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.
Under the Whyte notation for the classification of steam locomotives, a 2-10-4 locomotive has two leading wheels on one axle, usually in a Bissel truck, ten coupled driving wheels on five axles, and four trailing wheels on two axles, usually in a bogie. These were referred to as the Texas type in most of the United States, the Colorado type on the Burlington Route, and the Selkirk type in Canada.
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.
Main components found on a typical steam locomotive include:
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 the Erie Railroad main line, the Baltimore & Ohio's Cincinnati-Toledo main line and the Nickel Plate Road main line and shops.
Under the Whyte notation for the classification of steam locomotives, 4-2-0 represents the wheel arrangement of four leading wheels on two axles, two powered driving wheels on one axle and no trailing wheels. This type of locomotive is often called a Jervis type, the name of the original designer.
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.
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 wheels, and a four-wheel trailing truck. All 2-6-6-4s are simple articulated locomotives.
Under the Whyte notation for the classification of steam locomotives, 2-4-2 represents the wheel arrangement of two leading wheels on one axle, four powered and coupled driving wheels on two axles and two trailing wheels on one axle. The type is sometimes named Columbia after a Baldwin 2-4-2 locomotive was showcased at the 1893 World's Columbian Exposition held at Chicago, Illinois.
Under the Whyte notation for the classification of steam locomotives, a 4-8-8-2 is a locomotive with four leading wheels, two sets of eight driving wheels, and a two-wheel trailing truck.
The Union Pacific Railroad 9000 Class was a class of 88 steam locomotives, built by ALCO for the Union Pacific between 1926 and 1930.
Under the Whyte notation for the classification of steam locomotives, 0-8-2 represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles, and two trailing wheels on one axle.
Under the Whyte notation for the classification of steam locomotives, 2-12-2 represents the wheel arrangement of two leading wheels on one axle, twelve powered and coupled driving wheels on six axles, and two trailing wheels on one axle.
Under the Whyte notation for the classification of steam locomotives, a 2-8-8-8-4 has two leading wheels, three sets of eight driving wheels, and four trailing wheels.
The AA20 was a one-off steam locomotive constructed by the Soviet Union.
A 2-6-8-0 steam locomotive, in the Whyte notation for describing locomotive wheel arrangements, has two leading wheels, a set of six driving wheels, a set of eight driving wheels, and no trailing wheels. These locomotives usually employ the Mallet principle of articulation, with a swinging front engine and a rigidly attached rear engine.
Under the Whyte notation for the classification of steam locomotives, a 4-8-6 locomotive would have had four leading wheels, eight coupled driving wheels and six trailing wheels.
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 by wheel arrangement, a 2-8-2+2-8-2 is an articulated locomotive using a pair of 2-8-2 power units back to back, with the boiler and cab suspended between them. The 2-8-2 wheel arrangement has a single pair of leading wheels in a leading truck, followed by four coupled pairs of driving wheels and a pair of trailing wheels in a trailing truck. Since the 2-8-2 type was known as Mikado, the corresponding Garratt and Modified Fairlie types were usually known as Double Mikado.
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.
