A selection of early 20th century locomotive types according to their Whyte notation and their comparative size

Whyte notation as of 1906. From a handbook for railroad industry workers published in 1906. ^[1]

The Whyte notation for classifying steam locomotives by wheel arrangement was devised by Frederick Methvan Whyte^[2] and came into use in the early 20th century encouraged by an editorial in American Engineer & Railroad Journal (Editorial December 1900). A steam locomotive is a Locomotive powered by Steam. The term usually refers to its use on Railways but can also refer to a "road locomotive" Locomotive wheel arrangement is how the wheels of the locomotive are arranged by type position and connections Frederick Methvan Whyte ( March 2 1865 &ndash 1941 was a Mechanical engineer of Dutch background who worked for the New York Central The twentieth century of the Common Era began on Whyte's system counts the number of leading wheels, then the number of driving wheels, and finally the number of trailing wheels, groups of numbers being separated by dashes. The leading wheel or leading axle of a Steam locomotive is an unpowered Wheel or Axle located in front of the driving wheels On a Steam locomotive, a driving wheel is a powered Wheel which is driven by the Locomotive 's Pistons (or Turbine, in the On a Steam locomotive, a trailing wheel or trailing axle is an unpowered Wheel or Axle located behind the driving wheels ^[3] Other classification schemes, like UIC classification and the French, Turkish and Swiss systems for steam locomotives, count axles rather than wheels. The UIC classification is a comprehensive system for describing the Wheel arrangement of Locomotives Multiple units and Trams It is

Thus, a locomotive with two leading axles (and thus four wheels) in front, then three driving axles (six wheels) and followed by one trailing axle (two wheels) is classified as a 4-6-2. An axle is a central shaft for a rotating Wheel or Gear. In some cases the axle may be fixed in position with a bearing or Bushing Under the Whyte notation for the classification of Steam locomotives, a 4-6-2 Locomotive has four Leading wheels (generally arranged in a

Method

Articulated locomotives

Articulated locomotives such as Garratts, which are effectively two locomotives joined by a common boiler, have a + between the arrangements of each engine. Articulated locomotive usually means a Steam locomotive with one or more engine units which can move relative to the main frame A boiler is a closed vessel in which Water or other Fluid is heated Thus, a 'double Pacific' type Garratt is a 4-6-2+2-6-4.

Simpler articulated types such as Mallets, where there are no unpowered axles between powered axles, have extra groups of numbers in the middle. The Mallet Locomotive is a type of Articulated locomotive, invented by a Swiss engineer named Anatole Mallet Thus a Big Boy is a 4-8-8-4; there are two leading axles, one group of four driving axles, another group of four driving axles, and then two trailing axles. Big Boy was the name given to the Union Pacific Railroad 's twenty-five 4000 class 4-8-8-4 Mallet articulated Steam locomotives

Suffixes

The suffix T indicates a tank locomotive; otherwise, a tender locomotive is assumed. A tank locomotive is a Steam locomotive that carries its own fuel and water on it instead of pulling it behind it in a tender. In British practice, this is sometimes extended to indicate the type of tank locomotive: T means side tank, PT pannier tank, ST saddle tank, WT well tank. A tank locomotive is a Steam locomotive that carries its own fuel and water on it instead of pulling it behind it in a tender. A tank locomotive is a Steam locomotive that carries its own fuel and water on it instead of pulling it behind it in a tender. A tank locomotive is a Steam locomotive that carries its own fuel and water on it instead of pulling it behind it in a tender. T+T means a tank locomotive that has a tender for additional coal or water capacity.

In Europe, the suffix R could mean rack (0-6-0RT) or it could mean reversible (0-6-0TR). The latter case being the Bi-cabine locomotives used in France.

Other suffixes have been used at times, including ng for narrow-gauge locomotives (i. A narrow gauge railway (or narrow gauge railroad) is a Railway that has a Track gauge narrower than the of Standard gauge railways e. , less than 56. 5 in / 1435 mm) and CA or ca for compressed air (i. e. , running on compressed air from a tank instead of steam).

Internal combustion locomotives

In Britain, small diesel and petrol locomotives are usually classified in the same way as steam locomotives, e. g. 0-4-0, 0-6-0, 0-8-0. This may be followed by D for diesel, P petrol, and another letter describing the transmission: E for electric, H hydraulic, M mechanical. Thus 0-6-0DE denotes a six-wheel diesel locomotive with electric transmission. Where the axles are coupled by chains or shafts (rather than side-rods), or are individually driven, the terms 4w, 6w or 8w are generally used. Thus 4wPE indicates a four-wheel petrol locomotive with electric transmission. For large diesel locomotives the UIC classification is used. The UIC classification is a comprehensive system for describing the Wheel arrangement of Locomotives Multiple units and Trams It is

Limitations

The limitations of the Whyte system in classifying locomotives that did not fit the standard steam locomotive pattern led to the design of other forms of classification. Most commonly used in Europe is the UIC classification scheme, based on German practice, which can more completely define the exact layout of a locomotive. The UIC classification is a comprehensive system for describing the Wheel arrangement of Locomotives Multiple units and Trams It is Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe.

Naming

In American (and to a lesser extent British) practice, most wheel arrangements in common use were given names, often from the name of the first such locomotive built. The United States of America —commonly referred to as the The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located (For example, the 2-2-0 is named Planet. ) (This naming convention is reminiscent of the naming of warship classes. A warship is a Ship that is built and primarily intended for Combat. )

Common wheel arrangements

Here is a list of the most common wheel arrangements: in the illustration the front of the locomotive is to the left.

Arrangement (locomotive front is to the left)	Whyte classification	Name
Non-articulated locomotives
	0-2-2	Northumbrian
	2-2-0	Planet
	2-2-2	Single,[2] Jenny Lind
	2-2-4
	4-2-0	Jervis[4]
	4-2-2	Bicycle
	4-2-4
	6-2-0	Crampton[5]
	0-4-0	Four-Coupled
	0-4-2
	0-4-4	Forney[1]
	2-4-0	Porter
	2-4-2	Columbia[1]
	2-4-4
	4-4-0	American,[1][6] Eight-wheeler
	4-4-2	Atlantic[1][7]
	4-4-4	Reading, Jubilee (Canada)[8]
	0-3-0	(one driving wheel per axle; used on Patiala State monorail and also on the Listowel and Ballybunion Railway)
	0-6-0	Six-Coupled,[1] Bourbonnais (France), USRA 0-6-0 (United States)
	0-6-2
	0-6-4	Forney six-coupled[1]
	2-6-0	Mogul[1][9]
	2-6-2	Prairie[1][2]
	2-6-4	Adriatic
	2-6-6
	4-6-0	Ten-Wheeler[1][10] (not Britain)[11]
	4-6-2	Pacific[1][2][12][13]
	4-6-4	Hudson,[14] Baltic[2]
	0-8-0	Eight-Coupled,[1] USRA 0-8-0 (United States)
	0-8-2	[15]
	0-8-4
	2-8-0	Consolidation[1][2][16]
	2-8-2	Mikado,[1][2] Mike, MacArthur[17][18]
	2-8-4	Berkshire, Kanawha[19][20]
	2-8-6	Used only on four Mason Bogie locomotives
	4-8-0	Mastodon, Twelve-Wheeler[1]
	4-8-2	Mountain,[2][21] Mohawk[22]
	4-8-4	Northern, Niagara, Confederation, Dixie, Greenbrier, Pocono, Potomac, Golden State, Western, General, Governor, Big Apple, GS Series "Daylight" (Southern Pacific)[23]
	4-8-6	Proposed by Lima, never built
	6-8-6	(PRR S2 steam turbine locomotive)[24]
	0-10-0	Ten-Coupled,[1][25] (rarely) Decapod
	0-10-2	Union[25]
	2-10-0	Decapod,[1][26] Russian Decapod
	2-10-2	Santa Fe,[1] Central, Decapod (only on the Southern Pacific)
	2-10-4	Texas, Colorado (CB&Q), Selkirk (Canada)[27]
	4-10-0	Mastodon,[1] Gobernador (in honor of El Gobernador)
	4-10-2	Southern Pacific, Overland[28]
	0-12-0	Twelve-Coupled
	2-12-0	Centipede[1]
	2-12-2	Javanic
	2-12-4
	4-12-2	Union Pacific[29]
	4-14-4	AA20[30]
Duplex locomotives
	4-4-4-4	(PRR T1)[31]
	6-4-4-6	(PRR S1)[32]
	4-4-6-4	(PRR Q2)[33]
	4-6-4-4	(PRR Q1)
Mallet[17] (simple and compound) articulated locomotives
	0-4-4-0	[34]
	2-4-4-2
	0-6-6-0	Erie
	2-6-6-0	Denver & Salt Lake
	2-6-6-2
	2-6-6-4	Norfolk & Western
	2-6-6-6	Allegheny,[35] Blue Ridge
	4-6-6-2	(Southern Pacific class MM-2)[36]
	4-6-6-4	Challenger[37]
	2-6-8-0	(Southern Railway, Great Northern Railway)[38]
	0-8-8-0	Angus
	2-8-8-0	Bull Moose
	2-8-8-2	Chesapeake
	2-8-8-4	Yellowstone[39]
	4-8-8-2	Southern Pacific cab forward classes AC-4 through AC-12 (except AC-9)[36]
	4-8-8-4	Big Boy[40]
	2-10-10-2	(Santa Fe and Virginian railroads)[38]
	2-8-8-8-2	Triplex (Erie RR)
	2-8-8-8-4	Triplex (Virginian RR)[41]
Garratt articulated locomotives
	0-4-0+0-4-0
	2-6-2+2-6-2

References

• Boylan, Richard, and Barris, Wes (1991-05-30). A 2-2-0, in the Whyte notation for the classification of Steam locomotives by Wheel arrangement, has one unpowered Leading axle and one powered Under the Whyte notation for the classification of steam locomotives, a 2-2-2 Locomotive has two Leading wheels two Driving wheels In Whyte notation, a 2-2-4 is a Railroad Steam locomotive that has two Leading wheels followed by two coupled Driving wheels and four In the Whyte notation, a 4-2-0 is a Railroad Steam locomotive that consists of a 4-wheel Leading truck followed by a single Driving axle Under the Whyte notation for the classification of Steam locomotives, a 4-2-2 Locomotive has four Leading wheels two Driving wheels In Whyte notation, a 4-2-4 is a Steam locomotive that has a four-wheel Leading truck, one powered driving axle and a four-wheel unpowered 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 In Whyte notation, a 2-4-0 is a Railroad Steam locomotive that has two Leading wheels followed by two coupled Driving wheels with In the Whyte notation for the classification of Steam locomotives by Wheel arrangement, a 2-4-2 has two Leading wheels four Driving In Whyte notation, a 2-4-4 is a Steam locomotive with two unpowered Leading wheels followed by four powered Driving wheels and four unpowered A 4-4-0 is a type of Steam locomotive. In the Whyte notation, 4-4-0 signifies that it has a two-axle Bogie ( Am In the Whyte notation a 4-4-2 is a Steam locomotive that has a two-axle Leading truck, two powered Driving axles and a one-axle Trailing A 4-4-4, in the Whyte notation for the classification of Steam locomotives by Wheel arrangement, is one with four Leading wheels four coupled Lartigue Lokomotivepng|thumb|Sketch of a Lartigue locomotive]] The Lartigue Monorail system was invented by the French Engineer Charles Lartigue The USRA 0-6-0 was a USRA standard class of Steam locomotive designed under the control of the United States Railroad Administration, the nationalized In the Whyte notation for the classification of Steam locomotives by Wheel arrangement, a 2-6-0 has a pair of Leading wheels followed by six Under the Whyte notation for the classification of Steam locomotives by Wheel arrangement, a 2-6-2 has two Leading wheels six coupled Under the Whyte notation for the classification of Steam locomotives, a 2-6-4 Locomotive has two Leading wheels six coupled Driving In the Whyte notation for describing Steam locomotive Wheel arrangement, a 2-6-6 is a locomotive with a two-wheeled Leading truck, six In the Whyte notation, a 4-6-0 is a Railroad Steam locomotive that has a two-axle Leading truck followed by three Driving axles Under the Whyte notation for the classification of Steam locomotives, a 4-6-2 Locomotive has four Leading wheels (generally arranged in a 4-6-4 Locomotive, in the Whyte notation for the classification of Steam locomotives has four Leading wheels (generally arranged in a leading The USRA 0-8-0 was a USRA standard class of Steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad In the Whyte notation, a 2-8-0 is a Railroad Steam locomotive that has a single-axle Leading truck followed by four powered Driving axles In the Whyte notation, a 2-8-2 is a Railroad Steam locomotive that has one Leading axle followed by four powered driving axles and In the Whyte notation, a 2-8-4 is a Railroad Steam locomotive that has one unpowered Leading axle followed by four powered Driving 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 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 Under the Whyte notation for the classification of Steam locomotives, a 4-8-0 Locomotive has four Leading wheels eight coupled Driving Under the Whyte notation for the classification of Steam locomotives a 4-8-2 Locomotive has four Leading wheels (generally arranged in a Under the Whyte notation for the classification of Steam locomotives, a 4-8-4 Locomotive has four Leading wheels eight coupled Driving The Central of Georgia Railway (CofG like most other railroads were in need of motive power during World War II The GS-4 was a streamlined 4-8-4 Northern type Steam locomotive that served the Southern Pacific Railroad from 1941 to 1958 Under the Whyte notation for the classification of Steam locomotives, a 4-8-6 Locomotive would have had four Leading wheels eight coupled Lima Locomotive Works was an American firm that manufactured Railroad Locomotives from the 1870s through the 1950s In Whyte notation a 6-8-6 is a Steam locomotive with six unpowered Leading wheels arranged into a three-axle Leading truck, eight powered The Pennsylvania Railroad 's class S2 was a Steam turbine locomotive. A steam turbine is a mechanical device that extracts Thermal energy from pressurized Steam, and converts it into useful mechanical work Under the Whyte notation for the classification of Steam locomotives, a 2-10-0 is a locomotive with two Leading wheels generally in a radially swinging A 2-10-2 Steam locomotive in the Whyte notation for Wheel arrangements has two Leading wheels (one axle ten Driving wheels (five driven Under the Whyte notation for the classification of Steam locomotives a 2-10-4 Locomotive has two Leading wheels ten Driving wheels The State of Colorado ( or chiefly by nonresidents) is a state located in the Rocky Mountain region of the United States of America. The Chicago Burlington and Quincy Railroad was a railroad that operated in the Midwestern United States. Under the Whyte notation for the classification of Steam locomotives a 4-10-0 Locomotive has four Leading wheels followed by ten Driving El Gobernador was a 4-10-0 Steam locomotive built by Central Pacific Railroad at the railroad's Sacramento California shops Under the Whyte notation for the classification of Steam locomotives, a 4-10-2 Locomotive has four Leading wheels ten Driving wheels In Whyte notation for the classification of Steam locomotives by Wheel arrangement, a 2-12-0 is a locomotive with one pair of unpowered Leading wheels Under the Whyte notation for the classification of Steam locomotives, a 2-12-2 Locomotive has two Leading wheels twelve Driving 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 A 4-12-2, in the Whyte notation for the classification of Steam locomotives by Wheel arrangement, is a locomotive with four Leading wheels twelve A 4-14-4, in the Whyte notation for the classification of Steam locomotives by Wheel arrangement, is a locomotive with four Leading wheels fourteen A duplex locomotive is a Steam locomotive that divides the driving force on its wheels by using two pairs of cylinders rigidly mounted to a single Locomotive frame A 4-4-4-4 Steam locomotive, in the Whyte notation for describing Locomotive Wheel arrangements has a four-wheel Leading truck, two The Pennsylvania Railroad 's 52 T1 class duplex-drive 4-4-4-4 Steam locomotives introduced in 1942 (2 prototypes and 1946 A 6-4-4-6 Steam locomotive, in the Whyte notation for describing Locomotive Wheel arrangements is one with six Leading wheels two The PRR S1 class Steam locomotive (nicknamed "The Big Engine" was an experimental locomotive that was the largest rigid frame passenger locomotive ever A 4-4-6-4, in the Whyte notation for the classification of Steam locomotives by Wheel arrangement, is one that has four Leading wheels followed The Pennsylvania Railroad 's class Q2 comprised one prototype and twenty-five production duplex Steam locomotives of 4-4-6-4 Wheel arrangement In Whyte notation, a 4-6-4-4 is a Railroad Steam locomotive that has four Leading wheels followed by six coupled Driving wheels a second The Pennsylvania Railroad 's class Q1 comprised a single experimental Steam locomotive for freight service #6130 built in March 1942. The Mallet Locomotive is a type of Articulated locomotive, invented by a Swiss engineer named Anatole Mallet In Whyte notation, 2-4-4-2 refers to a Railroad Steam locomotive that has two Leading wheels followed by four coupled Driving wheels In Whyte notation for the classification of Steam locomotives by Wheel arrangement, a 2-6-6-0 is a locomotive with one pair of unpowered Leading wheels In Whyte notation, 2-6-6-2 refers to a Railroad Steam locomotive that has two Leading wheels followed by six coupled Driving wheels 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, The 2-6-6-6 (in Whyte notation) is an Articulated locomotive type with 2 Leading wheels, two sets of six Driving wheels and six trailing In Whyte notation, a 4-6-6-2 is a Steam locomotive with four Leading wheels (two axles in an unpowered Bogie at the front of the locomotive followed Southern Pacific Railroad 's MM-2 class of Steam locomotives was Southern Pacific's (SP only class of 2-6-6-2 locomotives ordered and built as Cab forward In Whyte notation, a 4-6-6-4 is a Railroad Steam locomotive that has four Leading wheels followed by six coupled Driving wheels a second A 2-6-8-0 Steam locomotive, in the Whyte notation for describing Locomotive Wheel arrangements has two Leading wheels a set of six In the Whyte notation for the classification of Steam locomotives by Wheel arrangement, a 2-8-8-0 is a locomotive with a two-wheel Leading truck A 2-8-8-2, in the Whyte notation for describing Steam locomotive Wheel arrangements is an Articulated locomotive with a two-wheel Leading Under the Whyte notation for the classification of Steam locomotives a 2-8-8-4 is a locomotive with two Leading wheels two sets of eight Driving wheels 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 The term cab forward refers to various rail and Road Vehicle designs which place the driver's compartment substantially farther towards the front than Southern Pacific Railroad 's AC-4 class of Steam locomotives was the first class of Cab forward locomotives built with the 4-8-8-2 wheel arrangement Southern Pacific Railroad 's AC-12 class of Cab forward Steam locomotives was the last class of steam locomotives ordered by Southern Pacific The AC-9 was the Southern Pacific Railroad 's only articulated Steam locomotive class that ran Smokebox forward after 1920. In the Whyte notation for the classification of Steam locomotives by Wheel arrangement, a 4-8-8-4 is a locomotive with a four-wheel Leading truck Under the Whyte notation for the classification of Steam locomotive Wheel arrangements a 2-10-10-2 is a locomotive with two Leading wheels two the Whyte notation for the classification of Steam locomotives a 2-8-8-8-2 has two Leading wheels three sets of eight Driving wheels and two 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 A 2-6-2+2-6-2, in the Whyte notation for the classification of Steam locomotives by Wheel arrangement, is a Garratt Articulated locomotive Year 1991 ( MCMXCI) was a Common year starting on Tuesday (link will display full calendar of the Gregorian Calendar. Events 1416 - The Council of Constance, called by the Emperor Sigismund a supporter of Antipope John XXIII burns Jerome of Prague following American Steam Locomotive Wheel Arrangements. SteamLocomotive. com. Retrieved on 2008-02-08. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 421 - Constantius III becomes co- Emperor of the Western Roman Empire.
• White, John H. , Jr. (1968). A History of the American Locomotive - Its Development: 1830-1880. New York: Dover Publications. ISBN 0-486-23818-0.  

See also

• AAR wheel arrangement
• Wheel arrangement
• UIC classification
• Category:Locomotives by wheel arrangement