A steam locomotive is a type of railway locomotive
that produces its pulling power through a
steam engine. These locomotives are fueled
by burning combustible material – usually
coal, wood, or oil – to produce steam in
a boiler. The steam moves reciprocating pistons
which are mechanically connected to the locomotive's
main wheels (drivers). Both fuel and water
supplies are carried with the locomotive,
either on the locomotive itself or in wagons
(tenders) pulled behind.
Steam locomotives were first developed in
the United Kingdom during the early 19th century
and used for railway transport until the middle
of the 20th century. Richard Trevithick built
the first steam locomotive in 1802. The first
commercially successful steam locomotive was
built in 1812–13 by John Blenkinsop. Locomotion
No. 1, built by George Stephenson and his
son Robert's company Robert Stephenson and
Company, was the first steam locomotive to
haul passengers on a public railway, the Stockton
and Darlington Railway in 1825. In 1830, George
Stephenson opened the first public inter-city
railway, the Liverpool and Manchester Railway.
Robert Stephenson and Company was the pre-eminent
builder of steam locomotives for railways
in the United Kingdom, the United States,
and much of Europe in the first decades of
steam.In the 20th century, Chief Mechanical
Engineer of the London and North Eastern Railway
(LNER) Nigel Gresley designed some of the
most famous locomotives, including the Flying
Scotsman, the first steam locomotive officially
recorded over 100 mph in passenger service,
and a LNER Class A4, 4468 Mallard, which still
holds the record for being the fastest steam
locomotive in the world (126 mph).From the
early 1900s, steam locomotives were gradually
superseded by electric and diesel locomotives,
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. In 1784, William
Murdoch, a Scottish inventor, built a small-scale
prototype of a steam road locomotive in Birmingham.
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
John Fitch 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 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, who pioneered the use of steam
locomotives.
The first full-scale working railway steam
locomotive, was the 3 ft (914 mm) gauge Coalbrookdale
Locomotive, built by Trevithick in 1802. It
was constructed for the Coalbrookdale ironworks
in Shropshire in the United Kingdom 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 4 ft
4 in (1,321 mm) tramway from the Pen-y-darren
ironworks, near Merthyr Tydfil, to Abercynon
in South Wales. Accompanied by Andrew Vivian,
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 Newcastle 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 in 1808.
In 1812, Matthew Murray's successful twin-cylinder
rack locomotive Salamanca first ran on the
edge-railed rack-and-pinion Middleton Railway.
Another well-known early locomotive was Puffing
Billy, built 1813–14 by engineer William
Hedley. It was intended to work on the Wylam
Colliery near Newcastle upon Tyne. This locomotive
is the oldest preserved, and is on static
display in the Science Museum, London.
==== George Stephenson ====
George Stephenson, a former miner working
as an engine-wright at Killingworth Colliery,
developed up to sixteen Killingworth locomotives,
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, which
was the first steam locomotive to work in
Scotland.
In 1825, George Stephenson built Locomotion
No. 1 for the Stockton and Darlington Railway,
north-east England, which was the first public
steam railway in the world. In 1829, his son
Robert built in Newcastle The Rocket which
was entered in and won the Rainhill Trials.
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
opened a year later making exclusive use of
steam power for passenger and goods trains.
=== United States ===
Many of the earliest locomotives for American
railroads were imported from Great Britain,
including first the Stourbridge Lion and later
the John Bull (still the oldest operable engine-powered
vehicle in the United States of any kind,
as of 1981) however a domestic locomotive-manufacturing
industry was quickly established. The Baltimore
and Ohio Railroad's Tom Thumb in 1830, designed
and built by Peter Cooper, was the first US-built
locomotive to run in America, although it
was intended as a demonstration of the potential
of steam traction, rather than as a revenue-earning
locomotive. The DeWitt Clinton was also built
in the 1830s.
=== Continental Europe ===
The first railway service outside the United
Kingdom and North America was opened in 1829
in France between Saint-Etienne and Lyon.
Then on 5 May 1835, the first line in Belgium
linked Mechelen and Brussels. The locomotive
was named The Elephant.
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. 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 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 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 1837, the first steam railway started in
Austria on the Emperor Ferdinand Northern
Railway between Vienna-Floridsdorf and Deutsch-Wagram.
The oldest continually working steam engine
in the world also runs in Austria: the 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, was manufactured
by the Maschinenbaufirma Übigau near Dresden,
built by Prof. Johann Andreas Schubert. The
first independently designed locomotive in
Germany was the 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 Spanisch Brötli
Bahn, from Zürich to Baden was opened.
== Basic form ==
=== 
Boiler ===
The fire-tube boiler was standard practice
for steam locomotives and although other types
of boiler were evaluated they were not widely
used except for 1000 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, onto a set of 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.
Surrounding the boiler are layers of insulation
or lagging to reduce heat loss.
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 transmits power through a crosshead,
connecting rod (Main rod in the US) and a
crankpin on the driving wheel (Main driver
in the US) or to a crank on a driving axle.
The movement of the valves in the steam chest
is controlled through a set of rods and linkages
called the valve gear, actuated from the driving
axle or from the crankpin; the valve gear
includes devices that allow reversing the
engine, adjusting valve travel and the timing
of the admission and exhaust events. The cut-off
point determines the moment when the valve
blocks a steam port, "cutting off" admission
steam and thus determining the proportion
of the stroke during which steam is admitted
into the cylinder; for example a 50% cut-off
admits steam for half the stroke of the piston.
The remainder of the stroke is driven by the
expansive force of the steam. Careful use
of cut-off provides economical use of steam
and in turn, reduces fuel and water consumption.
The reversing lever (Johnson bar in the US),
or screw-reverser (if so equipped), that controls
the cut-off, therefore, performs a similar
function to a gearshift in an automobile – maximum
cut-off, providing maximum tractive effort
at the expense of efficiency, is used to pull
away from a standing start, whilst a cut-off
as low as 10% is used when cruising, providing
reduced tractive effort, and therefore lower
fuel/water consumption.Exhaust steam is directed
upwards out of the locomotive through the
chimney, by way of a nozzle called a blastpipe,
creating the familiar "chuffing" sound of
the steam locomotive. The blastpipe is placed
at a strategic point inside the smokebox that
is at the same time traversed by the combustion
gases drawn through the boiler and grate by
the action of the steam blast. The combining
of the two streams, steam and exhaust gases,
is crucial to the efficiency of any steam
locomotive, and the internal profiles of the
chimney (or, strictly speaking, the ejector)
require careful design and adjustment. This
has been the object of intensive studies by
a number of engineers (and often ignored by
others, sometimes with catastrophic consequences).
The fact that the draught depends on the exhaust
pressure means that power delivery and power
generation are automatically self-adjusting.
Among other things, a balance has to be struck
between obtaining sufficient draught for combustion
whilst giving the exhaust gases and particles
sufficient time to be consumed. In the past,
a strong draught could lift the fire off the
grate, or cause the ejection of unburnt particles
of fuel, dirt and pollution for which steam
locomotives had an unenviable reputation.
Moreover, the pumping action of the exhaust
has the counter-effect of exerting back pressure
on the side of the piston receiving steam,
thus slightly reducing cylinder power. Designing
the exhaust ejector became a specific science,
with engineers such as Chapelon, Giesl and
Porta making large improvements in thermal
efficiency and a significant reduction in
maintenance time and pollution. A similar
system was used by some early gasoline/kerosene
tractor manufacturers (Advance-Rumely/Hart-Parr)
– the exhaust gas volume was vented through
a cooling tower, allowing the steam exhaust
to draw more air past the radiator.
=== Running gear ===
Running gear includes the brake gear, wheel
sets, axleboxes, springing and the motion
that includes connecting rods and valve gear.
The transmission of the power from the pistons
to the rails and the behaviour of the locomotive
as a vehicle, being able to negotiate curves,
points and irregularities in the track, is
of paramount importance. Because reciprocating
power has to be directly applied to the rail
from 0 rpm upwards, this creates the problem
of adhesion of the driving wheels to the smooth
rail surface. Adhesive weight is the portion
of the locomotive's weight bearing on the
driving wheels. This is made more effective
if a pair of driving wheels is able to make
the most of its axle load, i.e. its individual
share of the adhesive weight. Equalising beams
connecting the ends of leaf springs have often
been deemed a complication in Britain, however,
locomotives fitted with the beams have usually
been less prone to loss of traction due to
wheel-slip. Suspension using equalizing levers
between driving axles, and between driving
axles and trucks, was standard practice on
North American locomotives to maintain even
wheel loads when operating on uneven track.
Locomotives with total adhesion, where all
of the wheels are coupled together, generally
lack stability at speed. To counter this,
locomotives often fit unpowered carrying wheels
mounted on two-wheeled trucks or four-wheeled
bogies centred by springs/inverted rockers/geared
rollers that help to guide the locomotive
through curves. These usually take on weight
– of the cylinders at the front or the firebox
at the rear — when the width exceeds that
of the mainframes. Locomotives with multiple
coupled-wheels on a rigid chassis would have
unacceptable flange forces on tight curves
giving excessive flange and rail wear, track
spreading and wheel climb derailments. One
solution was to remove or thin the flanges
on an axle. More common was to give axles
end-play and use lateral motion control with
spring or inclined-plane gravity devices.
Railroads generally preferred locomotives
with fewer axles, to reduce maintenance costs.
The number of axles required was dictated
by the maximum axle loading of the railroad
in question. A builder would typically add
axles until the maximum weight on any one
axle was acceptable to the railroad's maximum
axle loading. A locomotive with a wheel arrangement
of two lead axles, two drive axles, and one
trailing axle was a high-speed machine. Two
lead axles were necessary to have good tracking
at high speeds. Two drive axles had a lower
reciprocating mass than three, four, five
or six coupled axles. They were thus able
to turn at very high speeds due to the lower
reciprocating mass. A trailing axle was able
to support a huge firebox, hence most locomotives
with the wheel arrangement of 4-4-2 (American
Type Atlantic) were called free steamers and
were able to maintain steam pressure regardless
of throttle setting.
=== 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.
An S.N.C.F design study using welded tubular
frames
gave a rigid frame with a 30% weight reduction.
=== Fuel and water ===
Generally, the largest locomotives are permanently
coupled to a tender that carries the water
and fuel. Often, locomotives working shorter
distances do not have a tender and carry the
fuel in a bunker, with the water carried in
tanks placed next to the boiler. The tanks
can be in various configurations, including
two tanks alongside (side tanks or pannier
tanks), one on top (saddle tank) or one between
the frames (well tank).
The fuel used depended on what was economically
available to the railway. In the UK and other
parts of Europe, plentiful supplies of coal
made this the obvious choice from the earliest
days of the steam engine. Until 1870, the
majority of locomotives in the United States
burned wood, but as the Eastern forests were
cleared, coal gradually became more widely
used until it became the dominant fuel worldwide
in steam locomotives. Railways serving sugar
cane farming operations burned bagasse, a
byproduct of sugar refining. In the US, the
ready availability and low price of oil made
it a popular steam locomotive fuel after 1900
for the southwestern railroads, particularly
the Southern Pacific. In the Australian state
of Victoria, many steam locomotives were converted
to heavy oil firing after World War II. German,
Russian, Australian and British railways experimented
with using coal dust to fire locomotives.
During World War II, a number of Swiss steam
shunting locomotives were modified to use
electrically heated boilers, consuming around
480 kW of power collected from an overhead
line with a pantograph. These locomotives
were significantly less efficient than electric
ones; they were used because Switzerland had
access to plentiful hydroelectricity, and
suffered from a shortage of coal because of
the war.A number of tourist lines and heritage
locomotives in Switzerland, Argentina and
Australia have used light diesel-type oil.Water
was supplied at stopping places and locomotive
depots from a dedicated water tower connected
to water cranes or gantries. In the UK, the
US and France, water troughs (track pans in
the US) were provided on some main lines to
allow locomotives to replenish their water
supply without stopping, from rainwater or
snowmelt that filled the trough due to inclement
weather. This was achieved by using a deployable
"water scoop" fitted under the tender or the
rear water tank in the case of a large tank
engine; the fireman remotely lowered the scoop
into the trough, the speed of the engine forced
the water up into the tank, and the scoop
was raised again once it was full.
Water is an essential element in the operation
of a steam locomotive. As Swengel argued:
It has the highest specific heat of any common
substance; that is, more thermal energy is
stored by heating water to a given temperature
than would be stored by heating an equal mass
of steel or copper to the same temperature.
In addition, the property of vapourising (forming
steam) stores additional energy without increasing
the temperature… water is a very satisfactory
medium for converting thermal energy of fuel
into mechanical energy.
Swengel went on to note that "at low temperature
and relatively low boiler outputs", good water
and regular boiler washout was an acceptable
practice, even though such maintenance was
high. As steam pressures increased, however,
a problem of "foaming" or "priming" developed
in the boiler, wherein dissolved solids in
the water formed "tough-skinned bubbles" inside
the boiler, which in turn were carried into
the steam pipes and could blow off the cylinder
heads. To overcome the problem, hot mineral-concentrated
water was deliberately wasted (blown down)
from the boiler periodically. Higher steam
pressures required more blowing-down of water
out of the boiler. Oxygen generated by boiling
water attacks the boiler, and with increased
steam pressure the rate of rust (iron oxide)
generated inside the boiler increases. One
way to help overcome the problem was water
treatment. Swengel suggested that these problems
contributed to the interest in electrification
of railways.In the 1970s, L.D. Porta developed
a sophisticated system of heavy-duty chemical
water treatment (Porta Treatment) that not
only keeps the inside of the boiler clean
and prevents corrosion, but modifies the foam
in such a way as to form a compact "blanket"
on the water surface that filters the steam
as it is produced, keeping it pure and preventing
carry-over into the cylinders of water and
suspended abrasive matter.
=== 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 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 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; while
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 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's
term for a wooden barrel stave. Two of the
earliest steam locomotives used wooden lagging
to insulate their boilers: the Salamanca,
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 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 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 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 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 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.
G.J. Churchward fitted this arrangement to
the high end of his domeless coned boilers.
Other British lines such as the LBSCR 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 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 King's
Cross and 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 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.
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 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 sandboxes
from which sand can be deposited on top of
the rail to improve 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 lubricated by the enginemen dropping
a lump of tallow down the blast pipe.As speeds
and distances increased, mechanisms were developed
that injected thick mineral oil into the steam
supply. The first, a 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,
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 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.
=== Buffers ===
In British and European (except former Soviet
Union countries) practice, locomotives usually
have buffers at each end to absorb compressive
loads ("buffets"). The tensional load of drawing
the train (draft force) is carried by the
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 was usually fixed to the front end
of locomotives, although in European and a
few other railway systems including 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.
=== Headlights ===
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
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 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, eg 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 Kb 4-8-4 locomotives were fitted with
boosters, the only 3 ft 6 in (1,067 mm) 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 lots of 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 and U1 classes.
Most British express-passenger locomotives
built between 1930 and 1950 were 4-6-0 or
4-6-2 types with three or four cylinders (e.g.
GWR 6000 Class, LMS Coronation Class, SR Merchant
Navy Class, LNER Gresley Class A3). From 1951,
all 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 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 ===
More-powerful locomotives tend to be longer,
but long rigid-framed designs are impractical
for the tight curves frequently found on narrow-gauge
railways. Various designs for articulated
locomotives were developed to overcome this
problem. The Mallet and the Garratt were the
two most popular, both using a single boiler
and two engines (sets of cylinders and driving
wheels). The Garratt has two power bogies,
whereas the Mallet has one. There were also
a few examples of triplex locomotives that
had a third engine under the tender. Both
the front and tender engines were low-pressure
compounded, though they could be operated
simple (high-pressure) for starting off. Other
less common variations included the Fairlie
locomotive, which had two boilers back-to-back
on a common frame, with two separate power
bogies.
=== Duplex types ===
Duplex locomotives, containing two engines
in one rigid frame, were also tried, but were
not notably successful. For example, the 4-4-4-4
Pennsylvania Railroad's T1 class, 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, the Climax
and the 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
turbines using direct-drive and electrical
transmissions in various countries proved
mostly unsuccessful. The London, Midland and
Scottish Railway built the 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
and 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, (212 °F (100 °C)) 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 locomotiveMixed power
locomotives, utilising both steam and diesel
propulsion, have been produced in Russia,
Britain and Italy.
Electric-steam locomotiveUnder 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 is similar in
concept to a diesel-electric locomotive, 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 Jean Jacques
Heilmann 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
0-4-0 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 4-6-2. Different arrangements
were given names which usually reflect the
first usage of the arrangement; for instance,
the "Santa Fe" type (2-10-2) 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 4-6-2 designation would
be an equivalent to a 2-C-1 UIC designation.
On many railroads, locomotives were organised
into 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 "Pugs", 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
=
c
P
d
2
s
D
{\displaystyle t={\frac {cPd^{2}s}{D}}}
.where d is the bore of the cylinder (diameter)
in inches,
s is the cylinder stroke, in inches,
P is boiler pressure in pounds per square
inch,
D is the diameter of the driving wheel in
inches,
and c is a factor that depends on the effective
cut-off. In the US, c 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.
=== Relation to wheel arrangement ===
Whyte classification is indirectly connected
to locomotive performance. Given adequate
proportions of the rest of the locomotive,
power output is determined by the size of
the fire, and for a bituminous coal-fuelled
locomotive, this is determined by the grate
area. Modern non-compound locomotives are
typically able to produce about 40 drawbar
horsepower per square foot of grate. Tractive
force, as noted earlier, is largely determined
by the boiler pressure, the cylinder proportions
and the size of the driving wheels. However,
it is also limited by the weight on the driving
wheels (termed "adhesive weight"), which needs
to be at least four times the tractive effort.The
weight of the locomotive is roughly proportional
to the power output; the number of axles required
is determined by this weight divided by the
axleload limit for the trackage where the
locomotive is to be used. The number of driving
wheels is derived from the adhesive weight
in the same manner, leaving the remaining
axles to be accounted for by the leading and
trailing bogies. Passenger locomotives conventionally
had two-axle leading bogies for better guidance
at speed; on the other hand, the vast increase
in the size of the grate and firebox in the
20th century meant that a trailing bogie was
called upon to provide support. In Europe,
some use was made of several variants of the
Bissel bogie in which the swivelling movement
of a single axle truck controls the lateral
displacement of the front driving axle (and
in one case the second axle too). This was
mostly applied to 8-coupled express and mixed
traffic locomotives, and considerably improved
their ability to negotiate curves whilst restricting
overall locomotive wheelbase and maximising
adhesion weight.
As a rule, "shunting engines" (US: switching
engines) omitted leading and trailing bogies,
both to maximise tractive effort available
and to reduce wheelbase. Speed was unimportant;
making the smallest engine (and therefore
smallest fuel consumption) for the tractive
effort was paramount. Driving wheels were
small and usually supported the firebox as
well as the main section of the boiler. Banking
engines (US: helper engines) tended to follow
the principles of shunting engines, except
that the wheelbase limitation did not apply,
so banking engines tended to have more driving
wheels. In the US, this process eventually
resulted in the Mallet type engine with its
many driven wheels, and these tended to acquire
leading and then trailing bogies as guidance
of the engine became more of an issue.
As locomotive types began to diverge in the
late 19th century, freight engine designs
at first emphasised tractive effort, whereas
those for passenger engines emphasised speed.
Over time, freight locomotive size increased,
and the overall number of axles increased
accordingly; the leading bogie was usually
a single axle, but a trailing truck was added
to larger locomotives to support a larger
firebox that could no longer fit between or
above the driving wheels. Passenger locomotives
had leading bogies with two axles, fewer driving
axles, and very large driving wheels in order
to limit the speed at which the reciprocating
parts had to move.
In the 1920s, the focus in the United States
turned to horsepower, epitomised by the "super
power" concept promoted by the Lima Locomotive
Works, although tractive effort was still
the prime consideration after World War I
to the end of steam. Goods trains were designed
to run faster, while passenger locomotives
needed to pull heavier loads at speed. This
was achieved by increasing the size of grate
and firebox without changes to the rest of
the locomotive, requiring the addition of
a second axle to the trailing truck. Freight
2-8-2s became 2-8-4s while 2-10-2s became
2-10-4s. Similarly, passenger 4-6-2s became
4-6-4s. In the United States this led to a
convergence on the dual-purpose 4-8-4 and
the 4-6-6-4 articulated configuration, which
was used for both freight and passenger service.
Mallet locomotives went through a similar
transformation, evolving from bank engines
into huge mainline locomotives with much larger
fireboxes; their driving wheels were also
increased in size in order to allow faster
running.
== Manufacture ==
=== 
Most manufactured classes ===
The most-manufactured single class of steam
locomotive in the world is the 0-10-0 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 2-10-0 Kriegslok.
In Britain, 863 of the GWR 5700 class were
built, and 943 of the DX class of the London
and North Western Railway - including 86 engines
built for the Lancashire and Yorkshire Railway.
=== United Kingdom ===
Before the 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 and Scottish Railway, the
London and 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
allowed the former "Big Four" companies (now
designated as "Regions") to continue to produce
their own designs, but also created a range
of 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
Evening Star.
Some independent manufacturers produced steam
locomotives for a few more years, with the
last British-built industrial steam locomotive
being constructed by 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, 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" (4-6-0),
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 (2-6-4)
and class E2 (2-8-0) locomotives can now be
seen in Britain, the Netherlands, Germany
and Canada.
=== United States ===
Locomotives for American railroads were nearly
always built in the United States with very
few imports, except in the earliest days of
steam engines. This was due to the basic differences
of markets in the United States which initially
had many small markets located large distances
apart, in contrast to Europe's higher density
of markets. Locomotives that were cheap and
rugged and could go large distances over cheaply
built and maintained tracks were required.
Once the manufacture of engines was established
on a wide scale there was very little advantage
to buying an engine from overseas that would
have to be customised to fit the local requirements
and track conditions. Improvements in engine
design of both European and US origin were
incorporated by manufacturers when they could
be justified in a generally very conservative
and slow-changing market. With the notable
exception of the USRA standard locomotives
built during World War I, in the United States,
steam locomotive manufacture was always semi-customised.
Railroads ordered locomotives tailored to
their specific requirements, though some basic
design features were always present. Railroads
developed some specific characteristics; for
example, the Pennsylvania Railroad and the
Great Northern Railway had a preference for
the Belpaire firebox. In the United States,
large-scale manufacturers constructed locomotives
for nearly all rail companies, although nearly
all major railroads had shops capable of heavy
repairs and some railroads (for example, the
Norfolk and Western Railway and the Pennsylvania
Railroad, which had two erecting shops) constructed
locomotives entirely in their own shops. Companies
manufacturing locomotives in the US included
Baldwin Locomotive Works, American Locomotive
Company (Alco), and Lima Locomotive Works.
Altogether, between 1830 and 1950, over 160,000
steam locomotives were built in the United
States, with Baldwin accounting for the largest
share, nearly 70,000.Steam locomotives required
regular and, compared to a diesel-electric
engine, frequent service and overhaul (often
at government-regulated intervals in Europe
and the US). Alterations and upgrades regularly
occurred during overhauls. New appliances
were added, unsatisfactory features removed,
cylinders improved or replaced. Almost any
part of the locomotive, including boilers,
was replaced or upgraded. When service or
upgrades got too expensive the locomotive
was traded off or retired. On the Baltimore
and Ohio Railroad two 2-10-2 locomotives were
dismantled; the boilers were placed onto two
new Class T 4-8-2] locomotives and the residual
wheel machinery made into a pair of Class
U 0-10-0 switchers with new boilers. Union
Pacific's fleet of 3-cylinder 4-10-2 engines
were converted into two-cylinder engines in
1942, because of high maintenance problems.
=== Australia ===
In Sydney, Clyde Engineering and the workshops
in Eveleigh both built steam locomotives for
the New South Wales Government Railways. These
include the C38 class 4-6-2; the first five
were built at Clyde with streamlining, the
other 25 locomotives were built at Eveleigh
(13) and Cardiff Workshops (12) near Newcastle.
In Queensland, steam locomotives were locally
constructed by Walkers. Similarly, the South
Australian state government railways also
manufactured steam locomotives locally at
Islington Railway Workshops in Adelaide. Victorian
Railways constructed most of their locomotives
at their 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 2-6-2 T built for the narrow
gauge, up to the H class 4-8-4 – 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 NSWGR AD60 class 4-8-4+4-8-4
Garratt, built by Beyer-Peacock in the United
Kingdom. 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, which can cause "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.
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.
=== United States ===
The first diesel locomotive appeared on the
Central Railroad of New Jersey in 1925 and
on the New York Central in 1927. Since then,
diesel locomotives began to appear in mainline
service in the United States in the mid-1930s.
The diesel engines reduced maintenance costs
dramatically, while increasing locomotive
availability. On the Chicago, Rock Island
and Pacific Railroad the new units delivered
over 350,000 miles (560,000 km) a year, compared
with about 120,000–150,000 miles (190,000–240,000
km) for a mainline steam locomotive. World
War II delayed dieselisation in the US. In
1949 the Gulf, Mobile and Ohio Railroad became
the first large mainline railroad to convert
completely to diesel locomotives, and Life
Magazine ran an article on 5 December 1949
titled "The GM&O puts all its steam engines
to torch, becomes first major US railroad
to dieselize 100%". The Susquehanna was one
of the earliest railroads in America to fully
dieselize by 1947 and retiring their steam
locomotives by 1949. The final 2-8-4 Berkshire
built was Nickle Plate Road's 779 built in
1949. The last steam locomotive manufactured
for general service was a Norfolk and Western
0-8-0, built in its Roanoke shops in December,
1953. In Spring of 1960, Norfolk and Western
Y6b 2190 and S1 290 doused their fires for
the last time in a Williamson, West Virginia
roundhouse. 1960 is normally considered the
final year of regular Class 1 main line standard
gauge steam operation in the United States,
with operations on the Grand Trunk Western,
Illinois Central, Norfolk and Western and
Duluth Missabe and Iron Range Railroads, as
well as Canadian Pacific operations in Maine.However,
the Grand Trunk Western used some steam power
for regular passenger trains until 1961, the
last instance of this occurring unannounced
on trains 56 and 21 in the Detroit area on
20 September 1961 with 4-8-4 6323, one day
before its flue time expired. The last steam-powered
standard-gauge regular freight service by
a class 1 railroad was on the isolated Leadville
branch of the Colorado and Southern (Burlington
Lines) 11 October 1962 with 2-8-0 641. Narrow-gauge
steam was used for freight service by the
Denver and Rio Grande Western on the 250-mile
(400 km) run from Alamosa, Colorado to Farmington,
New Mexico via Durango until service ceased
on 6 December 1968. The Union Pacific is the
only Class I railroad in the US to have never
completely dieselised, at least nominally.
It has always had at least one operational
steam locomotive, Union Pacific 844, on its
roster. Some US shortlines continued steam
operations into the 1960s, and the Northwestern
Steel and Wire mill in Sterling, Illinois,
continued to operate steam locomotives until
December 1980. Two surviving sections of the
Denver and Rio Grande Western's Alamosa to
Durango narrow-gauge line mentioned above,
now operating separately as the Cumbres and
Toltec Scenic Railroad and the Durango and
Silverton Narrow Gauge Railroad, continue
to use steam locomotives and operate as tourist
railroads.
By the end of the 20th century, around 1,800
of the over 160,000 steam locomotives built
in the United States between 1830 and 1950
still existed, but with only a few still in
operating condition.
=== 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. 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, 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 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 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.
=== Germany ===
After the Second World War, Germany was divided
into the Federal Republic of Germany, with
the Deutsche Bundesbahn (founded in 1949)
as the new state-owned railway, and the German
Democratic Republic (GDR), where railway service
continued under the old pre-war name Deutsche
Reichsbahn.
For a short period after the war, both the
Bundesbahn (DB) and Reichsbahn (DR) still
placed orders for new steam locomotives. They
needed to renew the rolling stock, mostly
with steam locomotives designed for accelerated
passenger trains. Many of the existing predecessors
of those types of steam locomotives in Germany
had been lost in the battles or simply reached
the end of their lifetime, such as the famous
Prussian P 8. There was no need for new freight
train engines, however, because thousands
of the Classes 50 and 52 had been built during
the Second World War.
Because the concept of the so-called "Einheitslokomotiven",
the standard locomotives built in the 1920s
and 1930s, and still in wide use, was already
outdated in the pre-war era, a whole new design
for the new steam locomotives was developed
by DB and DR, called "Neubaudampflokomotiven"
(new-build steam locomotives). The steam locomotives
made by the DB in West Germany, under the
guidance of Friedrich Witte, represented the
latest evolution in steam locomotive construction
including fully welded frames, high-performance
boilers and roller bearings on all moving
parts. Although these new DB classes (10,
23, 65, 66 and 82) were said to be among the
finest and best-performing German steam locomotives
ever built, none of them exceeded 25 years
in service. The last one, 23 105 (still preserved),
went into service in 1959.
The Democratic Republic in East Germany began
a similar procurement plan, including engines
for a narrow gauge. The DR-Neubaudampflokomotiven
were the classes 23.10, 25.10, 50.40, 65.10,
83.10, 99.23-24 and 99.77-79. The purchase
of new-build steam locomotives by the DR ended
in 1960 with 50 4088, the last standard-gauge
steam locomotive built in Germany. No locomotive
of the classes 25.10 and 83.10 was in service
for more than 17 years. The last engines of
the classes 23.10, 65.10 and 50.40 were retired
in the late 1970s, with some units older than
25 years. Some of the narrow-gauge locomotives
are still in service for tourism purposes.
Later, during the early 1960s, the DR developed
a way to reconstruct older locomotives to
conform with contemporary requirements. The
high-speed locomotive 18 201 and the class
01.5 are examples of designs from that programme.
Around 1960, the Bundesbahn in West Germany
began to phase out all steam-hauled trains
over a period of ten years, but still had
about 5,000 of them in running condition.
Even though DB were very assertive in continuing
the electrification on the main lines – in
1963 they reached 5,000 km (3,100 mi) of electrified
routes – and dieselisation with new developed
stock, they had not completely removed steam
locomotives within the ten-year goal. In 1972,
the Hamburg and Frankfurt departments of the
DB rail networks became the first to no longer
operate steam locomotives in their areas.
The remaining steam locomotives began to gather
in rail yards in Rheine, Tübingen, Hof, Saarbrücken,
Gelsenkirchen-Bismarck and others, which soon
became popular with rail enthusiasts.
In 1975, DB's last steam express train made
its final run on the Emsland-Line from Rheine
to Norddeich in the upper north of Germany.
Two years later, on 26 October 1977, the heavy
freight engine 44 903 (computer-based new
number 043 903-4) made her final run at the
same railway yard. After this date, no regular
steam service took place on the network of
the DB until their privatisation in 1994.
In the GDR, the Reichsbahn continued steam
operation until 1988 on standard gauge tracks
for economic and political reasons, despite
strong efforts to phase out steam being made
since the 1970s. The last locomotives in service
where of the classes 50.35 and 52.80, which
hauled goods trains on rural main and branch
lines. Unlike the DB, there was never a large
concentration of steam locomotives in just
a few yards in the East, because throughout
the DR network the infrastructure for steam
locomotives remained intact until the end
of the GDR in 1990. This was also the reason
that there was never a strict "final cut"
at steam operations, with the DR continuing
to use steam locomotives from time to time
until they merged with the DB in 1994.
On their narrow-gauge lines, however, steam
locomotives continued to be used on a daily
year-round basis, mainly for tourist reasons.
The largest of these is the Harzer Schmalspurbahn
(Harz Narrow Gauge Railways) network in the
Harz Mountains, but the lines in Saxony and
on the coast of the Baltic Sea are also notable.
Even though all former DR narrow-gauge railways
have undergone privatisation, steam operations
are still commonplace there.
=== Russia ===
In the USSR, although the first mainline diesel-electric
locomotive was built in USSR in 1924, the
last steam locomotive (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 2-10-0s and LV-class 2-10-2s
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 Ji-Tong line at the end of 2005. Some
steam locomotives are as of 2019 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 2-8-2 SY 1772, finished
in 1999. As of 2011, at least six Chinese
steam locomotives exist in the United States
– 3 QJs bought by the Rail Development Corporation
(Nos. 6988 and 7081 for 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 NYSW
for tourist operations, re-painted and modified
to represent a 1920s-era US locomotive; No.
58 is operated by the Valley Railroad and
has been modified to represent New Haven Railroad
number 3025.
=== Japan ===
Owing to the destruction of most 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
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 steam passenger
train, pulled by a 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 D51-class locomotive
built in 1939, left 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.
=== 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.
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 2-6-2+2-6-2 Garratts from Hunslet
Taylor for the 2-foot (610 mm) 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 2-foot (610 mm) gauge NGG16 Garratts
operating on the privatised Port Shepstone
and Alfred County Railway (ACR) received some
L.D. Porta modifications in 1990, becoming
a new NGG16A class.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 4-8-4s 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 4-6-0, two 2-6-2s and one 2-8-2.
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.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 MOTAT) hauled a Farmers Trading
Company "Santa Special" from 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 4-8-2 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 AB class
4-6-2 tender locomotives, AB 778 and AB 795,
were retained at 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) 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.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 4-6-2
steam locomotives with the exception of a
single 2-8-2.
Indonesia has also used steam locomotives
since 1876. The last batch of E10 0-10-0 RT
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).Pakistan Railways still has
a regular steam locomotive service; a line
operates in the 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.
== Revival ==
Dramatic increases in the cost of diesel fuel
prompted several initiatives to revive steam
power. However none of these has progressed
to the point of production and, as of the
early 21st century, steam locomotives operate
only in a few isolated regions of the world
and in tourist operations.
As early as 1975, railway enthusiasts in the
United Kingdom began building new steam locomotives.
That year, Trevor Barber completed his 2 ft
(610 mm) gauge locomotive Trixie which ran
on the Meirion Mill Railway. From the 1990s
onwards, the number of new builds being completed
rose dramatically with new locos completed
by the narrow-gauge Ffestiniog and Corris
railways in Wales. The Hunslet Engine Company
was revived in 2005, and began building steam
locomotives on a commercial basis. A standard-gauge
LNER Peppercorn Pacific "Tornado" was completed
at Hopetown Works, Darlington, and made its
first run on 1 August 2008. It entered main
line service later in 2008, to great public
acclaim. Demonstration trips in France and
Germany have been planned. As of 2009 over
half-a-dozen projects to build working replicas
of extinct steam engines are going ahead,
in many cases using existing parts from other
types to build them. Examples include BR Class
6MT Hengist, BR Class 3MT No. 82045, BR Class
2MT No. 84030, Brighton Atlantic Beachy Head,
the LMS "Patriot 45551 The Unknown Warrior"
project, GWR "47xx 4709, BR" Class 6 72010
Hengist, GWR Saint 2999 Lady of Legend, 1014
County of Glamorgan and 6880 Betton Grange
projects. These United Kingdom based new build
projects are further complimented by the new
build Pennsylvania Railroad T1 class No. 5550
project in the United States, which will attempt
to surpass the speed record held by the LNER
Class A4 4468 Mallard when completed.In 1980,
American financier Ross Rowland established
American Coal Enterprises to develop a modernised
coal-fired steam locomotive. His ACE 3000
concept attracted considerable attention,
but was never built.In 1998, in his book The
Red Devil and Other Tales from the Age of
Steam, David Wardale put forward the concept
of a high-speed high-efficiency "Super Class
5 4-6-0" locomotive for future steam haulage
of tour trains on British main lines. The
idea was formalised in 2001 by the formation
of 5AT Project dedicated to developing and
building the 5AT Advanced Technology Steam
Locomotive, but it never received any major
railway backing.
Locations where new builds are taking place
include:
GWR 1014 County of Glamorgan & GWR 2999 Lady
of Legend, both being built at Didcot Railway
Centre.
GWR 6880 Betton Grange, GWR 4709 & LMS 45551
The Unknown Warrior, all being built at Llangollen
Railway.
LNER 2007 Prince of Wales, Darlington Locomotive
Works.
LNER 2001 Cock O' The North, Doncaster.
PRR 5550, Pottstown, Pennsylvania
BR 72010 Hengist, Great Central Railway.
BR 77021, TBA.
BR 82045, Severn Valley Railway.
BR 84030 & LBSCR 32424 Beachy Head, both being
built at Bluebell Railway.
MS&LR/GCR 567, Ruddington Great Central Railway,
Northern Section.
VR V499, Victoria, Australia.In 2012, the
Coalition for Sustainable Rail project was
started in the US with the goal of creating
a modern higher-speed steam locomotive, incorporating
the improvements proposed by Livio Dante Porta
and others, and using torrefied biomass as
solid fuel. The fuel has been recently developed
by the University of Minnesota in a collaboration
between the university's Institute on the
Environment (IonE) and Sustainable Rail International
(SRI), an organisation set up to explore the
use of steam traction in a modern railway
setup. The group have received the last surviving
(but non-running) ATSF 3460 class steam locomotive
(No. 3463) via donation from its previous
owner in Kansas, the Great Overland Station
Museum. They hope to use it as a platform
for developing "the world's cleanest, most
powerful passenger locomotive", capable of
speeds up to 130 mph (210 km/h). Named "Project
130", it aims to break the world steam-train
speed record set by LNER Class A4 4468 Mallard
in the UK at 126 mph (203 km/h). However,
any demonstration of the project's claims
is yet to be seen.
In Germany, a small number of fireless steam
locomotives are still working in industrial
service, e.g. at power stations, where an
on-site supply of steam is readily available.
The Swiss company Dampflokomotiv- und Maschinenfabrik
DLM AG delivered eight steam locomotives to
rack railways in Switzerland and Austria between
1992 and 1996. Four of them are now the main
traction on the Brienz Rothorn Bahn; the four
others were built for the Schafbergbahn in
Austria, where they run 90% of the trains.
The same company also rebuilt a German DR
Class 52.80 2-10-0 locomotive to new standards
with modifications such as roller bearings,
light oil firing and boiler insulation.
== 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.
== 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 "Ballad of John Henry"
are a mainstay of American music and culture.
Many steam locomotive toys have been made,
and railway modelling is a popular hobby.
Steam locomotives are often portrayed in fictional
works, notably The Railway Series by the 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 animated
movie of the same name.
An elaborate, themed funicular 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. Railroad Tycoon produced
in 1990, was as "one of the best computer
games of the year".
There are two notable examples of steam locomotives
used as charges on heraldic 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 Biedermeier Period coin, minted
11 June 2003, shows on the obverse an early
model steam locomotive (the Ajax) on Austria's
first railway line, the 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 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.
== See also ==
=== 
General ===
=== 
Types of steam locomotives ===
=== 
Historic locomotives
