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 or engine is a rail transport vehicle that provides the Power (physics), 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 (rail), motor ...

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 contr ...

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 are ...

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 North ...

, which uses a slightly simplified form of UIC (except for steam locomotives and small diesel shunters, where

Whyte notation 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 ce ...

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 the Car ...

, 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 in ...

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 engin ...

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 gas ...

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 wikt:chemin de fer, chemins de fer) is an international rail transport industry body. History The railways of Europe originated as many separate concerns, and there wer ...

(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 vehicle, electric or hydrogen vehicles, elevators or electric multiple unit. Traction motors are used in electrically powered rail vehicles (ele ...

s. ; Numbers : Consecutive non-driving axles, starting with 1 for a single axle. ;

Prime symbol The prime symbol , double prime symbol , triple prime symbol , and quadruple prime symbol are used to designate units and for other purposes in mathematics, science, linguistics and music. Although the characters differ little in appearance fr ...

" ′ " : 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 locomotive An articulated locomotive is a steam locomotive (rarely, an electric locomotive) with one or more engine units that can move independent of the main frame. Articulation allows the operation of locomotives that would otherwise be too large to neg ...

s 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 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 until 1962. The 25 Big ...

, 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 "bridge ...

-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 locom ...

:* 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) ;

B′B′ B-B and Bo-Bo are the Association of American Railroads (AAR) and British classifications of wheel arrangement for railway locomotives with four axles in two individual bogies. They are equivalent to the B′B′ and Bo′Bo′ classifications in ...

: 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′ B-B and Bo-Bo are the Association of American Railroads (AAR) and British classifications of wheel arrangement for railway locomotives with four axles in two individual bogies. They are equivalent to the B′B′ and Bo′Bo′ classifications i ...

: 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 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 arrangemen ...

). ; 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 Southern Pacific 9010 is a KM ML 4000 C'C' diesel-hydraulic locomotive, built in 1964 by German manufacturer Krauss-Maffei for the Southern Pacific Railroad. SP 9010 generated from two V16 Maybach MD870 diesel engines. It was painted to So ...

. ; 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 The is a class of Japanese 2-C+C-2 wheel arrangement DC electric locomotives. 172 locomotives were built between 1946 and 1958. The later years In 1984, 64 out of 172 EF58 locos built were still in service or temporary storage. However, th ...

, and the

PRR GG1 The Pennsylvania Railroad GG1 is a class of streamliner, streamlined electric locomotives built for the Pennsylvania Railroad (PRR), in the northeastern United States. The class was known for its striking Art Deco, art deco shell, its ability to p ...

. ; 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 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 wheel ...

). ; 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). ; 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). ; 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 (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