2-10-2

A 2-10-2 steam locomotive in the Whyte notation for wheel arrangements has two leading wheels (one axle), ten driving wheels (five driven axles), and two trailing wheels (one axle). In the United States, the 2-10-2 is known as the Santa Fe type, after the railroad "AT&SF" that first used the type in 1903.

Other equivalent classifications are:

UIC classification: 1E1 (also known as German classification and Italian classification)

French classification: 151

Turkish classification: 57

Swiss classification: 5/7

Swengel demonstrated how the 2-10-2 evolved from the ATSF 2-10-0 (decapod)cite book |author=Swengel, Frank, M. |title=The American Steam Locomotive, Vol. 1. The Evolution of the Steam Locomotive |publisher=MidWest Rail Publications |year=1967pp.138 & 192-193] Swengel wrote the ATSFs existing 2-10-0 locomotives used as pushers up Raton Pass encountered problems reversing back down the grade for their next assignments. The 2-10-0s, being unable to track around curves, ran 'very slow' so as not to derail. Consequently, the ATSF added a trailing wheel to the engines allowing them to operate successfully in both directions. These first 2-10-2 became the forerunners to the entire 2-10-2 fleets.(p. 92.) Like all ten-coupled designs, the long rigid wheelbase of the driving wheels presents a problem on curves, requiring blind drivers, lateral motion devices and much play on the outer axles. To limit this problem, plus the weight of the rods, the driving wheels were generally small (up to 64 in (1.63 m)), which inturn generated another problem, insufficient counterweights.

Swengel claimed there were two forms of 2-10-2 the 'heavy' locomotive and 'light'. The 2-10-2's inherent problem was the low speed restriction on the type, which was 'about 35 miles per hour' and that the peak of the design limitation was achieved in 1926, with the advent of the superior 2-10-4 design. pp.172-173] Further, Swengel said that the 2-10-2 had other inherent restrictions including: the massive cylinders on the USA locomotives required for the high tractive effort ensured no reasonable sized valves could admit and exhaust steam at a rate to permit fast running and that the 2-10-2, like the 2-6-2, had its main rod connected to the third axle 'very near to the centre of gravity', which created a 'violent nosing action' when operating. pp.148-149]

2-10-2s were used in a number of countries around the world, including those in North America, Western Europe, China and others.

North America

In North America the 2-10-2 was a type produced between approximately 1914-1920, after which its limitations became apparent and larger locomotives were built. Approximately 2,200 of the type were produced, including about 500 of the USRA WWI standard design.

The Baltimore And Ohio placed its first order for a 2-10-2 in 1914 with Baldwin (No.6000). From 1914-1956 the engines bore their numbers commencing with 6; hence their nickname 'big sixes'. Known as S class there were several variant sub-classes. The engines were heavy and powerful. They held off the diesels until 1951, when they were gradually withdrawn and finally all scrapped by 1959. (Staufer, p.152-167)

China

2-10-2s were the mainstay of Chinese steam, this being the arrangement of the Chinese QJ class locomotives (based in turn on the Soviet LV class) which were built until 1988 and were still in widespread service until the final steam runs in 2003. Some of these QJs are finding their way to the United States for excursion service.

In 2006, Multipower International, Inc. restored two Chinese QJ (2-10-2) steam locomotives to FRA Part 230 specifications and delivered them to Railroad Development Corp.

Europe

Continental Europe saw a fair number of 2-10-2s, although the type was always less popular than 2-8-2s and 2-10-0s. The German railways built 28 3-cylinder 2-10-2 tender freight locomotives of class BR45 from 1936, which were the largest steam locomotives on the system. A large number of European 2-10-2s were tank locomotives, taking advantage of the symmetrical nature of the arrangement. Examples on the German railway systems included classes BR84 and BR85, both standard designs built in 1935 and 1937 respectively, and class BR95, built in 1922 by the Prussian State Railways.

In Spain, the 2-10-2 wheel arrangement had one series of 22 units. Initially ordered for the Norte Co., the RENFE kept the entire series on hand. Built in 1941-44 in La Maquinista Terrestre y Marítima factory in Barcelona for hauling heavy coal trains they were among the most powerful steam locomotives in Europe. They had three cylinders but simple expansion and were known as "Santa Fe"s

Soviet Union

In Soviet Union 2-10-2 type locomotives were used to haul heavy freight trains. Two series were relatively common: FD (for Felix Dzerzhinsky) and LV (Lebedyanskii, modified by Voroshilovrgad factory). The FD class was developed from ALCO and Baldwin heavy freight locomotives imported to Soviet Russia where they were designated as Ta and Tb-class,respectively. The LV class was developed from the previous L-class 2-10-0 locomotive by Voroshilovgrad factory. It used a feedwater heater to increase thermal efficiency- it was the most efficient freight steam locomotive in Soviet Union with thermal efficiency of 9.3%. The first prototype was named OR18-01(October Revolution factory , 18 tonn axle load). 522 LV-class locomotives were built. Several, including the first OR18-01 and the last LV-0522 were preserved.

References

*Staufer, Alvin F. (ed.), "B & O Power: Steam , Diesel and Electric Power of the Baltimore and Ohio Railroad 1829-1965", Staufer, Medina, n.d.