SR U class

The SR U class are 2-6-0 steam locomotives designed by Richard Maunsell for passenger duties on the Southern Railway (SR). The class represented the penultimate stage in the development of the Southern Railway's 2-6-0 "family", which improved upon the basic principles established by GWR Chief Mechanical Engineer (CME) George Jackson Churchward for Great Western Railway (GWR) locomotives. The U class design drew from experience with the GWR 4300s and N classes, improved by applying Midland Railway ideas to the design, enabling the SECR to influence development of the 2-6-0 in Britain. The U class was designed in the mid-1920s for production at a time when more obsolete 4-4-0 locomotives were withdrawn, and derived from Maunsell's earlier SECR K (“River”) class 2-6-4 tank locomotives. The first 20 members of the U class were rebuilds of the K class locomotives, one of which was involved in the Sevenoaks railway accident. A further 20 U class locomotives were built in 1928 to fill the gap in cross-country and semi-fast express passenger services after the withdrawal of the K class. The design also continued the standardisation of the Southern Railway locomotive fleet by using parts designed to be interchangeable with other Maunsell-designed classes. A total of 50 locomotives were built over three batches between 1928 and 1931, and the design formed the basis for the 3-cylinder U1 class of 1928. They were able to operate over most of the Southern Railway network, gaining the nickname "U-boats" after the submarine warfare of the First World War, and continued to operate with British Railways (BR). The class saw continuous use until 1966, when all members of the U class were withdrawn from service. Four U class locomotives have been preserved on two heritage railways in the south of England.

K class rebuilds

The rebuilding programme that followed the derailment of K class No. A800 "River Cray" at Sevenoaks began at Ashford works in June 1928. The work involved in converting a 2-6-4 tank engine to a 2-6-0 tender locomotive included the removal of the side water tanks, rear coal bunker and trailing axles, although the 6 ft (1.83 m) driving wheels, right-hand drive and N class–type boiler were retained. The aesthetic aspects inherited from the K class were the former Midland Railway engineer James Clayton’s contributions to the design, creating a simple, functional locomotive similar to the N class. The rebuilt locomotives were given a tender and a re-designed cab that bore a strong resemblance to those featured on designs by Henry Fowler. Two designs of Maunsell tender were used, the straight-sided variety, and the larger design used on later batches of the N class with inward-sloping raves to prevent coal spillage. The first rebuild was No. A805 River Camel, which also became the first U class locomotive into service in March 1928, three months before the first production locomotive under construction at Brighton. The rapid turnaround was achieved as design work was already in place, and the rebuilding of existing locomotives was cheaper than building from scratch. No. A805 was put on performance trials prior to work commencing on rebuilding of the rest of the class at Brighton and Eastleigh works. The rebuilds lost their names because of the bad publicity attached to the "River" class after the 1927 crash, and the heavily damaged No. A800 was the last member of the K class to be rebuilt to U class configuration in December 1928. The unique 3-cylinder "River" tank, K1 class No. A890 River Frome was also rebuilt to the general U class specification, becoming the prototype of Maunsell's 3-cylinder U1 class derivative in June 1928.

First production batch and differences with rebuilt locomotives

Construction of the delayed 1926 order for 20 K class locomotives began in 1928 after alteration to the U class specification. As a result of Harold Holcroft's position as one of Maunsell's assistants, the new-builds also displayed the Churchward GWR 4300 Class influence. The ideas applied to this class were already used on the N, N1 and K class rebuilds, including long-travel valves for fast running, Belpaire firebox and conical boilers, constructed at the North British Locomotive Works in Glasgow. The first of the production batch emerged from Brighton works in August 1928 and featured a tapered chimney and smokebox snifting valves, both of which were used on the K and N class locomotives. The 20 locomotives of the first production batch were split equally between Brighton and Ashford works, and all were completed by December 1929. The production locomotives had a slightly different profile to the K class rebuilds and featured left-hand drive to improve the visibility of signals from the driver's side of the footplate. They also had higher running plates along the sides of the boiler than the rebuilds, which required smaller wheel splashers to cover the tops of the driving wheels. Another variation was the flatter top to the dome covers, as the rebuilds retained the high N class type used on the K class. In common with the N, N1 and K class locomotives, the Midland Railway influence of Clayton showed in the placement of locomotive fittings on the production batch, as the water top-feed into the boiler was located inside a dome, whilst the cab area was a modified version of those on the 0-6-0s of Henry Fowler and the K class rebuilds. The rebuilds had Midland Railway-style double spectacle plates (the small windows on the front face of the cab) left over from the K class cabs, whereas the production versions had one each side of the boiler. Such modifications were becoming typical of the Southern Railway's attempt to produce a fleet of standardised locomotives. However, all members of the U class were to vary from GWR practice, as the superheating surface area was increased, and all were equipped with outside Walschaerts valve gear.

Second production batch and modifications

The second batch of ten new-build U class locomotives was constructed between February and May 1931 when more obsolete locomotives were withdrawn from service. This brought the total of new-build locomotives to 30, and the total number of operational U class engines to 50. The new batch also featured detail differences from the rest of the class, such as the arrangement of the footsteps at the front of the locomotive, though continued to use the standard left-hand drive cab layout to improve the driver's forward vision from the cab. Smoke deflectors were fitted to the whole class from 1933 to prevent drifting smoke from obscuring forward vision. The smokebox snifting valves applied to the class by Maunsell were removed by his successor Oliver Bulleid, who also fitted U1 class chimneys to improve the draughting.

Withdrawal

The class were withdrawn between 1962 and 1966.

Accidents and incidents

On 25 May 1933, a passenger train, hauled by LSWR M7 Class 0-4-4T No. 107, was derailed at , London, coming to rest foul of an adjacent line. A U class locomotive, hauling a passenger train, was in a side-long collision with it. Five people were killed and 35 were injured. The cause of the accident was the failure to implement a speed restriction on a section of track that was under maintenance. The U class engine is given as No. 1621 in the official accident report but as No. 1618 in another source. On 14 November 1949, a rake of carriages was left foul of an adjacent line at station, Hampshire. Locomotive No. 31624 collided with them and was derailed. One person was injured. On 18 November 1962, locomotive No. 31816 was derailed at Tipton Yard, Eastleigh, Hampshire. On 26 July 2010, the tender of locomotive No. 31806 was damaged in a fire at Ropley sheds on the Watercress Line. The tender wasn't severely damaged and was reunited with 31806 soon after being repaired.

Livery and numbering

British Railways

The entire class was absorbed by British Railways in 1948, and in January 1949 was given the power classification 4MT, denoting a mixed traffic locomotive. In October 1953 this was revised to 4P3F. Livery was initially similar to the Southern Railway, though with "British Railways" on the tender, and an "S" prefix to the Southern number. This was succeeded by the British Railways mixed-traffic lined black livery with red, cream and grey lining and the British Railways crest on the tender. The British Railways standard numbering system was used to replace the Southern Railway system, and the class was allocated the series 31790–31809 for the K class rebuilds, and 31610–31639 for the rest.

Notes

Bibliography

Casserley, H.C.: 'End of the Maunsell moguls—the Southern maids-of-all-work' (Railway World: 1966, 27), pps. 436–440) Clarke, Jeremy: 'The locomotives of R.E.L. Maunsell, Part 3: The 'Mogul' family – SECR' (Steam World, 2008 (248)), pp. 38–41 Clarke, Jeremy: 'The locomotives of R.E.L. Maunsell, Part 4: The 'Mogul' family – SR' (Steam World, 2008 (249)), pp. 54–57 Haresnape, Brian: Maunsell Locomotives – a pictorial history (Ian Allan Ltd, 1977), Herring, Peter: Classic British Steam Locomotives (Abbeydale Press: London, 2000) Section "U Class" 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) 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), Southgate, Bill: 'Platform: Order amended seven months after Sevenoaks' (Steam World, 2008 (251)), p. 21

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