This article possibly contains original research .(September 2024) |
The 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, [2] and came into use in the early twentieth century following a December 1900 editorial in American Engineer and Railroad Journal.
The notation was adopted and remains in use in North America and the United Kingdom to describe the wheel arrangements of steam locomotives, but for modern locomotives, multiple units and trams it has been supplanted by the UIC system in Europe and by the AAR system (essentially a simplification of the UIC system) in North America. However, geared steam locomotives do not use the notation. They are classified by their model and their number of trucks.
The notation in its basic form 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] For example, 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 a 4-6-2 locomotive, and is commonly known as a Pacific.
For articulated locomotives that have two wheelsets, such as Garratts, which are effectively two locomotives joined by a common boiler, each wheelset is denoted separately, with a plus sign (+) between them. Thus a 4-6-2-type Garratt is a 4-6-2+2-6-4 . For Garratt locomotives, the plus 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 plus 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. Sometimes articulated locomotives of this type are denoted with a “+” between each driving wheels set (so in the previous case, the Big Boy would be a 4-8+8-4). This may have been developed to distinguish articulated and duplex arrangements; duplex arrangements would get a “-“ being rigid and articulated locomotives would get a “+” being flexible. However, given all the wheel arrangements for duplex locomotives have been mutually exclusive to them, it is usually considered unnecessary and thus another “-“ is usually used.
Triplex locomotives, and any theoretical larger ones, simply expand on basic articulated locomotives, for example, 2-8-8-8-2. In the case of the Belgian quadruplex locomotive, the arrangement is listed as 0-6-2+2-4-2-4-2+2-6-0. [4]
For duplex locomotives, which have two sets of coupled driving wheels mounted rigidly on the same frame, the same method is used as for Mallet articulated locomotives – the number of leading wheels is placed first, followed by the leading set of driving wheels, followed by the trailing set of driving wheels, followed by the trailing wheels, each number being separated by a hyphen.
A number of standard suffixes can be used to extend the Whyte notation for tank locomotives: [5]
Suffix | Meaning | Example |
---|---|---|
[No Suffix] | Tender locomotive | 0-6-0 |
T | Tank locomotive | 0-6-2 T |
ST | Saddle tank locomotive | 0-4-0 ST |
WT | Well tank locomotive | 0-4-0 WT |
PT | Pannier tank locomotive | 0-6-0 PT |
C or CT | Crane tank locomotive | 0-6-2 CT |
IST | Inverted saddle tank locomotive | 0-4-2 IST |
T+T (or ST+T, WT+T, etc.) | Tender-tank locomotive | 0-4-0 T+T |
WT | Wing tank locomotive | 0-4-0 WT |
RT | Rear tank locomotive | 0-4-4 RT |
Various other types of steam locomotive can be also denoted through suffixes: [5]
VB or VBT | Vertical boilered locomotive | 0-6-0 VB | |
F | Fireless locomotive | 0-6-0 F | |
CA | Compressed air locomotive | 0-6-0 CA | |
R | Railcar | 0-4-4-0 R | |
R or RT | Rack locomotive | 0-4-0 RT |
The wheel arrangement of small diesel and petrol locomotives can be classified using the same notation as steam locomotives, e.g. 0-4-0, 0-6-0, 0-8-0. Where the axles are coupled by chains or shafts (rather than side rods) or are individually driven, the terms 4w (4-wheeled), 6w (6-wheeled) or 8w (8-wheeled) are generally used. For larger locomotives, the UIC classification is more commonly used.
Various suffixes are also used to denote the different types of internal combustion locomotives: [5]
Suffix | Meaning | Example |
---|---|---|
PM | Petrol-mechanical locomotive | 4w PM |
PE | Petrol-electric locomotive | 0-6-0 PE |
D | Diesel locomotive | 6w D |
DM | Diesel–mechanical locomotive | 8w DM |
DE | Diesel–electric locomotive | 0-4-0 DE |
DH | Diesel–hydraulic locomotive | 0-6-0 DH |
The wheel arrangement of small electric locomotives can be denoted using this notation, like with internal combustion locomotives.
Suffixes used for electric locomotives include:
Suffix | Meaning | Example |
---|---|---|
BE | Battery-electric locomotive | 4w BE |
OE | Overhead-lines electric locomotive | 0-8-0 OE |
RE | Third rail electric locomotive | 4wRE |
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.) Note that several wheel arrangements had multiple names, and some names were only used in some countries.
Wheel arrangements under the Whyte system 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 | No. of units produced |
---|---|---|---|
Non-articulated locomotives | |||
0-2-2 | Northumbrian (after the 1830 locomotive Northumbrian) | ||
0-2-4 | |||
2-2-0 | Planet | ||
2-2-2 | Single, [2] Jenny Lind [6] | ||
2-2-4 | Aerolite | ||
4-2-0 | Jervis [7] | ||
4-2-2 | Bicycle [6] | ||
4-2-4 | Huntington | ||
6-2-0 | Crampton [8] | ||
0-4-0 | Four-wheel switch [6] | ||
0-4-0+4 | |||
0-4-2 | Olomana | ||
0-4-4 | Forney [1] | ||
2-4-0 | Porter, 'Old English' [9] | ||
2-4-2 | Columbia [1] | ||
2-4-4 | Forney, Mason Bogie | ||
4-4-0 | American, [1] [10] eight-wheeler | ||
4-4-2 | Atlantic [1] [11] | ||
4-4-4 | Reading, Jubilee (Canada) [12] | ||
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] Six-wheel switch, [6] Bourbonnais (France - tender), Boer (France - tank) | ||
0-6-2 | Branchliner, Webb | ||
0-6-4 | Forney six-coupled [1] | ||
0-6-6 | Forney six-coupled | ||
2-6-0 | Mogul [1] [13] | 11,000 | |
2-6-2 | Prairie [1] [2] | ||
2-6-4 | Adriatic [6] | ||
2-6-6 | Mason Bogie | ||
4-6-0 | Ten-wheeler [1] [14] (not Britain) [15] | ||
4-6-2 | Pacific [1] [2] [16] [17] | 6,800 | |
4-6-4 | Hudson, [18] Baltic [2] | ||
4-6-6 | Use on the Boston and Albany Railroad. [19] | ||
0-8-0 | Eight-coupled [1] | ||
0-8-2 | Transfer | ||
0-8-4 | |||
2-8-0 | Consolidation [1] [2] [20] | 35,000 | |
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] [25] Mastodon [6] | ||
4-8-2 | Mountain, [2] [26] Mohawk (NYC) [27] | ||
4-8-4 | Northern, Niagara, Confederation, Dixie, Greenbrier, Pocono, Potomac, Heavy Mountain (Atchison, Topeka, and Santa Fe), Golden State (Southern Pacific), [28] Western, Laurentian (Delaware & Hudson Railroad), General, Wyoming (Lehigh Valley [29] ), Governor, Big Apple, GS Series "Daylight" (Southern Pacific) [28] | ||
4-8-6 | Proposed by Lima, never built | ||
6-8-6 | Turbine, only used on the PRR S2 Steam Turbine | 1 | |
0-10-0 | Ten-coupled, [1] [30] Ten-wheel switch [6] | ||
0-10-2 | Union [30] | ||
2-10-0 | Decapod, [1] [31] Russian Decapod | ||
2-10-2 | Santa Fe [1] | ||
2-10-4 | Texas, Colorado (CB&Q), Selkirk (Canada) [32] | ||
2-10-6 | Proposed by Indian Railways, never built [33] | ||
4-10-0 | Mastodon [1] [25] | ||
4-10-2 | Reid Tenwheeler, [34] [35] Southern Pacific, Overland, [36] Super Mountain [6] | ||
0-12-0 | 12-coupled | ||
0-12-2 | Used in Argentina | ||
2-12-0 | Centipede [1] | ||
2-12-2 | Javanic [6] | 30 | |
2-12-4 | 20 | ||
2-12-6 | Proposed by Lima, never built | ||
4-12-2 | Union Pacific [37] | ||
4-14-4 | AA20, [38] Soviet [6] | 1 | |
Divided drive and duplex locomotives | |||
0-2-2-0 | Used on the Mount Washington Cog Railway | ||
2-2-2-0 | |||
2-2-2-2 | |||
2-2-4-0 | 1 | ||
4-2-2-0 | Double single [39] | ||
2-4-6-2 | |||
4-4-4-4 | (PRR T1) [40] | 53 | |
6-4-4-6 | (PRR S1) [41] | 1 | |
4-4-6-4 | (PRR Q2) [42] | 26 | |
4-6-4-4 | (PRR Q1) | 1 | |
Articulated locomotives (simple and compound) | |||
0-4-4-0 | |||
2-4-4-0 | 5 | ||
0-4-4-2 | |||
2-4-4-2 | Little River | ||
4-4-6-2 | Used by the Santa Fe [43] | 2 | |
0-6-6-0 | |||
2-6-6-0 | |||
2-6-6-2 | 1,300 | ||
2-6-6-4 | 60 | ||
2-6-6-6 | Allegheny, [44] Blue Ridge | 68 | |
4-6-6-2 | (Southern Pacific class AM-2) [45] | ||
4-6-6-4 | Challenger [46] | 252 | |
2-6-8-0 | (Southern Railway, Great Northern Railway) [47] | 39 | |
0-8-8-0 | Angus [48] | ||
2-8-8-0 | Bull Moose | ||
2-8-8-2 | Chesapeake | 222 | |
2-8-8-4 | Yellowstone [49] | 78 | |
4-8-8-2 | Cab Forward | 195 | |
4-8-8-4 | Big Boy [50] | 25 [51] | |
2-10-10-2 | (Santa Fe and Virginian railroads) [47] | 20 | |
2-8-8-8-2 | Triplex (Erie RR) | 3 | |
2-8-8-8-4 | Triplex (Virginian RR) [52] | 1 | |
Garratt articulated locomotives | |||
0-4-0+0-4-0 | |||
0-6-0+0-6-0 | |||
2-4-0+0-4-2 | |||
2-4-2+2-4-2 | |||
2-6-0+0-6-2 | |||
2-6-2+2-6-2 | Double Prairie | ||
2-8-0+0-8-2 | |||
2-8-2+2-8-2 | Double Mikado | ||
4-4-2+2-4-4 | |||
4-6-0+0-6-4 | |||
4-6-2+2-6-4 | Double Pacific | ||
4-6-4+4-6-4 | Double Hudson | ||
4-8-0+0-8-4 | |||
4-8-2+2-8-4 | |||
4-8-4+4-8-4 |
Under the Whyte notation for the classification of steam locomotives, a 2-10-4 locomotive has two leading wheels on one axle, usually in a Bissel truck, ten coupled driving wheels on five axles, and four trailing wheels on two axles, usually in a bogie. These were referred to as the Texas type in most of the United States, the Colorado type on the Burlington Route, and the Selkirk type in Canada.
The UIC classification of locomotive axle arrangements, sometimes known as the German classification or German system, describes the wheel arrangement of locomotives, multiple units and trams. It is used in much of the world, notable exceptions being the United Kingdom and North America.
Rail transport terms are a form of technical terminology applied to railways. Although many terms are uniform across different nations and companies, they are by no means universal, with differences often originating from parallel development of rail transport systems in different parts of the world, and in the national origins of the engineers and managers who built the inaugural rail infrastructure. An example is the term railroad, used in North America, and railway, generally used in English-speaking countries outside North America and by the International Union of Railways. In English-speaking countries outside the United Kingdom, a mixture of US and UK terms may exist.
In the Whyte notation for classifying the wheel arrangement of steam locomotives, an 0-8-8-0 is a locomotive with two sets of eight driving wheels and neither leading wheels nor trailing wheels. Two sets of driving wheels would give far too long a wheelbase to be mounted in a fixed locomotive frame, so all 0-8-8-0s have been articulated locomotives of the Mallet type, whether simple or compound. In the UIC classification, this arrangement would be, refined to Mallet locomotives, (D)D. The type was sometimes called Angus in North America.
Under the Whyte notation for the classification of steam locomotives, 0-10-2 represents the wheel arrangement of no leading wheels, ten powered and coupled driving wheels on five axles, and two trailing wheels on one axle.
A 2-8-8-2, in the Whyte notation for describing steam locomotive wheel arrangements, is an articulated locomotive with a two-wheel leading truck, two sets of eight driving wheels, and a two-wheel trailing truck. The equivalent UIC classification is, refined to Mallet locomotives, (1'D)D1'. These locomotives usually employ the Mallet principles of articulation—with the rear engine rigidly attached to the boiler and the front engine free to rotate—and compounding. The 2-8-8-2 was a design largely limited to American locomotive builders. The last 2-8-8-2 was retired in 1962 from the N&W's roster, two years past the ending of steam though steam was still used on steel mill lines and other railroads until 1983.
In the Whyte notation for the classification of steam locomotive wheel arrangement, an 0-4-4-0 is a locomotive with no leading wheels, two sets of four driving wheels, and no trailing wheels. The arrangement is chosen to give the articulation of a locomotive with only the short rigid wheelbase of an 0-4-0, but with its weight spread across eight wheels, and with all the weight carried on the driving wheels; effectively a flexible 0-8-0. Articulated examples were constructed as Mallet, Meyer, BMAG and Double Fairlie locomotives and also as geared locomotives such as Shay, Heisler, and Climax types. A similar configuration was used on some Garratt locomotives, but it is referred to as 0-4-0+0-4-0. In the electric and diesel eras, the Bo-Bo is comparable and closest to the Meyer arrangement of two swivelling bogies.
Under the Whyte notation for the classification of steam locomotives, 0-8-0 represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles and no trailing wheels. Locomotives of this type are also referred to as eight coupled.
On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle (wheelset) located behind the driving wheels. The axle of the trailing wheels is usually located in a trailing truck. On some large locomotives, a booster engine was mounted on the trailing truck to provide extra tractive effort when starting a heavy train and at low speeds on gradients.
In the Whyte notation for classifying steam locomotives by wheel arrangement, a 4-6-6-4 is a railroad steam locomotive that has four leading wheels followed by two sets of six coupled driving wheels and four trailing wheels. 4-6-6-4's are commonly known as Challengers.
The Union Pacific Railroad 9000 Class was a class of 88 steam locomotives, built by ALCO for the Union Pacific between 1926 and 1930.
Under the Whyte notation for the classification of steam locomotives, 4-10-0 represents the wheel arrangement of four leading wheels, ten powered and coupled driving wheels, and no trailing wheels. Central Pacific Railroad's El Gobernador, built in 1883, was the only locomotive with this wheel arrangement to operate in the United States. The name "Mastodon" has also been applied to this type, though this nickname has also been mistakenly used for the 4-8-0 arrangement, leading to some confusion. Sources refer to the 4-8-0 as the Twelve-wheeler. Later, these locomotives were named "Super Mastodon's."
A 2-6-8-0 steam locomotive, in the Whyte notation for describing locomotive wheel arrangements, has two leading wheels, a set of six driving wheels, a set of eight driving wheels, and no trailing wheels. These locomotives usually employ the Mallet principle of articulation, with a swinging front engine and a rigidly attached rear engine.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, the 2-8-0+0-8-2 is a Garratt locomotive. The wheel arrangement is effectively two 2-8-0 locomotives operating back to back, with the boiler and cab suspended between the two power units. Each power unit has a single pair of leading wheels in a leading truck, followed by four coupled pairs of driving wheels and no trailing wheels.
Under the Whyte notation for the classification of steam locomotives, 2-6-0+0-6-2 represents the wheel arrangement of an articulated locomotive with two separate swivelling engine units, arranged back to back with the boiler and cab suspended between them. Each engine unit has two leading wheels in a leading truck, six powered and coupled driving wheels on three axles and no trailing wheels.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, the 0-4-0+0-4-0 is an articulated locomotive of the Garratt type. The wheel arrangement is effectively two 0-4-0 locomotives operating back-to-back or face-to-face, with the boiler and cab suspended between the two power units. Each power unit has no leading wheels, four powered and coupled driving wheels on two axles and no trailing wheels. A similar arrangement exists for Mallet, Meyer and Fairlie locomotives, but is referred to as 0-4-4-0.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 2-4-0+0-4-2 is an articulated locomotive, usually of the Garratt type. The wheel arrangement is effectively two 2-4-0 locomotives operating back to back, with the boiler and cab suspended between the two power units. Each power unit has two leading wheels on one axle, four powered and coupled driving wheels on two axles and no trailing wheels. A similar wheel arrangement exists for Mallet locomotives, but is referred to as 2-4-4-2 since only the front engine unit can pivot.
Under the Whyte notation for the classification of steam locomotives by wheel arrangement, the 4-8-0+0-8-4 is a Garratt articulated locomotive. The wheel arrangement is effectively two 4-8-0 locomotives operating back to back, with the boiler and cab suspended between the two engine units. Each engine unit has two pairs of leading wheels in a leading bogie, followed by four coupled pairs of driving wheels and no trailing wheels. A similar wheel arrangement exists for the Union Pacific Big Boy, but is referred to as 4-8-8-4 since only the front engine unit swivels.
An 0-8-6-0, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is an articulated locomotive with no leading wheels, eight driving wheels fixed in a rigid frame, six driving wheels and no trailing wheels. In the UIC system, this would be described as a DC't arrangement.
The leading wheel or leading axle or pilot wheel of a steam locomotive is an unpowered wheel or axle located in front of the driving wheels. The axle or axles of the leading wheels are normally located on a leading truck. Leading wheels are used to help the locomotive negotiate curves and to support the front portion of the boiler.
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ignored (help)CS1 maint: location missing publisher (link)In the various names above of a 4-8-4, omitted was the letters "F E F" which simply means: four eight four.