4-8-0

Norfolk and Western Railway class M2 4-8-0.

Under the Whyte notation for the classification of steam locomotives, a 4-8-0 locomotive has four leading wheels arranged in a leading truck, eight coupled driving wheels and no trailing wheels. The type was nicknamed the Mastodon or Twelve-wheeler in North America. Mastodon (No. 229) was the unofficial name of the very first 4-8-0, which was built by the Central Pacific Railroad in 1882 at the Sacramento Locomotive Works.

In the United States the 4-8-0 was essentially a freight locomotive - a marginal devleopment of the 2-8-0. Most US 4-8-0s were built in the late 19th century or early 20th century, but the type never achieved great popularity. The wide-firebox 2-8-2 Mikado had much more potential. In continental Europe, notably France and Austria, the type was used for heavy passenger work. In Britain the type was use in small numbers for shunting tanks.

The equivalent UIC classification is 2'D.

In the United Kingdom, there were two classes of 4-8-0 tank locomotives, both built for hump shunting. Fifteen were built by the North Eastern Railway, designated NER Class X, later LNER Class T1. These had three cylinders, following Robinson's 0-8-4 design for the Great Central. The London and South Western Railway also built a class of four two-cylinder machines to Urie's design for Feltham marshalling yards. The Great Southern and Western Railway in Ireland similarly had a small class of inside-cylinder shunting machines .

Both the London Midland and Scottish Railway and the Southern Railway however contemplated 4-8-0 tender freight engines, but these never materialised.

In Austria, the wheel arrangement was used for some express locomotives: class 570 of 1915 and class 113 of 1923, both numbered as class 33 from 1938 on.

Australia

The 4-8-0 saw service in Australia from 1900.

In Tasmania the private railway company of Emu Bay ordered 4 of these 4-8-0 tendered locomotives for their narrow (1,066mm) gauge system. In 1910 another locomotive was delivered from the now reformed North British Coy. Two examples of these engines are preserved.

Initially designed in South Australia for use on its narrow gauge 3ft 6 ins (1,066mm) system, a new class of 4-8-0 engine proved suitable workhorses and by 1917 there were seventy eight locomotives in the class. During 1922-23 five of the class were converted to state's broad gauge system (1,600mm) and then reconverted during 1949 back to narrow gauge. In 1921-22 the Tasmanian Government purchased six of the SAR narrow gauged engines. During the Second World War the Commonwealth Railways also obtained four SAR narrow gauge locomotives for a period. Several ex-SAR engines are preserved.

In Queensland the QR which also operates a narrow gauge system a 4-8-0 class was introduced in 1903 as C16 class locomotives. A total of 152 engines were in service by 1917. During the Second World War (1939-45) the Commonwealth Government acquired eleven C16s on loan. Only one example of this class was preserved. From 1920, as the Queensland 4-8-0s acquired super heaters they were classed as C17 - and all up 227 engines were in this class. The Commonwealth Railways also ordered 22 engines of the same class for their narrow gauge rail system. Twenty examples of the class are preserved.

In 1922 the QR ordered 22 new 4-8-0s as class 19 engines. (all Australian details: Oberg)

France

In France this wheel arrangement appeared as the famous 240P, 2-4-0 referring to the number and arrangement of axles rather than wheels. These machines were technically rebuilds of some of the earliest Pacifics in Europe, built for the Paris-Orleans railway. The 240P was considered to be one of André Chapelon's finest works and benefitted from his thorough understanding of thermodynamics and his appreciation of the need to consider the entirety of the steam circuit. The locomotive was a 4 cylinder compound fitted with Lentz-Dabeg poppet valves. With a power output of 4700hp the 240P was reported to have the highest power to weight ratio of any steam locomotive. Discussion continues as to how robust they were mechanically - whether the size of the bearings was too near the bone, or whether they were simply worked to death during the difficult war years. Coupled with the elegant French style tender the second batch at least was also a very aesthetic locomotive. Unfortunately none have survived into preservation.

Soviet Union

In Soviet Union 4-8-0 were the first passenger locomotives built by the new state. They were represented by one hundred M-class locomotives built by Putilov Works in Leningrad (Saint Peterburg) in 1927. Initially built as a 3-cylinder machines they were later rebuilt as a 2-cylinder ones and redesignated as Mr. The M series were not considered a great success.

References

• Marsden, Richard. The Worsdell Class T1 4-8-0 Tank Locomotives. Retrieved on April 27, 2005.
• Oberg, Leon. Locomotives of Australia, Reed, Sydney, 1975.