2-4-2

2-4-2 (Columbia)
Diagram of a single small leading wheel, two large coupled wheels and a single small trailing wheel
A Baldwin 2-4-2T locomotive, used on a private railway in Raahe, Finland. It was later bought by Finnish State Railways.
Equivalent classifications
UIC class1B1, 1'B1'
French class121
Turkish class24
Swiss class2/4
Russian class1-2-1
First known tank engine version
First use1863
CountryUnited Kingdom
LocomotiveNo. 21 White Raven
RailwaySt Helens Railway
DesignerJames Cross
BuilderSutton Works
First known tender engine version
First use1877
CountryNew Zealand
LocomotiveK class
RailwayNew Zealand Railways
BuilderRogers Locomotive Works

Under the Whyte notation for the classification of steam locomotives, 2-4-2 represents the wheel arrangement of two leading wheels on one axle, four powered and coupled driving wheels on two axles and two trailing wheels on one axle. The type is sometimes named Columbia after a Baldwin 2-4-2 locomotive was showcased at the 1893 World's Columbian Exposition held at Chicago, Illinois.