4-10-2

4-10-2 (Reid Ten wheeler/Overland/Southern Pacific)

Front of locomotive at left

NGR Class C Reid Tenwheeler 4-10-2T no. 171

Equivalent classifications UIC class 2'E1' French class 251 Turkish class 58 Swiss class 5/8 Russian class 2-5-1

First known tank engine version First use 1899 Country Colony of Natal Locomotive NGR Class C Railway Natal Government Railways Designer George William Reid Builder Dübs and Company Evolved from 4-8-2T

First known tender engine version First use 1925 Country United States of America Locomotive SP-2 class Railway Southern Pacific Railroad Designer American Locomotive Company Builder American Locomotive Company Evolved from 2-10-2 Benefits Could handle roughly 20% more tonnage than the 2-10-2 while using around 16% less fuel than the 2-10-2. Drawbacks Complex to maintain because of the third cylinder

Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 4-10-2 represents the arrangement of four leading wheels, ten powered and coupled driving wheels and two trailing wheels. In South Africa, where the wheel arrangement was first used, the type was known as a Reid Tenwheeler. In the United States of America it was known as a Southern Pacific on the Southern Pacific Railroad and as an Overland on the Union Pacific Railroad.