In the

Whyte notation Whyte notation is a classification method for steam locomotives, and some internal combustion locomotives and electric locomotives, by wheel arrangement. It was devised by Frederick Methvan Whyte, and came into use in the early twentieth cen ...

for the classification of

steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the loco ...

wheel arrangement In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and c ...

, a 2-6-6-4 is a locomotive with a two-wheel

leading truck The leading wheel or leading axle or pilot wheel of a steam locomotive is an unpowered wheel or axle located in front of the driving wheels. The axle or axles of the leading wheels are normally located on a leading truck. Leading wheels are used ...

, two sets of six

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, and a four-wheel trailing truck. All 2-6-6-4s are

articulated locomotive An articulated locomotive is a steam locomotive (rarely, an electric locomotive) with one or more engine units that can move independent of the main frame. Articulation allows the operation of locomotives that would otherwise be too large to neg ...

s, of the

Mallet A mallet is a tool used for imparting force on another object, often made of rubber or sometimes wood, that is smaller than a maul or beetle, and usually has a relatively large head. The term is descriptive of the overall size and propor ...

or related simple articulated type. Other equivalent classifications are: *

UIC classification The UIC classification of locomotive axle arrangements, sometimes known as the German classification''The Railway Data File''. Leicester: Silverdale, 2000. p. 52. . or German system,Kalla-Bishop P.M. & Greggio, Luciano, ''Steam Locomotives'', Cre ...

: (1'C)C2 (also known as German classification and

Italian classification The UIC classification of locomotive axle arrangements, sometimes known as the German classification''The Railway Data File''. Leicester: Silverdale, 2000. p. 52. . or German system,Kalla-Bishop P.M. & Greggio, Luciano, ''Steam Locomotives'', Cre ...

) *

French classification Under the French classification system for locomotive wheel arrangements, the system is slightly different for steam and electric/diesel vehicles. Steam The French system counts axles, rather than wheels. As with Whyte notation, a conventional r ...

: 130+032 *

Turkish classification In the Turkish classification system for railway locomotives, the number of powered axles are followed by the total number of axles. It is identical to the Swiss system except that the latter places a slash between the two numbers. Thus 0-6-0 beco ...

: 34+35 *

Swiss classification For more than a century, the Swiss locomotive, multiple unit, motor coach and railcar classification system, in either its original or updated forms, has been used to name and classify the rolling stock operated on the railways of Switzerland. ...

: 3/4+3/5 The

is refined to (1'C)C2 for Mallet locomotives. The 2-6-6-4 was a fairly late development, a product of the

superpower steam "Superpower steam" was a term coined by Lima Locomotive Works in the mid-1920s, referring to steam locomotives with booster-equipped four-wheel trailing trucks supporting large fireboxes, as well as enlarged superheaters. The wheel arrangements in ...

concept, introduced by the

Lima Locomotive Works Lima Locomotive Works was an American firm that manufactured railroad locomotives from the 1870s through the 1950s. The company took the most distinctive part of its name from its main shop's location in Lima, Ohio. The shops were located between ...

, which encouraged the use of large

firebox Firebox may refer to: * Firebox (steam engine), the area where the fuel is burned in a steam engine * Firebox (architecture), the part of a fireplace where fuel is combusted *Firebox Records, a Finnish 8101705801record label * Firebox.com, an elect ...

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 Railroad The Pittsburgh and West Virginia Railway was a railroad in the Pittsburgh, Pennsylvania and Wheeling, West Virginia, areas. Originally built as the Wabash Pittsburgh Terminal Railway, a Pittsburgh extension of George J. Gould's Wabash Railroad ...

, and these were not high speed locomotives but rather mountain luggers. They received three in 1934 and four more in 1937 and operated the 2-6-6-4s until 1953. The next of the type were a class of ten ordered by the Seaboard Air Line in 1935 and 1937. These were high speed freight engines and were successful. Upon

dieselisation Dieselisation (US: dieselization) is the process of equipping vehicles with a diesel engine or diesel engines. It can involve replacing an internal combustion engine powered by petrol (gasoline) fuel with an engine powered by diesel fuel, as o ...

the road sold the locomotives to the

Baltimore and Ohio Railroad The Baltimore and Ohio Railroad was the first common carrier railroad and the oldest railroad in the United States, with its first section opening in 1830. Merchants from Baltimore, which had benefited to some extent from the construction of ...

in 1947, who operated them until 1953. The final class of 2-6-6-4s was the

Norfolk and Western Railway The Norfolk and Western Railway , commonly called the N&W, was a US class I railroad, formed by more than 200 railroad mergers between 1838 and 1982. It was headquartered in Roanoke, Virginia, for most of its existence. Its motto was "Precis ...

's class A, 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 45 mph (72 km/h) and could reach 70 mph (110 km/h), and could lug heavy coal trains. They were used until dieselisation in 1959. One locomotive,

Norfolk and Western 1218 Norfolk and Western 1218 is a preserved four-cylinder simple articulated 2-6-6-4 steam locomotive, built in June 1943 by the Norfolk and Western's (N&W) East End Shops in Roanoke, Virginia as part of the N&W's class "A" fleet of fast freight loco ...

, 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 The Virginia Museum of Transportation is a museum devoted to the topic of transportation located in Downtown Roanoke, Virginia, US. children under two years do not to buy tickets and students can get a discounted $10.5 ticket. History The Virg ...

. It is the only surviving 2-6-6-4 in the world. In all, sixty 2-6-6-4s were constructed in North America.

References

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

picture of N&W 1218 pulling an excursion train in 1988side view of N&W 1218 under steam in 1987builder's photo of N&W 1212, engineer's side, Virginia Tech collectionbuilder's photo of N&W 1212, fireman's side, Virginia Tech collection
{{Whyte types 66,2-6-6-4