2-8-2

2-8-2 (Mikado)

USRA Light Mikado of the Baltimore & Ohio Railroad

Equivalent classifications UIC class 1D1 French class 141 Turkish class 46 Swiss class 4/6 Russian class 1-4-1

First known tank engine version First use 1914 Country Germany Locomotive Prussian T 14 Railway Prussian state railways & Imperial Railways in Alsace-Lorraine

First known tender engine version First use 1884 Country United States of America Locomotive Calumet Railway Chicago & Calumet Terminal Railway Evolved from 2-8-0 Evolved to 2-8-4 Benefits Larger firebox aft of drivers

Under the Whyte notation for the classification of steam locomotives, 2-8-2 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 two trailing wheels on one axle, usually in a trailing truck. This configuration of steam locomotive is most often referred to as a Mikado, frequently shortened to Mike.

At times it was also referred to on some railroads in the United States of America as the McAdoo Mikado and, during the Second World War, the MacArthur.

The notation 2-8-2T indicates a tank locomotive of this wheel arrangement, the “T” suffix indicating a locomotive on which the water is carried in side-tanks mounted on the engine rather than in an attached tender.

The 2-8-2 wheel arrangement allowed the locomotive's firebox to be placed behind instead of above the driving wheels, thereby allowing a larger firebox that could be both wide and deep. This supported a greater rate of combustion and thus a greater capacity for steam generation, allowing for more power at higher speeds. Allied with the larger driving wheel diameter which was possible when they did not impinge on the firebox, it meant that the 2-8-2 was capable of higher speeds than a 2-8-0 with a heavy train. These locomotives did not suffer from the imbalance of reciprocating parts as much as did the 2-6-2 or the 2-10-2, because the center of gravity was between the second and third drivers instead of above the centre driver.

The first 2-8-2 locomotive was built in 1884. It was originally named Calumet by Angus Sinclair, in reference to the 2-8-2 engines built for the Chicago & Calumet Terminal Railway (C&CT). However, this name did not take hold.