4-6-2

4-6-2 (Pacific)
Diagram of two small leading wheels, three large driving wheels joined with a coupling rod, and a single small trailing wheel
Front of locomotive at left
New Zealand's Q class, the first true Pacific locomotive
Equivalent classifications
UIC class2C1 (refined to 2′C′1′ or 2′C1′)
French class231
Turkish class36
Swiss class3/6
Russian class2-3-1
First known tank engine version
First use1896
CountryAustralia
LocomotiveQ class
RailwayWestern Australian Government Railways
First known tender engine version
First use1887
CountryUnited States of America
RailwayLehigh Valley Railroad
Evolved from4-6-0
Evolved to4-6-4
BenefitsLarger firebox than the 4-6-0
DrawbacksRequired piloting (also known as double heading) when train lengths increased
First known "True type" version
First use1901
CountryNew Zealand
LocomotiveQ class
RailwayNew Zealand Railways Department
DesignerAlfred Beattie
BuilderBaldwin Locomotive Works
Evolved from4-4-2, 4-6-0 & 2-6-2
Evolved to4-6-4, 4-8-2
BenefitsWide and deep firebox behind coupled wheels

Under the Whyte notation for the classification of steam locomotives, 4-6-2 represents the wheel arrangement of four leading wheels on two axles, six powered and coupled driving wheels on three axles and two trailing wheels on one axle. The 4-6-2 locomotive became almost globally known as a Pacific type after a locomotive built by the Baldwin Locomotive Works in Philadelphia was shipped across the Pacific Ocean to New Zealand.[1][2]

  1. ^ PRC Rail Consulting Ltd. "Steam Glossary". The Railway Technical Website | PRC Rail Consulting Ltd.
  2. ^ Holland, D.F. (1971). Steam Locomotives of the South African Railways. Vol. 1: 1859–1910 (1st ed.). Newton Abbott, England: David & Charles. pp. 69–77, 88–89, 101–103, 128–130, 137–139. ISBN 978-0-7153-5382-0.