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, 2-(2-2)-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 two 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 on one axle, four powered but uncoupled 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 two 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.

Usage

This unusual wheel arrangement was used by Francis Webb

Francis Webb (engineer)

Francis William Webb was a British engineer responsible for the design and manufacture of locomotives for the London and North Western Railway .- Biography :...

 of the London and North Western Railway

London and North Western Railway

The London and North Western Railway was a British railway company between 1846 and 1922. It was created by the merger of three companies – the Grand Junction Railway, the London and Birmingham Railway and the Manchester and Birmingham Railway...

 between 1882 and 1890 on a number of compound locomotive

Compound locomotive

A compound engine unit is a type of steam engine where steam is expanded in two or more stages.A typical arrangement for a compound engine is that the steam is first expanded in a high-pressure cylinder, then having given up heat and losing pressure, it exhausts directly into one or more larger...

 classes including the LNWR Webb Experiment Class

LNWR Webb Experiment Class

The Experiment Class was a series of 30 three-cylinder 2--0 compound locomotives designed by Francis Webb for the London and North Western Railway between 1882 and 1884. They were Webb’s first large-scale experiment with a class of express compound locomotives, and the first engine was named...

, LNWR Dreadnought Class and LNWR Teutonic Class.
The locomotives were never reliable and Webb's successor George Whale

George Whale

George Whale was a British locomotive engineer who worked for the London and North Western Railway .Whale was born in Bocking, Essex. In 1858 he entered Wolverton Works under James Edward McConnell, and from 1862 under John Ramsbottom. In 1865 he entered the drawing office at Crewe Works, and in...

 withdrew them all within three years of taking up office in 1903.

The type was used with more success on French railways with a 4-cylinder compound locomotive

Compound locomotive

A compound engine unit is a type of steam engine where steam is expanded in two or more stages.A typical arrangement for a compound engine is that the steam is first expanded in a high-pressure cylinder, then having given up heat and losing pressure, it exhausts directly into one or more larger...

 designed by Alfred de Glehn

Alfred de Glehn

Alfred George de Glehn was a notable English-born French designer of steam locomotives, and an engineer at the Société Alsacienne de Constructions Mécaniques . His steam engines of the 1890s combined elegance, high speed and efficiency...

, of the Société Alsacienne de Constructions Mécaniques

Société Alsacienne de Constructions Mécaniques

The Société Alsacienne de Constructions Mécaniques [Society of Alsatian mechanical engineering] was an engineering company with its headquarters in Mulhouse, Alsace which produced railway locomotives, textile and printing machinery, diesel engines, boilers, lifting equipment, firearms and mining...

 (SACM) in 1886. Later examples were of the 4-2-2-0

4-2-2-0

Under the Whyte notation for the classification of steam locomotives, 4-2-2-0 represents the wheel arrangement of four leading wheels on two axles, four powered but uncoupled driving wheels on two axles, and no trailing wheels...

configuration.