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|fueltype = Coal |fuelcap = |watercap = |boilerpressure = |cylindercount = |cylindersize = |valvegear = K: Walschaerts K1 (outside): Walschaerts (inside): Holcroft |tractiveeffort = K: |operator = |operatorclass = K and K1 classes |fleetnumbers = K: 790–809 K1: 890 |officialname = ''River'' class |nicknames = ''Rolling Rivers'' |withdrawndate = 1927 |disposition = All rebuilt to U or U1 class — One rebuild surviving }} The SECR K class was a type of 2-6-4 tank locomotive designed in 1914 by Richard Maunsell for express passenger duties on the South Eastern and Chatham Railway (SECR). The Southern Railway (SR) K1 class was a three-cylinder variant of the K class, designed in 1925 to suit a narrower loading gauge. They were among the first non-Great Western Railway (GWR) types to use and improve upon the basic design principles of power and standardisation established by GWR Chief Mechanical Engineer (CME) George Jackson Churchward.〔 The locomotives were based on the GWR 4300 class, improved by the Midland Railway's ideals of simplicity and ease of maintenance.〔Scott-Morgan (2002), p. 18〕 The K class was designed to be mechanically similar to the SECR N class 2-6-0 mixed-traffic locomotives. The class was the earliest large-scale use of the 2-6-4 wheel arrangement in Britain.〔Casserley (1966), p. 436〕 Production began towards the end of the First World War, and the prototype rolled out of Ashford Works three years after design work was completed due to wartime production constraints. The class replaced obsolete 4-4-0 passenger locomotives in an SECR fleet standardisation programme. Twenty-one locomotives were built: twenty K class (two cylinders) and one K1 class (three cylinders), the first in 1917 and the remainder between 1925 and 1926. They operated over the Eastern section of the Southern Railway network and were given the names of rivers, being referred as the River class from 1925. Crews referred to the K and K1 classes as "Rolling Rivers" because of their instability when travelling at speed. They were rebuilt as 2-cylinder SR U class and 3-cylinder SR U1 class 2-6-0s (respectively) following a railway accident at Sevenoaks, Kent in 1927. They continued in service with British Railways (BR) until the last was withdrawn in 1966. One K class rebuild (No. 1806) is preserved on the Watercress Line in Hampshire and as of 2011 is operational. ==Background== Three factors dictated the type of locomotive that could operate on the South Eastern and Chatham Railway (SECR): the heavy passenger train loadings; the poor track quality; and the weak, lightly built bridges.〔 On the lines of the former London, Chatham and Dover Railway (LCDR) – inherited by the SECR in 1899 – beach pebbles had been used for ballast〔 instead of conventional ballast, which has irregular shapes that lock together to keep the track in place. These economies in construction meant that only locomotives with low axle loadings could operate safely over the track.〔 The SECR was therefore unable to follow a coherent strategy to reduce the number of locomotive types inherited from the two constituent railways. Despite increased passenger and freight traffic between and the Kentish coast during the first decades of the 20th century, the Operating Department had to use mismatched classes of underpowered and obsolete 4-4-0 and 0-6-0 locomotives, which could operate within the restrictions imposed by the infrastructure.〔Whitehouse & Thomas (2002), p. 50〕 This resulted in frequent double-heading, adding to operational costs.〔Whitehouse & Thomas (2002), p. 51〕 Richard Maunsell was appointed CME of the SECR in 1913, following the enforced retirement of Harry Wainwright, who had left a range of competent but unspectacular locomotive classes that struggled to cope with the increased train lengths and loadings.〔Whitehouse & Thomas (2002), p. 49〕 Maunsell reviewed the situation and planned to introduce six standard classes – using only two boiler designs – which would work the entire traffic of the railway.〔Bradley (1980), pp. 66–67〕 The first of these was the N class 2-6-0, which gave the SECR a capable mixed-traffic locomotive. For the express passenger design that could cope with the heavy boat trains, Maunsell wanted to enlarge the existing L class 4-4-0 with Walschaerts valve gear and an enlarged superheater, but this design would have resulted in a too heavy axle loading.〔〔 Maunsell's newly recruited assistants, G.H. Pearson and Harold Holcroft from the Great Western Railway at Swindon and James Clayton from the Midland Railway at Derby, had recently been involved in the design of large passenger tank engines and persuaded him to use the 2-6-4 wheel arrangement, which would allow the class to operate at high speeds on the poor-quality track in north Kent.〔 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 K and SR K1 classes」の詳細全文を読む スポンサード リンク
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