Under the Whyte notation

Whyte notation

The Whyte notation for classifying steam locomotives by wheel arrangement was devised by Frederick Methvan Whyte and came into use in the early twentieth century encouraged by an editorial in American Engineer and Railroad Journal...

 for the classification of steam locomotive

Steam locomotive

A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

s, 0-12-0 represents the wheel arrangement

Wheel arrangement

In rail transport, a wheel arrangement is a system of classifying the way in which wheels are distributed beneath a locomotive.. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and connections, with the adopted notations varying by country...

 of no leading wheel

Leading wheel

The leading wheel or leading axle 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 in a truck...

s, twelve powered and coupled driving wheel

Driving wheel

On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons...

s on six axles, and no trailing wheel

Trailing wheel

On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle located behind the driving wheels. The axle of the trailing wheels was usually located on a trailing truck...

s.

Equivalent classifications

Other equivalent classifications are:

• UIC classification
  UIC classification
  The UIC classification of locomotive axle arrangements describes the wheel arrangement of locomotives, multiple units and trams. It is set out in the International Union of Railways "Leaflet 650 - Standard designation of axle arrangement on locomotives and multiple-unit sets". It is used in much...
  
  : F (also known as German classification and Italian classification)
• French classification: 060
• Turkish classification
  Turkish classification
  In the Turkish classification system for railway locomotives, the number of powered axles are followed by the total number of axles. It is identical to the Swiss system except that the latter places a slash between the two numbers.Thus0-6-0 becomes 33...
  
  : 66
• Swiss classification: 6/6

First example

The only known 0-12-0 was the Pennsylvania, designed by Jame Milholland for the Philadelphia and Reading Railroad and built at its own shops in 1863. It weighed fifty tons and was, at the time, the heaviest steam locomotive in the world. It was intended to haul Pennsylvania coal trains.