{{Short description|Articulated locomotive wheel arrangement}} [[Image:NW Class A.jpg|thumb|300px|Norfolk & Western A class No. 1206 displayed at the New York World's Fair in 1939.]] In the [[Whyte notation]] for the classification of [[steam locomotive]] [[wheel arrangement]], a '''2-6-6-4''' is a locomotive with a two-wheel [[leading truck]], two sets of six [[driving wheel]]s, and a four-wheel [[trailing truck]]. All 2-6-6-4s are simple [[articulated locomotive]]s.
Other equivalent classifications are: *[[UIC classification]]: '''(1'C)C2{{'}}''' (also known as German classification and [[Italian classification]]) *[[French classification]]: '''130+032''' *[[Turkish classification]]: '''34+35''' *[[Swiss classification]]: '''3/4+3/5'''
The [[UIC classification]] is refined to '''(1'C)C2{{'}}''' for simple articulated locomotives.
The 2-6-6-4 was a fairly late development, a product of the [[superpower steam]] concept, introduced by the [[Lima Locomotive Works]], which encouraged the use of large [[Firebox (steam engine)|firebox]]es supported by four-wheel trailing trucks. Such a firebox could sustain a rate of steam generation to meet any demands of the locomotive's cylinders, even at high speed. High speeds were certainly among the design goals for the 2-6-6-4; most of the type were intended for use on fast freight trains.
The first 2-6-6-4s built in the United States were for the [[Pittsburgh and West Virginia Railway]], and these were not high-speed locomotives but rather mountain engines. They received three in 1934 and four more in 1937 and operated the 2-6-6-4s until 1953.
The next of the type was a class of ten ordered by the [[Seaboard Air Line]] in 1935 and 1937. These were high-speed freight engines and very successful. Upon [[dieselisation|dieselization]] the class was sold to the [[Baltimore and Ohio Railroad]] in 1947, who operated them until 1953.
The final class of 2-6-6-4s was the [[Norfolk and Western Railway]]'s [[Norfolk and Western A class|A class]], built starting in 1936. 43 were built until 1950 but were operated until 1959 to prepare the ending of steam power. The powerful 2-6-6-4s were capable of more than 5,000 drawbar horsepower at {{cvt|45|mph|km/h}} and could reach {{cvt|70|mph|km/h}}, while pulling heavy coal trains. They were used until dieselization in 1959.
In all, sixty 2-6-6-4s were constructed in North America. Only one remains: [[Norfolk and Western 1218]] was preserved and in 1987 was restored to running order, running on excursions until 1991. Today it is on display at the [[Virginia Museum of Transportation]].
== References == * [https://web.archive.org/web/20040918045529/http://www.trains.com/Content/Dynamic/Articles/000/000/001/817ygeos.asp Trains.com article on the 2-6-6-4 type]. * Jeffries, Lewis I., ''N&W: Giant of Steam'' (Rev. ed. 2005). * Wrinn, Jim, ''Steam's Camelot: Southern and Norfolk Southern Excursions in Color'' (2000).
==External links== *[http://www.railpictures.net/viewphoto.php?id=122917 picture of N&W 1218 pulling an excursion train in 1988] *[http://www.railpictures.net/viewphoto.php?id=143180 side view of N&W 1218 under steam in 1987] *[https://web.archive.org/web/20151024173944/http://spec.lib.vt.edu/imagebase/vahist/03VT/screen/03NS0004.jpg builder's photo of N&W 1212, engineer's side, Virginia Tech collection] *[https://web.archive.org/web/20151024173943/http://spec.lib.vt.edu/imagebase/vahist/03VT/screen/03NS0005.jpg builder's photo of N&W 1212, fireman's side, Virginia Tech collection]
{{clear}} {{Whyte types}}
[[Category:2-6-6-4 locomotives| ]] [[Category:Whyte notation|66,2-6-6-4]]