O class or Class O may refer to:
Rail transport
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Highland Railway O Class, a British class of 2-4-0, later 4-4-0T, steam locomotives built in the late 1870s
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NER Class O
The NER Class O (LNER Class G5) was a class of 0-4-4T steam locomotives of the North Eastern Railway, designed by the company's Chief Engineer, Wilson Worsdell. They all survived into British Railways ownership in 1948 and their BR numbers were ...
, a British 0-4-4T steam locomotive class
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NZR O class, a locomotive class of New Zealand steam engines built in the United States
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Russian locomotive class O
The Russian steam locomotive class O (from russian: Основной) was an early type of Russian steam locomotives. 9,129 locomotives were built between 1890 and 1928; hence it was the second most numerous class of locomotive in Russia, after ...
, an early type of Russian steam locomotive
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SER O class
The South Eastern Railway (SER) O Class (some of which were later rebuilt, becoming the O1 Class) was a class of 0-6-0 steam locomotive designed for freight work, and were the main freight engines of the SER, and later the South Eastern and ...
, a British 0-6-0 steam locomotive class
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WAGR O class
The Western Australian Government Railways (WAGR) O Class was a class consisting of fifty-six 2-8-0 steam locomotives which were introduced by the WAGR between 1896 and 1912. Despite them being tender locomotives, they also featured short boil ...
, Australian 2-8-0 steam locomotive class built in the late 19th century
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O-class Melbourne tram
The O-class Melbourne tram were a group of four trams built in 1912 by Duncan & Fraser (Adelaide) for the Prahran & Malvern Tramways Trust (P&MTT) upon the recommendation of W. G. T. Goodman, Chief Engineer and General manager of the Trams in Adel ...
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O-class Sydney tram
Stars
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Class O stars, the rarest of all main sequence stars
Vessels
* , the first ships built under the United Kingdom's War Emergency Programme destroyers
* , a class of warships planned for the German Navy just prior to the Second World War
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O-class submarine (disambiguation)
** Class O, several early
submarine classes of the Royal Netherlands Navy
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United States O-class submarine
The United States Navy's sixteen O-class submarines were created out of the lessons learned from the L class. The O class were about 80 tons larger than the L class, with greater power and endurance for ocean patrols. Due to the American entry ...
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