→Operational details and preservation: article uses "Churchward design" earlier on, so making this consistent; also, can we get away with removing that "design"? Unsure, but I think it's implicit it's about the class |
→Operational details and preservation: merging statements; the only thing lost from the meaning is "such as", which implies more locos. This could be fixed by adding "among others" to the end, or by listing *all* of those that it inspired |
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== Operational details and preservation == |
== Operational details and preservation == |
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The N class was the first to combine Churchward design principles with the best practices of other railways |
The N class was the first to combine Churchward design principles with the best practices of other railways; it was an important step in the development of the British 2-6-0,<ref name=Reynolds /> providing inspiration for the [[LMS Hughes Crab]] of 1926 and Maunsell's [[SR U class|SR U class]] of 1928.<ref name=Reynolds /> The quality of the design was such that the Southern Railway displayed No. A866 at the [[British Empire Exhibition]] at [[Wembley]] from May to November 1925.<ref name=Middlemass /> |
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The N class was adept at hauling passenger or freight traffic on the Southern Railway's Eastern section. The locomotives were well-received by crews, who nicknamed them "Woolworths",<ref name=Middlemass /> because the majority were fabricated from cheaply produced parts from Woolwich.<ref name=Middlemass /> The class had high-capacity tapered boilers to promote free steaming, and small 5 ft 6 in (1.68 m) driving wheels that delivered considerable tractive effort, useful attributes for hauling heavy loads during the [[Second World War]].<ref name=Casserley1>Casserley, p. 437</ref> The route availability and mixed-traffic role of the N class expanded their sphere of operation to the Central and Western sections of the network.<ref name=Casserley3>Casserley, p. 439</ref> However, the large cylinder and cab sizes prevented use on the Central section’s [[Hastings Line|Tonbridge–Hastings line]], where narrow bridges and tunnels were unable to accommodate the class.<ref name=steam4>Clarke (''Steam World'', 2008 (248)), p. 41</ref> |
The N class was adept at hauling passenger or freight traffic on the Southern Railway's Eastern section. The locomotives were well-received by crews, who nicknamed them "Woolworths",<ref name=Middlemass /> because the majority were fabricated from cheaply produced parts from Woolwich.<ref name=Middlemass /> The class had high-capacity tapered boilers to promote free steaming, and small 5 ft 6 in (1.68 m) driving wheels that delivered considerable tractive effort, useful attributes for hauling heavy loads during the [[Second World War]].<ref name=Casserley1>Casserley, p. 437</ref> The route availability and mixed-traffic role of the N class expanded their sphere of operation to the Central and Western sections of the network.<ref name=Casserley3>Casserley, p. 439</ref> However, the large cylinder and cab sizes prevented use on the Central section’s [[Hastings Line|Tonbridge–Hastings line]], where narrow bridges and tunnels were unable to accommodate the class.<ref name=steam4>Clarke (''Steam World'', 2008 (248)), p. 41</ref> |
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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.[2] The N class was based on the GWR 4300 class design, improved with Midland Railway concepts.[3]
The N class was mechanically similar to the SECR K class 2-6-4 passenger tank engine. It influenced future 2-6-0 development in Britain and provided the basis for the three-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 operated 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 Watercress Line in Hampshire, pending overhaul.[4]
Background
Three factors dictated the type of locomotive that could operate on the South Eastern and Chatham Railway (SECR): increased train loadings, poor track quality, and weak, lightly-built bridges.[5] An increasing number of passengers used the SECR to reach the cross-Channel ferries at Dover and Folkestone, stretching the capabilities of existing infrastructure.[6] On the lines of the former London, Chatham and Dover Railway (LCDR), beach pebbles had been used for ballast.[7] 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.[7] The economies in construction meant that only locomotives with low axle loadings could operate safely on the track.[5] 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 operate within the restrictions imposed by the infrastructure.[8] The Department also contended with increased passenger and freight traffic between London and the Kentish coast, leading to frequent double-heading that added to operational costs.[6]
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.[5] Maunsell took control of the short-term situation by improving existing designs, and he introduced new engines to progressively replace obsolete types and cope with the workload.[8] 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.
Design and construction
The N class was designed by Maunsell in 1914 to provide a sturdy mixed-traffic locomotive with high route availability.[9] Intended to replace several obsolete 0-6-0 types, the N class was the first step in the SECR's standardisation programme.[9] Maunsell enlisted the help of former GWR engineer Harold Holcroft, who suggested that a 2-6-0 wheel arrangement would allow the class to operate on the poor-quality track in north Kent.[2] This arrangement allowed for a longer wheelbase with a leading axle to permit greater stability at speed on track curves, which had constrained the size of locomotives operating on the SECR. A longer locomotive could also accommodate a larger boiler than an 0-6-0, giving the N class sufficient power to avoid double-heading of locomotives on heavier trains.[9]
The N class incorporated the first use of Churchward design principles outside the GWR, and included the use of a Belpaire firebox instead of a round-topped version, long-travel valves for free running up to 70 mph (110 km/h), a sharply tapered boiler, and a right-hand driving position.[9] These features are attributed to Holcroft, who worked on the GWR 4300 class before joining the SECR.[1]
Another of Maunsell's assistants, James Clayton, brought simpler and more functional Midland Railway influences to the design: the shape of the cab, the tender, and the running plate along the boiler sides.[10][11] Innovations added by Maunsell's team included greater superheating surface area, the location of the boiler water top feed inside a dome, outside Walschaerts valve gear, and parts that could be shared with similar locomotive classes to reduce maintenance costs.[7]
First SECR batch
Production of the first batch was delayed by the outbreak of the First World War. Assembly began towards the end of the war and the first locomotive, No. 810, emerged from Ashford Works in September 1917,[9] one month after the first K class 2-6-4T passenger tank locomotive, whose design was derived from the N class.[9] No. 810 was trialled for three years before 15 more locomotives were ordered and built between 1920 and 1923. All were assembled at Ashford Works, numbered 811–825 and equipped with 3,500-imperial-gallon (15,911 L) tenders.[1] Modifications were made to No. 822 during construction in 1922.[12] The cylinder arrangement was revised to increase the power and route availability of the N class concept.[12] A third "inside" cylinder was fitted between the frames, and the "outside" cylinders were reduced in diameter to accommodate the inside cylinder and its associated valve linkages. The differences between No. 822 and the rest of the N class meant that this locomotive required re-designation, becoming the prototype of the SR N1 class when completed in March 1923.[12]
Second "Woolwich" batch and exports to Ireland
Trials with the N class proved successful, and few problems were encountered with the first batch delivered.[13] The Ministry of Supply produced a contract to construct a second batch at the Royal Arsenal, Woolwich as a measure to retain staff when munitions production was scaled down. The government backing also came from a proposal to nationalise the railways, which would have required a standard fleet to promote economies in production and maintenance.[10] The nationalisation proposal was abandoned; instead, the government passed the 1921 Railways Act, which grouped the railways into the "Big Four" in 1923.[9] Construction of the second batch went ahead, but the fabrication of 119 boilers for allocation to the kits of parts at Woolwich was contracted out because of limited production capacity at Woolwich and Ashford;[10] the North British Locomotive Company built 85, Robert Stephenson and Company 20, and Kitson & Co. 14.[14]
By 1924, the prefabricated components stored at Woolwich formed 100 complete N class kits for purchase from the government. The Midland Great Western Railway of Ireland bought 12 kits prior to absorption by the Great Southern and Western Railway, which bought an extra 15. The latter 15 locomotives were divided into eight GSR K1 class with 5-foot-6-inch (1.676 m) driving wheels and six GSR K1a class with 6-foot-0-inch (1.829 m) driving wheels (the final kit was kept for spares).[15] The Metropolitan Railway purchased six kits for conversion to the Metropolitan Railway K Class 2-6-4T tank engines, which were similar to the SECR K class.[16]
Fifty "Woolwich" N class kits were purchased by the newly created Southern Railway, which had absorbed the SECR in the grouping. These were assembled at Ashford between June 1924 and August 1925. The remaining kits at Woolwich formed the basis for later locomotive classes such as the three-cylinder SR W class 2-6-4 tank locomotive.[12] The prototype W class was produced in 1932 from a kit of N class parts with the addition of water tanks, a coal bunker, a rear bogie and a third cylinder between the frames.[9]
Final Southern Railway batch and further modifications
The 1932 to 1934 batch of 15 locomotives differed from the previous 65 in a number of ways. The cabs were fitted for left-hand driving, which was adopted as standard by the Southern Railway, and the dome and chimney were replaced by lower-profile fittings used on the U1 class.[17] The latter modifications increased route availability by allowing the locomotives to pass under lower bridges and tunnels.[9]
The new batch had new 4,000-imperial-gallon (18,184 L) tenders that necessitated the addition of a step to the footplate, as the boiler backhead was lower than the fall-plate connecting the tender and cab floors.[11] The new batch was also equipped with steps on the front buffer beam below the smokebox; earlier locomotives were not provided with this refinement until overhauled later in their careers.[7] From 1933, the entire class was fitted with smoke deflectors. Smokebox-mounted anti-vacuum snifting valves were removed by Oliver Bulleid at the end of the Second World War.[12]
N class construction history
Year | Batch[1] | Quantity | SECR/SR numbers | Notes |
---|---|---|---|---|
1917, 1920–23 | 810, 811–824 | Locomotive No. 822 modified during construction to three-cylinder arrangement, became SECR N1 class prototype | ||
1924 | A825–A875 | Purchased by Southern Railway | ||
1924 | 33 sold, 17 spare for future projects | |||
1932–34 | 1400–1414 |
Operational details and preservation
The N class was the first to combine Churchward design principles with the best practices of other railways; it was an important step in the development of the British 2-6-0,[12] providing inspiration for the LMS Hughes Crab of 1926 and Maunsell's SR U class of 1928.[12] The quality of the design was such that the Southern Railway displayed No. A866 at the British Empire Exhibition at Wembley from May to November 1925.[9]
The N class was adept at hauling passenger or freight traffic on the Southern Railway's Eastern section. The locomotives were well-received by crews, who nicknamed them "Woolworths",[9] because the majority were fabricated from cheaply produced parts from Woolwich.[9] The class had high-capacity tapered boilers to promote free steaming, and small 5 ft 6 in (1.68 m) driving wheels that delivered considerable tractive effort, useful attributes for hauling heavy loads during the Second World War.[18] The route availability and mixed-traffic role of the N class expanded their sphere of operation to the Central and Western sections of the network.[19] However, the large cylinder and cab sizes prevented use on the Central section’s Tonbridge–Hastings line, where narrow bridges and tunnels were unable to accommodate the class.[20]
Although the design was ideal for the Southern Railway, the N class was subjected to component trials. No. A816 was fitted with Anderson steam heat conservation equipment in 1930, using a fan to condense spent steam.[21] The experiment was ended when the system's developers ran out of money, and the locomotive was rebuilt to the original configuration.[21] No. 1850 was fitted with J. T. Marshall valve gear between 1933 and 1934.[22] This showed little improvement over the standard Walschaerts type, and the engine was reverted to the original specification to save on maintenance. Before nationalisation in 1948, government-backed fuel trials were made in anticipation of post-war coal shortages and No. 1831 was converted to oil burning in 1947.[1] It was reverted to coal-firing when the crisis failed to materialise.[1]
Under British Railways ownership, the class was reclassified from 4MT to 4P5FB in 1953; the "B" representing the Southern Railway’s power classification.[23] They were used heavily by British Railways: 29 class members required replacement cylinders between 1955 and 1961 due to excessive wear.[9] Frames were occasionally replaced due to heavy use, but generally only the front end was re-conditioned when outside steam pipes behind the smoke deflectors replaced the inside versions to connect the new cylinders with the steam circuit and exhaust arrangement.[9] From 1957 some of the class had BR Standard Class 4 chimneys fitted to improve draughting.[4]
The class was withdrawn from service between 1962 and 1966 when work was taken over by Oliver Bulleid's Light Pacifics and the Eastern section electrification was imminent. One member of the class is preserved, BR No. 31874, rescued from the Woodham Brothers scrapyard in Barry, Vale of Glamorgan, South Wales in March 1974.[24] One of the "Woolworths" batch, this locomotive was purchased and restored for use on the Mid-Hants Railway, steamed for the first time in preservation in 1977, and was operational at the re-opening of the railway as a heritage attraction.[23][25] The locomotive was withdrawn in 1998 due to problems that require firebox reconstruction, and is currently stored pending overhaul.[26]
Livery and numbering
SECR and Southern Railway
N class locomotives were initially painted in an unlined dark grey livery with white lettering and numbering. This Maunsell grey livery was introduced by the SECR as a wartime economy measure.[1] On grouping in 1923 the SR replaced the liveries of the constituent companies with a standard sage green livery (the colour was that previously used by Urie on the LSWR) with black and white lining, primrose yellow numbering and "Southern" on the tender.[12] From 1925 the class was repainted in a darker olive green livery, introduced by Maunsell, with plain white lining and primrose yellow markings.[7] In 1939, shortly after the start of the Second World War, locomotives nos. 1413 and 1850 were painted in unlined olive green because of labour shortages.[12] In 1941 nos. 1821, 1825, 1847, 1878 and 1403 were operated in unlined olive green with gilt lettering; this style of lettering was introduced by Bulleid.[12] Labour shortages during the Second World War meant that all N class locomotives were painted in plain black by 1945.[1] In 1946 two locomotives, nos. 1817 and 1854, were repainted in Bulleid's malachite green livery, with yellow and black lining and "Sunshine Yellow" lettering.[1]
The 15 locomotives constructed by Ashford Works for the SECR between August 1917 and December 1923 were numbered 810–824.[12] The Royal Arsenal batch of 50 locomotives purchased by the newly formed Southern Railway from 1923 were numbered A825–A875,[1] the numbers following consecutively from the Ashford batch but with a prefix "A" to denote a locomotive designed for the former SECR.[12] The system of prefixes had been adopted by the SR to distinguish between locomotives with identical numbers acquired from different companies.[12] This system was replaced from 1928 when all Southern Railway locomotives were renumbered into one sequence, in which the N class became 1810–1875.[1] The final batch of 15 locomotives, built between 1932 and 1934, were numbered 1400–1414 from new.[1]
British Railways
The class was absorbed by British Railways in 1948, and given the BR power classification 4MT.[27] The locomotives at first retained their Southern Railway livery, but with "British Railways" on the tender. Those locomotives that had light repairs prior to 1950 had an "S" prefix added to the Southern number.[28] From 1949 to 1950 N class locomotives were repainted in the British Railways mixed-traffic lined black livery with red, cream and grey lining and the British Railways crest on the tender.[28] Numbering was changed to the British Railways standard numbering system: the series 31810–31875 was allocated to the earlier locomotives, and 31400–31414 to the final 15.[27]
References
Notes
- ^ a b c d e f g h i j k l Haresnape, section: "N class"
- ^ a b Casserley, p. 436
- ^ Scott-Morgan, p. 18
- ^ a b Casserley, p. 440
- ^ a b c Whitehouse & Thomas, p. 49
- ^ a b Whitehouse & Thomas, p. 51
- ^ a b c d e Clarke (Steam World, 2008 (248)), p. 38
- ^ a b Whitehouse & Thomas, p. 50
- ^ a b c d e f g h i j k l m n Middlemass, (Backtrack: 4), pp. 148–154
- ^ a b c Clarke (Steam World, 2008 (248)), p. 40
- ^ a b Clarke (Steam World, 2008 (248)), p. 39
- ^ a b c d e f g h i j k l m Reynolds, pp. 155–156 Cite error: The named reference "Reynolds" was defined multiple times with different content (see the help page).
- ^ Herring, pp. 120–121
- ^ Haresnape, p. 24
- ^ Haresnape, p. 116
- ^ Scott-Morgan, p. 4
- ^ Reynolds, p. 156
- ^ Casserley, p. 437
- ^ Casserley, p. 439
- ^ Clarke (Steam World, 2008 (248)), p. 41
- ^ a b Whitehouse & Thomas, p. 54
- ^ Locomotive, Railway Carriage and Wagon Review (44, 1938), pp. 373–376
- ^ a b Langston, p. 108
- ^ Great Western Society: Southern Locomotives at Barry (2000) No. 31874 leaves Woodham's Scrapyard, Retrieved June 16 2009
- ^ Mid-Hants Railway (2007) The re-opening of the Watercress Line, Retrieved June 16 2009
- ^ Mid-Hants Railway (1998) Current situation of No. 31874 on the Watercress Line, Retrieved June 16 2009
- ^ a b Ian Allan ABC, 1952–53
- ^ a b Banks, p. 66
Bibliography
- Banks, Chris: BR Locomotives 1955 (Oxford Publishing Company: Oxford, 2001), ISBN 0860935604
- Casserley, H.C. 'End of the Maunsell moguls—the Southern maids-of-all-work' (Railway World: 27, 1966), pp. 436–440
- Clarke, Jeremy: 'The locomotives of R.E.L. Maunsell, Part 3: The 'Mogul' family – SECR' (Steam World, 2008 (248)), pp. 38–41
- Haresnape, Brian: Maunsell Locomotives – a pictorial history (Ian Allan Ltd, 1977), ISBN 0711007438
- Herring, Peter: Classic British Steam Locomotives (Abbeydale Press: London, 2000) Section "U Class" ISBN 1861470576
- Ian Allan ABC of British Railways Locomotives, winter 1958–59 edition
- Langston, Keith: British Steam Preserved: Illustrated Comprehensive Listing of Ex-British Railways Steam Locomotives (Horncastle: Morton's Media Group Ltd., 2008)
- Longworth, Hugh: British Railway Steam Locomotives: 1948–1968 (Oxford Publishing Company: Oxford, 2005) ISBN 0860935930
- Middlemass, Tom: 'The "Woolworths" — Woolwich Arsenal's tentative entry into main line locomotive building' (Backtrack, 1990 (4)), pp. 148–54
- Reynolds, W.J.: 'The Maunsell moguls' (S.R. Railway Magazine, 1943, 89), pps. 155–8; 199–202; 279–82
- Scott-Morgan, John: Maunsell Locomotives (Ian Allan Publishing: Hinckley, 2002), ISBN 0711028729
- 'Some "improved" locomotive valve gears' (Locomotive, Railway Carriage and Wagon Review: 44, 1938), pp. 373–376
- Whitehouse, Patrick & Thomas, David St.John: SR 150: A Century and a Half of the Southern Railway (Newton Abbot: David and Charles, 2002)