spike is being driven. The Japanese televisual franchise Super Sentai has monsters based on steam locomotives.

## General

* History of rail transport * List of steam technology patents * Live steam * Reciprocating motion * Steam locomotive production * Steam railroad * Steam turbine locomotive * Timeline of railway history

## Types of steam locomotives

* Articulated locomotive ** Beyer-Garratt locomotive ** Fairlie locomotive ** Mallet locomotive * Cab forward locomotive * Compound locomotive * Duplex locomotive * Electric-steam locomotive * Geared steam locomotive * Heilmann locomotive * High-pressure steam locomotive * 5AT Advanced Technology Steam Locomotive * Steam dummy, Steam dummies and Steam trams * Steam turbine locomotive * Streamliner * Tank locomotive * Triplex locomotive * Whyte notation, Whyte Notation

## Historic locomotives

* 3801 * De Arend (locomotive), ''Arend'' * Canadian Pacific 374 * C&O 1308 * Chesapeake and Ohio 1309, C&O 1309 * Chesapeake and Ohio 614, C&O 614 * ''
Catch Me Who Can ''Catch Me Who Can'' was the fourth and last steam railway locomotive created by the inventor and mining engineer Richard Trevithick. It was an evolution of three earlier locomotives which had been built for Coalbrookdale Coalbrookdale is ...

'' * GWR 3700 Class 3440 City of Truro, 3440 ''City of Truro'' * BR Standard Class 9F 92220 Evening Star, 92220 ''Evening Star'' * Eureka (locomotive), Eureka * Fairy Queen (locomotive), ''Fairy Queen'' * LNER Class A3 4472 Flying Scotsman, 4472 ''Flying Scotsman'' * Tasmanian Government Railways K class, Garratt K1 * The General (locomotive), ''The General'' * GKB 671 * ''Gov. Stanford'' * Invicta (locomotive), ''Invicta'' * John Bull (locomotive), ''John Bull'' * Jupiter (locomotive), ''Jupiter'' * Kriegslokomotive * Locomotion No 1, ''Locomotion'' No. 1 * LMR 57 Lion, LMR 57 ''Lion'' * LNER Class A4 4468 Mallard, 4468 ''Mallard'' * Milwaukee Road 261 * Milwaukee Road class A * Milwaukee Road class F7 * Norfolk and Western 611 * Norfolk & Western 1218 * Norfolk & Western 2156 * Novelty (locomotive), ''Novelty'' * New York Central and Hudson River Railroad No. 999, NYC 999 * NYC Hudson * NYC Mohawk * NYC Niagara * Pere Marquette 1225 * Pennsylvania Railroad class K4 * Pennsylvania Railroad class I1s * Pennsylvania Railroad class Q2 * Puffing Billy (locomotive), ''Puffing Billy'' * Reuben Wells (locomotive), ''Reuben Wells'' * Santa Fe 3751 * Sierra Railway No. 3 * Soo Line 2719 * Stephenson's Rocket, Stephenson's ''Rocket'' * Norfolk and Western Railway 475, Strasburg Rail Road (Norfolk & Western) No. 475 * Southern Pacific 4449 * Southern Railway 4501 * Tom Thumb (locomotive), ''Tom Thumb'' * LNER Peppercorn Class A1 60163 Tornado, 60163 ''Tornado'' * Union Pacific 844 *
Union Pacific Big Boy The Union Pacific Big Boy is a type of simple articulated locomotive, articulated 4-8-8-4 steam locomotive manufactured by the American Locomotive Company (ALCO) between 1941 and 1944 and operated by the Union Pacific Railroad in revenue service u ...
* Union Pacific Challenger * Union Pacific No. 119 * Western Pacific 94 * William Crooks (locomotive), ''William Crooks''

# Bibliography

*

* C. E. Wolff, ''Modern Locomotive Practice: A Treatise on the Design, Construction, and Working of Steam Locomotives'' (Manchester, England, 1903) * Henry Greenly, ''Model Locomotive'' (New York, 1905) * G. R. Henderson, ''Cost of Locomotive Operation'' (New York, 1906) * W. E. Dalby, ''Economical Working of Locomotives'' (London, 1906) * A. I. Taylor, ''Modern British Locomotives'' (New York, 1907) * E. L. Ahrons, ''The Development of British Locomotive Design'' (London, 1914) * E. L. Ahrons
''Steam Engine Construction and Maintenance''
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(Rakov V.A. ''Locomotives of fatherland's railways 1845–1955'' Transport, Moscow, 1995 ''(in Russian)'') * J.J.G. Koopmans: ''The fire burns much better ...'' NL-Venray 2006,

TV and Radio programmes from the BBC archives celebrating steam trains

Database of surviving steam locomotives in North America

UK heritage railways and preserved locomotives database