2-10-4

2-10-4 (Texas)

Front of locomotive at left

ATSF 5000 Class Texas type

Equivalent classifications UIC class 1E2 French class 152 Turkish class 58 Swiss class 5/8 Russian class 1-5-2

First known tender engine version First use 1919 Country United States of America Locomotive No. 3829 Railway Atchison, Topeka and Santa Fe Railway Designer Baldwin Locomotive Works Builder Baldwin Locomotive Works Evolved from 2-10-2 Evolved to 2-8-4

Under the Whyte notation for the classification of steam locomotives, a 2-10-4 locomotive has two leading wheels on one axle, usually in a bissel truck, ten coupled driving wheels on five axles, and four trailing wheels on two axles, usually in a bogie. These were referred to as the Texas type in most of the United States, the Colorado type on the Burlington Route and the Selkirk type in Canada.

The 2-10-4 Texas wheel arrangement originated and was principally used in the United States of America. The evolution of this locomotive type began as a 2-10-2 Santa Fe type with a larger four-wheeled trailing truck that would allow an enlarged firebox. A subsequent development was as an elongated 2-8-4 Berkshire type that required extra driving wheels to remain within axle load limits. Examples of both of these evolutionary progressions can be found.

Some 2-10-4 tank locomotives also existed in eastern Europe. One extraordinary experimental 2-10-4 tender locomotive, built in the Soviet Union, had an opposed piston drive system.

The Texas type was rare in Africa. One locomotive, numbered 801, was built for the CF du Bas-Congo au Katanga by Société Anonyme John Cockerill in 1939. It had 540 by 550 millimetres (21 by 22 inches) cylinders and 1,100 millimetres (43 inches) diameter driving wheels, with a working order mass of 107.8 tonnes (106.1 long tons; 118.8 short tons), a grate area of 5.4 square metres (58 square feet) and a tractive effort at 65% boiler pressure of 14,690 kilograms-force (144,100 newtons; 32,400 pounds-force). The locomotive is believed to have been built for the line between Bukama and Kamina and accumulated 1,200,000 kilometres (750,000 miles) during its service lifetime. Even with its large size, it was hand-fired and had two firebox doors, with two firemen being carried.