4-2-4T

{{Short description|Tank locomotive wheel arrangement}} {{Infobox steam wheel arrangement | name = 4-2-4 | image = WheelArrangement 4-2-4.svg | alt = Diagram of two small leading wheels, a single large driving wheel and two small trailing wheels | caption = | image2 = 4-2-4 B&ER 44.jpg | alt2 = | caption2 = Pearson 4-2-4T no. 44 of the [[Bristol and Exeter Railway 4-2-4T locomotives|Bristol and Exeter Railway]], c. 1854  | hatnote = | UIC/Germany/Italy= 2A2 | French/Spanish = 212 | Turkish = 15 | Swiss = 1/5 | Russian = 2-1-2  | date = 1853 | country = United Kingdom | locomotive = Pearson 4-2-4T | railway = [[Bristol and Exeter Railway]] | designer = [[James Pearson (engineer)|James Pearson]] | builder = Bristol and Exeter Railway | evolvedfrom = | evolvedto = | mainbenefit = | maindrawback =  | date2 = | country2 = | locomotive2 = | railway2 = | designer2 = | builder2 = | evolvedfrom2 = | evolvedto2 = | mainbenefit2 = | maindrawback2 =  | date3 = | country3 = | locomotive3 = | railway3 = | designer3 = | builder3 = | evolvedfrom3 = | evolvedto3 = | mainbenefit3 = | maindrawback3 = }}

Under the [[Whyte notation]] for the classification of [[steam locomotive]]s, '''{{nowrap|4-2-4}}''' represents the [[wheel arrangement]] of four [[leading wheel]]s on two axles, two powered [[driving wheel]]s on one axle, and four [[trailing wheel]]s on two axles.

The configuration was only used for tank engines, which is noted by adding letter suffixes to the configuration, such as {{nowrap|4-2-4T}} for a conventional side-tank locomotive, {{nowrap|4-2-4ST}} for a saddle-tank locomotive, {{nowrap|4-2-4WT}} for a well-tank locomotive and {{nowrap|4-2-4RT}} for a rack-equipped tank locomotive. {{TOC limit|3}}

==Overview== This wheel arrangement was only used on various [[tank locomotive]] configurations. Eight 4-2-4 well- and back-tank locomotives which entered service on the [[Bristol and Exeter Railway]] in 1853 appear to have been the first with this wheel arrangement. The engine was designed by [[James Pearson (engineer)|James Pearson]], the railway company's engineer, and featured single large [[flange]]less driving wheels between two supporting four-wheeled [[bogie]]s. The water was carried in both well- and back-tanks, leaving the boilers exposed in the same way as on most tender locomotives.

==Usage==

===United Kingdom=== The [[Bristol and Exeter Railway 4-2-4T locomotives|first eight known 4-2-4T locomotives]] entered service on the [[broad gauge]] [[Bristol and Exeter Railway]] in 1853 and 1854, numbered in the range from 39 to 46. They had {{convert|9|ft|mm|0|abbr=off}} diameter flangeless driving wheels, supported by leading and trailing two-axle bogies. The water was carried in both [[tank locomotive#Well tank|well- and back-tanks]]. Two more engines were built in 1859 and 1862, but with much smaller {{convert|7|ft|6|in|mm|0|abbr=off}} diameter driving wheels.

[[File:4-2-4 B&ER No40.jpg|thumb|left|The second B&ER No. 40 of 1873]] Between 1869 and 1873, new locomotives were built to replace four of the original {{convert|9|ft|mm|0|abbr=off}} diameter driving wheeled engines, re-using the engine numbers of the locomotives being replaced. These four replacement engines had slightly smaller, {{convert|8|ft|10|in|mm|0|abbr=off}}, diameter driving wheels.

In 1881, this wheel arrangement was also used by the [[Great Western Railway]] on [[William Dean (engineer)|William Dean's]] [[GWR Dean experimental locomotives#No. 9|experimental locomotive No. 9]]. Since it was so prone to derailing as to be unable to be moved from the workshops where it was built, it did no work and was rebuilt to a {{nowrap|[[2-2-2]]}} tender locomotive in 1884. [[Dugald Drummond]] of the [[London and South Western Railway]] built a 4-2-4T [[LSWR F9 class|F9]] class combined locomotive and inspection saloon in 1899. It was little used after Drummond's death in 1912.<ref name="Bradley">D. L. Bradley, Locomotive of the London and South Western Railway, Part ii., Railway Correspondence and Travel Society, 1967. pp. 86-87.</ref>

===United States=== [[File:CP Huntington.jpg|thumb|The ''[[C.P. Huntington]]'']] The engine ''[[C. P. Huntington]]'' was one of three identical 4-2-4 tank locomotives. They were the first locomotives to be purchased by [[Southern Pacific Railroad]] in 1863, for use on light commuter services in the Sacramento area. The locomotives had serious shortcomings. The single driving axle did not carry the full weight of the engine's rear end due to the trailing truck and, in addition to being too light, it therefore lacked adhesion to reliably pull trains, especially on gradients. The short water tank on the [[Forney locomotive|Forney-type]] frame prevented the locomotives from travelling any moderate distance without consuming all of their water. As a result, these locomotives were only used when absolutely necessary.<ref name=DiebertStrapac>{{cite book| first1=Timothy S.| last1=Diebert| first2=Joseph A.| last2=Strapac| title=Southern Pacific Company Steam Locomotive Compendium| publisher=Shade Tree Books| year=1987| location=Huntington Beach, CA|pages=33, 51| isbn=0-930742-12-5}}</ref>

In 1863, a sister engine, the ''[[T. D. Judah]]'', was built by the Cooke Locomotive Works for a railroad which was unable to pay for it and was purchased by the [[Central Pacific Railroad]]. This locomotive was rebuilt to a [[4-2-2]] wheel arrangement in 1872.<ref name=DiebertStrapac/>

===South Africa=== In 1923, the South African Railways (SAR) conducted trials with a prototype petrol-paraffin powered road-rail tractor and, in 1924, placed at least two [[South African Dutton road-rail tractors|Dutton steam rail tractors]] in service on the new {{Track gauge|2ft|allk=on}} narrow gauge line between [[Naboomspruit]] and Singlewood in Transvaal. One of the latter had a {{nowrap|4-2-4}} wheel arrangement.<ref name="SAR&H Oct 1945">Espitalier, T.J.; Day, W.A.J. (1945). ''The Locomotive in South Africa - A Brief History of Railway Development. Chapter VII - South African Railways (Continued).'' South African Railways and Harbours Magazine, October 1945. pp. 782-783.</ref><ref name="Paxton-Bourne">{{Paxton-Bourne|pages=118-119}}</ref>

[[File:Dutton Road-Rail Tractor no. RR1155 b.jpg|thumb|left|Dutton rail-only tractor no. RR1155, c. 1924]] The designer, Major Frank Dutton, SAR Signal Engineer and the Motor Transport Superintendent, argued that a rubber tyre in contact with a hard road would be better at transferring tractive power than a steel wheel on steel rail. At least two Dutton Rail Tractors were built, both steam-powered and both rebuilt by the Britannia Engineering Works of Johannesburg from [[Yorkshire Patent Steam Wagon Co.|Yorkshire steam tractors]].<ref name="Paxton-Bourne"/><ref name="DaveMills">[http://dave-mills.yolasite.com/stronach-dutton-road-rail.php Stronach-Dutton Road-Rail - The Roadrail System of Traction]</ref>

The second Dutton tractor, no. RR1155, was a rail-only vehicle. It had a bogie at either end with the single pair of driving wheels on a differential axle in the centre. It was arranged for forward and reverse movement at all speeds, but it could only be used on the rails. Since, on occasion, the vehicle had to be transported by road, its construction was such that it could be readily disassembled into more easily transportable units, to be moved on road wheels to a workshop or for transfer of any other kind. In service, the tractor was often equipped with a water tank tender loaded with additional bags of coal on its running boards.<ref name="Paxton-Bourne"/><ref name="DuttonPatent1">[https://patents.google.com/patent/US1306051 Patent: Dutton Light Railway System and Locomotive Therefor, US 1306051 A, Jun 10, 1919]</ref><ref name="DuttonPatent3">[https://patents.google.com/patent/US1561510 Patent: Vehicle for Service on Roads and Rails, US 1561510 A, Nov 17, 1925]</ref>

==In fiction== The ''Little Blue Engine'' from the original 1906 book ''[[The Little Engine That Could]]'' was a [[Forney locomotive]] with this wheel arrangement.<ref>{{Cite web|title=I think I can. I think I can. - Original 1906 cover|date=19 July 2010|url=http://www.gettingthroughthis.com/2928/i-think-i-can-i-think-i-can/ }}</ref><ref>{{Cite web|title=The Little Engine That Could, Watty Piper, 1954 - yellow cloth cover with black print|url=http://www.myerscollectibles.com/store/item/1e3wp/Picture_Books_Post_1920/The_Little_Engine_That_Could_Watty_Piper_1954.html}}</ref>

==Preserved examples and replicas== *[[Central Pacific Railroad|Central Pacific]] no.3 [[C. P. Huntington]] built in October 1863 is on display at [[California State Railroad Museum]]

==References== {{Commons category}} {{Reflist}}

[[Category:4-2-4 locomotives| ]] [[Category:2A2 locomotives| ]] [[Category:Tank locomotives|2, 4-2-4T]] [[Category:Whyte notation]]