Editing Rail transport modelling (section)

== Methods of power ==
[[File:Tiny electric motor in a Z scale model locomotive.jpg|thumb|The sugar-cube sized [[electric motor]] in a Z scale model locomotive. The entire engine is only 50&nbsp;mm (2") long.]]
[[File:Guntur west terminal and a model train.jpg|thumb|right|Model of WP Steam Locomotive (1:3 size) at [[Guntur]], [[India]]]]

Static diorama models or "push along" scale models are a branch of model railways for unpowered locomotives, examples are [[Lone Star Toys|Lone Star]] and [[Airfix]] models. Powered model railways are now generally operated by low voltage [[direct current]] (DC) electricity supplied via the tracks, but there are exceptions, such as [[Märklin]] and [[Lionel Corporation]], which use [[alternating current]] (AC). Modern [[Digital Command Control]] (DCC) systems use alternating current. Other locomotives, particularly large models, can use steam. Steam and clockwork-driven engines are still sought by collectors.

=== Clockwork ===
Most early models for the toy market were powered by [[clockwork]] and controlled by levers on the locomotive. Although this made control crude the models were large and robust enough that handling the controls was practical. Various manufacturers introduced slowing and stopping tracks that could trigger levers on the locomotive and allow station stops.

=== Electricity ===
[[File:Bing electric American-type locomotive, circa 1914.jpg|thumb|Bing electric American-type locomotive, circa 1914]]
;Three-rail
The first miniature electric trains used a [[Third rail (model railroading)|three-rail]] track, with non-insulated wheels resting on the two outer rails that were in contact with the metal sleepers. The insulated central rail supplied the current to a skid under the locomotive. The outer rails ensured the return of the current. The current was alternating, supplied by the domestic network, lowered by various means (transformer or serial resistances). This kind of track made sense at the time as models were metal and conductive. Modern plastics were not available and insulation was a problem. In addition the notion of accurate models had yet to evolve and [[toy train]]s and track were crude tinplate.

In 1938, Hornby, a manufacturer of ‘O’ scale model trains in the UK, launched a range of ‘OO’ scale electric trains (Hornby Dublo) with 1/76 scale rolling stock using 1/87 scale 16.5 mm wide track with a third centre rail. The power supply was 12 V DC and the track was equipped with an electrically insulated central rail and two non-insulated running rails. In 1959 Hornby abandoned its three-rail track in favour of a two-rail track for its ‘OO’ scale electric trains.<ref>https://uk.hornby.com/about-hornby The History of Hornby</ref>

Other systems such as Märklin instead used, since 1953,<ref>{{cite web|url=https://hobbystation811378889.wordpress.com/home/generalites/evolution-technique | title=Évolution technique du modélisme ferroviaire| date=November 2020}} Technical evolution of model railways (page in French, retrieved 2025-05-04).</ref> [[Stud contact electrification on model railways|fine metal studs]] to replace the central rail, allowing existing three-rail models to use more realistic track.

A variation on the three-rail system, early introduced by Trix in 1935, used a track with three insulated rails that allowed two trains to be independently controlled on the same track. The use of a catenary made it possible for three trains to be independently controlled. The center rail ensured the common return of the current.<ref>Explanatory diagram in the 1964 Trix catalog</ref> That system, known as Trix Express or Trix Twin in the UK, which first used alternative current and then direct current after 1953, was abandoned in 1997 when Märklin took over Trix. This three-rail system enabled DC and AC locomotives to run on the same track.<ref>http://www.trix.nl/bedrijf/uitgebreide-historie | History of Trix (in Dutch)</ref>

;Two-rail
When [[DC motor|DC motors]] with more powerful magnets began to be used for model trains in the 1950s,<ref>Jean-François Guy, L’évolution technique dans le jouet électrique. In: Bulletin d'histoire de l'électricité, n°31, juin 1998, p. 46. (French-language article on  https://www.persee.fr/doc/helec_0758-7171_1998_num_31_1_1381)</ref> the two-rail track was generally preferred because at the same time accuracy became important. The two insulated rails from each other are to be used with insulated wheels on the same axle. In the direction of travel, the right-hand rail carries the positive potential and the left-hand rail the negative.<ref>Standards for European Model Railroads, Norm 631 https://www.morop.org/images/NEM_register/NEM_E/nem631_en_1985.pdf</ref> This system excludes certain track layouts such as the reversing loop, the reversing triangle and the diagonal in a circle without insulated sections and suitable cabling.

;Overhead line
Where the model is of an [[electric locomotive]], it may be supplied by [[overhead lines]], like the full-size locomotive. Before [[Digital Command Control]] became available, this was one way of controlling two trains separately on the same track. The electric-outline model would be supplied by the overhead wire and the other model could be supplied by one of the running rails. The other running rail would act as a common return.

;Battery
Early electric trains ran on trackside [[battery (electricity)|batteries]] because few homes in the late 19th century and early 20th century had electricity. Today, inexpensive train sets running on batteries are again common but regarded as [[toy train|toys]] and seldom used by hobbyists. Batteries located in the model often power garden railway and larger scale systems because of the difficulty in obtaining reliable power supply through the outdoor rails. The high-power consumption and current draw of large-scale garden models is more easily and safely met with internal rechargeable batteries. Most large-scale battery-powered models use radio control.

=== Live steam ===
Engines powered by [[live steam]] are often built in large outdoor gauges of {{convert|5|in}} and {{convert|7+1/2|in}}, are also available in [[Gauge 1]], [[G scale]], [[16 mm scale]] and can be found in O and OO/HO. [[Hornby Railways]] produce live steam locomotives in OO, based on designs first arrived at by an amateur modeller. Other modellers have built live steam models in HO/OO, OO9 and N, and there is one in Z in [[Australia]].<ref>{{cite web |title=Ultraminiature Live Steam |url=http://www.zen98812.zen.co.uk/steam.html}}</ref>

=== Internal combustion ===
Occasionally [[gasoline]]-electric models, patterned after real diesel-electric locomotives, come up among hobbyists and companies like Pilgrim Locomotive Works have sold such locomotives. Large-scale petrol-mechanical and petrol-hydraulic models are available but unusual and pricier than the electrically powered versions.