Steam locomotives are described by the arrangement of their leading, driving and trailing wheels. In fact, only the driving wheels are connected to the cylinders that provide the engine’s power. So a 2-8-2 has two leading wheels, eight driving wheels and two trailing wheels.
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.
The wheel arrangement name “Mikado” originated from a group of Japanese type 9700 2-8-2 locomotives that were built by Baldwin Works for the 3 ft 6 in (1,067 mm) gauge Nippon Railway of Japan in 1897. In the 19th century, the Emperor of Japan was often referred to as “the Mikado” in English. Also, the Gilbert and Sullivan opera The Mikado had premiered in 1885 and achieved great popularity in both Britain and America.
Picture Credit : Google