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The Whyte notation is a form of classification for steam locomotives,

Whyte Notation

A graphic of the Whyte notation, with the wheel-arrangement shown being a 4-8-4. (Four leading wheels, eight drive wheels, and four trailing wheels.

(which is also the main form of classifying steam locomotive wheel arrangements) is a wheel arrangement classification developed by Frederick Whyte in the mid-1800s. The notation classifies different forms of steam locomotives, as well as distinguishing them from one another. There are also different nicknames for the different types and forms of wheel arrangements as well.

How to read Whyte notation:[]

Whyte notation works by counting the wheels, and not the axles unlike the AAR and UIC classifications. Because of this, all the numbers in the Whyte notation are even and are never odd. There are 3-6 numbers in Whyte notation, separated by hyphens (-). The first number was always the leading wheels and the last number was always the trailing numbers. The 1-3 numbers in the center were the driving wheels, which moved the locomotive. A plus sign (+) between two groups of three numbers usually denotes that it is an articulated Garratt locomotive. A notation that contains 4 or 5 numbers is a Mallet articulated locomotive.

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Pacific 4-6-2

Problems[]

A few wheel arrangements can't be covered by the Whyte notation. This includes a Turkish arrangement that started out as a 2-6-0. But when a pair of carrying wheels were added to the design, between the central and rear driving axles to fix an axle load issue, it cannot be explained using the Whyte notation. Some steam locomotives, although rare, don't rest their driving wheels on the rails. This is also impossible to explain using the Whyte notation. The driving wheels rest atop other wheels. This was be done to try to multiply the power (or speed) of the locomotive, or to act like gearing. Such designs were not set into production by railroad (railway) companies. Either through cost, height or other factors such as axle weight, they weren't able to be used on most railroads (railways).

Wheel arrangements[]

Experimental 4-4-4 steam locomotive

An experimental 4-4-4 steam locomotive.

There are many different forms of wheel arrangements for steam locomotives, this is an incomplete list.

Such examples are:

Non-articulated types:[]

  • 0-2-2
  • 2-2-0 "Planet"
  • 2-2-2 "Jenny Lind"
  • 2-4-0 "Porter"
  • 2-4-2 "Columbian"
  • 4-2-0 "Jervis"
  • 4-2-2
  • 4-2-4 "Huntington"
  • 6-2-0 "Crampton"
  • 0-4-0 "Four-coupled"
  • 0-4-2 "Olomana"
  • 0-4-4 "Forney"
  • 4-4-0 "American"
  • 4-4-2 "Atlantic"
  • 4-4-4 "Jubilee"
  • 2-6-0 "Mogul"
  • 2-6-2 "Prairie"
  • 2-6-4 "Adriatic"
  • 4-6-0 "Ten-wheeler"
  • 4-6-2 "Pacific"
  • 4-6-4 "Hudson" (Baltic on CMStP&P and in UK)
  • 0-8-0 "Eight-coupled"
  • 2-8-0 "Consolidation"
  • 2-8-2 "Mikado" ("MacArthur" during WWII)
  • 2-8-4 "Berkshire" (the Chesapeake & Ohio called them Kanawhas)
  • 4-8-0 "Mastodon"
  • 4-8-2 "Mountain" (Mohawk on NYC)
  • 4-8-4 "Northern" and various other names for various railroads
  • 6-8-6 "Turbine"
  • 0-10-0 "Ten-coupled" (or also known as the "Decapod" elsewhere)
  • 0-10-2 "Union"
  • 2-10-0 "Decapod" (In the USA)
  • 4-10-0 "El Gobernador"
  • 4-10-2 "Overland"
  • 2-10-2 "Santa Fe"
  • 2-10-4 "Texas"
  • 0-12-0
  • 2-12-0
  • 4-12-2 "Union Pacific" (unique to the actual railroad)
  • 4-14-4 "AA20" (only one of its kind)

Duplex drive[]

Tenderless (tank engine) types:[]

Suffixes: "T": "side-tank", "ST": "saddle-tank" (considered to be a modification), "PT": "pannier-tank", "WT": "well-tank".

  • 2-2-0T
  • 2-2-2T
  • 2-2-4T
  • 0-4-0T
  • 0-4-2T
  • 0-4-4T
  • 2-4-0T
  • 2-4-2T
  • 0-6-0T
  • 0-6-2T
  • 2-6-0T
  • 2-6-2T
  • 2-6-4T
  • 2-6-6T
  • 4-6-2T
  • 4-6-4T
  • 4-6-6T
  • 0-8-0T
  • 0-8-2T
  • 0-8-4T
  • 2-8-0T
  • 2-8-2T
  • 2-10-2T
  • 2-10-4T
  • 0-12-0T
  • 2-12-2T
  • 2-12-4T

Articulated Locomotives[]

Mallet Locomotives[]

Meyer:[]

  • 0-4-0+0-4-0
  • 0-6-2+0-6-2
  • 0-6-0+0-6-0

Garratt:[]

  • 0-4-0+0-4-0
  • 0-6-0+0-6-0
  • 2-6-0+0-6-2
  • 2-6-2+2-6-2
  • 4-6-2+2-6-4
  • 2-8-0+0-8-2
  • 2-8-2+2-8-2
  • 2-8-4+4-8-2
  • 4-8-2+2-8-4
  • 4-8-0+4-8-4 (C&O M-1 steam turbine)
  • 4-8-4+4-8-4
  • 2-6-6-2+2-6-6-2 (only a concept)
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