2-4-6

Last updated

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.

Whyte notation

The Whyte notation for classifying steam locomotives by wheel arrangement 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 notation counts the number of leading wheels, then the number of driving wheels, and finally the number of trailing wheels, numbers being separated by dashes. Other classification schemes, like UIC classification and the French, Turkish and Swiss systems for steam locomotives, count axles rather than wheels.

Steam locomotive railway locomotive that produces its pulling power through a steam engine

A steam locomotive is a type of railway locomotive that produces its pulling power through a steam engine. These locomotives are fueled by burning combustible material – usually coal, wood, or oil – to produce steam in a boiler. The steam moves reciprocating pistons which are mechanically connected to the locomotive's main wheels (drivers). Both fuel and water supplies are carried with the locomotive, either on the locomotive itself or in wagons (tenders) pulled behind.

Leading wheel unpowered wheel at the front of a locomotive

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.

Equivalent classifications

Other equivalent classifications are:

The equivalent UIC classification is 1'B3' (or (1'B)'3' for a Mason Bogie).

Examples

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 US during the 1880s. Two examples were constructed at the Mason Machine Works for the narrow gauge Boston, Revere Beach and Lynn Railroad in 1892.

The main line, or mainline in American English, of a railway is a track that is used for through trains or is the principal artery of the system from which branch lines, yards, sidings and spurs are connected. It generally refers to a route between towns, as opposed to a route providing suburban or metro services. For capacity reasons, main lines in many countries have at least a double track and often contain multiple parallel tracks. Main line tracks are typically operated at higher speeds than branch lines and are generally built and maintained to a higher standard than yards and branch lines. Main lines may also be operated under shared access by a number of railway companies, with sidings and branches operated by private companies or single railway companies.

Mason Bogie

The Mason Bogie is a type of articulated steam locomotive suited for sharp curves and uneven track, once commonly used on narrow gauge lines in the United States. The design is a development of the single Fairlie, and is sometimes, and perhaps more properly known as the Mason Fairlie.

Articulated locomotive

The term "articulated locomotive" usually means a steam locomotive with one or more engine units which can move independent of the main frame. This is done to allow a longer locomotive to negotiate tighter curves. Articulated locomotives are generally used either on lines with extreme curvature—logging, industrial, or mountain railways, for example—or to allow very large locomotives to run on railways with regular track curvature. Articulation is also applied to some electric locomotives, such as the Italian FS Class E656.


This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

Related Research Articles

4-8-8-4 articulated locomotive wheel arrangement

A 4-8-8-4 in the Whyte notation for the classification of steam locomotives by wheel arrangement, is a locomotive with a four-wheel leading truck, two sets of eight driving wheels, and a four-wheel trailing truck. These are commonly known as "Union Pacific Big Boys".

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 connections, with the adopted notations varying by country. Within a given country, different notations may also be employed for different kinds of locomotives, such as steam, electric, and diesel powered.

The UIC classification of locomotive axle arrangements, sometimes known as German classification or German system, describes the wheel arrangement of locomotives, multiple units and trams. It is set out in the International Union of Railways (UIC) "Leaflet 650 – Standard designation of axle arrangement on locomotives and multiple-unit sets". It is used in much of the world. The United Kingdom uses the Whyte notation. The United States uses the simplified AAR wheel arrangement for modern locomotives.

6-2-0 locomotive wheel arrangement

In the Whyte notation, a 6-2-0 is a railroad steam locomotive that has an unpowered three-axle leading truck followed by a single powered driving axle. This wheel arrangement is associated with the Crampton locomotive type, and in the USA the single class were sometimes referred to as Cramptons.

2-4-4T tank locomotive wheel arrangement

In Whyte notation, a 2-4-4, or Boston-type, is a steam locomotive with two unpowered leading wheels followed by four powered driving wheels and four unpowered trailing wheels.

6-8-6 locomotive wheel arrangement

Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 6-8-6 represents the arrangement of six unpowered leading wheels arranged into a three-axle leading truck, eight powered driving wheels, and six unpowered trailing wheels arranged into a three-axle trailing truck.

Trailing wheel unpowered locomotive wheel located rear of the driving wheel(s)


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.

In Whyte notation, 2-4-4-2 refers to a railroad steam locomotive that has two leading wheels followed by four coupled driving wheels, a second set of four coupled driving wheels, and two trailing wheels.

In Whyte notation for the classification of steam locomotives by wheel arrangement, a 2-12-4 is a locomotive with one pair of unpowered leading wheels, followed by six pairs of powered driving wheels, and two pairs of unpowered trailing wheels.

Co-Co locomotives locomotive wheel arrangement

Co-Co is the wheel arrangement for a diesel locomotive with two six-wheeled bogies with all axles powered, with a separate motor per axle. The equivalent UIC classification (Europe) for this arrangement is Co′Co′ or C-C for AAR (USA).

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.

0-8-4T tank locomotive wheel arrangement

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.

2-6-6T locomotive wheel arrangement

In the Whyte notation for describing steam locomotive wheel arrangement, a 2-6-6 is a locomotive with a two-wheeled leading truck, six driving wheels, and a six-wheeled trailing truck. All the locomotives produced of this arrangement have been tank locomotives, and the vast majority in the United States. It was a popular arrangement for the larger Mason Bogies, as well as some of the largest suburban tank locomotives.

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 2-8-6T tank locomotives of the Mason Bogie pattern.

Under the French classification system for locomotive wheel arrangements, the system is slightly different for steam and electric/diesel vehicles.

0-6-6 wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles and six trailing wheels on three axles

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.

Under the Whyte notation for the classification of steam locomotive wheel arrangements, a 4-4-6-2 is a locomotive with two pairs of leading wheels, one set of four driving wheels, a second set of six driving wheels, and a pair of trailing wheels.