Wheel arrangement

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Locomotives of different types (Whyte and UIC wheel notation) Locotypes mod.gif
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. [1] 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.

Contents

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 schemes

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.

Comparison of wheel arrangements and wheel picture

VDEV/VMEV/UIC-systemWhyte-notationAmerican namePicture scheme
Locomotive front is to the left
A1 0-2-2 Northumbrian WheelArrangement 0-2-2.svg
A2 0-2-4
1A 2-2-0 Planet WheelArrangement 2-2-0.svg
1A1 2-2-2 Single, Jenny Lind, Patentee WheelArrangement 2-2-2.svg
1A2 2-2-4 Aerolite WheelArrangement 2-2-4.svg
2A 4-2-0 Jervis WheelArrangement 4-2-0.svg
2A1 4-2-2 WheelArrangement 4-2-2.svg
2A2 4-2-4 Huntington WheelArrangement 4-2-4.svg
3A 6-2-0 Crampton WheelArrangement 6-2-0.svg
N/A 0-3-0 WheelArrangement 0-6-0.svg
B 0-4-0 Four-Wheel-Switcher WheelArrangement 0-4-0.svg
B1 0-4-2 Olomana WheelArrangement 0-4-2.svg
B2 0-4-4 Forney four-coupled WheelArrangement 0-4-4.svg
B3 0-4-6
1B 2-4-0 Porter WheelArrangement 2-4-0.svg
1B1 2-4-2 Columbia WheelArrangement 2-4-2.svg
1B2 2-4-4 Forney, Mason Bogie WheelArrangement 2-4-4.svg
1B3 2-4-6
2B 4-4-0 American, Eight-Wheeler WheelArrangement 4-4-0.svg
2B1 4-4-2 Atlantic WheelArrangement 4-4-2.svg
2B2 4-4-4 Jubilee (CA), Reading (US) WheelArrangement 4-4-4.svg
2B3 4-4-6
C 0-6-0 Six-Wheel-Switcher WheelArrangement 0-6-0.svg
C1 0-6-2 Webb, Branchline WheelArrangement 0-6-2.svg
C2 0-6-4 WheelArrangement 0-6-4.svg
1C 2-6-0 Mogul WheelArrangement 2-6-0.svg
1′C1′ 2-6-2 Prairie WheelArrangement 2-6-2.svg
1C2 2-6-4 Adriatic, Lionel WheelArrangement 2-6-4.svg
1C3 2-6-6 WheelArrangement 2-6-6.svg
2C 4-6-0 Ten-Wheeler WheelArrangement 4-6-0.svg
2C1 4-6-2 Pacific WheelArrangement 4-6-2.svg
2C2 4-6-4 Hudson (NYC), Baltic (MR), Shore Line (NH) WheelArrangement 4-6-4.svg
D 0-8-0 Eight-Wheel-Switcher WheelArrangement 0-8-0.svg
D1 0-8-2 Transfer WheelArrangement 0-8-2.svg
D2 0-8-4 WheelArrangement 0-8-4.svg
D3 0-8-6
1D 2-8-0 Consolidation WheelArrangement 2-8-0.svg
1D1 2-8-2 Mikado, MacArthur (USATC) WheelArrangement 2-8-2.svg
1D2 2-8-4 Berkshire, Kanawha (C&O), Lima (B&M)&(IC) WheelArrangement 2-8-4.svg
1D3 2-8-6 WheelArrangement 2-8-6.svg
2D 4-8-0 Twelve-Wheeler, Mastodon WheelArrangement 4-8-0.svg
2D1 4-8-2 Mountain, Mohawk (NYC), New Haven (NH) WheelArrangement 4-8-2.svg
2D2 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), WheelArrangement 4-8-4.svg
2D3 4-8-6 WheelArrangement 4-8-6.svg
3D3 6-8-6 Turbine (Pennsylvania Railroad Steam Turbine) WheelArrangement 6-8-6.svg
E 0-10-0 Ten-Wheel Switcher WheelArrangement 0-10-0.svg
E1 0-10-2 Union WheelArrangement 0-10-2.svg
1E 2-10-0 Decapod WheelArrangement 2-10-0.svg
2E 4-10-0 Mastodon, El Gobernador, WheelArrangement 4-10-0.svg
1E1 2-10-2 Santa Fe, Decapod (SP), Central (IC) WheelArrangement 2-10-2.svg
1E2 2-10-4 Texas, Selkirk (CP), Colorado (CB&Q) WheelArrangement 2-10-4.svg
2E1 4-10-2 Southern Pacific, Overland (UP) WheelArrangement 4-10-2.svg
F 0-12-0 Pennsylvania, Twelve-Wheel-Switcher WheelArrangement 0-12-0.svg
1F 2-12-0 Centipede WheelArrangement 2-12-0.svg
1F1 2-12-2 Javanic WheelArrangement 2-12-2.svg
2F1 4-12-2 Union Pacific WheelArrangement 4-12-2.svg
2G2 4-14-4 Soviet (AA) WheelArrangement 4-14-4.svg
AA 0-2-2-0
BB 0-4-4-0 nameless (Mallet)
BB1 0-4-4-2 nameless (Mallet)
2BB2 4-4-4-4 nameless (Pennsylvania Railroad Duplex) WheelArrangement 4-4-4-4.svg
3BB3 6-4-4-6 WheelArrangement 6-4-4-6.svg
2CB2 4-6-4-4 nameless (Pennsylvania Railroad Duplex) WheelArrangement 4-6-4-4.svg
CC 0-6-6-0 Old Maude (Mallet) WheelArrangement 0-6-6-0.svg
(1C)C 2-6-6-0 nameless (Mallet) WheelArrangement 2-6-6-0.svg
(1C)C1 2-6-6-2 nameless (Mallet) WheelArrangement 2-6-6-2.svg
(1C)C2 2-6-6-4 nameless (Simple articulated) WheelArrangement 2-6-6-4.svg
(2C)C2 4-6-6-4 Challenger (Simple articulated) WheelArrangement 4-6-6-4.svg
(1C)C3 2-6-6-6 Allegheny, Blue Ridge (Simple articulated) WheelArrangement 2-6-6-6.svg
DD 0-8-8-0 Angus (Mallet) WheelArrangement 0-8-8-0.svg
(1D)D 2-8-8-0 Bull Moose (Mallet) WheelArrangement 2-8-8-0.svg
(1D)D1 2-8-8-2 Chesapeake (C&O), Cab Forward (SP) (Mallet) WheelArrangement 2-8-8-2.svg
(1D)D2 2-8-8-4 Yellowstone (Simple articulated) WheelArrangement 2-8-8-4.svg
(2D)D1 4-8-8-2 Cab Forward (Simple articulated) WheelArrangement 4-8-8-2.svg
(2D)D2 4-8-8-4 Big Boy (Simple articulated) WheelArrangement 4-8-8-4.svg
(1E)E1 2-10-10-2 Virginian (Mallet) WheelArrangement 2-10-10-2.svg
(1D1)(1D1) 2-8-2+2-8-2 Nameless, Garratt WheelArrangement 2-8-2+2-8-2.svg
(2C1)(1C2) 4-6-2+2-6-4 nameless (Garratt) WheelArrangement 4-6-2+2-6-4.svg
(2C2)(2C2) 4-6-4+4-6-4 nameless (Garratt) WheelArrangement 4-6-4+4-6-4.svg
(2D)(D2) 4-8-0+0-8-4 nameless (Garratt)
(2D1)(1D2) 4-8-2+2-8-4 Double Mountain (Garratt) WheelArrangement 4-8-2+2-8-4.svg
(2D2)(2D2) 4-8-4+4-8-4 nameless (Garratt) WheelArrangement 4-8-4+4-8-4.svg

Geared steam locomotives

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 trucksAmerican namePicture scheme
2-truckClass A Shay, Class B Shay, Class A Climax, Class B Climax, Heisleroo oo
3-truckClass C Shay, Class C Climax, Heisleroo oo oo
4-truckClass D Shayoo oo oo oo

See also

References

  1. "Wheel Arrangements". Railway Technical Web Pages. 1 August 2011. Archived from the original on 4 March 2016. Retrieved 1 August 2011.