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 of

locomotive A locomotive or engine is a rail transport vehicle that provides the motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a multiple unit, motor coach, railcar or power car; the ...

multiple unit A multiple-unit train or simply multiple unit (MU) is a self-propelled train composed of one or more carriages joined together, which when coupled to another multiple unit can be controlled by a single driver, with multiple-unit train cont ...

s and

tram A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport ...

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 Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...

, which uses a slightly simplified form of UIC (except for steam locomotives and small diesel shunters, where Whyte notation is used), and in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

, where the

AAR wheel arrangement The AAR wheel arrangement system is a method of classifying locomotive (or unit) wheel arrangements that was developed by the Association of American Railroads. Essentially a simplification of the European UIC classification, it is widely used ...

system (essentially another simplification of the UIC system) is used to describe

diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engi ...

and

electric locomotive An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor. Locomotives with on-board fuelled prime movers, such as diesel engines or g ...

s; Whyte notation is used in North America only for steam locomotives. The classification system is managed by the

International Union of Railways The International Union of Railways (UIC, french: Union internationale des chemins de fer) is an international rail transport industry body. History The railways of Europe originated as many separate concerns, and there were many border chang ...

(UIC).

Structure

The UIC uses the following structure: ; Upper-case letters : Indicate driving axles, starting at A for a single axle. C thus 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 or hydrogen vehicles, elevators or electric multiple unit. Traction motors are used in electrically powered rail vehicles ( electric multip ...

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 ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...

. ; 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 A Garratt (often referred to as a Beyer Garratt) is a type of steam locomotive invented by British engineer Herbert William Garratt that is articulated into three parts. Its boiler, firebox, and cab are mounted on a centre frame or "brid ...

-type locomotives are indicated by bracketing or placing plus signs between all individual units. ; Other suffixes: :* h: superheated steam (german: Heißdampf, link=no, lit=hot steam) :* n: saturated steam (german: Nassdampf, link=no, lit=wet steam) :* v: compound (german: Verbund, link=no) :* Turb: turbine :* number: number of cylinders :* t:

tank locomotive A tank locomotive or tank engine is a steam locomotive that carries its water in one or more on-board water tanks, instead of a more traditional tender. Most tank engines also have bunkers (or fuel tanks) to hold fuel; in a tender-tank loc ...

:* tr: tram (urban) locomotive :* E: Engerth-type locomotive :* G: freight (german: Güterzug, link=no, lit=goods train). Also used to indicate shunting locomotives :* P: passenger (german: Personenzug, link=no, lit=passenger train) :* S: fast passenger (german: Schnellzug, link=no, lit=express train) 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 In the Whyte notation for the classification of steam locomotive wheel arrangement, a 0-4-4-0 is a locomotive with no leading truck, two sets of four driving wheels, and no trailing truck. Examples of this type were constructed as Shay, Heisle ...

) ; 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′ A Bo-Bo-Bo or Bo′Bo′Bo′ (UIC classification) is a locomotive with three independent two-axle bogies with all axles powered by separate traction motors. In the AAR system, this is simplified to B-B-B. The Bo-Bo-Bo configuration is ofte ...

: 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 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles and no trailing wheels. This was the most common wheel arrang ...

). ; 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 Under the Whyte notation for the classification of steam locomotives, 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 referr ...

). ; 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 incr ...

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 Trailing can mean, among others: * Facing and trailing, in railroads * The act f using a Trailer (promotion) * Trailing wheel * Trailing arm * Trailing edge * Hound trailing Hound trailing, or hound racing, is a dog sport that uses specially b ...

idle axle mounted in a bogie (Whyte notation:

2-8-2 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, eight powered and coupled driving wheels on four axles and two trailing w ...

). ; E : Five powered axles, mounted in the locomotive's frame (Whyte notation: 0-10-0). ; 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 Under the Whyte notation for the classification of steam locomotives, 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 know ...

). ; 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:

2-10-2T T, or t, is the twentieth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''tee'' (pronounced ), plural ''tees''. It is deri ...

). ; 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 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, eight powered and coupled driving wheels on four axles, and no trailing wh ...

). ; D′Dh4vtG (hypothetical example) : 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: 0-8-8-0T).

References

External links

* {{Locostyles Rail transport standards

Classification Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...

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

Structure

Examples

See also

References

External links