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Locomotives of different types (Whyte and UIC wheel notation)

In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Several notations exist to describe the wheel assemblies of a locomotive by type, position, and connections, with the adopted notations varying by country. Within a given country, different notations may also be employed for different kinds of locomotives, such as steam, electric, and diesel powered.

Especially in steam days, wheel arrangement was an important attribute of a locomotive because there were many different types of layout adopted, each wheel being optimised for a different use (often with only some being actually "driven"). Modern diesel and electric locomotives are much more uniform, usually with all axles driven.

Major notation schemesEdit

Template:Sister project Template:Worldwide The main notations are the Whyte notation (based on counting the wheels), the AAR wheel arrangement notation (based on counting either the axles or the bogies), and the UIC classification of locomotive axle arrangements (based on counting either the axles or the bogies).

The Whyte notation is generally used for steam locomotives throughout the United States, Canada, the United Kingdom and Ireland. For diesels and electrics, North America uses the AAR wheel arrangement scheme while British practice uses a slightly simplified form of the European UIC classification scheme (except for small diesel shunters, where Whyte notation is used).

In mainland Europe, the UIC classification scheme is generally used for all locomotive types including steam, with some exceptions. In France, the UIC classification is used for diesels and electrics while a scheme similar to the Whyte notation, but counting axles instead of wheels, is used for steam locomotives. Notably, Switzerland had its own separate notation system until 1989, with the Swiss locomotive and railcar classification now only retained for its narrow-gauge railways.

  • AAR wheel arrangement - Used largely throughout the US and Canada for diesel and electric locomotives.
  • UIC classification - Used in mainland Europe for all locomotive types. Used in the UK for electric and large diesel locomotives.
  • Whyte notation - Used in North America, the UK and Ireland for steam locomotives, and for shunter locomotives (US: switcher locomotives) in the UK.

Comparison of wheel arrangements and wheel pictureEdit

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VDEV/VMEV/UIC-system Whyte-notation American name Picture scheme
Locomotive front is to the left
A1 0-2-2 Northumbrian Oo
A2 0-2-4 Ooo
1A 2-2-0 Planet oO
1A1 2-2-2 Single, Jenny Lind, Patentee oOo
1A2 2-2-4 Aerolite oOoo
2Template:PrimeA 4-2-0 Jervis ooO
2Template:PrimeA1 4-2-2 ooOo
2A2 4-2-4 Huntington ooOoo
3A 6-2-0 Crampton oooO
N/A 0-3-0 OOO
B 0-4-0 Four-Wheel-Switcher OO
B1 0-4-2 Olomana OOo
B2Template:Prime 0-4-4 Forney four-coupled OOoo
B3Template:Prime 0-4-6 OOooo
1B 2-4-0 Porter oOO
1Template:PrimeB1Template:Prime 2-4-2 Columbia oOOo
1B2Template:Prime 2-4-4 Forney, Mason Bogie oOOoo
1B3Template:Prime 2-4-6 oOOooo
2Template:PrimeB 4-4-0 American, Eight-Wheeler ooOO
2Template:PrimeB1Template:Prime 4-4-2 Atlantic ooOOo
2Template:PrimeB2Template:Prime 4-4-4 Jubilee (CA), Reading (US) ooOOoo
2Template:PrimeB3Template:Prime 4-4-6 ooOOooo
C 0-6-0 Six-Wheel-Switcher OOO
C1 0-6-2 Webb, Branchline OOOo
C2Template:Prime 0-6-4 OOOoo
1Template:PrimeC 2-6-0 Mogul oOOO
[[1Template:PrimeC1Template:Prime]] 2-6-2 Prairie oOOOo
1Template:PrimeC2Template:Prime 2-6-4 Adriatic, Lionel oOOOoo
1Template:PrimeC3Template:Prime 2-6-6 oOOOooo
2Template:PrimeC 4-6-0 Ten-Wheeler ooOOO
2Template:PrimeC1Template:Prime 4-6-2 Pacific ooOOOo
2Template:PrimeC2Template:Prime 4-6-4 Hudson (NYC), Baltic (MR), Shore Line (NH) ooOOOoo
D 0-8-0 Eight-Wheel-Switcher OOOO
D1 0-8-2 Transfer OOOOo
D2Template:Prime 0-8-4 OOOOoo
D3Template:Prime 0-8-6 OOOOooo
1Template:PrimeD 2-8-0 Consolidation oOOOO
1Template:PrimeD1Template:Prime 2-8-2 Mikado, MacArthur (USATC) oOOOOo
1Template:PrimeD2Template:Prime 2-8-4 Berkshire, Kanawha (C&O), Lima (B&M)&(IC) oOOOOoo
1Template:PrimeD3Template:Prime 2-8-6 oOOOOooo
2Template:PrimeD 4-8-0 Twelve-Wheeler, Mastodon ooOOOO
2Template:PrimeD1Template:Prime 4-8-2 Mountain, Mohawk (NYC), New Haven (NH) ooOOOOo
2Template:PrimeD2Template:Prime 4-8-4 Northern, General Service (SP), Golden State (SP), Niagara (NYC), Wyoming (LV), Potomac (WM), Confederation (CN), Dixie (NC&St.L), Greenbrier (C&O), Laurentian (D&H), Montana (GN), Pocono (Lackawanna), ooOOOOoo
2D3 4-8-6 ooOOOOooo
3Template:PrimeD3Template:Prime 6-8-6 Turbine (Pennsylvania Railroad Steam Turbine) oooOOOOooo
E 0-10-0 Ten-Wheel Switcher OOOOO
E1Template:Prime 0-10-2 Union OOOOOo
1Template:PrimeE 2-10-0 Decapod oOOOOO
2Template:PrimeE 4-10-0 Mastodon, El Gobernador, ooOOOOO
1Template:PrimeE1Template:Prime 2-10-2 Santa Fe, Decapod (SP), Central (IC) oOOOOOo
1Template:PrimeE2Template:Prime 2-10-4 Texas, Selkirk (CP), Colorado (CB&Q) oOOOOOoo
2Template:PrimeE1Template:Prime 4-10-2 Southern Pacific, Overland (UP) ooOOOOOo
F 0-12-0 Pennsylvania, Twelve-Wheel-Switcher OOOOOO
1Template:PrimeF 2-12-0 Centipede oOOOOOO
1Template:PrimeF1Template:Prime 2-12-2 Javanic oOOOOOOo
2Template:PrimeF1Template:Prime 4-12-2 Union Pacific ooOOOOOOo
2Template:PrimeG2Template:Prime 4-14-4 Soviet (AA) ooOOOOOOOoo
ATemplate:PrimeA 0-2-2-0 O O
BTemplate:PrimeB 0-4-4-0 nameless (Mallet) OO OO
BTemplate:PrimeB1 0-4-4-2 nameless (Mallet) OO OOo
2Template:PrimeBB2Template:Prime 4-4-4-4 nameless (Pennsylvania Railroad Duplex) ooOO OOoo
3Template:PrimeBB3Template:Prime 6-4-4-6 oooOO OOooo
2Template:PrimeCB2Template:Prime 4-6-4-4 nameless (Pennsylvania Railroad Duplex) ooOOO OOoo
CTemplate:PrimeC 0-6-6-0 Old Maude (Mallet) OOO OOO
(1Template:PrimeC)C 2-6-6-0 nameless (Mallet) oOOO OOO
(1Template:PrimeC)C1Template:Prime 2-6-6-2 nameless (Mallet) oOOO OOOo
(1Template:PrimeC)C2Template:Prime 2-6-6-4 nameless (Simple articulated) oOOO OOOoo
(2Template:PrimeC)C2Template:Prime 4-6-6-4 Challenger (Simple articulated) ooOOO OOOoo
(1Template:PrimeC)C3Template:Prime 2-6-6-6 Allegheny, Blue Ridge (Simple articulated) oOOO OOOooo
DTemplate:PrimeD 0-8-8-0 Angus (Mallet) OOOO OOOO
(1Template:PrimeD)D 2-8-8-0 Bull Moose (Mallet) oOOOO OOOO
(1Template:PrimeD)D1Template:Prime 2-8-8-2 Chesapeake (C&O), Cab Forward (SP) (Mallet) oOOOO OOOOo
(1Template:PrimeD)D2Template:Prime 2-8-8-4 Yellowstone (Simple articulated) oOOOO OOOOoo
(2Template:PrimeD)D1Template:Prime 4-8-8-2 Cab Forward (Simple articulated) ooOOOO OOOOo
(2Template:PrimeD)D2Template:Prime 4-8-8-4 Big Boy (Simple articulated) ooOOOO OOOOoo
(1Template:PrimeE)E1Template:Prime 2-10-10-2 Virginian (Mallet) oOOOOO OOOOOo
(1Template:PrimeD1Template:Prime)(1Template:PrimeD1Template:Prime) 2-8-2+2-8-2 Nameless, Garratt oOOOOo+oOOOOo
(2Template:PrimeC1Template:Prime)(1Template:PrimeC2Template:Prime) 4-6-2+2-6-4 nameless (Garratt) ooOOOo+oOOOoo
(2Template:PrimeC2Template:Prime)(2Template:PrimeC2Template:Prime) 4-6-4+4-6-4 nameless (Garratt) ooOOOoo+ooOOOoo
(2Template:PrimeD)(D2Template:Prime) 4-8-0+0-8-4 nameless (Garratt) ooOOOO+OOOOoo
(2Template:PrimeD1Template:Prime)(1Template:PrimeD2Template:Prime) 4-8-2+2-8-4 Double Mountain (Garratt) ooOOOOo+oOOOOoo
(2Template:PrimeD2Template:Prime)(2Template:PrimeD2Template:Prime) 4-8-4+4-8-4 nameless (Garratt) ooOOOOoo+ooOOOOoo

Geared steam locomotivesEdit

Geared steam locomotives such as Shays, Heislers, and Climaxes do not have a standard wheel arrangement classification system. Instead of being classified by wheel arrangement, they are instead classified by their design and their number of trucks.

No. of trucks American name Picture scheme
2-truck Class A Shay, Class B Shay, Class A Climax, Class B Climax, Heisler oo oo
3-truck Class C Shay, Class C Climax, Heisler oo oo oo
4-truck Class D Shay oo oo oo oo

See alsoEdit

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ReferencesEdit

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