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A selection of early 20th century locomotive types according to their Whyte notation and their comparative size
Whyte notation 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 twentieth century following a December 1900 editorial in American Engineer and Railroad Journal. The notation counts the number of leading wheels, then the number of driving wheels, and finally the number of trailing wheels, numbers being separated by dashes.[3] Other classification schemes, like UIC classification and the French, Turkish and Swiss systems for steam locomotives, count axles rather than wheels.

In the notation a locomotive with two leading axles (four wheels) in front, then three driving axles (six wheels) and then one trailing axle (two wheels) is classified as 4-6-2, and is commonly known as a Pacific.

Contents

MethodEdit

Articulated locomotivesEdit

Articulated locomotives such as Garratts, which are effectively two locomotives joined by a common boiler, have a + between the arrangements of each engine. Thus a "double Pacific" type Garratt is a 4-6-2+2-6-4. For Garratt locomotives the + sign is used even when there are no intermediate unpowered wheels, e.g. the LMS Garratt 2-6-0+0-6-2. This is because the two engine units are more than just power bogies. They are complete engines, carrying fuel and water tanks. The + sign represents the bridge (carrying the boiler) that links the two engines.

Simpler articulated types such as Mallets have a jointed frame under a common boiler where there are no unpowered wheels between the sets of powered wheels. Typically, the forward frame is free to swing, whereas the rear frame is rigid with the boiler. Thus a Union Pacific Big Boy is a 4-8-8-4; four leading wheels, one group of eight driving wheels, another group of eight driving wheels, and then four trailing wheels.

Duplex locomotivesEdit

This numbering system is shared by duplex locomotives, which have powered wheel sets sharing a rigid frame.

SuffixesEdit

No suffix means a tender locomotive.

T indicates a tank locomotive: in European 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. T+T means a tank locomotive that also has a tender.

In Europe, the suffix R can signify rack (0-6-0RT) or reversible (0-6-0TR), the latter being Bi-cabine locomotives used in France.

The suffix F indicates a fireless locomotive (0-4-0F). This locomotive has no tender.

Other suffixes have been used, including ng for narrow-gauge (less than 1,435 mm (4 ft 8 12 in) ) and CA or ca for compressed air (running on compressed air from a tank instead of steam from a boiler).

Internal combustion locomotivesEdit

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 or P for 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.

LimitationsEdit

The main limitation of Whyte Notation is that it does not cover non-standard types such as Shay locomotives, which use geared trucks rather than driving wheels. The most commonly used system in Europe outside the United Kingdom is UIC classification, based on German practice, which can define the exact layout of a locomotive.

NamingEdit

In American (and to a lesser extent British) practice, most wheel arrangements in common use were given names, sometimes from the name of the first such locomotive built. For example, the 2-2-0 type arrangement is named Planet, after the 1830 locomotive on which it was first used. (This naming convention is similar to the naming of warship classes.)

Common wheel arrangementsEdit

The most common wheel arrangements are listed below. In the diagrams, the front of the locomotive is to the left.

Arrangement
(locomotive front is to the left)
Whyte classification Name # of units produced
Non-articulated locomotives
  0-2-2 Northumbrian
  2-2-0 Planet
  2-2-2 Single,[2] Jenny Lind
  2-2-4 Aerolite
  4-2-0 Jervis[4]
  4-2-2 Bicycle
  4-2-4 Huntington
  6-2-0 Crampton[5]
  0-4-0 Four-Coupled
  0-4-0+4 Four-Coupled as used on Railmotors
  0-4-2 Olomana
  0-4-4 Forney[1]
  2-4-0 Porter, 'Old English'[6]
  2-4-2 Columbia[1]
  2-4-4 Boston
  4-4-0 American,[1][7] Eight-wheeler
  4-4-2 Atlantic[1][8]
  4-4-4 Reading, Jubilee (Canada)[9]
  0-3-0 (one driving wheel per axle; used on Patiala State Monorail Trainways 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 Branchliner, Webb
  0-6-4 Forney six-coupled[1]
  0-6-6
  2-6-0 Mogul[1][10] 11,000[11]
  2-6-2 Prairie[1][2]
  2-6-4 Adriatic
  2-6-6 Suburban
  4-6-0 Ten-Wheeler[1][12] (not Britain)[13]
  4-6-2 Pacific[1][2][14][15] 6,800[16]
  4-6-4 Hudson,[17] Baltic[2]
  0-8-0 Eight-Coupled,[1] USRA 0-8-0 (United States)
  0-8-2 Kado  [18]
  0-8-4 London
  2-8-0 Consolidation[1][2][19] 35,000[20]
  2-8-2 Mikado,[1][2] Mike, MacArthur[21][22]
  2-8-4 Berkshire, Kanawha[23][24]
  2-8-6 Used only on four Mason Bogie locomotives
  4-8-0 Twelve-Wheeler[1]
  4-8-2 Mountain,[2][25] Mohawk (NYC)[26]
  4-8-4 Northern, Niagara, Confederation, Dixie, Greenbrier, Pocono, Potomac, Golden State (Southern Pacific),[27] Western, Laurentian (Delaware & Hudson Railroad), General, Wyoming (Lehigh Valley[28]), Governor, Big Apple, GS Series "Daylight" (Southern Pacific)[27]
  4-8-6 Proposed by Lima, never built
  6-8-6 (PRR S2 steam turbine locomotive)[29]
  0-10-0 Ten-Coupled,[1][30] (rarely) Decapod
  0-10-2 Union[30]
  2-10-0 Decapod,[1][31] Russian Decapod
  2-10-2 Santa Fe,[1] Central, Decapod (only on the Southern Pacific)
  2-10-4 Texas, Colorado (CB&Q), Selkirk (Canada)[32]
  4-10-0 Mastodon,[1] Gobernador (in honor of El Gobernador)
  4-10-2 Reid Tenwheeler,[33][34] Southern Pacific, Overland[35]
  0-12-0 Twelve-Coupled
  2-12-0 Centipede[1]
  2-12-2 Javanic
  2-12-4 Bulgaria
2-12-6 Proposed by Lima, never built
  4-12-2 Union Pacific[36]
  4-14-4 AA20[37]
Duplex locomotives
  4-4-4-4 (PRR T1)[38]
  6-4-4-6 (PRR S1)[39]
  4-4-6-4 (PRR Q2)[40]
  4-6-4-4 (PRR Q1)
Articulated locomotives (simple and compound)
  0-4-4-0 Bavarian BB II [41]
   2-4-4-0 Vivarais
   0-4-4-2 Swiss
  2-4-4-2 Skookum
4-4-6-2 AT&SF[42]
  0-6-6-0 Erie
  2-6-6-0 Denver & Salt Lake
  2-6-6-2 C&O/N&W. C&O Class H-2 thru H-5. Alco 1912.
  2-6-6-4 Norfolk & Western
  2-6-6-6 Allegheny,[43] Blue Ridge 68[44]
  4-6-6-2 (Southern Pacific class AM-2)[45]
  4-6-6-4 Challenger[46] 252[47]
  2-6-8-0 (Southern Railway, Great Northern Railway)[48]
  0-8-8-0 Angus
  2-8-8-0 Bull Moose
  2-8-8-2 Chesapeake, Norfolk & Western
  2-8-8-4 Yellowstone[49]
  4-8-8-2 Southern Pacific cab forward classes AC-4 through AC-12 (except AC-9)[45]
  4-8-8-4 Big Boy[50] 25[51]
  2-10-10-2 (Santa Fe and Virginian railroads)[48]
  2-8-8-8-2 Triplex (Erie RR)
  2-8-8-8-4 Triplex (Virginian RR)[52]
Garratt articulated locomotives
  0-4-0+0-4-0 Welsh Highland
  0-6-0+0-6-0 Kitson Meyer
  2-4-0+0-4-2 Double Porter
  2-4-2+2-4-2 Double Columbia
  2-6-0+0-6-2 Double Mogul
  2-6-2+2-6-2 Double Prairie
  2-8-0+0-8-2 Double Consolidation
  2-8-2+2-8-2 Double Mikado
  4-4-2+2-4-4 Double Atlantic
  4-6-0+0-6-4 Mogyana
  4-6-2+2-6-4 Double Pacific
  4-6-4+4-6-4 Double Baltic, Double Hudson
  4-8-0+0-8-4 Double Mastodon
  4-8-2+2-8-4 Double Mountain
  4-8-4+4-8-4 Double Northern

See alsoEdit

ReferencesEdit

  1. ^ a b c d e f g h i j k l m n o p q r s t Colvin, Fred H. (1906). The railroad pocket-book: a quick reference cyclopedia of railroad information. New York, Derry-Collard; London, Locomotive Publishing Company (US-UK co-edition). p. L‑9.
  2. ^ a b c d e f g h "Steam Locomotive Glossary". Railway Technical Web Pages. 28 June 2007. Archived from the original on 28 January 2008. Retrieved 8 February 2008.
  3. ^ Thompson, Keith (1 May 2006). "Builder's plates: A locomotive's birth certificate". Kalmbach Publishing. Archived from the original on 22 November 2008. Retrieved 8 February 2008.
  4. ^ White, John H., Jr. (1968). A History of the American Locomotive - Its Development: 1830-1880. New York: Dover Publications. ISBN 0-486-23818-0.CS1 maint: Multiple names: authors list (link), p. 33.
  5. ^ Adams, Bob (December 1968). "The Crampton Type Locomotive on the Camden & Amboy Railroad". NMRA Bulletin. National Model Railroad Association.
  6. ^ Ellis, C Hamilton, Some Classic Locomotives, Allen & Unwin, 1949.173 p.
  7. ^ White (1968), p. 46.
  8. ^ Marsden, Richard (2008). "The LNER 4-4-2 Atlantic Locomotives". The London & North Eastern Railway (LNER) Encyclopedia. Archived from the original on 13 February 2008. Retrieved 8 February 2008.
  9. ^ "Canadian Pacific Railway No. 2929". Steamtown NHS Special History Study. United States National Park Service. 14 February 2002. Archived from the original on 19 May 2007. Retrieved 8 February 2008.
  10. ^ White (1968), p 62-65.
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  12. ^ White (1968), p. 57.
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  28. ^ "Archived copy". Archived from the original on 13 August 2010. Retrieved 25 May 2010.CS1 maint: Archived copy as title (link)
  29. ^ Staufer, Alvin F.; Pennypacker, Bert (1962). Pennsy Power: Steam and Electric Locomotives of the Pennsylvania Railroad, 1900-1957. Research by Martin Flattley. Carollton, OH: Alvin F. Staufer. ISBN 978-0-9445-1304-0. LCCN 62020878. OCLC 602543182.
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Further readingEdit

External linksEdit