2-8-0

2-8-0 (Consolidation)

Front of locomotive at left

Lehigh and Mahanoy Railroad's Consolidation of 1866

Equivalent classifications UIC class 1D French class 140 Turkish class 45 Swiss class 4/5 Russian class 1-4-0

First known tank engine version First use 1907 Country German South-West Africa Locomotive South West African 2-8-0T Railway Lüderitzbucht Eisenbahn Designer Orenstein & Koppel Builder Orenstein & Koppel

First known tender engine version First use c. 1864 Country United States of America Railway Pennsylvania Railroad Designer John P. Laird Builder John P. Laird Evolved from 0-8-0

First known "True type" version First use 1866 Country United States of America Locomotive Consolidation Railway Lehigh and Mahanoy Railroad Designer Alexander Mitchell Builder Baldwin Locomotive Works Evolved from 0-8-0

Under the Whyte notation for the classification of steam locomotives, 2-8-0 represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, eight powered and coupled driving wheels on four axles and no trailing wheels. In the United States and elsewhere, this wheel arrangement is commonly known as a Consolidation.

Of all the locomotive types that were created and experimented with in the 19th century, the 2-8-0 was a relative latecomer.

The first locomotive of this wheel arrangement was possibly built by the Pennsylvania Railroad (PRR). Like the first 2-6-0s, this first 2-8-0 had a leading axle that was rigidly attached to the locomotive's frame, rather than on a separate truck or bogie. To create this 2-8-0, PRR master mechanic John P. Laird modified an existing 0-8-0, the Bedford, between 1864 and 1865.

The 2-6-0 Mogul type, first created in the early 1860s, is often considered as the logical forerunner to the 2-8-0. However, a claim is made that the first true 2-8-0 engine evolved from the 0-8-0 and was ordered by the United States' Lehigh and Mahanoy Railroad, which named all its engines. The name given to the new locomotive was Consolidation, the name that was later almost globally adopted for the type. According to this viewpoint, the first 2-8-0 order by Lehigh dates to 1866 and antedates the adoption of the type by other railways and coal and mountain freight haulers.

From its introduction in 1866 and well into the early 20th century, the 2-8-0 design was considered to be the ultimate heavy-freight locomotive. The 2-8-0's forte was starting and moving "impressive loads at unimpressive speeds" and its versatility gave the type its longevity. The practical limit of the design was reached in 1915, when it was realised that no further development was possible with a locomotive of this wheel arrangement.

As in the United States, the 2-8-0 was also a popular type in Europe, again largely as a freight hauler. The type was also used in Australia, New Zealand, and Southern Africa.