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The SECR N class was a type of 2-6-0 ("mogul") steam locomotive designed in 1914 by Richard Maunsell for mixed-traffic duties on the South Eastern and Chatham Railway (SECR). Built between 1917 and 1934, it was the first non-Great Western Railway (GWR) type to use and improve upon the basic design principles established by GWR Chief Mechanical Engineer (CME) George Jackson Churchward.〔 The N class was based on the GWR 4300 Class design, improved with Midland Railway concepts. The N class was mechanically similar to the SECR K class 2-6-4 passenger tank engine, also by Maunsell. It influenced future 2-6-0 development in Britain and provided the basis for the 3-cylinder N1 class of 1922. Production was delayed by the outbreak of the First World War in 1914, and the first N class rolled out of Ashford Works in 1917, three years after design work was completed. The class replaced obsolete 0-6-0s as part of the SECR's fleet standardisation, as they used parts interchangeable with those of other classes. Eighty N class locomotives were built in three batches between the First and Second World Wars. Fifty were assembled from kits of parts made at the Royal Arsenal, Woolwich, giving rise to the nickname of "Woolworths". They worked over most of the Southern Railway (SR) network, and were used by the Southern Region of British Railways (BR) until the last was withdrawn in 1966. One N class locomotive is preserved on the Swanage Railway in Dorset, undergoing overhaul.〔 ==Background== Three factors dictated the type of locomotive that could run on the South Eastern and Chatham Railway (SECR): increased freight and passenger train loadings, poor track quality, and weak, lightly built bridges.〔 An increasing number of passengers used the SECR to reach the cross-Channel ferries at Dover and Folkestone between 1910 and 1913, and heavy goods trains between Tonbridge and Hither Green marshalling yard stretched the capabilities of existing locomotives and infrastructure. On the lines of the former London, Chatham and Dover Railway (LCDR), flint beach pebbles on a bed of ash had been used for ballast.〔 Conventional track ballast has irregular shapes that "lock" together to keep the track in place, whereas the smooth pebbles used by the LCDR failed to prevent track movement under strain.〔 The economies in construction meant that only locomotives with low axle loadings could run safely on the track.〔 These restrictions meant that the SECR was unable to follow a coherent locomotive strategy that reduced costs and increased serviceability. The railway's Operating Department had to use mismatched classes of underpowered and obsolete 4-4-0 and 0-6-0 locomotives because they could run within the restrictions imposed by the infrastructure. This meant frequent double-heading that increased operational costs. Richard Maunsell was appointed CME of the SECR in 1913, following the retirement of Harry Wainwright due to ill health. Wainwright left a legacy of competent but unspectacular locomotives that struggled to cope with the increased train lengths and loadings. Maunsell took control of the short-term situation by improving existing designs, and he introduced new engines to progressively replace obsolete classes. New designs could also cut costs on the SECR, as one capable mixed-traffic locomotive could undertake the work of two separate passenger or freight types.〔 The first new design was to become Maunsell's N class 2-6-0. 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「SECR N class」の詳細全文を読む スポンサード リンク
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