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A locomotive or engine is a rail transport vehicle that provides the motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a
multiple unit A multiple-unit train or simply multiple unit (MU) is a self-propelled train composed of one or more carriages joined together, which when coupled to another multiple unit can be controlled by a single driver, with multiple-unit train contr ...
, motor coach, railcar or power car; the use of these self-propelled vehicles is increasingly common for
passenger train A passenger train is a train used to transport people along a railroad line. These trains may consist of unpowered passenger railroad cars (also known as coaches or carriages) hauled by one or more locomotives, or may be self-propelled; self pr ...
s, but rare for freight (see
CargoSprinter The CargoSprinter is a freight multiple unit designed to transport freight or equipment. The CargoSprinter was designed by Windhoff GmbH (Germany) in the mid-1990s. Initially seven vehicles were built for Deutsche Bahn. Four were built by Win ...
). Traditionally, locomotives pulled trains from the front. However, push-pull operation has become common, where the train may have a locomotive (or locomotives) at the front, at the rear, or at each end. Most recently railroads have begun adopting DPU or distributed power. The front may have one or two locomotives followed by a mid-train locomotive that is controlled remotely from the lead unit. __TOC__


Etymology

The word ''locomotive'' originates from the Latin 'from a place', ablative of 'place', and the Medieval Latin 'causing motion', and is a shortened form of the term ''locomotive engine'', which was first used in 1814 to distinguish between self-propelled and
stationary steam engine Stationary steam engines are fixed steam engines used for pumping or driving mills and factories, and for power generation. They are distinct from locomotive engines used on railways, traction engines for heavy steam haulage on roads, steam cars ...
s.


Classifications

Prior to locomotives, the motive force for railways had been generated by various lower-technology methods such as human power, horse power, gravity or stationary engines that drove cable systems. Few such systems are still in existence today. Locomotives may generate their power from fuel (wood, coal, petroleum or natural gas), or they may take power from an outside source of electricity. It is common to classify locomotives by their source of energy. The common ones include:


Steam

A steam locomotive is a locomotive whose primary power source is a
steam engine A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be trans ...
. The most common form of steam locomotive also contains a boiler to generate the steam used by the engine. The water in the boiler is heated by burning combustible material – usually coal, wood, or oil – to produce steam. The steam moves reciprocating
piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tig ...
s which are connected to the locomotive's main wheels, known as the "
driving wheel On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled ...
s". Both fuel and water supplies are carried with the locomotive, either on the locomotive itself, in
bunkers A bunker is a defensive military fortification designed to protect people and valued materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. T ...
and tanks, (this arrangement is known as a " tank locomotive") or pulled behind the locomotive, in tenders, (this arrangement is known as a " tender locomotive"). The first full-scale working railway steam locomotive was built by Richard Trevithick in 1802. It was constructed for the Coalbrookdale ironworks in Shropshire in England 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 from the Penydarren ironworks, in
Merthyr Tydfil Merthyr Tydfil (; cy, Merthyr Tudful ) is the main town in Merthyr Tydfil County Borough, Wales, administered by Merthyr Tydfil County Borough Council. It is about north of Cardiff. Often called just Merthyr, it is said to be named after Tydf ...
, to
Abercynon Abercynon (), is both a village and a community (and electoral ward) in the Cynon Valley within the unitary authority of Rhondda Cynon Taf, Wales. The community comprises the village and the districts of Carnetown and Grovers Field to the south, ...
in South Wales. Accompanied by Andrew Vivian, it ran with mixed success. The design incorporated a number of important innovations including the use of high-pressure steam which reduced the weight of the engine and increased its efficiency. In 1812, Matthew Murray's twin-cylinder rack locomotive '' Salamanca'' first ran on the edge-railed rack-and-pinion Middleton Railway; this is generally regarded as the first commercially successful locomotive. Another well-known early locomotive was '' Puffing Billy'', built 1813–14 by engineer William Hedley for 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 built '' Locomotion No. 1'' for the Stockton & Darlington Railway in the north-east of England, which was the first public steam railway in the world. In 1829, his son Robert built '' The Rocket'' in Newcastle upon Tyne. Rocket was entered into, and won, the Rainhill Trials. This success led to the company emerging as the pre-eminent early builder of steam locomotives used on railways in the UK, US and much of Europe. The Liverpool & Manchester Railway, built by Stephenson, opened a year later making exclusive use of steam power for passenger and goods trains. The steam locomotive remained by far the most common type of locomotive until after World War II. Steam locomotives are less efficient than modern diesel and electric locomotives, and a significantly larger workforce is required to operate and service them.
British Rail British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most of the overground rail transport in Great Britain from 1948 to 1997. It was formed from the nationalisation of the Big Four British rai ...
figures showed that the cost of crewing and fuelling a steam locomotive was about two and a half times larger than the cost of supporting an equivalent diesel locomotive, and the daily mileage they could run was lower. Between about 1950 and 1970, the majority of steam locomotives were retired from commercial service and replaced with electric and diesel-electric locomotives. While North America transitioned from steam during the 1950s, and continental Europe by the 1970s, in other parts of the world, the transition happened later. Steam was a familiar technology that used widely-available fuels and in low-wage economies did not suffer as wide a cost disparity. It continued to be used in many countries until the end of the 20th century. By the end of the 20th century, almost the only steam power remaining in regular use around the world was on
heritage railway A heritage railway or heritage railroad (US usage) is a railway operated as living history to re-create or preserve railway scenes of the past. Heritage railways are often old railway lines preserved in a state depicting a period (or periods) i ...
s.


Internal combustion

Internal combustion locomotives use an internal combustion engine, connected to the
driving wheel On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled ...
s by a transmission. Typically they keep the engine running at a near-constant speed whether the locomotive is stationary or moving. Internal combustion locomotives are categorised by their fuel type and sub-categorised by their transmission type.


Benzene

Benzene locomotives have an internal combustion engines that use benzene as fuel. Between the late 1890's and 1900's, a number of commercial manufacturers for Benzene Locomotives had been operating. This began with
Deutz Deutz may refer to: People * Emmanuel Deutz (1763–1842), German-born French rabbi * Rupert of Deutz, (–), Benedictine theologian and writer * Simon Deutz (1802–1852), German-born French courtier Places * Deutz, Cologne, a former town, si ...
, that produced an operating system based upon a design prototype for a manganese mine in Giessen. Following, in the early 1900's, they had been sold for multiple mining and Tunnelling operations. Post the 1900's, no wide spread use was necessary or required, their inadequacy had increased with the existence of petrol and diesel locomotives.


Kerosene

Kerosene locomotives use kerosene as the fuel. They were the world's first internal combustion locomotives, preceding diesel and other oil locomotives by some years. The first known kerosene rail vehicle was a draisine built by Gottlieb Daimler in 1887, but this was not technically a locomotive as it carried a payload. A kerosene locomotive was built in 1894 by the Priestman Brothers of Kingston upon Hull for use on Hull docks. This locomotive was built using a 12 hp double-acting marine type engine, running at 300 rpm, mounted on a 4-wheel wagon chassis. It was only able to haul one loaded wagon at a time, due to its low power output, and was not a great success. The first successful kerosene locomotive was "Lachesis" built by
Richard Hornsby & Sons Richard Hornsby & Sons was an engine and machinery manufacturer in Grantham, Lincolnshire, England from 1828 until 1918. The company was a pioneer in the manufacture of the oil engine developed by Herbert Akroyd Stuart, which was marketed un ...
and delivered to Woolwich Arsenal railway in 1896. The company built four kerosene locomotives between 1896 and 1903, for use at the Arsenal.


Petrol

Petrol locomotives use petrol ( gasoline) as their fuel. The first commercially successful petrol locomotive was a petrol-mechanical locomotive built by the Maudslay Motor Company in 1902, for the Deptford Cattle Market in London. It was an 80 hp locomotive using a 3-cylinder vertical petrol engine, with a two speed mechanical gearbox.


=Petrol-mechanical

= The most common type of petrol locomotive are petrol-mechanical locomotives, which use
mechanical Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations of ...
transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission *** ...
in the form of
gearboxes Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...
(sometimes in conjunction with
chain drive Chain drive is a way of transmitting mechanical power from one place to another. It is often used to convey power to the wheels of a vehicle, particularly bicycles and motorcycles. It is also used in a wide variety of machines besides vehicles. ...
s) to deliver the power output of the engine to the driving wheels, in the same way as a
car A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods. The year 1886 is regarded as ...
. The second petrol-mechanical locomotive was built by F.C. Blake of Kew in January 1903 for the Richmond Main Sewerage Board.


=Petrol-electric

= Petrol-electric locomotives are petrol locomotives which use
electric transmission Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...
to deliver the power output of the engine to the driving wheels. This avoids the need for
gearboxes Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...
by converting the rotary
mechanical force In physical sciences, mechanical energy is the sum of potential energy and kinetic energy. The principle of conservation of mechanical energy states that if an isolated system is subject only to conservative forces, then the mechanical energy is ...
of the engine into
electrical energy Electrical energy is energy related to forces on electrically charged particles and the movement of electrically charged particles (often electrons in wires, but not always). This energy is supplied by the combination of electric current and electr ...
by a dynamo, and then powering the wheels by multi-speed electric traction motors. This allows for smoother acceleration, as it avoids the need for gear changes, however, it is more expensive, heavier, and sometimes bulkier than mechanical transmission. A notable early petrol-electric locomotive was built in 1913 for the Minneapolis, St. Paul, Rochester and Dubuque Electric Traction Company. It weighed 60 tons, generated 350 hp and drove through a pair of
bogie A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...
s in a Bo-Bo arrangement.


Diesel

Diesel locomotive A diesel locomotive is a type of railway locomotive in which the prime mover is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conveyed to the driving whee ...
s are powered by diesel engines. In the early days of diesel propulsion development, various transmission systems were employed with varying degrees of success, with electric transmission proving to be the most popular.


=Diesel-mechanical

= A diesel–mechanical locomotive uses
mechanical transmission Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differ ...
to transfer power to the wheels. This type of transmission is generally limited to low-powered, low speed shunting (switching) locomotives, lightweight
multiple unit A multiple-unit train or simply multiple unit (MU) is a self-propelled train composed of one or more carriages joined together, which when coupled to another multiple unit can be controlled by a single driver, with multiple-unit train contr ...
s and self-propelled railcars. The earliest diesel locomotives were diesel-mechanical. In 1906, Rudolf Diesel, Adolf Klose and the steam and diesel engine manufacturer
Gebrüder Sulzer Sulzer Ltd. is a Swiss industrial engineering and manufacturing firm, founded by Salomon Sulzer-Bernet in 1775 and established as Sulzer Brothers Ltd. (Gebrüder Sulzer) in 1834 in Winterthur, Switzerland. Today it is a publicly traded company w ...
founded Diesel-Sulzer-Klose GmbH to manufacture diesel-powered locomotives. The Prussian State Railways ordered a diesel locomotive from the company in 1909. The world's first diesel-powered locomotive (a diesel-mechanical locomotive) was operated in the summer of 1912 on the Winterthur–Romanshorn railway in Switzerland, but was not a commercial success. Small numbers of prototype diesel locomotives were produced in a number of countries through the mid-1920s.


=Diesel-electric

= Diesel–electric locomotives are diesel locomotives using
electric transmission Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...
. The diesel engine drives either an electrical DC generator (generally, less than net for traction), or an electrical AC alternator-rectifier (generally net or more for traction), the output of which provides power to the traction motors that drive the locomotive. There is no mechanical connection between the diesel engine and the wheels. The vast majority of diesel locomotives today are diesel-electric. In 1914,
Hermann Lemp Hermann Lemp born: Heinrich Joseph Hermann Lemp (August 8, 1862 – March 31, 1954) was a Switzerland, Swiss-United States, American electrical engineer; he is credited as the inventor of the modern system of Diesel-electric transmission, di ...
, a General Electric electrical engineer, developed and patented a reliable direct current electrical control system (subsequent improvements were also patented by Lemp). Lemp's design used a single lever to control both engine and generator in a coordinated fashion, and was the
prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...
for all diesel–electric locomotive control. In 1917–18, GE produced three experimental diesel–electric locomotives using Lemp's control design. In 1924, a diesel-electric locomotive ( Eel2 original number Юэ 001/Yu-e 001) started operations. It had been designed by a team led by
Yury Lomonosov Yury Vladimirovich Lomonosov (russian: Юрий Владимирович Ломоносов; 24 April 1876 – 19 November 1952) was a Russian railway engineer and a leading figure in the development of Russian Railways in the early 20th century ...
and built 1923–1924 by Maschinenfabrik Esslingen in Germany. It had 5 driving axles (1'E1'). After several test rides, it hauled trains for almost three decades from 1925 to 1954.


=Diesel-hydraulic

= Diesel–hydraulic locomotives are diesel locomotives using hydraulic transmission. In this arrangement, they use one or more torque converters, in combination with gears, with a mechanical final drive to convey the power from the diesel engine to the wheels. The main worldwide user of main-line hydraulic transmissions was the Federal Republic of Germany, with designs including the 1950s DB Class V 200, and the 1960 and 1970s DB V 160 family.
British Rail British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most of the overground rail transport in Great Britain from 1948 to 1997. It was formed from the nationalisation of the Big Four British rai ...
introduced a number of diesel hydraulic designs during it
1955 Modernisation Plan Events January * January 3 – José Ramón Guizado becomes president of Panama. * January 17 – , the first nuclear-powered submarine, puts to sea for the first time, from Groton, Connecticut. * January 18– 20 – Battle of Yijian ...
, initially license built versions of German designs. In Spain Renfe used high power to weight ratio twin engined German designs to haul high speed trains from the 1960s to 1990s. (see Renfe Classes 340,
350 __NOTOC__ Year 350 (Roman numerals, CCCL) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Sergius and Nigrinianus (or, less frequentl ...
,
352 Year 352 (Roman numerals, CCCLII) was a leap year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Decentius and Paulus (or, less frequently, year 110 ...
,
353 __NOTOC__ Year 353 ( CCCLIII) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Magnentius and Decentius (or, less frequently, year 110 ...
,
354 __NOTOC__ Year 354 ( CCCLIV) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Constantius and Constantius (or, less frequently, yea ...
). Hydrostatic drive systems have also been applied to rail use, for example shunting locomotives by CMI Group (Belgium). Hydrostatic drives are also used in railway maintenance machines such as tampers and rail grinders.


Gas turbine

A
gas turbine locomotive A gas turbine locomotive is a type of railway locomotive in which the prime mover is a gas turbine. Several types of gas turbine locomotive have been developed, differing mainly in the means by which mechanical power is conveyed to the driving w ...
is an internal combustion engine locomotive consisting of a gas turbine. ICE engines require a transmission to power the wheels. The engine must be allowed to continue to run when the locomotive is stopped. Gas turbine-mechanical locomotives use a
mechanical transmission Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differ ...
to deliver the power output of gas turbines to the wheels. A gas turbine locomotive was patented in 1861 by Marc Antoine Francois Mennons (British patent no. 1633). There is no evidence that the locomotive was actually built but the design includes the essential features of gas turbine locomotives, including compressor, combustion chamber, turbine and air pre-heater. In 1952, Renault delivered a prototype four-axle 1150 hp gas-turbine-mechanical locomotive fitted with the Pescara "free turbine" gas- and compressed-air producing system, rather than a co-axial multi-stage compressor integral to the turbine. This model was succeeded by a pair of six-axle 2400 hp locomotives with two turbines and Pescara feeds in 1959. Several similar locomotives were built in USSR by Kharkov Locomotive Works. Gas turbine-electric locomotives, use a gas turbine to drive an electrical generator or alternator which produced electric current powers the traction motor which drive the wheels. In 1939 the
Swiss Federal Railways Swiss Federal Railways (german: link=no, Schweizerische Bundesbahnen, ''SBB''; french: link=no, Chemins de fer fédéraux suisses, ''CFF''; it, Ferrovie federali svizzere, ''FFS'') is the national railway company of Switzerland. It is usuall ...
ordered Am 4/6, a GTEL with a of maximum engine power from Brown Boveri. It was completed in 1941, and then underwent testing before entering regular service. The Am 4/6 was the first gas turbine – electric locomotive.
British Rail 18000 British Rail 18000 was a prototype mainline gas turbine-electric locomotive built for British Railways in 1949 by Brown, Boveri & Cie. An earlier gas-turbine locomotive, 18100, had been ordered from Metropolitan-Vickers by the Great Western Ra ...
was built by Brown Boveri and delivered in 1949.
British Rail 18100 British Rail 18100 was a prototype main line gas turbine-electric locomotive built for British Railways in 1951 by Metropolitan-Vickers, Manchester. It had, however, been ordered by the Great Western Railway in the 1940s, but construction was de ...
was built by Metropolitan-Vickers and delivered in 1951. A third locomotive, the
British Rail GT3 GT3 (''gas turbine number 3'') was a prototype mainline gas turbine locomotive built in 1961 by English Electric at their Vulcan Foundry in Newton-le-Willows to investigate the use of its gas turbines in rail traction applications. It followed ...
, was constructed in 1961. Union Pacific ran a large fleet of turbine-powered freight locomotives starting in the 1950s. These were widely used on long-haul routes, and were cost-effective despite their poor fuel economy due to their use of "leftover" fuels from the petroleum industry. At their height the railroad estimated that they powered about 10% of Union Pacific's freight trains, a much wider use than any other example of this class. A gas turbine offers some advantages over a
piston engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common featu ...
. There are few moving parts, decreasing the need for
lubrication Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology. Lubrication mechanisms such as fluid-lubric ...
and potentially reducing maintenance costs, and the
power-to-weight ratio Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measuremen ...
is much higher. A turbine of a given power output is also physically smaller than an equally powerful piston engine, allowing a locomotive to be very powerful without being inordinately large. However, a turbine's power output and efficiency both drop dramatically with rotational speed, unlike a piston engine, which has a comparatively flat power curve. This makes GTEL systems useful primarily for long-distance high-speed runs. Additional problems with gas turbine-electric locomotives included that they were very noisy.


Electric

An electric locomotive is a locomotive powered only by electricity. Electricity is supplied to moving trains with a (nearly) continuous
conductor Conductor or conduction may refer to: Music * Conductor (music), a person who leads a musical ensemble, such as an orchestra. * ''Conductor'' (album), an album by indie rock band The Comas * Conduction, a type of structured free improvisation ...
running along the track that usually takes one of three forms: an overhead line, suspended from poles or towers along the track or from structure or tunnel ceilings; a third rail mounted at track level; or an onboard
battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...
. Both overhead wire and third-rail systems usually use the running rails as the return conductor but some systems use a separate fourth rail for this purpose. The type of electrical power used is either direct current (DC) or alternating current (AC). Various collection methods exist: a trolley pole, which is a long flexible pole that engages the line with a wheel or shoe; a bow collector, which is a frame that holds a long collecting rod against the wire; a pantograph, which is a hinged frame that holds the collecting shoes against the wire in a fixed geometry; or a contact shoe, which is a shoe in contact with the third rail. Of the three, the pantograph method is best suited for high-speed operation. Electric locomotives almost universally use axle-hung traction motors, with one motor for each powered axle. In this arrangement, one side of the motor housing is supported by plain bearings riding on a ground and polished journal that is integral to the axle. The other side of the housing has a tongue-shaped protuberance that engages a matching slot in the truck (bogie) bolster, its purpose being to act as a torque reaction device, as well as a support. Power transfer from motor to axle is effected by spur gearing, in which a
pinion A pinion is a round gear—usually the smaller of two meshed gears—used in several applications, including drivetrain and rack and pinion systems. Applications Drivetrain Drivetrains usually feature a gear known as the pinion, which may ...
on the motor shaft engages a
bull gear This page lists the standard US nomenclature used in the description of mechanical gear construction and function, together with definitions of the terms. The terminology was established by the American Gear Manufacturers Association (AGMA), under ...
on the axle. Both gears are enclosed in a liquid-tight housing containing lubricating oil. The type of service in which the locomotive is used dictates the gear ratio employed. Numerically high ratios are commonly found on freight units, whereas numerically low ratios are typical of passenger engines. Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches and transformers. Electric locomotives usually cost 20% less than diesel locomotives, their maintenance costs are 25–35% lower, and cost up to 50% less to run.


Direct current

The earliest systems were DC systems. The first electric passenger train was presented by Werner von Siemens at Berlin in 1879. The locomotive was driven by a 2.2 kW, series-wound motor, and the train, consisting of the locomotive and three cars, reached a speed of 13 km/h. During four months, the train carried 90,000 passengers on a 300-metre-long (984 feet) circular track. The electricity (150 V DC) was supplied through a third insulated rail between the tracks. A contact roller was used to collect the electricity. The world's first electric tram line opened in Lichterfelde near Berlin, Germany, in 1881. It was built by Werner von Siemens (see Gross-Lichterfelde Tramway and Berlin Straßenbahn). The Volk's Electric Railway opened in 1883 in Brighton, and is the oldest surviving electric railway. Also in 1883,
Mödling and Hinterbrühl Tram Mödling and Hinterbrühl Tram or ''Mödling and Hinterbrühl Local Railway'' (German: ''Lokalbahn Mödling–Hinterbrühl'') was an electric tramway in Austria, running 4.5 km (2.8 mi) from Mödling to Hinterbrühl, in the southwest ...
opened near Vienna in Austria. It was the first in the world in regular service powered from an overhead line. Five years later, in the U.S. electric trolleys were pioneered in 1888 on the Richmond Union Passenger Railway, using equipment designed by Frank J. Sprague. The first electrically worked
underground Underground most commonly refers to: * Subterranea (geography), the regions beneath the surface of the Earth Underground may also refer to: Places * The Underground (Boston), a music club in the Allston neighborhood of Boston * The Underground (S ...
line was the
City & South London Railway The City and South London Railway (C&SLR) was the first successful deep-level underground "tube" railway in the world, and the first major railway to use electric traction. The railway was originally intended for cable-hauled trains, but owing ...
, prompted by a clause in its enabling act prohibiting use of steam power. It opened in 1890, using electric locomotives built by
Mather & Platt Mather & Platt is the name of several large engineering firms in Europe, South Africa and Asia that are subsidiaries of Wilo SE, Germany or were founded by former employees. The original company was founded in the Newton Heath area of Manchester, ...
. Electricity quickly became the power supply of choice for subways, abetted by the Sprague's invention of multiple-unit train control in 1897. The first use of electrification on a main line was on a four-mile stretch of the Baltimore Belt Line of the Baltimore & Ohio (B&O) in 1895 connecting the main portion of the B&O to the new line to New York through a series of tunnels around the edges of Baltimore's downtown. Three
Bo+Bo A Bo+Bo (UK usage) is a locomotive with two four-wheeled bogies with articulated connection between them and with all axles powered by individual traction motors.Encyclopædia Britannica, Volume 18, 1969 Edition, p1118 Table IV, SBN(GB) 85229 004 ...
units were initially used, at the south end of the electrified section; they coupled onto the locomotive and train and pulled it through the tunnels. DC was used on earlier systems. These systems were gradually replaced by AC. Today, almost all main-line railways use AC systems. DC systems are confined mostly to urban transit such as metro systems, light rail and trams, where power requirement is less.


Alternating current

The first practical AC electric locomotive was designed by Charles Brown, then working for Oerlikon, Zürich. In 1891, Brown had demonstrated long-distance power transmission, using three-phase AC, between a
hydro-electric plant Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...
at Lauffen am Neckar and Frankfurt am Main West, a distance of 280 km. Using experience he had gained while working for Jean Heilmann on steam-electric locomotive designs, Brown observed that three-phase motors had a higher power-to-weight ratio than DC motors and, because of the absence of a
commutator In mathematics, the commutator gives an indication of the extent to which a certain binary operation fails to be commutative. There are different definitions used in group theory and ring theory. Group theory The commutator of two elements, a ...
, were simpler to manufacture and maintain. However, they were much larger than the DC motors of the time and could not be mounted in underfloor
bogie A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...
s: they could only be carried within locomotive bodies. In 1894, Hungarian engineer
Kálmán Kandó Kálmán Kandó de Egerfarmos et Sztregova (''egerfarmosi és sztregovai Kandó Kálmán''; 10 July 1869 – 13 January 1931) was a Hungarian engineer, the inventor of phase converter and a pioneer in the development of AC electric railway tract ...
developed a new type 3-phase asynchronous electric drive motors and generators for electric locomotives. Kandó's early 1894 designs were first applied in a short three-phase AC tramway in Evian-les-Bains (France), which was constructed between 1896 and 1898. In 1918, Kandó invented and developed the rotary phase converter, enabling electric locomotives to use three-phase motors whilst supplied via a single overhead wire, carrying the simple industrial frequency (50 Hz) single phase AC of the high voltage national networks. In 1896, Oerlikon installed the first commercial example of the system on the Lugano Tramway. Each 30-tonne locomotive had two motors run by three-phase 750 V 40 Hz fed from double overhead lines. Three-phase motors run at constant speed and provide regenerative braking, and are well suited to steeply graded routes, and the first main-line three-phase locomotives were supplied by Brown (by then in partnership with
Walter Boveri Walter Boveri (born 21 February 1865 in Bamberg, Bavaria, died 28 October 1924 in Baden, Switzerland) was a Swiss-German industrialist and co-founder of the global electrical engineering group Brown, Boveri & Cie. (BBC). Biography Boveri's ances ...
) in 1899 on the 40 km Burgdorf—Thun line, Switzerland. The first implementation of industrial frequency single-phase AC supply for locomotives came from Oerlikon in 1901, using the designs of
Hans Behn-Eschenburg Hans Behn-Eschenburg (10 January 1864 – 18 May 1938) was born in Obertrass (now Zurich), Switzerland. His work on the AC single-phase motor was important to the electrification of railways. He studied mathematics and physics in Zurich and Be ...
and
Emil Huber-Stockar Emil Huber-Stockar (July 15, 1865 - May 9, 1939) was a Swiss entrepreneur and railway pioneer. He was an instrumental figure in the electrification of the Swiss railway network and worked as lead engineer and consultant for the Swiss Federal Rai ...
; installation on the Seebach-Wettingen line of the Swiss Federal Railways was completed in 1904. The 15 kV, 50 Hz , 48 tonne locomotives used transformers and rotary converters to power DC traction motors. Italian railways were the first in the world to introduce electric traction for the entire length of a main line rather than just a short stretch. The 106 km Valtellina line was opened on 4 September 1902, designed by Kandó and a team from the Ganz works. The electrical system was three-phase at 3 kV 15 Hz. The voltage was significantly higher than used earlier and it required new designs for electric motors and switching devices. The three-phase two-wire system was used on several railways in Northern Italy and became known as "the Italian system". Kandó was invited in 1905 to undertake the management of Società Italiana Westinghouse and led the development of several Italian electric locomotives.


Battery-electric

A battery-electric locomotive (or battery locomotive) is an electric locomotive powered by on-board
batteries Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...
; a kind of battery electric vehicle. Such locomotives are used where a conventional diesel or electric locomotive would be unsuitable. An example is maintenance trains on electrified lines when the electricity supply is turned off. Another use is in industrial facilities where a combustion-powered locomotive (i.e., steam- or diesel-powered) could cause a safety issue due to the risks of fire, explosion or fumes in a confined space. Battery locomotives are preferred for mines where gas could be ignited by trolley-powered units arcing at the collection shoes, or where electrical resistance could develop in the supply or return circuits, especially at rail joints, and allow dangerous current leakage into the ground. The first known electric locomotive was built in 1837 by chemist Robert Davidson of Aberdeen, and it was powered by galvanic cells (batteries). Davidson later built a larger locomotive named ''Galvani'', exhibited at the Royal Scottish Society of Arts Exhibition in 1841. The seven-ton vehicle had two direct-drive reluctance motors, with fixed electromagnets acting on iron bars attached to a wooden cylinder on each axle, and simple
commutators In mathematics, the commutator gives an indication of the extent to which a certain binary operation fails to be commutative. There are different definitions used in group theory and ring theory. Group theory The commutator of two elements, a ...
. It hauled a load of six tons at four miles per hour (6 kilometers per hour) for a distance of . It was tested on the Edinburgh and Glasgow Railway in September of the following year, but the limited power from batteries prevented its general use.Renzo Pocaterra, ''Treni'', De Agostini, 2003 Another example was at the
Kennecott Copper Mine The Bingham Canyon Mine, more commonly known as Kennecott Copper Mine among locals, is an open-pit mining operation extracting a large porphyry copper deposit southwest of Salt Lake City, Utah, in the Oquirrh Mountains. The mine is the largest m ...
, Latouche, Alaska, where in 1917 the underground haulage ways were widened to enable working by two battery locomotives of tons. In 1928, Kennecott Copper ordered four 700-series electric locomotives with on-board batteries. These locomotives weighed 85 tons and operated on 750-volt overhead trolley wire with considerable further range whilst running on batteries. The locomotives provided several decades of service using Nickel–iron battery (Edison) technology. The batteries were replaced with lead-acid batteries, and the locomotives were retired shortly afterward. All four locomotives were donated to museums, but one was scrapped. The others can be seen at the
Boone and Scenic Valley Railroad The Boone and Scenic Valley Railroad is a heritage railroad that operates freight and passenger excursions in Boone County, Iowa. History The heritage and excursion railroad was begun in 1983 by a group of volunteers who wanted to preserve a sce ...
, Iowa, and at the Western Railway Museum in Rio Vista, California. The Toronto Transit Commission previously operated a battery electric locomotive built by
Nippon Sharyo , formed in 1896, is a major rolling stock manufacturer based in Nagoya, Japan. In 1996, it abbreviated its name to "日本車両" Nippon Sharyō. Its shortest abbreviation is Nissha "日車". It was a listed company on Nikkei 225 until 2 ...
in 1968 and retired in 2009. London Underground regularly operates battery-electric locomotives for general maintenance work.


Other types


Fireless


Atomic-electric

In the early 1950s, Dr. Lyle Borst of the University of Utah was given funding by various US railroad line and manufacturers to study the feasibility of an electric-drive locomotive, in which an onboard atomic reactor produced the steam to generate the electricity. At that time, atomic power was not fully understood; Borst believed the major stumbling block was the price of uranium. With the Borst atomic locomotive, the center section would have a 200-ton reactor chamber and steel walls 5 feet thick to prevent releases of radioactivity in case of accidents. He estimated a cost to manufacture atomic locomotives with 7000 h.p. engines at approximately $1,200,000 each."Atomic Locomotive Produces 7000 h.p."
''Popular Mechanics'', April 1954, p. 86.
Consequently, trains with onboard nuclear generators were generally deemed unfeasible due to prohibitive costs.


Fuel cell-electric

In 2002, the first 3.6 tonne, 17 kW hydrogen (fuel cell) -powered mining locomotive was demonstrated in Val-d'Or, Quebec. In 2007 the educational mini-hydrail in
Kaohsiung Kaohsiung City (Mandarin Chinese: ; Wade–Giles: ''Kao¹-hsiung²;'' Pinyin: ''Gāoxióng'') is a special municipality located in southern Taiwan. It ranges from the coastal urban center to the rural Yushan Range with an area of . Kaohsi ...
, Taiwan went into service. The Railpower GG20B finally is another example of a fuel cell-electric locomotive.


Hybrid locomotives

There are many different types of hybrid or dual-mode locomotives using two or more types of motive power. The most common hybrids are electro-diesel locomotives powered either from an electricity supply or else by an onboard diesel engine. These are used to provide continuous journeys along routes that are only partly electrified. Examples include the EMD FL9 and Bombardier ALP-45DP


Use

There are three main uses of locomotives in rail transport operations: for hauling
passenger A passenger (also abbreviated as pax) is a person who travels in a vehicle, but does not bear any responsibility for the tasks required for that vehicle to arrive at its destination or otherwise operate the vehicle, and is not a steward. The ...
trains, freight trains, and for switching (UK English: shunting). Freight locomotives are normally designed to deliver high starting tractive effort and high sustained power. This allows them to start and move long, heavy trains, but usually comes at the cost of relatively low maximum speeds. Passenger locomotives usually develop lower starting tractive effort but are able to operate at the high speeds required to maintain passenger schedules. Mixed-traffic locomotives (US English: general purpose or road switcher locomotives) meant for both passenger and freight trains do not develop as much starting tractive effort as a freight locomotive but are able to haul heavier trains than a passenger locomotive. Most steam locomotives have reciprocating engines, with pistons coupled to the driving wheels by means of connecting rods, with no intervening gearbox. This means the combination of starting tractive effort and maximum speed is greatly influenced by the diameter of the driving wheels. Steam locomotives intended for freight service generally have smaller diameter driving wheels than passenger locomotives. In diesel-electric and electric locomotives the control system between the traction motors and
axle An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing ...
s adapts the power output to the rails for freight or passenger service. Passenger locomotives may include other features, such as head-end power (also referred to as hotel power or electric train supply) or a steam generator. Some locomotives are designed specifically to work
steep grade railway A steep grade railway is a railway that ascends and descends a slope that has a steep grade. Such railways can use a number of different technologies to overcome the steepness of the grade. Usage Many steep grade railways are located in mountain ...
s, and feature extensive additional braking mechanisms and sometimes rack and pinion. Steam locomotives built for steep rack and pinion railways frequently have the boiler tilted relative to the locomotive frame, so that the boiler remains roughly level on steep grades. Locomotives are also used on some High-speed trains: All
TGV The TGV (french: Train à Grande Vitesse, "high-speed train"; previously french: TurboTrain à Grande Vitesse, label=none) is France's intercity high-speed rail service, operated by SNCF. SNCF worked on a high-speed rail network from 1966 to 19 ...
, many AVE, some Korea Train Express and the
ICE 1 The ICE 1 is the first batch-produced German high-speed train and one of six in the Intercity Express family. Revenue service at speeds up to started in 1991. It was raised to in May 1995 and temporary reduced to again, as a result of ...
and ICE 2 trains all use locomotives, which may also be known as power cars. On the other hand, many high-speed trains such as the Shinkansen network never use locomotives. Instead of locomotives, they use
electric multiple unit An electric multiple unit or EMU is a multiple-unit train consisting of self-propelled carriages using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a numbe ...
s (EMUs) -- passenger cars that also have traction motors. Using power cars allows for a high ride quality and less electrical equipment; but EMUs have less axle weight, which reduces maintenance costs, and EMUs also have higher acceleration and higher seating capacity. The KTX-Sancheon and ICE 3/4/T use a mixture of electric multiple units and power cars.


Operational role

Locomotives occasionally work in a specific role, such as: * Train engine is the technical name for a locomotive attached to the front of a railway train to haul that train. Alternatively, where facilities exist for push-pull operation, the train engine might be attached to the rear of the train; *
Pilot engine In railroad terminology, double heading indicates the use of two locomotives at the front of a train, each operated individually by its own crew. The practice of triple-heading involves the use of three locomotives. The practice of multi-headi ...
– a locomotive attached in front of the train engine, to enable double-heading; * Banking engine – a locomotive temporarily assisting a train from the rear, due to a difficult start or a sharp incline gradient; *
Light engine Rail terminology is a form of technical terminology. The difference between the American term ''railroad'' and the international term ''railway'' (used by the International Union of Railways and English-speaking countries outside the United St ...
– a locomotive operating without a train behind it, for relocation or operational reasons. Occasionally, a light engine is referred to as a train in and of itself. *
Station pilot A switcher, shunter, yard pilot, switch engine, yard goat, or shifter is a small railroad locomotive used for manoeuvring railroad cars inside a rail yard in a process known as ''switching'' (US) or ''shunting'' (UK). Switchers are not inten ...
– a locomotive used to shunt passenger trains at a railway station.


Wheel arrangement

The wheel arrangement of a locomotive describes how many wheels it has; common methods include the AAR wheel arrangement, UIC classification, and Whyte notation systems.


Remote control locomotives

In the second half of the twentieth century remote control locomotives started to enter service in switching operations, being remotely controlled by an operator outside of the locomotive cab. The main benefit is one operator can control the loading of grain, coal, gravel, etc. into the cars. In addition, the same operator can move the train as needed. Thus, the locomotive is loaded or unloaded in about a third of the time.


See also


Notes


References


Bibliography

* * * *


External links


An engineer's guide from 1891

Locomotive cutaways and historical locomotives of several countries ordered by dates
* Pickzone Locomotiv
Model

International Steam Locomotives
* ''Turning a Locomotive into a Stationary Engine'',
Popular Science ''Popular Science'' (also known as ''PopSci'') is an American digital magazine carrying popular science content, which refers to articles for the general reader on science and technology subjects. ''Popular Science'' has won over 58 awards, incl ...
monthly, February 1919, page 72, Scanned by Google Books
Popular Science
{{Authority control 19th-century inventions