Type designation of locomotives

from Wikipedia, the free encyclopedia

The type designation of locomotives is the umbrella term for various naming systems for the various types of rail locomotives . The most widespread are the systems based on the axle sequence (according to DIN: wheel set sequence ). This allows the very different axle and wheel set arrangements of locomotives and railcars to be displayed alphanumerically in a short form .

Various systems for coding the wheel sequence have emerged. The system first defined by the Association of German Railway Administrations in 1908 has developed into today's international standard , which is recorded by the International Union of Railways UIC in UIC Code 612 and from January 1, 1983 in UIC Code 650. The Association of American Railroads uses a simplification of this system.

VDEV / VMEV / UIC system

This system covers almost all types in use today.

Systematics and examples

Basic signs and their meaning

Bogie locomotives with 2 × 2 axles each
BLS Ce 4/4 with B'B ' wheel sequence (two coupled axes each )
DB class E10.jpg
DB series E 10 with wheel arrangement Bo'Bo ' ( single axle drive )

The number and order of the axes is given from front to back. Non-driven axles, so-called wheel sets , are denoted by Arabic numerals, drive wheel sets are given Latin capital letters. Hence:

1, 2, 3, ...
Number of leading and / or trailing running axes
A, B, C, ...
without addition
Number of coupled or jointly driven axles in a frame or bogie according to the alphabet position (A = one axle, B = two axles, C = three axles, ...)
with addition o (Ao, Bo, Co, ...)
Number of individually driven axles according to the alphabet. Each axis has its own drive motor.
An apostrophe indicates movably mounted axes or groups of axes of running or coupling axes .
Steam locomotive with the wheel arrangement 2'C1 '
if the running and coupling axles are together in a common frame or bogie separate from other existing axle groups, they are put in brackets.
A plus sign marks the separation point in the axle sequence between individually movable parts in the case of individual vehicles that are constantly connected during operation

A steam locomotive as shown on the right with a leading, two-axle bogie, followed by three coupled driving axles and finally with a laterally moveable running axle is a 2'C1 'locomotive.

Obsolete addition

Crocodile locomotive Ce 6/8 II of the SBB with the wheel arrangement (1'C) (C1 ')
a half-square was previously used to indicate an existing close coupling between the bogies.

The crocodile locomotive Ce 6/8 II of the SBB was previously designated with 1'C - C1 'to indicate the close coupling between the two engine frames and to indicate that no tractive effort is passed through the locomotive body. Later the designation (1'C) (C1 ') became established for this type.

Additional comments on the above

The SBB Re 4/4 II locomotives were called Bo'Bo 'when they were commissioned.

Uncoupled drive axles are represented by the subscript numeral zero ( 0 in). Since typewriters did not previously have a type for the zero, this was replaced by the lowercase letter o , which has also established itself in linguistic usage. Most of the newer electric locomotives have a single axle drive , which means that a six-axle locomotive with two bogies has the Co'Co 'wheel arrangement. The pronunciation according to the standard would be "toe-zero-dash toe-zero-dash", but the apostrophes are often left out and the zero is spoken as the letter O, resulting in "toe-oh-toe-oh". Even more often, the individual letters are tied together to form a word, resulting in the very short term "Koko". The term "six-axle bogie locomotive" or "six-axle vehicle" is even more common, as new locomotives are basically designed without running axles and with bogies. So these locomotives have

  • two bogies ( ' ) ...
    • ... with three drive axes each ( C ) ...
    • ... with its own drive (mostly one drive motor, but there were also several) per drive axle ( 0 ).

Additional comments on 'and ()

  • Sometimes the apostrophes are left out, but this can lead to ambiguities: Due to the design limitations, a 2D1 can usually be assumed to be a 2'D1 ', a 1B or a 2B1 can also be a 1'B or a 2'B1, 2B1 'or 2'B1', in which one or all running axles are in the same frame as the two drive axles.
  • A bracket for a mixed group of running and coupling axes can technically mean the same thing as an apostrophe for a "pure" group of running or coupling axes. The NoHAB AA16 series was built in the variants Co'Co 'and (A1A) (A1A), which only differ in whether the middle axle of the two bogies is driven or not.
  • On the other hand, brackets and apostrophes can also be combined, in which case an apostrophe denotes a movable axis within a common frame, for example (1'C) (C1 ').
  • No apostrophe is required after a group of brackets, although it is often seen - the last example would thus be incorrectly written (1'C) '(C1') '.
  • Axles that can be shifted laterally without radial adjustability (this applies in particular to the central axes of three-axle bogies) and radially adjustable axes in the form of free steering axles without additional lateral shiftability as with the SBB Re 460 are considered to be mounted in the frame or bogie frame concerned. The latter was not always strictly adhered to in the past, for example not with the Saxon 1B and B1 with Nowotny steering axle.


Railcars often consist of firmly connected, but theoretically separable cars. If these units cannot be used separately in normal operation, the boundary between two individually movable parts of a locomotive or a railcar is indicated by a plus sign. However, if multiple units can also be used individually in a multiple unit, it is often preferred to consider them as individual vehicles . If the units can only be separated using technical aids, e.g. B. if they are supported on shared Jakobs bogies or have "floating" middle parts, they are considered as a whole vehicle. The use of a dash above the axis designation of the Jakobs bogie, as provided for by UIC Code 650, has not caught on because of the difficulties with typewriter or computer typesetting. If there are both driven and non-driven axles in a bogie, the information is enclosed in brackets.

Here are two examples:

Railcar 610 013 from DB Regio with the wheel arrangement 2 '(A1) + (1A) (A1) in Cheb
  • The wheel arrangement of the tilting technology multiple unit series 610 is 2 '(A1) + (1A) (A1)
    • The railcar consists of two individually movable but inoperable cars (the plus sign)
    • The first wagon has a two-axle running bogie ...
    • ... and a bogie with one driving and one running axle.
    • The second car runs on two bogies, each with a running and a driving axle.
  • The Reichsbahn express railcars of type Leipzig (137 153, 154, 233, 234) had the axle sequences B'2'2'B 'or 2'Bo'Bo'2' depending on the drive technology. The railcar train has normal bogies at the outer ends, which, however, carry the diesel engine with generator or gearbox for decoupling from the car body, while the ends of the car are supported on a common bogie inside, whereby the driven axles are in the machine bogie with hydraulic power transmission , while the four electric motors of the units with diesel-electric drive sat in the Jakobs bogies because of the better mass distribution. However, some other vehicle combinations lead to the same representation. Among other things, it can also refer to a vehicle in which a third car body without its own axles is suspended between two normal bogie cars , as is not unusual with articulated tram cars.

Limits and special variants

Axles that can be moved laterally and special arrangements such as Krauss-Helmholtz frames cannot be displayed, nor can the Jakobs bogies often used in modern multiple units . Today the most common axle sequences are B'B 'and C'C' on diesel-hydraulic locomotives and Bo'Bo 'or Co'Co' on electric locomotives and diesel-electric locomotives. Axle sequences with running axles are common in railcars. The NoHAB diesel locomotives from the formerly Danish My series also have a wheel arrangement with running axles (A1A) (A1A) to reduce the axle load of the locomotive.

Markings for auxiliary drives and cogwheel locomotives

Occasionally there were steam locomotives that had auxiliary drives that could be activated for individual axles (so-called boosters ; as a starting aid). Such axes with auxiliary drive are sometimes marked with lower case letters, example: 2'Ba '. Since these additional drives did not catch on, their identification in the axle formula remained largely unknown.

Gear drives are marked with z . Either write a z for each gear wheel or count the gear wheels with lowercase letters ( b = 2), possibly with a subsequent z . A triple-coupled steam locomotive with no running axles and two gear wheels is called a Czz or Cbz or Cb.

Additions to the wheel arrangement for steam locomotives

For steam locomotives , some extensions to the VMEV system have prevailed, mainly in the German-speaking area, which describe the design of a locomotive in more detail. These additions are appended to the axis sequence with a space or hyphen. These and similar additions were also common in other countries, but since they were based on the national language, they could not be universally valid.

  • Type of steam:
  • A v after the number of cylinders indicates compound machines

Example: 2'C1 'n4v is a wet steam four-cylinder compound locomotive, 1'E h3 is a superheated steam triplet.

There is no sign of saturated steam , as the steam immediately after being withdrawn through the steam dome cools down on contact surfaces and practically begins to turn into wet steam. It is therefore not a typical railway name for saturated steam.

A tank locomotive is identified by an appended t (in front of or behind the steam engine type) (e.g. 1'C1't h2 or 1'C1 'h2t).

A potentially entrained Tender counts strictly speaking no longer the locomotive. For this purpose, however, information is often added, for example according to the pattern "+ 2'3 T38 oil", which means in plain language: "With a tender, two axles in a bogie and three in the tender frame, water tank capacity 38 cubic meters, fuel tank for oil". The amount of fuel is not specified.

The full name for the DR series 02 with a four-cylinder compound engine and the four-axle 32 cubic meter standard tender would therefore be “2'C1 'h4v + 2'2' T32”, provided it is coupled to your standard tender. Tender often, however, were combined as needed ( "cross-country Tender", z. B. preuß. P8 with Wannentender the DRG class 52 ).

Additions to the wheel arrangement for traction vehicles with internal combustion engines

The following additional terms are sometimes used for locomotives and railcars with combustion engines :

  • Fuel: d = D iesel, b = B Enzol
  • Transmission: m = m echanical, e = e lectric, h = h ydraulisch (hydrodynamic)

Examples: A1-bm, B'B'-dh, B 0 'B 0 ' -de

If the bogies are driven together, the axle sequence can be underlined. The most common of these: B'B ' = Two two-axle bogies that are driven together, for example by cardan shafts from a common transmission.

Additions to the wheel arrangement for electric traction vehicles

The additional terms for electric traction vehicles are hardly used:

  • Current: g = G facilitated stream, w = W echselstrom, d = D rehstrom
  • the number after the type of current indicates the number of motors
  • Engine type: k = K urbelantrieb without countershaft, u = crank drive with gear ( ü translated), e = E inzelachsantrieb with mounted in the frame motors, t = T atzlagerantrieb , gf = Einzelachsantrieb with mounted in the bogie motors g e f edertem drive.

Examples: 1'D 0 1'-w4e, B 0 'B 0 ' -w4gf

The practical value of this additional information is low. Regarding the type of current, it is not clear whether that of the catenary or that of the motors is meant (this distinction did not play a role at the time this system was established, as there were hardly any inverter vehicles ).

Generic symbol

DRG and later DR used a so-called generic symbol that was attached to the lower front side wall of the driver's cab; the DB and ÖBB have not applied it since the 1950s. The community of Yugoslavian railways JŽ also used the generic symbol, albeit with the omission of the letters.

The generic symbol consists of the generic letter (S, P, G and R), followed by a small t for tank locomotives , followed by a two-digit number, the digits of which are to be read individually: first the number of coupling axles, followed by the total number of axles. The mean axle pressure in megapond follows after a point in subscript (this outdated unit of measurement corresponds approximately to 10 kN (kilo newtons )).

A filled triangle above the axle pressure indicated that the locomotive exceeded the (smaller) vehicle boundary I. If there was a horizontal line above the triangle, the vehicle could be adapted to this boundary line by dismantling parts, mostly the chimney top. The triangle and line were still attached by the DB after the generic designation was abolished.

The DB class 10 as a 2'C1 'express train locomotive with 22 maN axle pressure had the generic symbol S36. 22 ; the DR-02 0401 express locomotive S36. 18 , as well as the DRG standard locomotive 03.

Tank locomotives received a lowercase t after the letter; Before the conversion in 02 0201, the 61 002 had the generic symbol St 38. 18 (axle formula 2'C3 'h3t).

The generic symbol made it possible to quickly identify the suitability for a superstructure, as well as (by multiplying the first digit by the axle pressure) the friction pressure and with the second digit the approximate total weight of the vehicle.

Other designation systems

Swiss system

The Swiss system, which was also used in Bavaria until 1924 , is based on the clutch ratio. This is not a system for describing the wheel alignment. The ratio of the driven axles to the total number of axles is only given in the form of a fraction. A 3/6 coupled locomotive could be a 2'C1 'or a 1'C2' or theoretically any six-axle locomotive with three driving axles.

In Bavaria and Switzerland the clutch ratio was used as part of the series designation. The Bavarian S 3/6 was an express train locomotive with the wheel arrangement 2'C1 ', the Swiss Ce 6/8 II was the famous Swiss crocodile with the wheel arrangement (1'C) (C1').

American naming system

Pacific locomotive 3-231.G.558 of the SNCF

For certain axle sequences, names were established in North American railways as early as the 19th century. Coming from North America, these names were also used in Europe, albeit not as a formal system or official names. For example, a locomotive with a 1'D wheel arrangement is called Consolidation . The designation Pacific for the 2'C1 'wheel arrangement , which, for example, also appears in the title Pacific 231 of the orchestral work by Arthur Honeggers , has the highest level of recognition, also outside of railroad circles . Other well-known names are Atlantic for locomotives with the 2'B1 or 2'B1 'wheel arrangement and Prairie with the 1'C1' wheel arrangement, sometimes also referred to as prairie in German-speaking countries .

Locomotives without running axles are named after the number of wheels with the addition switcher , for example six wheel switcher for a locomotive with the wheel arrangement C. Locomotives without leading axles, which have a trailing axle or trailing axle and thus have the axle order B1 ', C1' and so on, are given the names Four coupled and trailer , Six coupled and trailer and so on. The axle sequences B2 ', C2' and other similar axle sequences with towing bogies are called Forney four coupled , Forney six coupled and so on.

In the course of time the system became more and more confusing and people switched to Whyte notation. Some names like Soviet for the Soviet 2'G2 'locomotive or Adriatic for the Austrian 1'C2' are replicas.

AAR notation

The AAR notation of the eponymous Association of American Railroads is a simplification of the UIC notation, which uses + and - as connecting symbols instead of the identification and grouping of movable axles with brackets and inverted commas. For example, the wheel sequence according to UIC notation (1'C) (C1 ') is written in AAR notation as 1-C + C-1.

The AAR notation is the standard for electric thermal locomotives in the Americas (with the exception of some Argentine railroad companies). Brazil uses both AAR and UIC notation; normally an unofficial, but generally accepted, mixed system between AAR and UIC based on the British simplification of the UIC notation is used.

Whyte notation

Examples of designations based on the Whyte notation

The Whyte notation (after the engineer Frederick Methvan Whyte of the New York Central Railroad ), which is used not only in the USA and Great Britain , but also in general in English and in the entire Spanish-speaking area as well as in Canada and Brazil, counts the successive running wheels and driving wheels of a locomotive (not the axles!) indiscriminately with Arabic numerals in the order from front to back with dividing lines between the wheelset groups.

The Whyte notation proposed in 1900 is only used for steam locomotives.


  • A steam locomotive with the UIC wheel arrangement 2'D1 'h2 would be a 4-8-2 according to the Whyte system (scheme: ooOOOOo)
  • A (1'D) D2 'h4 Mallet locomotive is a 2-8-8-4 (scheme: oOOOO OOOOoo) according to Whyte

The Whyte system takes into account that steam locomotives can still have running wheels in front of and behind the drive wheels . If this is not the case, a "0" is set here. A steam locomotive with the UIC notation 2'C would be a 4-6-0 according to the Whyte system, an E corresponds to 0-10-0.

In Garratt locomotives , the system was applied to both engine groups separately and connected with a +. The well-known class GMA / GMAM of the South African SAR has the designation (2'D1 ') (1'D2') according to UIC, the Whyte notation was 4-8-2 + 2-8-4 (scheme: ooOOOOo oOOOOoo).

French system

The French axle formula system is similar to the English-American one (Whyte), but counts the axles instead of the wheels and does not use hyphens. A 2'D1 'locomotive would be a "241" according to the French system. The SNCF also used this system to designate its steam locomotive series, e.g. B. 221 A or 240 P . The French system is also in use in Spain and Russia, in Spain also as part of the series designation for steam locomotives.

Turkish system

The Turkish axle formula system consists of two one- or two-digit numbers, the first number indicating the number of driving axles, the second number the total number of axles. As in France, the classification number is also used as the series designation in Turkey. A 2'D1 'locomotive is a "241" according to the French system and a "4-8-2" according to the Whyte system, and a "47" according to the Turkish system. The system does not provide any information about the exact wheel alignment. A "46" can be, for example, a 2'D locomotive or a 1'D1 'locomotive.

Comparison of the systems

VDEV / VMEV / UIC system Whyte notation American name Picture scheme
A1 0-2-2 Oo
1A 2-2-0 planet oO
1A1 2-2-2 Patent tea oOo
2'A 4-2-0 Jervis, Crampton, Norris ooO
3A 6-2-0 Crampton oooO
B. 0-4-0 Four wheel switcher OO
B1 0-4-2 OOo
B2 (B2 ') 0-4-4 - OOoo
1'B (1B) 2-4-0 Hanscom oOO
1'B1 ' 2-4-2 Columbia oOOo
2 B 4-4-0 American , eight-wheeler ooOO
2'B1 ' 4-4-2 Atlantic ooOOo
2'B2 ' 4-4-4 Jubilee ooOOoo
C. 0-6-0 Six wheel switcher, six coupler OOO
C1 0-6-2 OOOo
1'C 2-6-0 Mogul oOOO
2'C 4-6-0 Ten-wheeler ooOOO
1'C1 ' 2-6-2 Prairie oOOOo
2'C1 ' 4-6-2 Pacific ooOOOo
1'C2 ' 2-6-4 Adriatic oOOOoo
2'C2 ' 4-6-4 Hudson , Baltic ooOOOoo
D. 0-8-0 Eight wheel switcher OOOO
1'D 2-8-0 Consolidation oOOOO
1'D1 ' 2-8-2 Mikado , Mac Arthur oOOOOo
1'D2 ' 2-8-4 Berkshire oOOOOoo
2'D 4-8-0 Twelve-Wheeler, Mastodon ooOOOO
2'D1 ' 4-8-2 Mountain , Mohawk (NYC) ooOOOOo
2'D2 ' 4-8-4 Northern , Niagara (NYC), Wyoming ooOOOOoo
E. 0-10-0 Ten-wheel switcher OOOOO
E1 ' 0-10-2 union OOOOOo
1'E 2-10-0 Decapod oOOOOO
2'E 4-10-0 mastodon ooOOOOO
1'E1 ' 2-10-2 Santa Fe oOOOOOo
1'E2 ' 2-10-4 Texas oOOOOOoo
2'E1 ' 4-10-2 Texas, Southern Pacific, Overland ooOOOOOo
1'F 2-12-0 Centipede oOOOOOO
1'F1 ' 2-12-2 Javanic oOOOOOOo
2'F1 ' 4-12-2 Union Pacific ooOOOOOOo
C'C 0-6-6-0 Erie (articulated locomotive) OOO OOO
(1'C) C 2-6-6-0 nameless (articulated locomotive) oOOO OOO
(1'C) C1 ' 2-6-6-2 Joint Mogul (SP), Prairie Articulated (ATSF) oOOO OOOo
(1'C) C2 ' 2-6-6-4 nameless (articulated locomotive) oOOO OOOoo
(2'C) C2 ' 4-6-6-4 Challenger (articulated locomotive) ooOOO OOOoo
(1'C) C3 ' 2-6-6-6 Allegheny (articulated locomotive) oOOO OOOooo
D'D 0-8-8-0 nameless (articulated locomotive) OOOO OOOO
(1'D) D1 ' 2-8-8-2 Chesapeake (articulated locomotive) oOOOO OOOOo
(1'D) D2 ' 2-8-8-4 Yellowstone (articulated locomotive) oOOOO OOOOoo
(2'D) D2 ' 4-8-8-4 Big Boy (articulated locomotive) ooOOOO OOOOoo
(1'E) E1 ' 2-10-10-2 Virginian (articulated locomotive) oOOOOO OOOOOo
(2'C1 ') (1'C2') 4-6-2 + 2-6-4 Double Pacific ( Garratt ) ooOOOo oOOOoo
(2'D1 ') (1'D2') 4-8-2 + 2-8-4 Double Mountain (Garratt) ooOOOOo oOOOOoo


  1. Not all details of the system described here are contained in UIC Code 612. There are some unofficial extensions, especially for the additional labels. Furthermore, DIN 30052 regulates the marking of the wheel set sequence in rail vehicles.


  • Helmut Griebl, Friedrich Schadow: Directory of German locomotives 1923-1965. With an overview of the locomotive designation systems in Europe. Slezak, Vienna 1967 (contains a detailed description of the axis formula marking)
  • DIN 30052 rail vehicles - marking of the wheel set sequence.
  • UIC Code 650 Train Funding - Uniform designation of the wheelset sequence for locomotives and multiple units.

Web links

Individual evidence

  1. Karl Sachs: Electric Vollbahnlokomotiven: A manual for practice as well as for students . Springer-Verlag, 1928, ISBN 978-3-642-51847-8 , The mechanical part (carriage part): Introduction, p. 37-39 ( Google Book [accessed March 28, 2016]).
  2. The Confusion of Types - A Logical Locomotive Classification Needed . In: American Engineer and Railroad Journal . No. 12 , 1900, p. 374 ( html [accessed May 2, 2016]).
  3. ^ A History of the American Locomotive: Its Development, 1830-1880 . Courier Corporation, 1979, ISBN 978-0-486-23818-0 , The 4-2-0, pp. 33-46 ( Google Books [accessed May 26, 2015]).