A steam engine is a heat engine that performs mechanical work using
steam as its working fluid.
Steam engines are external combustion engines, where the working
fluid is separated from the combustion products. Non-combustion heat
sources such as solar power, nuclear power or geothermal energy may be
used. The ideal thermodynamic cycle used to analyze this process is
called the Rankine cycle. In the cycle, water is heated and changes
into steam in a boiler operating at a high pressure. When expanded
using pistons or turbines mechanical work is done. The
reduced-pressure steam is then exhausted to the atmosphere, or
condensed and pumped back into the boiler.
In general usage, the term steam engine can refer to either complete
steam plants (including boilers etc.) such as railway steam
locomotives and portable engines, or may refer to the piston or
turbine machinery alone, as in the beam engine and stationary steam
engine. However, a more detailed look at the steam locomotive referred
to the engine as only that part where the heat in the steam was turned
into motion of the piston, and hence enabled separate statements for
boiler efficiency and engine efficiency. Specialized devices such as
steam hammers and steam pile drivers are dependent on the steam
pressure supplied from a separate boiler.
The use of boiling water to produce mechanical motion goes back over
2000 years, but early devices were not practical. The Spanish inventor
Jerónimo de Ayanz y Beaumont obtained a patent for a rudimentary
steam-powered water pump in 1606. In 1698
Thomas Savery patented a
steam pump that used steam in direct contact with the water being
pumped. Savery's steam pump used condensing steam to create a vacuum
and draw water into a chamber, and then applied pressurized steam to
further pump the water.
Thomas Newcomen's atmospheric engine was the first commercial true
steam engine using a piston, and was used in 1712 for pumping flood
water from a mine. 104 were in use by 1733. Eventually over two
thousand of them were installed.
In 1781 Scottish engineer
James Watt patented a steam engine that
produced continuous rotary motion. Watt's ten-horsepower engines
enabled a wide range of manufacturing machinery to be powered. The
engines could be sited anywhere that water and coal or wood fuel could
be obtained. By 1883, engines that could provide 10,000 hp had
become feasible. The stationary steam engine was a key component of
the Industrial Revolution, allowing factories to locate where water
power was unavailable. The atmospheric engines of Newcomen and Watt
were large compared to the amount of power they produced, but
high-pressure steam engines were light enough to be applied to
vehicles such as traction engines and railway locomotives.
Reciprocating piston type steam engines remained the dominant source
of power until the early 20th century, when advances in the design of
electric motors and internal combustion engines gradually resulted in
the replacement of reciprocating (piston) steam engines in commercial
usage, and the ascendancy of steam turbines in power generation.
Considering that the great majority of worldwide electric generation
is produced by turbine type steam engines, the "steam age" is
continuing with energy levels far beyond those of the turn of the 19th
and 20th century.
1.1 Early designs and modifications
1.2 Early experiments
1.3 Pumping engines
Piston steam engines
1.5 High-pressure engines
1.6 Horizontal stationary engine
1.7 Road vehicles
1.8 Marine engines
1.11 Present development
2 Components and accessories of steam engines
2.1 Heat source
2.3 Motor units
2.4 Cold sink
2.5 Water pump
2.6 Monitoring and control
3 Engine configuration
3.1 Simple engine
3.2 Compound engines
3.3 Multiple-expansion engines
4 Types of motor units
4.1 Reciprocating piston
4.2 Uniflow (or unaflow) engine
4.4 Oscillating cylinder steam engines
4.5 Rotary steam engines
4.6 Rocket type
8 See also
11 Further reading
12 External links
Early designs and modifications
History of the steam engine
History of the steam engine and Timeline of steam power
Although steam powered devices were developed before the first
practical piston steam engine, they were not directly connected to the
Newcomen atmospheric engine. The Newcomen engine owes its development
to the discovery of atmospheric pressure and to shared technical
information whose path is traceable. For development of the commercial
steam engine see: History of the steam engine#Development of the
commercial steam engine
In Roman Egypt, the aeolipile (also known as a Hero's engine)
Hero of Alexandria
Hero of Alexandria in the 1st century AD is considered to
be the first recorded steam engine. Torque was produced by steam jets
exiting the turbine.
In Ottoman Egypt, the inventor Taqi al-Din Muhammad ibn Ma'ruf
described a steam turbine device for rotating a spit in 1551.
In the Spanish Empire, the inventor Jerónimo de Ayanz y Beaumont
obtained a patent for a rudimentary steam-powered water pump in 1606.
Thomas Savery, in 1698, patented the first practical, atmospheric
pressure, steam engine of 1 horsepower (750 W). It had no piston
or moving parts, only taps. It was a fire engine, a kind of thermic
syphon, in which steam was admitted to an empty container and then
condensed. The vacuum thus created was used to suck water from the
sump at the bottom of the mine. The "fire engine" had to be mounted
within 25 ft (8 m) of the water level though it could then
lift the water another 80 ft (24 m) using positive pressure.
Thomas Newcomen, in 1712, developed the first commercially successful
piston steam engine of 5 horsepower (3,700 W). Its principle was
to condense steam in a cylinder, thus causing atmospheric pressure to
drive a piston and produce mechanical work.
James Watt, in 1781, patented a steam engine that produced continued
rotary motion with a power of about 10 horsepower (7,500 W). It
was the first type of steam engine to make use of steam at a pressure
just above atmospheric to drive the piston helped by a partial vacuum.
It was an improvement of Newcomen's engine.
Richard Trevithick invented the lightweight, high-pressure steam
engine in 1797-1799, steam engines became small enough to be used in
smaller businesses and for use in steam locomotives.
Steam power during the Industrial Revolution
Since the early 18th century, steam power has been applied to a
variety of practical uses. At first it powered reciprocating pumps,
but from the 1780s rotative engines (those converting reciprocating
motion into rotary motion) began to appear, driving factory machinery
such as power looms. Speed control in response to changing load made
direct application of a steam engine to spinning machinery impractical
until the invention of the Corliss engine in 1848. Until then steam
engines were used to pump water to turn a water wheel, which powered
the spinning machinery. At the turn of the 19th century,
steam-powered transport on both sea and land began to make its
appearance, becoming more dominant as the century progressed.
Steam engines can be said to have been the moving force behind the
Industrial Revolution and saw widespread commercial use driving
machinery in factories, mills and mines; powering pumping stations;
and propelling transport appliances such as railway locomotives,
ships, steamboats and road vehicles. Their use in agriculture led to
an increase in the land available for cultivation. There have at one
time or another been steam-powered farm tractors, motorcycles (without
much success) and even automobiles as the Stanley Steamer.
The weight of boilers and condensers generally makes the
power-to-weight ratio of a steam plant lower than for internal
combustion engines. For mobile applications steam has been largely
superseded by internal combustion engines or electric motors. However,
most electric power is generated using steam turbine plant, so that
indirectly the world's industry is still dependent on steam power.
Recent concerns about fuel sources and pollution have incited a
renewed interest in steam both as a component of cogeneration
processes and as a prime mover. This is becoming known as the Advanced
Steam movement.
The history of the steam engine stretches back as far as the first
century; the first recorded rudimentary steam-powered "engine" being
the aeolipile described by Hero of Alexandria, a mathematician and
engineer in Roman Egypt. In the following centuries, the few
steam-powered "engines" known were, like the aeolipile,
essentially experimental devices used by inventors to demonstrate the
properties of steam. A rudimentary steam turbine device was described
by Taqi al-Din in
Ottoman Egypt in 1551 and by Giovanni Branca
Italy in 1629.
Jerónimo de Ayanz y Beaumont received patents
in 1606 for fifty steam powered inventions, including a water pump for
draining inundated mines. Denis Papin, a
Huguenot refugee, did
some useful work on the steam digester in 1679, and first used a
piston to raise weights in 1690.
The first commercial steam-powered device was a water pump, developed
in 1698 by Thomas Savery. It used condensing steam to create a
vacuum which was used to raise water from below, then it used steam
pressure to raise it higher. Small engines were effective though
larger models were problematic. They proved only to have a limited
lift height and were prone to boiler explosions. It received some use
in mines, pumping stations and for supplying water wheels used to
power textile machinery. An attractive feature of the Savery
engine was its low cost.
Bento de Moura Portugal introduced an
ingenious improvement of Savery's construction "to render it capable
of working itself", as described by
John Smeaton in the Philosophical
Transactions published in 1751. It continued to be manufactured
until the late 18th century. One engine was still known to be
operating in 1820.
Piston steam engines
Steam engine 1720
The first commercially successful true engine, in that it could
generate power and transmit it to a machine, was the atmospheric
engine, invented by
Thomas Newcomen around 1712. It was an
improvement over Savery's steam pump, using a piston as proposed by
Papin. Newcomen's engine was relatively inefficient, and in most cases
was used for pumping water. It worked by creating a partial vacuum by
condensing steam under a piston within a cylinder. It was employed for
draining mine workings at depths hitherto impossible, and also for
providing a reusable water supply for driving waterwheels at factories
sited away from a suitable "head". Water that had passed over the
wheel was pumped back up into a storage reservoir above the wheel.
Jacob Leupold described a two-cylinder high-pressure steam
engine. The invention was published in his major work "Theatri
Machinarum Hydraulicarum". The engine used two heavy pistons to
provide motion to a water pump. Each piston was raised by the steam
pressure and returned to its original position by gravity. The two
pistons shared a common four way rotary valve connected directly to a
Early Watt pumping engine
The next major step occurred when
James Watt developed (1763–1775)
an improved version of Newcomen's engine, with a separate condenser.
Boulton and Watt's early engines used half as much coal as John
Smeaton's improved version of Newcomen's. Newcomen's and Watt's
early engines were "atmospheric". They were powered by air pressure
pushing a piston into the partial vacuum generated by condensing
steam, instead of the pressure of expanding steam. The engine
cylinders had to be large because the only usable force acting on them
was due to atmospheric pressure.
Watt proceeded to develop his engine further, modifying it to provide
a rotary motion suitable for driving factory machinery. This enabled
factories to be sited away from rivers, and further accelerated the
pace of the Industrial Revolution.
The meaning of high pressure, together with an actual value above
ambient, depends on the era in which the term was used. For early use
of the term Van Reimsdijk refers to steam being at a sufficiently
high pressure that it could be exhausted to atmosphere without
reliance on a vacuum to enable it to perform useful work. Ewing
states that Watt's condensing engines were known, at the time, as low
pressure compared to high pressure, non-condensing engines of the same
Watt's patent prevented others from making high pressure and compound
engines. Shortly after Watt's patent expired in 1800, Richard
Trevithick and, separately,
Oliver Evans in 1801 introduced
engines using high-pressure steam; Trevithick obtained his
high-pressure engine patent in 1802, and Evans had made several
working models before then. These were much more powerful for a
given cylinder size than previous engines and could be made small
enough for transport applications. Thereafter, technological
developments and improvements in manufacturing techniques (partly
brought about by the adoption of the steam engine as a power source)
resulted in the design of more efficient engines that could be
smaller, faster, or more powerful, depending on the intended
Cornish engine was developed by Trevithick and others in the
1810s. It was a compound cycle engine that used high-pressure
steam expansively, then condensed the low-pressure steam, making it
relatively efficient. The
Cornish engine had irregular motion and
torque though the cycle, limiting it mainly to pumping. Cornish
engines were used in mines and for water supply until the late 19th
Horizontal stationary engine
Main article: Stationary steam engine
Early builders of stationary steam engines considered that horizontal
cylinders would be subject to excessive wear. Their engines were
therefore arranged with the piston axis vertical. In time the
horizontal arrangement became more popular, allowing compact, but
powerful engines to be fitted in smaller spaces.
The acme of the horizontal engine was the Corliss steam engine,
patented in 1849, which was a four-valve counter flow engine with
separate steam admission and exhaust valves and automatic variable
steam cutoff. When Corliss was given the Rumford Medal, the committee
said that "no one invention since Watt's time has so enhanced the
efficiency of the steam engine". In addition to using 30% less
steam, it provided more uniform speed due to variable steam cut off,
making it well suited to manufacturing, especially cotton
Main article: History of steam road vehicles
The first experimental road going steam powered vehicles were built in
the late 18th century, but it was not until after Richard Trevithick
had developed the use of high-pressure steam, around 1800, that mobile
steam engines became a practical proposition. The first half of the
19th century saw great progress in steam vehicle design, and by the
1850s it was becoming viable to produce them on a commercial basis.
This progress was dampened by legislation which limited or prohibited
the use of steam powered vehicles on roads. Improvements in vehicle
technology continued from the 1860s to the 1920s.
Steam road vehicles
were used for many applications. In the 20th century, the rapid
development of internal combustion engine technology led to the demise
of the steam engine as a source of propulsion of vehicles on a
commercial basis, with relatively few remaining in use beyond the
Second World War. Many of these vehicles were acquired by enthusiasts
for preservation, and numerous examples are still in existence. In the
1960s the air pollution problems in California gave rise to a brief
period of interest in developing and studying steam powered vehicles
as a possible means of reducing the pollution. Apart from interest by
steam enthusiasts, the occasional replica vehicle, and experimental
technology no steam vehicles are in production at present.
A triple-expansion marine steam engine on the 1907 oceangoing tug
Main article: Marine steam engine
Near the end of the 19th century compound engines came into widespread
use. Compound engines exhausted steam in to successively larger
cylinders to accommodate the higher volumes at reduced pressures,
giving improved efficiency. These stages were called expansions, with
double- and triple-expansion engines being common, especially in
shipping where efficiency was important to reduce the weight of coal
Steam engines remained the dominant source of power until
the early 20th century, when advances in the design of electric motors
and internal combustion engines gradually resulted in the replacement
of reciprocating (piston) steam engines, with shipping in the
20th-century relying upon the steam turbine.
Steam locomotive and Traction engine
As the development of steam engines progressed through the 18th
century, various attempts were made to apply them to road and railway
use. In 1784, William Murdoch, a Scottish inventor, built a
prototype steam road locomotive. An early working model of a steam
rail locomotive was designed and constructed by steamboat pioneer John
Fitch in the United States probably during the 1780s or 1790s. His
steam locomotive used interior bladed wheels guided by rails or
The first full-scale working railway steam locomotive was built by
Richard Trevithick in the United Kingdom and, on 21 February 1804, the
world's first railway journey took place as Trevithick's unnamed steam
locomotive hauled a train along the tramway from the Pen-y-darren
Merthyr Tydfil to
Abercynon in south
Wales. 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 later in 1804 and the colliery railways in
north-east England became the leading centre for experimentation and
development of steam locomotives.
Trevithick continued his own experiments using a trio of locomotives,
concluding with the
Catch Me Who Can
Catch Me Who Can in 1808. Only four years later,
the successful twin-cylinder locomotive Salamanca by Matthew Murray
was used by the edge railed rack and pinion Middleton Railway. In
George Stephenson built the Locomotion for the Stockton and
Darlington Railway. This was the first public steam railway in the
world and then in 1829, he built The Rocket which was entered in and
won the Rainhill Trials. The Liverpool and Manchester Railway
opened in 1830 making exclusive use of steam power for both passenger
and freight trains.
Steam locomotives continued to be manufactured until the late
twentieth century in places such as China and the former East Germany
DR Class 52.80
DR Class 52.80 was produced).
The final major evolution of the steam engine design was the use of
steam turbines starting in the late part of the 19th century. Steam
turbines are generally more efficient than reciprocating piston type
steam engines (for outputs above several hundred horsepower), have
fewer moving parts, and provide rotary power directly instead of
through a connecting rod system or similar means.
virtually replaced reciprocating engines in electricity generating
stations early in the 20th century, where their efficiency, higher
speed appropriate to generator service, and smooth rotation were
advantages. Today most electric power is provided by steam turbines.
In the United States 90% of the electric power is produced in this way
using a variety of heat sources.
Steam turbines were extensively
applied for propulsion of large ships throughout most of the 20th
Main article: Advanced steam technology
Although the reciprocating steam engine is no longer in widespread
commercial use, various companies are exploring or exploiting the
potential of the engine as an alternative to internal combustion
engines. The company Energiprojekt AB in
Sweden has made progress in
using modern materials for harnessing the power of steam. The
efficiency of Energiprojekt's steam engine reaches some 27-30% on
high-pressure engines. It is a single-step, 5-cylinder engine (no
compound) with superheated steam and consumes approx. 4 kg
(8.8 lb) of steam per kWh.[not in citation given]
Components and accessories of steam engines
There are two fundamental components of a steam plant: the boiler or
steam generator, and the "motor unit", referred to itself as a "steam
engine". Stationary steam engines in fixed buildings may have the
boiler and engine in separate buildings some distance apart. For
portable or mobile use, such as steam locomotives, the two are mounted
The widely used reciprocating engine typically consisted of a cast
iron cylinder, piston, connecting rod and beam or a crank and
flywheel, and miscellaneous linkages.
Steam was alternately supplied
and exhausted by one or more valves. Speed control was either
automatic, using a governor, or by a manual valve. The cylinder
casting contained steam supply and exhaust ports.
Engines equipped with a condenser are a separate type than those that
exhaust to the atmosphere.
Other components are often present; pumps (such as an injector) to
supply water to the boiler during operation, condensers to recirculate
the water and recover the latent heat of vaporisation, and
superheaters to raise the temperature of the steam above its saturated
vapour point, and various mechanisms to increase the draft for
fireboxes. When coal is used, a chain or screw stoking mechanism and
its drive engine or motor may be included to move the fuel from a
supply bin (bunker) to the firebox. See: Mechanical stoker
The heat required for boiling the water and raising the temperature of
the steam can be derived from various sources, most commonly from
burning combustible materials with an appropriate supply of air in a
closed space (called variously combustion chamber, firebox, furnace).
In some cases the heat source is a nuclear reactor, geothermal energy,
solar energy or waste heat from an internal combustion engine or
industrial process. In the case of model or toy steam engines, the
heat source can be an electric heating element.
Boiler (steam generator)
An industrial boiler used for a stationary steam engine
Boilers are pressure vessels that contain water to be boiled, and
features that transfer the heat to the water as effectively as
The two most common types are:
water-tube boiler – water is passed through tubes surrounded by hot
fire-tube boiler – hot gas is passed through tubes immersed in
water, the same water also circulates in a water jacket surrounding
the firebox and, in high-output locomotive boilers, also passes
through tubes in the firebox itself (thermic syphons and security
Fire tube boilers were the main type used for early high-pressure
steam (typical steam locomotive practice), but they were to a large
extent displaced by more economical water tube boilers in the late
19th century for marine propulsion and large stationary applications.
Many boilers raise the temperature of the steam after it has left that
part of the boiler where it is in contact with the water. Known as
superheating it turns 'wet steam' into 'superheated steam'. It avoids
the steam condensing in the engine cylinders, and gives a
significantly higher efficiency.
Further information: § Types of motor units
In a steam engine, a piston or steam turbine or any other similar
device for doing mechanical work takes a supply of steam at high
pressure and temperature and gives out a supply of steam at lower
pressure and temperature, using as much of the difference in steam
energy as possible to do mechanical work.
These "motor units" are often called 'steam engines' in their own
right. Engines using compressed air or other gases differ from steam
engines only in details that depend on the nature of the gas although
compressed air has been used in steam engines without change.
As with all heat engines, the majority of primary energy must be
emitted as waste heat at relatively low temperature.
The simplest cold sink is to vent the steam to the environment. This
is often used on steam locomotives, as the released steam is vented up
the chimney so as to increase the draw on the fire, which greatly
increases engine power, but reduces efficiency.
Sometimes the waste heat is useful itself, and in those cases very
high overall efficiency can be obtained. For example, combined heat
and power (CHP) systems use the waste steam for district heating,
exceeding 80% combined efficiency.
Where CHP is not used, steam turbines in stationary power plants use
surface condensers as a cold sink. The condensers are cooled by water
flow from oceans, rivers, lakes, and often by cooling towers which
evaporate water to provide cooling energy removal. The resulting
condensed hot water, is then pumped back up to pressure and sent back
to the boiler. A dry type cooling tower is similar to an automobile
radiator and is used in locations where water is costly. Waste heat
can also be ejected by evaporative (wet) cooling towers use pass the
rejected to external water cycle that evaporates some of flow to the
air.[clarification needed] Cooling towers often have visible plumes
due to the evaporated water condensing into droplets carried up by the
warm air. Evaporative cooling towers need less water flow than
"once-through" cooling by river or lake water; a 700 megawatt
coal-fired power plant may use about 3600 cubic metres of make-up
water every hour for evaporative cooling, but would need about twenty
times as much if cooled by river water. Evaporative water
cannot be used for subsequent purposes (other than rain somewhere),
whereas river water can be re-used. In all cases, the steam plant
water, which must be kept pure, is kept separate from the cooling
water or air, and once the low-pressure steam condenses into water, it
is returned to the boiler.
An injector uses a jet of steam to force water into the boiler.
Injectors are inefficient but simple enough to be suitable for use on
Rankine cycle and most practical steam engines have a water pump
to recycle or top up the boiler water, so that they may be run
continuously. Utility and industrial boilers commonly use multi-stage
centrifugal pumps; however, other types are used. Another means of
supplying lower-pressure boiler feed water is an injector, which uses
a steam jet usually supplied from the boiler. Injectors became popular
in the 1850s but are no longer widely used, except in applications
such as steam locomotives. It is the pressurization of the water
that circulates through the steam boiler that allows the water to be
raised to temperatures well above 100 °C boiling point of water
at one atmospheric pressure, and by that means to increase the
efficiency of the steam cycle.
Monitoring and control
Richard's indicator instrument of 1875. See:
Indicator diagram (below)
For safety reasons, nearly all steam engines are equipped with
mechanisms to monitor the boiler, such as a pressure gauge and a sight
glass to monitor the water level.
Many engines, stationary and mobile, are also fitted with a governor
to regulate the speed of the engine without the need for human
The most useful instrument for analyzing the performance of steam
engines is the steam engine indicator. Early versions were in use by
1851, but the most successful indicator was developed for the high
speed engine inventor and manufacturer Charles Porter by Charles
Richard and exhibited at London Exhibition in 1862. The steam
engine indicator traces on paper the pressure in the cylinder
throughout the cycle, which can be used to spot various problems and
calculate developed horsepower. It was routinely used by
engineers, mechanics and insurance inspectors. The engine indicator
can also be used on internal combustion engines. See image of
indicator diagram below (in Types of motor units section).
Centrifugal governor in the Boulton & Watt engine 1788 Lap Engine.
Main article: Governor (device)
The centrifugal governor was adopted by
James Watt for use on a steam
engine in 1788 after Watt's partner Boulton saw one on the equipment
of a flour mill Boulton & Watt were building. The governor
could not actually hold a set speed, because it would assume a new
constant speed in response to load changes. The governor was able to
handle smaller variations such as those caused by fluctuating heat
load to the boiler. Also, there was a tendency for oscillation
whenever there was a speed change. As a consequence, engines equipped
only with this governor were not suitable for operations requiring
constant speed, such as cotton spinning. The governor was improved
over time and coupled with variable steam cut off, good speed control
in response to changes in load was attainable near the end of the 19th
In a simple engine, or "single expansion engine" the charge of steam
passes through the entire expansion process in an individual cylinder,
although a simple engine may have one or more individual
cylinders. It is then exhausted directly into the atmosphere or
into a condenser. As steam expands in passing through a high-pressure
engine, its temperature drops because no heat is being added to the
system; this is known as adiabatic expansion and results in steam
entering the cylinder at high temperature and leaving at lower
temperature. This causes a cycle of heating and cooling of the
cylinder with every stroke, which is a source of inefficiency.
The dominant efficiency loss in reciprocating steam engines is
cylinder condensation and re-evaporation. The steam cylinder and
adjacent metal parts/ports operate at a temperature about half way
between the steam admission saturation temperature and the saturation
temperature corresponding to the exhaust pressure. As high pressure
steam is admitted into the working cylinder, much of the high
temperature steam is condensed as water droplets onto the metal
surfaces, significantly reducing the steam available for expansive
work. When the expanding steam reaches low pressure (especially during
the exhaust stroke), the previously deposited water droplets that had
just been formed within the cylinder/ports now boil away
(re-evaporation) and this steam does no further work in the cylinder.
There are practical limits on the expansion ratio of a steam engine
cylinder, as increasing cylinder surface area tends to exacerbate the
cylinder condensation and re-evaporation issues. This negates the
theoretical advantages associated with a high ratio of expansion in an
Main article: Compound engine
A method to lessen the magnitude of energy loss to a very long
cylinder was invented in 1804 by British engineer Arthur Woolf, who
patented his Woolf high-pressure compound engine in 1805. In the
compound engine, high-pressure steam from the boiler expands in a
high-pressure (HP) cylinder and then enters one or more subsequent
lower-pressure (LP) cylinders. The complete expansion of the steam now
occurs across multiple cylinders, with the overall temperature drop
within each cylinder reduced considerably. By expanding the steam in
steps with smaller temperature range (within each cylinder) the
condensation and re-evaporation efficiency issue (described above) is
reduced. This reduces the magnitude of cylinder heating and cooling,
increasing the efficiency of the engine. By staging the expansion in
multiple cylinders, variations of torque can be reduced. To derive
equal work from lower-pressure cylinder requires a larger cylinder
volume as this steam occupies a greater volume. Therefore, the bore,
and in rare cases the stroke, are increased in low-pressure cylinders,
resulting in larger cylinders.
Double-expansion (usually known as compound) engines expanded the
steam in two stages. The pairs may be duplicated or the work of the
large low-pressure cylinder can be split with one high-pressure
cylinder exhausting into one or the other, giving a three-cylinder
layout where cylinder and piston diameter are about the same, making
the reciprocating masses easier to balance.
Two-cylinder compounds can be arranged as:
Cross compounds: The cylinders are side by side.
Tandem compounds: The cylinders are end to end, driving a common
Angle compounds: The cylinders are arranged in a V (usually at a 90°
angle) and drive a common crank.
With two-cylinder compounds used in railway work, the pistons are
connected to the cranks as with a two-cylinder simple at 90° out of
phase with each other (quartered). When the double-expansion group is
duplicated, producing a four-cylinder compound, the individual pistons
within the group are usually balanced at 180°, the groups being set
at 90° to each other. In one case (the first type of Vauclain
compound), the pistons worked in the same phase driving a common
crosshead and crank, again set at 90° as for a two-cylinder engine.
With the three-cylinder compound arrangement, the LP cranks were
either set at 90° with the HP one at 135° to the other two, or in
some cases all three cranks were set at 120°.
The adoption of compounding was common for industrial units, for road
engines and almost universal for marine engines after 1880; it was not
universally popular in railway locomotives where it was often
perceived as complicated. This is partly due to the harsh railway
operating environment and limited space afforded by the loading gauge
(particularly in Britain, where compounding was never common and not
employed after 1930). However, although never in the majority, it was
popular in many other countries.
Main article: Compound engine
An animation of a simplified triple-expansion engine.
High-pressure steam (red) enters from the boiler and passes through
the engine, exhausting as low-pressure steam (blue), usually to a
It is a logical extension of the compound engine (described above) to
split the expansion into yet more stages to increase efficiency. The
result is the multiple-expansion engine. Such engines use either three
or four expansion stages and are known as triple- and
quadruple-expansion engines respectively. These engines use a series
of cylinders of progressively increasing diameter. These cylinders are
designed to divide the work into equal shares for each expansion
stage. As with the double-expansion engine, if space is at a premium,
then two smaller cylinders may be used for the low-pressure stage.
Multiple-expansion engines typically had the cylinders arranged
inline, but various other formations were used. In the late 19th
century, the Yarrow-Schlick-Tweedy balancing "system" was used on some
marine triple-expansion engines. Y-S-T engines divided the
low-pressure expansion stages between two cylinders, one at each end
of the engine. This allowed the crankshaft to be better balanced,
resulting in a smoother, faster-responding engine which ran with less
vibration. This made the four-cylinder triple-expansion engine popular
with large passenger liners (such as the Olympic class), but this was
ultimately replaced by the virtually vibration-free turbine
engine. It is noted however that triple expansion
reciprocating steam engines were used to drive the WWII Liberty ships,
by far the largest number of identical ships ever built. 2700 ships
were built, in the USA, from a British original design.
The image to the right shows an animation of a triple-expansion
engine. The steam travels through the engine from left to right. The
valve chest for each of the cylinders is to the left of the
Land-based steam engines could exhaust their steam to atmosphere, as
feed water was usually readily available. Prior to and during World
War I, the expansion engine dominated marine applications, where high
vessel speed was not essential. It was, however, superseded by the
British invention steam turbine where speed was required, for instance
in warships, such as the dreadnought battleships, and ocean liners.
HMS Dreadnought of 1905 was the first major warship to replace
the proven technology of the reciprocating engine with the then-novel
steam turbine.
Types of motor units
Double acting stationary engine. This was the common mill engine of
the mid 19th century. Note the slide valve with concave, almost "D"
Indicator diagram showing the four events in a double piston
stroke. See: Monitoring and control (above)
Main article: Reciprocating engine
In most reciprocating piston engines, the steam reverses its direction
of flow at each stroke (counterflow), entering and exhausting from the
same end of the cylinder. The complete engine cycle occupies one
rotation of the crank and two piston strokes; the cycle also comprises
four events – admission, expansion, exhaust, compression. These
events are controlled by valves often working inside a steam chest
adjacent to the cylinder; the valves distribute the steam by opening
and closing steam ports communicating with the cylinder end(s) and are
driven by valve gear, of which there are many types.
The simplest valve gears give events of fixed length during the engine
cycle and often make the engine rotate in only one direction. Many
however have a reversing mechanism which additionally can provide
means for saving steam as speed and momentum are gained by gradually
"shortening the cutoff" or rather, shortening the admission event;
this in turn proportionately lengthens the expansion period. However,
as one and the same valve usually controls both steam flows, a short
cutoff at admission adversely affects the exhaust and compression
periods which should ideally always be kept fairly constant; if the
exhaust event is too brief, the totality of the exhaust steam cannot
evacuate the cylinder, choking it and giving excessive compression
("kick back").
In the 1840s and 50s, there were attempts to overcome this problem by
means of various patent valve gears with a separate, variable cutoff
expansion valve riding on the back of the main slide valve; the latter
usually had fixed or limited cutoff. The combined setup gave a fair
approximation of the ideal events, at the expense of increased
friction and wear, and the mechanism tended to be complicated. The
usual compromise solution has been to provide lap by lengthening
rubbing surfaces of the valve in such a way as to overlap the port on
the admission side, with the effect that the exhaust side remains open
for a longer period after cut-off on the admission side has occurred.
This expedient has since been generally considered satisfactory for
most purposes and makes possible the use of the simpler Stephenson,
Joy and Walschaerts motions. Corliss, and later, poppet valve gears
had separate admission and exhaust valves driven by trip mechanisms or
cams profiled so as to give ideal events; most of these gears never
succeeded outside of the stationary marketplace due to various other
issues including leakage and more delicate mechanisms.
Before the exhaust phase is quite complete, the exhaust side of the
valve closes, shutting a portion of the exhaust steam inside the
cylinder. This determines the compression phase where a cushion of
steam is formed against which the piston does work whilst its velocity
is rapidly decreasing; it moreover obviates the pressure and
temperature shock, which would otherwise be caused by the sudden
admission of the high-pressure steam at the beginning of the following
The above effects are further enhanced by providing lead: as was later
discovered with the internal combustion engine, it has been found
advantageous since the late 1830s to advance the admission phase,
giving the valve lead so that admission occurs a little before the end
of the exhaust stroke in order to fill the clearance volume comprising
the ports and the cylinder ends (not part of the piston-swept volume)
before the steam begins to exert effort on the piston.
Uniflow (or unaflow) engine
Schematic animation of a uniflow steam engine.
The poppet valves are controlled by the rotating camshaft at the top.
High-pressure steam enters, red, and exhausts, yellow.
Main article: Uniflow steam engine
Uniflow engines attempt to remedy the difficulties arising from the
usual counterflow cycle where, during each stroke, the port and the
cylinder walls will be cooled by the passing exhaust steam, whilst the
hotter incoming admission steam will waste some of its energy in
restoring working temperature. The aim of the uniflow is to remedy
this defect and improve efficiency by providing an additional port
uncovered by the piston at the end of each stroke making the steam
flow only in one direction. By this means, the simple-expansion
uniflow engine gives efficiency equivalent to that of classic compound
systems with the added advantage of superior part-load performance,
and comparable efficiency to turbines for smaller engines below one
thousand horsepower. However, the thermal expansion gradient uniflow
engines produce along the cylinder wall gives practical
difficulties.. The
Quasiturbine is a uniflow rotary
steam engine where steam intakes in hot areas, while exhausting in
A rotor of a modern steam turbine, used in a power plant
A steam turbine consists of one or more rotors (rotating discs)
mounted on a drive shaft, alternating with a series of stators (static
discs) fixed to the turbine casing. The rotors have a propeller-like
arrangement of blades at the outer edge.
Steam acts upon these blades,
producing rotary motion. The stator consists of a similar, but fixed,
series of blades that serve to redirect the steam flow onto the next
rotor stage. A steam turbine often exhausts into a surface condenser
that provides a vacuum. The stages of a steam turbine are typically
arranged to extract the maximum potential work from a specific
velocity and pressure of steam, giving rise to a series of variably
sized high- and low-pressure stages. Turbines are only efficient if
they rotate at relatively high speed, therefore they are usually
connected to reduction gearing to drive lower speed applications, such
as a ship's propeller. In the vast majority of large electric
generating stations, turbines are directly connected to generators
with no reduction gearing. Typical speeds are 3600 revolutions per
minute (RPM) in the USA with 60 Hertz power, and 3000 RPM in Europe
and other countries with 50 Hertz electric power systems. In nuclear
power applications the turbines typically run at half these speeds,
1800 RPM and 1500 RPM. A turbine rotor is also only capable of
providing power when rotating in one direction. Therefore, a reversing
stage or gearbox is usually required where power is required in the
Steam turbines provide direct rotational force and therefore do not
require a linkage mechanism to convert reciprocating to rotary motion.
Thus, they produce smoother rotational forces on the output shaft.
This contributes to a lower maintenance requirement and less wear on
the machinery they power than a comparable reciprocating
Turbinia – the first steam turbine-powered ship
The main use for steam turbines is in electricity generation (in the
1990s about 90% of the world's electric production was by use of steam
turbines) however the recent widespread application of large gas
turbine units and typical combined cycle power plants has resulted in
reduction of this percentage to the 80% regime for steam turbines. In
electricity production, the high speed of turbine rotation matches
well with the speed of modern electric generators, which are typically
direct connected to their driving turbines. In marine service,
(pioneered on the Turbinia), steam turbines with reduction gearing
Turbinia has direct turbines to propellers with no
reduction gearbox) dominated large ship propulsion throughout the late
20th century, being more efficient (and requiring far less
maintenance) than reciprocating steam engines. In recent decades,
reciprocating Diesel engines, and gas turbines, have almost entirely
supplanted steam propulsion for marine applications.
Virtually all nuclear power plants generate electricity by heating
water to provide steam that drives a turbine connected to an
electrical generator. Nuclear-powered ships and submarines either use
a steam turbine directly for main propulsion, with generators
providing auxiliary power, or else employ turbo-electric transmission,
where the steam drives a turbo generator set with propulsion provided
by electric motors. A limited number of steam turbine railroad
locomotives were manufactured. Some non-condensing direct-drive
locomotives did meet with some success for long haul freight
Sweden and for express passenger work in Britain, but
were not repeated. Elsewhere, notably in the U.S.A., more advanced
designs with electric transmission were built experimentally, but not
reproduced. It was found that steam turbines were not ideally suited
to the railroad environment and these locomotives failed to oust the
classic reciprocating steam unit in the way that modern diesel and
electric traction has done.
Operation of a simple oscillating cylinder steam engine
Oscillating cylinder steam engines
Main article: Oscillating cylinder steam engine
An oscillating cylinder steam engine is a variant of the simple
expansion steam engine which does not require valves to direct steam
into and out of the cylinder. Instead of valves, the entire cylinder
rocks, or oscillates, such that one or more holes in the cylinder line
up with holes in a fixed port face or in the pivot mounting
(trunnion). These engines are mainly used in toys and models, because
of their simplicity, but have also been used in full size working
engines, mainly on ships where their compactness is valued.[citation
Rotary steam engines
It is possible to use a mechanism based on a pistonless rotary engine
such as the
Wankel engine in place of the cylinders and valve gear of
a conventional reciprocating steam engine. Many such engines have been
designed, from the time of
James Watt to the present day, but
relatively few were actually built and even fewer went into quantity
production; see link at bottom of article for more details. The major
problem is the difficulty of sealing the rotors to make them
steam-tight in the face of wear and thermal expansion; the resulting
leakage made them very inefficient. Lack of expansive working, or any
means of control of the cutoff, is also a serious problem with many
such designs.
By the 1840s, it was clear that the concept had inherent problems and
rotary engines were treated with some derision in the technical press.
However, the arrival of electricity on the scene, and the obvious
advantages of driving a dynamo directly from a high-speed engine, led
to something of a revival in interest in the 1880s and 1890s, and a
few designs had some limited success.. The
Quasiturbine is a new type of uniflow rotary steam engine.
Of the few designs that were manufactured in quantity, those of the
Hult Brothers Rotary
Steam Engine Company of Stockholm, Sweden, and
the spherical engine of
Beauchamp Tower are notable. Tower's engines
were used by the
Great Eastern Railway
Great Eastern Railway to drive lighting dynamos on
their locomotives, and by the
Admiralty for driving dynamos on board
the ships of the Royal Navy. They were eventually replaced in these
niche applications by steam turbines.
An aeolipile rotates due to the steam escaping from the arms. No
practical use was made of this effect.
The aeolipile represents the use of steam by the rocket-reaction
principle, although not for direct propulsion.
In more modern times there has been limited use of steam for rocketry
– particularly for rocket cars.
Steam rocketry works by filling a
pressure vessel with hot water at high pressure and opening a valve
leading to a suitable nozzle. The drop in pressure immediately boils
some of the water and the steam leaves through a nozzle, creating a
Steam engines possess boilers and other components that are pressure
vessels that contain a great deal of potential energy.
and boiler explosions (typically BLEVEs) can and have in the past
caused great loss of life. While variations in standards may exist in
different countries, stringent legal, testing, training, care with
manufacture, operation and certification is applied to ensure safety.
Failure modes may include:
over-pressurisation of the boiler
insufficient water in the boiler causing overheating and vessel
buildup of sediment and scale which cause local hot spots, especially
in riverboats using dirty feed water
pressure vessel failure of the boiler due to inadequate construction
escape of steam from pipework/boiler causing scalding
Steam engines frequently possess two independent mechanisms for
ensuring that the pressure in the boiler does not go too high; one may
be adjusted by the user, the second is typically designed as an
ultimate fail-safe. Such safety valves traditionally used a simple
lever to restrain a plug valve in the top of a boiler. One end of the
lever carried a weight or spring that restrained the valve against
steam pressure. Early valves could be adjusted by engine drivers,
leading to many accidents when a driver fastened the valve down to
allow greater steam pressure and more power from the engine. The more
recent type of safety valve uses an adjustable spring-loaded valve,
which is locked such that operators may not tamper with its adjustment
unless a seal illegally is broken. This arrangement is considerably
Lead fusible plugs may be present in the crown of the boiler's
firebox. If the water level drops, such that the temperature of the
firebox crown increases significantly, the lead melts and the steam
escapes, warning the operators, who may then manually suppress the
fire. Except in the smallest of boilers the steam escape has little
effect on dampening the fire. The plugs are also too small in area to
lower steam pressure significantly, depressurizing the boiler. If they
were any larger, the volume of escaping steam would itself endanger
the crew.
Main article: Rankine cycle
Thermodynamics and Heat transfer
Flow diagram of the four main devices used in the Rankine cycle. 1).
Feedwater pump 2).
Boiler or steam generator 3).
Turbine or engine 4).
Condenser; where Q=heat and W=work. Most of the heat is rejected as
Rankine cycle is the fundamental thermodynamic underpinning of the
steam engine. The cycle is an arrangement of components as is
typically used for simple power production, and utilizes the phase
change of water (boiling water producing steam, condensing exhaust
steam, producing liquid water)) to provide a practical heat/power
conversion system. The heat is supplied externally to a closed loop
with some of the heat added being converted to work and the waste heat
being removed in a condenser. The
Rankine cycle is used in virtually
all steam power production applications. In the 1990s, Rankine steam
cycles generated about 90% of all electric power used throughout the
world, including virtually all solar, biomass, coal and nuclear power
plants. It is named after William John Macquorn Rankine, a Scottish
Rankine cycle is sometimes referred to as a practical Carnot cycle
because, when an efficient turbine is used, the
TS diagram begins to
resemble the Carnot cycle. The main difference is that heat addition
(in the boiler) and rejection (in the condenser) are isobaric
(constant pressure) processes in the
Rankine cycle and isothermal
(constant temperature) processes in the theoretical Carnot cycle. In
this cycle a pump is used to pressurize the working fluid which is
received from the condenser as a liquid not as a gas. Pumping the
working fluid in liquid form during the cycle requires a small
fraction of the energy to transport it compared to the energy needed
to compress the working fluid in gaseous form in a compressor (as in
the Carnot cycle). The cycle of a reciprocating steam engine differs
from that of turbines because of condensation and re-evaporation
occurring in the cylinder or in the steam inlet passages.
The working fluid in a
Rankine cycle can operate as a closed loop
system, where the working fluid is recycled continuously, or may be an
"open loop" system, where the exhaust steam is directly released to
the atmosphere, and a separate source of water feeding the boiler is
supplied. Normally water is the fluid of choice due to its favourable
properties, such as non-toxic and unreactive chemistry, abundance, low
cost, and its thermodynamic properties. Mercury is the working fluid
in the mercury vapor turbine. Low boiling hydrocarbons can be used in
a binary cycle.
The steam engine contributed much to the development of thermodynamic
theory; however, the only applications of scientific theory that
influenced the steam engine were the original concepts of harnessing
the power of steam and atmospheric pressure and knowledge of
properties of heat and steam. The experimental measurements made by
Watt on a model steam engine led to the development of the separate
condenser. Watt independently discovered latent heat, which was
confirmed by the original discoverer Joseph Black, who also advised
Watt on experimental procedures. Watt was also aware of the change in
the boiling point of water with pressure. Otherwise, the improvements
to the engine itself were more mechanical in nature. The
thermodynamic concepts of the
Rankine cycle did give engineers the
understanding needed to calculate efficiency which aided the
development of modern high-pressure and -temperature boilers and the
Main article: Thermal efficiency
See also: Engine efficiency §
The efficiency of an engine cycle can be calculated by dividing the
energy output of mechanical work that the engine produces by the
energy input to the engine by the burning fuel.
The historical measure of a steam engine's energy efficiency was its
"duty". The concept of duty was first introduced by Watt in order to
illustrate how much more efficient his engines were over the earlier
Newcomen designs. Duty is the number of foot-pounds of work delivered
by burning one bushel (94 pounds) of coal. The best examples of
Newcomen designs had a duty of about 7 million, but most were closer
to 5 million. Watt's original low-pressure designs were able to
deliver duty as high as 25 million, but averaged about 17. This was a
three-fold improvement over the average Newcomen design. Early Watt
engines equipped with high-pressure steam improved this to 65
No heat engine can be more efficient than the Carnot cycle, in which
heat is moved from a high temperature reservoir to one at a low
temperature, and the efficiency depends on the temperature difference.
For the greatest efficiency, steam engines should be operated at the
highest steam temperature possible (superheated steam), and release
the waste heat at the lowest temperature possible.
The efficiency of a
Rankine cycle is usually limited by the working
fluid. Without the pressure reaching supercritical levels for the
working fluid, the temperature range the cycle can operate over is
quite small; in steam turbines, turbine entry temperatures are
typically 565 °C (the creep limit of stainless steel) and
condenser temperatures are around 30 °C. This gives a
Carnot efficiency of about 63% compared with an actual
efficiency of 42% for a modern coal-fired power station. This low
turbine entry temperature (compared with a gas turbine) is why the
Rankine cycle is often used as a bottoming cycle in combined-cycle gas
turbine power stations.
One of the principal advantages the
Rankine cycle holds over others is
that during the compression stage relatively little work is required
to drive the pump, the working fluid being in its liquid phase at this
point. By condensing the fluid, the work required by the pump consumes
only 1% to 3% of the turbine (or reciprocating engine)power and
contributes to a much higher efficiency for a real cycle. The benefit
of this is lost somewhat due to the lower heat addition temperature.
Gas turbines, for instance, have turbine entry temperatures
approaching 1500 °C. Nonetheless, the efficiencies of actual
large steam cycles and large modern gas turbines are fairly well
In practice, a reciprocating steam engine cycle exhausting the steam
to atmosphere will typically have an efficiency (including the boiler)
in the range of 1-10%, but with the addition of a condenser and
multiple expansion, and high steam pressure/temperature, it may be
greatly improved, historically into the regime of 10-20%, and very
rarely slightly higher.
A modern large electrical power station (producing several hundred
megawatts of electrical output) with steam reheat, economizer etc.
will achieve efficiency in the mid 40% range, with the most efficient
units approaching 50% thermal efficiency.
It is also possible to capture the waste heat using cogeneration in
which the waste heat is used for heating a lower boiling point working
fluid or as a heat source for district heating via saturated
A steam locomotive – a GNR N2 Class No.1744 at Weybourne nr.
A steam-powered bicycle
Preserved British steam-powered fire engine – an example of a
mobile steam engine. This is a horse-drawn vehicle: the steam engine
drives the water pump
Geared steam locomotive
History of steam road vehicles
Lean's Engine Reporter
List of steam fairs
List of steam museums
List of steam technology patents
Model steam engine
Salomon de Caus
Steam power during the Industrial Revolution
Timeline of steam power
^ This model was built by Samuel Pemberton between 1880-1890.
^ American Heritage Dictionary of the English Language (Fourth ed.).
Houghton Mifflin Company. 2000.
^ Davids, Karel & Davids, Carolus A. (2012). Religion, Technology,
and the Great and Little Divergences: China and Europe Compared, C.
700-1800. Brill. ISBN 9789004233881. , p.207
^ Preston, Eric James (2012).
Thomas Newcomen of Dartmouth and the
Engine That Changed the World. Dartmouth History Research Group.
^ Hills 1989, p. 63.
^ Hills 1989, p. 223.
^ a b c d Wiser, Wendell H. (2000). Energy resources: occurrence,
production, conversion, use. Birkhäuser. p. 190.
^ a b
Ahmad Y Hassan (1976). Taqi al-Din and Arabic Mechanical
Engineering, p. 34–35. Institute for the History of Arabic Science,
University of Aleppo.
^ Benett, Stuart (1986). A History of Control Engineering 1800-1930.
Institution of Engineering and Technology.
^ Thompson, Ross (2009). Structures of Change in the Mechanical Age:
Technological Invention in the United States 1790-1865. Baltimore, MD:
The Johns Hopkins University Press. ISBN 978-0-8018-9141-0.
^ Kristensen, Søren B. P. (2009), Geografisk Tidssckrift -Danish
Journal of Geography (PDF), p. 50, archived from the original
(PDF) on 2010-01-08
^ Lightweight steam turbines powered by decomposing high-test peroxide
used neither boilers nor condensers, and were used in the
other rocket turbopumps, and torpedo propulsion.
^ "turbine." Encyclopædia Britannica. 2007. Encyclopædia Britannica
Online. 18 July 2007
^ "De Architectura": Chapter VI (paragraph 2)
from "Ten Books on Architecture" by
Vitruvius (1st century BC),
published 17, June, 08  accessed 2009-07-07
^ "University of Rochester, NY, The growth of the steam engine online
history resource, chapter one". History.rochester.edu. Retrieved
Power plant engineering". P. K. Nag (2002). Tata McGraw-Hill.
p.432. ISBN 0-07-043599-5
^ Garcia, Nicholas (2007). Mas alla de la Leyenda Negra. Valencia:
Universidad de Valencia. pp. 443–454.
^ Hills 1987, pp. 15.,16,33.
^ Lira, Carl T. (21 May 2013). "The Savery Pump". Introductory
Chemical Engineering Thermodynamics. Michigan State University.
Retrieved 11 April 2014.
^ Hills, 1989 & pp16–20
^ "Phil. Trans. 1751-1752 47, 436-438, published 1 January
^ a b Landes, David. S. (1969). The Unbound Prometheus: Technological
Change and Industrial Development in Western Europe from 1750 to the
Present. Cambridge, New York: Press Syndicate of the University of
Cambridge. ISBN 0-521-09418-6.
^ Jenkins, Ryhs (1971) [First published 1936]. Links in the History of
Engineering and Technology from Tudor Times. Cambridge (1st) , Books
for Libraries Press (2nd): The Newcomen Society at the Cambridge
University Press. ISBN 0-8369-2167-4Collected Papers of Rhys
Jenkins, Former Senior Examiner in the British Patent Office
^ Landes & year-1969, pp. 101 Lands refers to Thurston's
definition of an engine and Thurston's calling Newcomen's the "first
^ Brown, Richard (1991). Society and economy in modern Britain,
1700–1850 (Repr. ed.). London: Routledge. p. 60.
^ a b c d e f g h Hunter, Louis C. (1985). A History of Industrial
Power in the United States, 1730–1930. Vol. 2:
Charolttesville: University Press of Virginia.
^ Galloway, Elajah (1828). History of the
Steam Engine. London: B.
Steill, Paternoster-Row. pp. 23–24.
^ Leupold, Jacob (1725). Theatri Machinarum Hydraulicarum. Leipzig:
^ Hunter & Bryant 1991 Duty comparison was based on a carefully
conducted trial in 1778.
^ a b Rosen, William (2012). The Most Powerful Idea in the World: A
Story of Steam, Industry and Invention. University Of Chicago Press.
p. 185. ISBN 978-0-226-72634-2.
^ Hunter 1985
^ a b c d Thomson, Ross (2009). Structures of Change in the Mechanical
Age: Technological Invention in the United States 1790–1865.
Baltimore, MD: The Johns Hopkins University Press. p. 34.
^ "The Pictorial History Of
Steam Power" J.T. Van Reimsdijk and
Kenneth Brown, Octopus Books Limited 1989, ISBN 0 7064 0976 0,
^ Cowan, Ruth Schwartz (1997), A Social History of American
Technology, New York: Oxford University Press, p. 74,
^ Dickinson, Henry W; Titley, Arthur (1934). "Chronology". Richard
Trevithick, the engineer and the man. Cambridge, England: Cambridge
University Press. p. xvi. OCLC 637669420.
^ The American Car since 1775, Pub. L. Scott. Baily, 1971, p. 18
^ Hunter 1985, pp. 601–628
^ Hunter 1985, pp. 601
^ Van Slyck, J.D. (1879). New England Manufacturers and Manufactories.
New England Manufacturers and Manufactories. volume 1. Van Slyck.
^ a b Payton, Philip (2004). Oxford Dictionary of National Biography.
Oxford University Press.
^ Gordon, W.J. (1910). Our Home Railways, volume one. London:
Frederick Warne and Co. pp. 7–9.
^ "Nation Park Service
Steam Locomotive article with photo of Fitch
Steam model and dates of construction as 1780–1790". Nps.gov.
2002-02-14. Retrieved 2009-11-03.
^ "Richard Trevithick's steam locomotive Rhagor". Museumwales.ac.uk.
Archived from the original on 15 April 2011. Retrieved 3 November
Steam train anniversary begins". BBC. 2004-02-21. Retrieved
2009-06-13. A south
Wales town has begun months of celebrations to
mark the 200th anniversary of the invention of the steam locomotive.
Merthyr Tydfil was the location where, on 21 February 1804, Richard
Trevithick took the world into the railway age when he set one of his
high-pressure steam engines on a local iron master's tram rails
^ Garnett, A.F. (2005). Steel Wheels. Cannwood Press.
^ Young, Robert (2000). Timothy Hackworth and the Locomotive
((=reprint of 1923 ed.) ed.). Lewes, UK: the Book Guild Ltd.
^ Hamilton Ellis (1968). The Pictorial Encyclopedia of Railways. The
Hamlyn Publishing Group. pp. 24–30.
^ Michael Reimer, Dirk Endisch: Baureihe 52.80 – Die rekonstruierte
Kriegslokomotive, GeraMond, ISBN 3-7654-7101-1
^ Vaclav Smil (2005), Creating the Twentieth Century: Technical
Innovations of 1867–1914 and Their Lasting Impact, Oxford University
Press, p. 62, ISBN 0-19-516874-7, retrieved 2009-01-03
^ "Energiprojekt LTD –
Biomass power plant,
Energiprojekt.com. Retrieved 2010-02-03.
^ Hunter, year-1985 & Description of the Colt portable engine,
^ McNeil, 1990 & See description of steam locomotives
^ Jerome, Harry (1934). Mechanization in Industry, National Bureau of
Economic Research (PDF). pp. 166–7.
^ Hills 1989, p. 248.
^ a b "DOE – Fossil Energy: How
Turbine Power Plants Work".
Fossil.energy.gov. Archived from the original on 12 August 2011.
^ Cooling System Retrofit Costs EPA Workshop on Cooling Water Intake
Technologies, John Maulbetsch, Maulbetsch Consulting, May 2003
^ Thomas J. Feeley, III, Lindsay Green, James T. Murphy, Jeffrey
Hoffmann, and Barbara A. Carney (2005). "Department of Energy/Office
of Fossil Energy’s Power Plant Water Management R&D Program."
Archived 27 September 2007 at the Wayback Machine. U.S. Department of
Energy, July 2005.
^ Hunter 1985, pp. 341–343
^ Hunter, Louis C.; Bryant, Lynwood (1991). A History of Industrial
Power in the United States, 1730–1930, Vol. 3: The Transmission of
Power. Cambridge, Massachusetts, London: MIT Press. p. 123.
Steam Engine Indicator' Stillman, Paul
^ Walter, John (2008). "The Engine Indicator" (PDF).
pp. xxv–xxvi. Archived from the original (PDF) on 10 March
^ Bennett, S. (1979). A History of Control Engineering 1800-1930.
London: Peter Peregrinus Ltd. ISBN 0-86341-047-2.
^ Bennett 1979
^ Basic Mechanical Engineering by Mohan Sen pg. 266
^ Hunter 1985, pp. 445
^ a b van Riemsdijk, John (1994). Compound Locomotives. Penrhyn, UK:
Atlantic Transport Publishers. pp. 2–3.
^ Brooks, John. Dreadnought Gunnery at the Battle of Jutland. [Pg. 14]
^ Carpenter, George W. & contributors (2000): La locomotive à
vapeur, English translation of André Chapelon's seminal work (1938):
pp. 56-72; 120 et seq; Camden Miniature
Steam Services, UK.
^ Bell, A.M. (1950). Locomotives. London: Virtue and Company.
Steam Rockets Tecaeromax
^ Hunter & year-1985, pp. 445
^ John Enys, "Remarks on the Duty of the
Steam Engines employed in the
Mines of Cornwall at different periods", Transactions of the
Institution of Civil Engineers, Volume 3 (14 January 1840), pg. 457
^ "Power Engineering and PEI Magazines: Daily coverage of electric
power generation technology, fuels, transmission, equipment, coal
power plants, renewable energy sources, emission control, more –
Power-Gen Worldwide". Pepei.pennnet.com. Retrieved 2010-02-03.
Crump, Thomas (2007). A Brief History of the Age of Steam: From the
First Engine to the Boats and Railways.
Hills, Richard L. (1989). Power from Steam: A history of the
stationary steam engine. Cambridge: Cambridge University Press.
ISBN 0 521 34356 9.
Hunter, Louis C. (1985). A History of Industrial Power in the United
States, 1730–1930, Vol. 2:
Steam Power. Charolttesville: University
Press of Virginia.
Marsden, Ben (2004). Watt's Perfect Engine:
Steam and the Age of
Invention. Columbia University Press.
Robinson, Eric H. "The Early Diffusion of
Steam Power" Journal of
Economic History Vol. 34, No. 1, (March 1974), pp. 91–107
Rose, Joshua. Modern
Steam Engines (1887, reprint 2003)
Stuart, Robert, A Descriptive History of the
Steam Engine (London: J.
Knight and H. Lacey, 1824.)
Van Riemsdijk, J. T. Pictorial History of
Steam Power (1980).
Thurston, Robert Henry (1878). A History of the Growth of the
Steam-engine. The International Scientific Series. New York: D.
Appleton and Company. OCLC 16507415.
Wikimedia Commons has media related to
Wikiquote has quotations related to:
Look up steam engine in Wiktionary, the free dictionary.
Animated engines – Illustrates a variety of engines
Howstuffworks - "How
Steam Engines Work"
Video of the 1900 steam engine aboard paddle steamer Unterwalden
Timeline of heat engine technology
Sun and planet gear
Babcock & Wilcox
Single- and double-acting
Condensing steam locomotive
Return connecting rod engine
Six-column beam engine
Steeple compound engine
Savery Engine (1698)
Newcomen Memorial Engine
Newcomen Memorial Engine (1725)
Fairbottom Bobs (1760)
Elsecar Engine (1795)
Kinneil Engine (1768)
Old Bess (1777)
Chacewater Mine engine (1778)
Smethwick Engine (1779)
Soho Manufactory engine (1782)
Bradley Works engine (1783)
Whitbread Engine (1785)
National Museum of
Scotland engine (1786)
Lap Engine (1788)
Puffing Devil (1801)
Steam Carriage (1803)
"Coalbrookdale Locomotive" (1803)
"Pen-y-Darren" locomotive (1804)
Woolf's compound engine (1803)
Murray's Hypocycloidal Engine
Murray's Hypocycloidal Engine (1805)
Glossary of steam locomotive components
History of steam road vehicles
Cugnot's fardier à vapeur (1769)
Murdoch's model steam carriage (1784)
Lean's Engine Reporter
List of steam technology patents
Stationary steam engine
Timeline of steam power
Steam engine applications
Steam tank (tracked)
steam tank (wheeled)
Space and air:
Glossary of steam locomotive components
BNF: cb11966647v (d