Editing Locomotive (section)

===Electric===
{{Main|Electric locomotive}}
[[File:Lokomotif listrik ESS 3200 di Stasiun Tanjung Priuk..jpg|thumb|The [[ESS 3200 class|ESS 3200]] electric locomotive was introduced in 1925 in the [[Dutch East Indies]], now [[Indonesia]]. ]]
An electric locomotive is a locomotive powered only by electricity. Electricity is supplied to moving trains with a (nearly) continuous [[Electrical conductor|conductor]] 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 [[Electric battery|battery]]. 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).

[[File:Eastleigh Works geograph-2383942-by-Ben-Brooksbank.jpg|thumb|right|[[British Rail Class 70 (electric)|Southern Railway (UK) 20002]] was equipped with both a pantograph and contact shoes.]]

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 (transport)|pantograph]], which is a hinged frame that holds the collecting shoes against the wire in a fixed geometry; or a [[Current collector#Contact shoe|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 [[Gear#Spur|spur gearing]], in which a [[pinion]] on the motor shaft engages a [[List of gear nomenclature#Bull gear|bull gear]] 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 [[Power station|generating stations]], transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and [[Electric power transmission|transmission lines]] but most purchase power from an [[electric utility]]. The railway usually provides its own distribution lines, switches and [[transformer]]s.

Electric locomotives usually cost 20% less than diesel locomotives, their maintenance costs are 25–35% lower, and cost up to 50% less to run.<ref>{{Cite web|url=https://www.eesi.org/articles/view/electrification-of-u.s.-railways-pie-in-the-sky-or-realistic-goal|title=Electrification of U.S. Railways: Pie in the Sky, or Realistic Goal? &#124; Article &#124; EESI|website=eesi.org|access-date=7 April 2020|archive-date=27 May 2021|archive-url=https://web.archive.org/web/20210527201918/https://www.eesi.org/articles/view/electrification-of-u.s.-railways-pie-in-the-sky-or-realistic-goal|url-status=live}}</ref>

====Direct current====
[[File:First electric locomotive, built in 1879 by Werner von Siemens.jpg|thumb|Werner von Siemens experimental DC electric train, 1879]]
[[File:B-and-O electric.jpg|thumb|Baltimore & Ohio electric engine, 1895]]

The earliest systems were [[Direct current|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&nbsp;kW, series-wound motor, and the train, consisting of the locomotive and three cars, reached a speed of 13&nbsp;km/h. During four months, the train carried 90,000 passengers on a {{convert|300|m|ft|adj=mid|-long|abbr=off|sp=us}} 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 [[Trams in Berlin|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]] 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 [[Tram|trolleys]] were pioneered in 1888 on the [[Richmond Union Passenger Railway]], using equipment designed by [[Frank J. Sprague]].<ref>{{cite web|url=http://www.ieee.org/web/aboutus/history_center/richmond.html|title=Richmond Union Passenger Railway|publisher=[[Institute of Electrical and Electronics Engineers|IEEE History Center]]|access-date=18 January 2008|archive-url=https://web.archive.org/web/20081201032737/http://www.ieee.org/web/aboutus/history_center/richmond.html|archive-date=1 December 2008|url-status=dead}}</ref>

The first electrically worked [[Rapid transit|underground]] line was the [[City & South London Railway]], prompted by a clause in its enabling act prohibiting use of steam power.<ref>{{cite book | last = Badsey-Ellis | first =Antony | title =London's Lost Tube Schemes | publisher = Capital Transport | year = 2005 | location = Harrow | page = 36 | isbn = 1-85414-293-3 }}</ref> It opened in 1890, using electric locomotives built by [[Mather & Platt]]. 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 [[UIC classification of locomotive axle arrangements|Bo+Bo]] 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.<ref>''B&O Power'', Sagle, Lawrence, Alvin Stauffer</ref>

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====
[[File:Ganz engine Valtellina.jpg|thumb|A prototype of a Ganz AC electric locomotive in Valtellina, Italy, 1901]]
The first practical [[Alternating current|AC]] electric locomotive was designed by [[Charles Eugene Lancelot Brown|Charles Brown]], then working for [[Maschinenfabrik Oerlikon|Oerlikon]], Zürich. In 1891, Brown had demonstrated long-distance power transmission, using [[Three-phase electric power|three-phase AC]], between a [[Hydroelectricity|hydro-electric plant]] at [[Lauffen am Neckar]] and [[Frankfurt]] am Main West, a distance of 280&nbsp;km. Using experience he had gained while working for [[Heilmann locomotive|Jean Heilmann]] on steam–electric locomotive designs, Brown observed that [[AC motor#Three-phase AC synchronous motors|three-phase motors]] had a higher power-to-weight ratio than [[Direct current|DC]] motors and, because of the absence of a [[Commutator (electric)|commutator]], were simpler to manufacture and maintain.{{efn|Heilmann evaluated both AC and DC electric transmission for his locomotives, but eventually settled on a design based on [[Thomas Edison]]'s DC system.{{sfnp|Duffy|2003|pp=39–41}}}} However, they were much larger than the DC motors of the time and could not be mounted in underfloor [[bogie]]s: they could only be carried within locomotive bodies.{{sfnp|Duffy|2003|p=129}}

In 1894, Hungarian engineer [[Kálmán Kandó]] developed a new type 3-phase asynchronous electric drive motors and generators for electric locomotives. The new 3-phase asynchronous electric drive motors were more effective than the synchronous electric motors of earlier locomotive designs. 
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.<ref>{{cite book|author=Andrew L. Simon|title=Made in Hungary: Hungarian Contributions to Universal Culture|publisher=Simon Publications LLC|year=1998|page=[https://archive.org/details/madeinhungaryhun0000simo/page/264 264]|isbn=978-0-9665734-2-8|url=https://archive.org/details/madeinhungaryhun0000simo|url-access=registration|quote=Evian-les-Bains kando.}}</ref><ref>{{cite book|author=Francis S. Wagner|title=Hungarian Contributions to World Civilization|publisher=Alpha Publications|year=1977|page=67|isbn=978-0-912404-04-2}}</ref><ref>{{cite book|author=C.W. Kreidel|title=Organ für die fortschritte des eisenbahnwesens in technischer beziehung|year=1904|page=315}}</ref><ref>{{cite book|title=Elektrotechnische Zeitschrift: Beihefte, Volumes 11–23|page=163|publisher=VDE Verlag|year=1904}}</ref><ref>{{cite book|title=L'Eclairage électrique, Volume 48|page=554|year=1906}}</ref> In 1918,{{sfnp|Duffy|2003|p=137}} 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&nbsp;Hz) single phase AC of the high voltage national networks.<ref name="Patent Office">{{cite web|url=http://www.mszh.hu/English/feltalalok/kando.html|title=Kálmán Kandó (1869–1931)|author=Hungarian Patent Office|publisher=mszh.hu|access-date=10 August 2008|archive-date=8 October 2010|archive-url=https://web.archive.org/web/20101008073106/http://www.mszh.hu/English/feltalalok/kando.html|url-status=dead}}</ref>

In 1896, Oerlikon installed the first commercial example of the system on the [[Trams in Lugano|Lugano Tramway]]. Each 30-tonne locomotive had two {{convert|110|kW|hp|-1|abbr=on}} motors run by three-phase 750&nbsp;V 40&nbsp;Hz fed from double overhead lines. Three-phase motors run at constant speed and provide [[Regenerative brake|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 [[Brown, Boveri & Cie|Walter Boveri]]) in 1899 on the 40&nbsp;km [[List of railway electrification systems#Burgdorf-Thun Bahn|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]] and [[Emil Huber-Stockar]]; installation on the Seebach-Wettingen line of the Swiss Federal Railways was completed in 1904. The 15&nbsp;kV, 50&nbsp;Hz {{convert|345|kW|hp|-1|abbr=on}}, 48&nbsp;tonne locomotives used transformers and rotary converters to power DC traction motors.{{sfnp|Duffy|2003|p=124}}

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&nbsp;km Valtellina line was opened on 4 September 1902, designed by Kandó and a team from the Ganz works.{{sfnp|Duffy|2003|p=120–121}}<ref name="Patent Office" /> The electrical system was three-phase at 3&nbsp;kV 15&nbsp;Hz. The voltage was significantly higher than used earlier and it required new designs for electric motors and switching devices.<ref name="Kalman Kando2">{{cite web|url=http://www.omikk.bme.hu/archivum/angol/htm/kando_k.htm|title=Kalman Kando|access-date=26 October 2011|archive-date=3 March 2016|archive-url=https://web.archive.org/web/20160303191742/http://www.omikk.bme.hu/archivum/angol/htm/kando_k.htm|url-status=live}}</ref><ref>{{cite web|url=http://profiles.incredible-people.com/kalman-kando/ |archive-url=https://archive.today/20120712234334/http://profiles.incredible-people.com/kalman-kando/ |url-status=dead |archive-date=12 July 2012 |title=Kalman Kando |access-date=5 December 2009 }}</ref> 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.<ref name="Kalman Kando2" />

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====Battery–electric====
[[File:Battery loco 16 at West Ham.JPG|thumb|right|A [[London Underground]] battery–electric locomotive used for hauling engineers' trains, at [[West Ham station]]]]
[[File:Wingrove & Rogers 6092.jpg|thumb|right|A narrow-gauge battery–electric locomotive used for mining]]

A battery–electric locomotive (or battery locomotive) is an electric locomotive powered by onboard [[Electric battery|batteries]]; 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 locomotive|steam-]] or [[Diesel locomotive|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 pole|trolley-powered]] units [[Electric arc|arcing]] at the collection shoes, or where [[Electrical resistance and conductance|electrical resistance]] could develop in the supply or return circuits, especially at rail joints, and allow dangerous current leakage into the ground.<ref>{{cite book|last=Strakoš|first=Vladimír|title=Mine Planning and Equipment Selection |year=1997|publisher=Balkema|location=Rotterdam, Netherlands|isbn=90-5410-915-7|page=435|display-authors=etal}}</ref> Battery locomotives in over-the-road service can recharge while absorbing dynamic-braking energy.<ref>{{cite web|last=Lustig|first=David|title=EMD Joule Battery Electric Locomotive arrives in Southern California|url=https://www.trains.com/trn/train-basics/abcs-of-railroading/emd-joule-battery-electric-locomotive-arrives-in-southern-california/|date=21 April 2023|publisher=[[Kalmbach Media]]|work=[[Trains (magazine)|Trains]]|access-date=12 May 2023|archive-date=28 April 2023|archive-url=https://web.archive.org/web/20230428043623/https://www.trains.com/trn/train-basics/abcs-of-railroading/emd-joule-battery-electric-locomotive-arrives-in-southern-california/|url-status=live}}</ref>

The first known electric locomotive was built in 1837 by chemist [[Robert Davidson (inventor)|Robert Davidson]] of [[Aberdeen]], and it was powered by [[galvanic cell]]s (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 mechanism|direct-drive]] [[reluctance motor]]s, with fixed electromagnets acting on iron bars attached to a wooden cylinder on each axle, and simple [[Commutator (electric)|commutators]]. It hauled a load of six tons at four miles per hour (6 kilometers per hour) for a distance of {{convert|1+1/2|mi|km|abbr=off|spell=in}}. 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.<ref>{{cite book|last1=Day|first1=Lance|last2=McNeil|first2=Ian|title=Biographical dictionary of the history of technology|year=1966|publisher=Routledge|location=London|isbn=978-0-415-06042-4|chapter=Davidson, Robert|url=https://archive.org/details/isbn_9780415060424}}</ref><ref>{{cite book|last=Gordon|first=William|title=Our Home Railways|publisher=Frederick Warne and Co|location=London|year=1910|volume=2|page=156|chapter=The Underground Electric}}</ref><ref name="ReferenceA">Renzo Pocaterra, ''Treni'', De Agostini, 2003</ref>

Another example was at the [[Kennecott, Alaska|Kennecott Copper Mine]], [[Latouche, Alaska]], where in 1917 the underground haulage ways were widened to enable working by two battery locomotives of {{frac|4|1|2}} tons.<ref>{{cite book|last=Martin|first=George Curtis|title=Mineral resources of Alaska|url=https://archive.org/details/mineralresource01sgoog|year=1919|publisher=Government Printing Office|location=Washington, DC|page=[https://archive.org/details/mineralresource01sgoog/page/n156 144]}}</ref> 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.<ref>{{Cite web|url=http://utahrails.net/bingham/kcc-diesel-elec-loco.php#700-elec|title=List of Kennecott Copper locomotives|access-date=2 December 2017|archive-date=6 March 2012|archive-url=https://web.archive.org/web/20120306040601/http://utahrails.net/bingham/kcc-diesel-elec-loco.php#700-elec|url-status=dead}}</ref> The locomotives provided several decades of service using [[Nickel–iron battery]] (Edison) technology. The batteries were replaced with [[Lead–acid battery|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]], 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]] in 1968 and retired in 2009.<ref>{{Cite web | url=http://transittoronto.ca/subway/5510.shtml | title=A Rogue's Gallery: The TTC's Subway Work Car Fleet – Transit Toronto – Content | access-date=16 March 2020 | archive-date=27 April 2021 | archive-url=https://web.archive.org/web/20210427041014/http://transittoronto.ca/subway/5510.shtml | url-status=live }}</ref>

London Underground regularly operates [[London Underground battery–electric locomotives|battery–electric locomotives]] for general maintenance work.