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Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 2-4-4 is a steam locomotive with two unpowered leading wheels followed by four powered driving wheels and four unpowered trailing wheels. This configuration was only used for tank locomotives; no tender locomotives with this wheel arrangement were made.
Other equivalent classifications are:
The equivalent UIC classification is 1′B2′ t (or (1′B)2′ t for a Mason Bogie).
This unusual wheel arrangement does not appear to have been used on the mainline railways in the UK. It was however one of the configurations used on the Mason Bogie articulated locomotives, in the USA during the 1870s and 1880s. Five examples were constructed at the Mason Machine Works for the narrow gauge Boston, Revere Beach and Lynn Railroad 1883–1887. The railway subsequently received twenty-one further examples between 1900 and 1914, constructed by the Taunton Locomotive Manufacturing Company, Manchester Locomotive Works, and ALCO. Developmentally, there are two logical ways of reaching this wheel formula: to add a forward axle to a Forney locomotive to improve its ability to negotiate curves, or to add a second trailing axle to a Columbia design, notably in a 2-4-4(T) configuration to expand its coal capacity.
Four 2-4-4T passenger locomotives were built by the Czechoslovak Škoda for Lithuania in 1932 and marked as Tk class. They were seized by the USSR in 1940, then by the Germans. [1] One was used after World War II in Poland as the OKf100-1 until 1950. [2]
Other tank locomotives with 2-4-4T arrangement:
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A Fairlie locomotive is a type of articulated steam locomotive that has the driving wheels on bogies. The locomotive may be double-ended or single ended.
The 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 century following a December 1900 editorial in American Engineer and Railroad Journal.
The UIC classification of locomotive axle arrangements, sometimes known as the German classification or German system, describes the wheel arrangement of locomotives, multiple units and trams. It is used in much of the world, notable exceptions being the United Kingdom, which uses a slightly simplified form of UIC, and in North America, where the AAR wheel arrangement system is used to describe diesel and electric locomotives. In North America, the Whyte notation is only used for steam locomotives.
The AAR wheel arrangement system is a method of classifying locomotive wheel arrangements that was developed by the Association of American Railroads. Essentially a simplification of the European UIC classification, it is widely used in North America to describe diesel and electric locomotives. It is not used for steam locomotives,, which use the Whyte notation instead.
Under the Whyte notation for the classification of steam locomotives, 4-4-4 represents the wheel arrangement of four leading wheels on two axles, four powered and coupled driving wheels on two axles, and four trailing wheels on two axles. In the United States, this arrangement was named the Reading type, since the Philadelphia and Reading Railroad was the first to use it. In Canada, this type is known as the Jubilee.
Under the Whyte notation for the classification of steam locomotives, 4-2-2 represents the wheel arrangement of four leading wheels on two axles, two powered driving wheels on one axle, and two trailing wheels on one axle.
Under the Whyte notation for the classification of steam locomotives, a 2-6-4 locomotive has two leading wheels, six coupled driving wheels and four trailing wheels.
In the Whyte notation for the classification of steam locomotive wheel arrangement, an 0-4-4-0 is a locomotive with no leading wheels, two sets of four driving wheels, and no trailing wheels. The arrangement is chosen to give the articulation of a locomotive with only the short rigid wheelbase of an 0-4-0, but with its weight spread across eight wheels, and with all the weight carried on the driving wheels; effectively a flexible 0-8-0. Articulated examples were constructed as Mallet, Meyer, BMAG and Double Fairlie locomotives and also as geared locomotives such as Shay, Heisler, and Climax types. A similar configuration was used on some Garratt locomotives, but it is referred to as 0-4-0+0-4-0. In the electric and diesel eras, the Bo-Bo is comparable and closest to the Meyer arrangement of two swivelling bogies.
On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle (wheelset) located behind the driving wheels. The axle of the trailing wheels is usually located in a trailing truck. On some large locomotives, a booster engine was mounted on the trailing truck to provide extra tractive effort when starting a heavy train and at low speeds on gradients.
Under the Whyte notation for the classification of steam locomotives, 4-2-4 represents the wheel arrangement of four leading wheels on two axles, two powered driving wheels on one axle, and four trailing wheels on two axles.
Under the Whyte notation for the classification of steam locomotives, 0-4-4 represents the wheel arrangement of no leading wheels, four powered and coupled driving wheels on two axles, and four trailing wheels on two axles. This type was only used for tank locomotives.
Under the Whyte notation for the classification of steam locomotives, 0-6-4 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and four trailing wheels on two axles.
B-B and Bo-Bo are the Association of American Railroads (AAR) and British classifications of wheel arrangement for railway locomotives with four axles in two individual bogies. They are equivalent to the B′B′ and Bo′Bo′ classifications in the UIC system. The arrangement of two, two-axled, bogies is a common wheel arrangement for modern electric and diesel locomotives.
In Whyte notation, a 4-6-6-2 is a steam locomotive with four leading wheels in an unpowered bogie at the front of the locomotive followed by two sets of driving wheels with six wheels each, followed by two unpowered trailing wheels at the rear of the locomotive.
Under the Whyte notation for the classification of steam locomotives, 0-8-4 represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles, and four trailing wheels on two axles.
In the Whyte notation for describing steam locomotive wheel arrangement, a 2-8-6 is a locomotive with a two-wheel leading truck, eight driving wheels, and a six-wheel trailing truck. All 2-8-6 locomotives constructed have been Mason Bogie tank locomotives.
Under the French classification system for locomotive wheel arrangements, the system is slightly different for steam and electric/diesel vehicles.
In Whyte notation, a 2-4-6 is a steam locomotive with two unpowered leading wheels followed by four powered driving wheels and six unpowered trailing wheels. This wheel arrangement was only used for tank locomotives; no 2-4-6 tender locomotives were made.
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 to help the locomotive negotiate curves and to support the front portion of the boiler.
Under the Whyte notation for the classification of steam locomotives, 0-6-6 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles and six trailing wheels on three axles. All locomotives with this wheel arrangement were tank locomotives; no 0-6-6 tender locomotives were recorded.