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In the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of four leading wheels on two axles, usually in a leading bogie, six powered and coupled driving wheels on three axles, and two trailing wheels on one axle, usually in a trailing truck. The first South African were named the Karoo class, but a locomotive subsequently became almost globally known as a Pacific type.〔(Railway Technical Web Pages (Steam Locomotive Glossary) )〕〔 Other equivalent classifications are: * UIC classification: 2C1 (also known as German and Italian classifications, refined as 2′C′1′ or 2′C1′ depending on the mounting of the final axle) * French classification: 231 (also known as Spanish classification) * Turkish classification: 36 * Swiss classification: 3/6 * Russian classification: 2-3-1 ==Overview== The introduction of the design in 1901 has been described as "a veritable milestone in locomotive progress".〔(Progress: ''Locomotive Development in New Zealand - The "Pacific" Type. Its Genesis and Triumph.'' The New Zealand Railways Magazine, Volume 9, Issue 7 (October 1, 1934). )〕 On many railways worldwide, Pacific steam locomotives provided the motive power for express passenger trains throughout much of the early to mid-20th century, before either being superseded by larger types in the late 1940s and 1950s, or replaced by electric or diesel-electric locomotives during the 1950s and 1960s. Nevertheless, new Pacific designs continued to be built until the mid-1950s. The type is generally considered to be an enlargement of the type, although its prototype had a direct relationship to the and Prairie, effectively being a combination of the two types.〔(Steamlocomotive.com - 4-6-2 "Pacific" Type Locomotives )〕 The success of the type can be attributed to a combination of its four-wheel leading truck which provided better stability at speed than a , the six driving wheels which allowed for a larger boiler and the application of more tractive effort than the earlier Atlantic, and the two-wheel trailing truck, used wisely on the New Zealand of 1885, which permitted the firebox to be sited behind the high driving wheels, thereby allowing it to be both wide and deep, unlike the Ten-wheeler which had either a narrow and deep firebox between the driving wheels or a wide and shallow one above. The type is well-suited to high speed running. The world speed record for steam traction of has been held by a British Pacific locomotive, the "Mallard", since 3 July 1938. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「4-6-2」の詳細全文を読む スポンサード リンク
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