Under the Whyte notation for the classification of steam locomotives, 4-6-2 represents the wheel arrangement of four leading wheels on two axles, six powered and coupled driving wheels on three axles and two trailing wheels on one axle. The 4-6-2 locomotive became almost globally known as a Pacific type after a New Zealand locomotive that was shipped across the Pacific Ocean.
Under the Whyte notation for the classification of steam locomotives, 4-8-2 represents the wheel arrangement of four leading wheels, eight powered and coupled driving wheels and two trailing wheels. This type of steam locomotive is commonly known as the Mountain type.
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.
0-6-0 is the Whyte notation designation for steam locomotives with a wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and no trailing wheels. Historically, this was the most common wheel arrangement used on both tender and tank locomotives in versions with both inside and outside cylinders.
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, Whyte notation is only used for steam locomotives.
4-4-0 is a locomotive type with a classification that uses the Whyte notation for the classification of steam locomotives by wheel arrangement and represents the arrangement: four leading wheels on two axles, four powered and coupled driving wheels on two axles, and a lack of trailing wheels. Due to the large number of the type that were produced and used in the United States, the 4-4-0 is most commonly known as the American type, but the type subsequently also became popular in the United Kingdom, where large numbers were produced.
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.
Under the Whyte notation for the classification of steam locomotives, 0-8-0 represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles and no trailing wheels. Locomotives of this type are also referred to as eight coupled.
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 by wheel arrangement, a 2-6-6-2 is a locomotive with one pair of unpowered leading wheels, followed by two sets of three pairs of powered driving wheels and one pair of trailing wheels. The wheel arrangement was principally used on Mallet-type articulated locomotives, although some tank locomotive examples were also built. A Garratt locomotive or Golwé locomotive with the same wheel arrangement is designated 2-6-0+0-6-2 since both engine units are pivoting.
Under the Whyte notation for the classification of steam locomotives, 0-12-0 represents the wheel arrangement of no leading wheels, twelve powered and coupled driving wheels on six axles, and no trailing wheels.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 2-6-6-0 is a locomotive with one pair of unpowered leading wheels, followed by two sets of three pairs of powered driving wheels and no trailing wheels. The wheel arrangement was principally used on Mallet-type articulated locomotives. Some tank locomotive examples were also built, for which various suffixes to indicate the type of tank would be added to the wheel arrangement, for example 2-6-6-0T for an engine with side-tanks.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, a 4-6-2+2-6-4 is a Garratt or Union Garratt articulated locomotive using a pair of 4-6-2 engine units back to back, with the boiler and cab suspended between them. The 4-6-2 wheel arrangement of each engine unit has four leading wheels on two axles, usually in a leading bogie, six powered and coupled driving wheels on three axles, and two trailing wheels on one axle, usually in a trailing truck. Since the 4-6-2 type is known as a Pacific, the corresponding Garratt type is usually known as a Double Pacific.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, the 0-4-0+0-4-0 is an articulated locomotive of the Garratt type. The wheel arrangement is effectively two 0-4-0 locomotives operating back-to-back or face-to-face, with the boiler and cab suspended between the two power units. Each power unit has no leading wheels, four powered and coupled driving wheels on two axles and no trailing wheels. A similar arrangement exists for Mallet and Meyer locomotives, but is referred to as 0-4-4-0.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 2-6-2+2-6-2 is an articulated locomotive using a pair of 2-6-2 power units back to back, with the boiler and cab suspended between them. The 2-6-2 wheel arrangement has a single pair of leading wheels in a leading truck, followed by three coupled pairs of driving wheels and a pair of trailing wheels in a trailing truck. Since the 2-6-2 type was often called the Prairie type, the corresponding Garratt and Modified Fairlie types were usually known as a Double Prairie.
The South African Railways Class 21 2-10-4 of 1937 was a class of steam locomotives used in South Africa.
The Central South African Railways Rack 4-6-4RT of 1905 was a South African steam locomotive from the pre-Union era in Transvaal Colony.
The South West African 2-8-0T of 1907 was a steam locomotive from the German South West Africa era.
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.
