The UIC classification of locomotive axle arrangements, sometimes known as the German classification''The Railway Data File''. Leicester: Silverdale, 2000. p. 52. . or German system,Kalla-Bishop P.M. & Greggio, Luciano, ''Steam Locomotives'', Crescent, 1985, p. 226. describes the

wheel arrangement 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 c ...

locomotive A locomotive is a rail transport, rail vehicle that provides the motive power for a train. Traditionally, locomotives pulled trains from the front. However, Push–pull train, push–pull operation has become common, and in the pursuit for ...

multiple unit A multiple-unit train (or multiple unit (MU)) is a self-propelled train composed of one or more Coach (rail), carriages joined, and where one or more of the carriages have the means of propulsion built in. By contrast, a locomotive-hauled ...

s and

tram A tram (also known as a streetcar or trolley in Canada and the United States) is an urban rail transit in which Rolling stock, vehicles, whether individual railcars or multiple-unit trains, run on tramway tracks on urban public streets; some ...

s. It is used in much of the world, notable exceptions being the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

and

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. The classification system is managed by the International Union of Railways (UIC).

Structure

The UIC uses the following structure: ; Upper-case letters : Indicate driving axles, starting at A for a single axle. B thus indicates two and C indicates three consecutive pairs of driving wheels. ; Lower-case "o" : Related to driving axles (minimum 2, "B"), indicates they are individually driven by separate

traction motor A traction motor is an electric motor used for propulsion of a vehicle, such as locomotives, electric vehicle, electric or hydrogen vehicles, or electric multiple unit trains. Traction (engineering), Traction motors are used in electrically powe ...

s. ; Numbers : Consecutive non-driving axles, starting with 1 for a single axle. ; Prime symbol " ′ " : The axles indicated by a single letter or number are mounted on a

bogie A bogie ( ) (or truck in North American English) comprises two or more Wheelset (rail transport), wheelsets (two Railroad wheel, wheels on an axle), in a frame, attached under a vehicle by a pivot. Bogies take various forms in various modes ...

. ; Parentheses : Groups letters and numbers describing the same bogie. For example, (A1A) indicates a three-axle bogie with the outer two axles driven. When parentheses are used around a single letter or number, a prime is not needed to indicate a bogie. Articulated locomotives can be indicated by bracketing the front power unit — for example, the

Union Pacific Big Boy The Union Pacific Big Boy is a type of simple articulated locomotive, articulated 4-8-8-4 steam locomotive manufactured by the American Locomotive Company (ALCO) between 1941 and 1944 and operated by the Union Pacific Railroad in revenue service ...

, 4-8-8-4 in Whyte notation, is (2′D)D2′ in UIC notation. ; Plus sign "+" : The locomotive or multiple unit consists of permanently coupled but mechanically separate traction units. Garratt locomotives are indicated by bracketing or placing plus signs between all individual units. ; Other suffixes: :* h: superheated steam () :* n: saturated steam () :* v: compound () :* Turb: turbine :* number: number of cylinders :* t:

tank locomotive A tank locomotive is a steam locomotive which carries its water in one or more on-board water tanks, instead of a more traditional tender (rail), tender. Most tank engines also have Fuel bunker, bunkers (or fuel tanks) to hold fuel; in a #Tender ...

:* tr: tram (urban) locomotive :* E: Engerth-type locomotive :* G: freight (). Also used to indicate shunting locomotives :* P: passenger () :* S: fast passenger () The most common wheel arrangements in modern locomotives are Bo′Bo′ and Co′Co′.

Examples

The following examples are based on the UIC classification: ; (A1A)(A1A) : Two bogies or wheel assemblies under the unit. Each bogie has one powered axle, one idle axle, and one more powered axle. All powered axles are individually driven by traction motors. ; BB : Four powered axles all mounted in the locomotive's frame, driven in pairs, i.e. each pair of axles is connected by driving rods or gears. Compare with "D" below. (Whyte notation: 0-4-4-0) ; B′B′ : Two bogies or wheel assemblies under the unit. Each bogie has two powered axles, connected by driving rods or gears. ; Bo′(A1A) : Two bogies or wheel assemblies. The "Bo′" bogie is under one end of the unit, and has two powered axles, while the "(A1A)" bogie under the other end of the unit has one powered axle, one idle axle, and another powered axle. All powered axles are individually driven by traction motors. ; Bo′Bo′ : Two bogies or wheel assemblies under the unit. Each bogie has two powered axles individually driven by traction motors. Three-quarters of all modern locomotives (and power cars of self-propelled trains) are configured in either this or the "B′B′" arrangement. ; Bo′Bo′Bo′ : Three bogies or wheel assemblies under the unit. Each bogie has two powered axles individually driven by traction motors. ; C : Three powered axles, connected by driving rods or gears, all mounted in the locomotive's frame (Whyte notation: 0-6-0). ; C′C′ : Two bogies or wheel assemblies under the unit. Each bogie has three powered axles, connected by driving rods or gears. One such example of this type is Southern Pacific 9010. ; Co′Co′ : Two bogies or wheel assemblies under the unit. Each bogie has three powered axles individually driven by traction motors. ; (2Co)() : A locomotive with two

s, each with two leading axles and three individually powered axles. A number of Japanese electric locomotives used this wheel arrangement, including the JNR Class EF58, and the PRR GG1. ; D : Four powered axles, connected by driving rods or gears, all mounted in the locomotive's frame (Whyte notation: 0-8-0). ; 1′D1′ : One

leading In typography, leading ( ) is the space between adjacent lines of type; the exact definition varies. In hand typesetting, leading is the thin strips of lead (or aluminium) that were inserted between lines of type in the composing stick to incre ...

idle (non-driven) axle mounted in a bogie, four driven axles mounted in the frame and connected by driving rods or gears, followed by one trailing idle axle mounted in a bogie (Whyte notation: 2-8-2). ; E : Five powered axles, mounted in the locomotive's frame (Whyte notation:

0-10-0 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of no leading wheels, ten powered and coupled driving wheels on five axles and no trailing wheels. In the United Kingdom, this type is known ...

). ;Cn2Gt : No leading axle, three driven axles mounted in the frame, no trailing axle, simple steam expansion, saturated steam, two cylinders, for freight trains/shunting duties, tank engine (Whyte notation: 0-6-0 T). ; 2′D1′h3S : Two front leading axles grouped in a bogie, four driving axles, one trailing axle in a bogie, simple steam expansion, superheated steam, three-cylinders, for fast trains (Whyte notation: 4-8-2). ; 1′E1′h2Gt : One front leading axle in a bogie, five driving axles, one rear trailing axle, simple steam expansion, superheated steam, two-cylinder machine, for freight trains, tank engine (Whyte notation: 2-10-2 T). ; 1′Dn4vP : One front leading axle in a bogie, four driving axles, saturated steam, four-cylinder machine, compound (double steam expansion), for passenger trains (Whyte notation: 2-8-0). ; D′Dh4vtG : No front leading axle, four driving axles in a bogie, four more driven axles mounted in the frame (Mallet locomotive), superheated steam, four-cylinder machine, compound (double steam expansion), tank locomotive, for freight trains (Whyte notation: 0-8-8-0 T).

References

External links

* {{Locostyles Rail transport standards

Classification Classification is the activity of assigning objects to some pre-existing classes or categories. This is distinct from the task of establishing the classes themselves (for example through cluster analysis). Examples include diagnostic tests, identif ...

Locomotive classification systems Rail transport in Europe de:Bauartbezeichnung von Triebfahrzeugen#VDEV/VMEV/UIC-System

Structure

Examples

See also

References

External links