SR U class
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 Preserved SR U class number 1638 on the Bluebell Railway | |||||||||||||||||||||||
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The SR U Class were 2-6-0 mogul steam locomotives designed by Richard Maunsell for passenger duties on the Southern Railway. They were to be used on cross-country and semi-fast expresses. A highly standardised class of locomotive, the U Class concept came from the failure of another class of locomotive, the SECR K Class.
Several members of the class were rebuilds of the K Class at the Ashford railway works, and were soon granted the nickname 'U-Boats.' Able to operate over most of the Southern Railway network after grouping in 1923, the U Class survived until 1966, when all had been withdrawn from service. Four examples have been preserved.
Background
The class was a response to the failure of the South Eastern and Chatham Railway's K Class of 2-6-4T, which had been introduced as a development of the N Class moguls, had a reputation for rough riding.[2] Coupled with the cheaply-laid rails of the SECR system, this resulted in the Sevenoaks rail crash of 1927.[2] The resultant inquiry recommended the rebuilding of the 20 members of the K Class as 2-6-0 tender locomotives, therefore satisfying an ongoing requirement for a sturdy mixed-traffic locomotive with high route availability on its network.[2]
The design was to act as a replacement for elderly classes that were still present in the Southern Railway's running fleet, resulting in a requirement for standardization and ease of maintenance.[2] This had to be married to the ability for the new locomotive to operate over the lightly laid track-work inherited from the former SECR, and as a result, the 2-6-0 wheel arrangement was settled upon.[3] The design was to have mass production in mind, and the result was the two-cylinder U Class.[2]
Construction details
As a result of the derailing of K Class number A800 River Cray at Sevenoaks, Maunsell rebuilt No. A805 to the 2-6-0 Mogul wheel arrangement in 1928, and that by the end of 1929, 19 had been rebuilt.[1] This answered the Southern Railway's need for a new class of two cylinder passenger tender locomotives. As a result, the entire K Class was rebuilt with great speed, with A805 preceding the next rebuild by three months.[1]
The rebuilding involved the removal of the side water tanks, the rear coal bunker and the trailing axles.[4] Two designs of Maunsell tender was added, one of which was of the same 4000 gallon design used on the N Class, with the raves sloped inwards.[5] This helped to allow the standardization of components between the two classes. The other tender design was of 3500 gallon capacity, sporting straight sides.[5] Fifty engines were released for duty in due course when a further batch of 30 locomotives was built from scratch.[1] The K Class rebuilds visibly differed from the as-built locomotives in that they had a lower running plate along the sides of the boiler, necessitating larger wheel splashers.[5] They also had N Class-style double spectacle plates rather than the single incorporated on as-built versions.[2] The cabside cutaways were also cut into the roof. Later builds of the class had a flatter top to the dome covers than those seen on the K Class rebuilds.[5]
The U Class as originally designed had tapered chimneys and smokebox snifting valves, once again a feature seen on the N class.[2] These were later removed and new chimneys of the U1 pattern fitted.[4] Smoke deflectors were fitted from 1933, as with most of the locomotives designed by Maunsell.[5] Ex-K Class locomotive A890 was rebuilt once again into the prototype of Maunsell's newer U1 Class three cylinder derivative in 1928.
Livery and numbering
Southern Railway
The entire class, from construction in 1928, was finished in Maunsell lined Southern Railway Olive Green with yellow markings and 'Southern' on the tender. During the Second World War, the U Class was released in wartime black livery with Oliver Bulleid's "Sunshine Yellow" lettering. The class was initially numbered in the Southern's post-grouping parlance from A790 to A809 for the K Class rebuilds, and A610 to A639 with the as-built batch. This was subsequently changed to 1790–1809, and 1610–1639 respectively during the 1930s.[5]
Post-1948 (nationalisation)
The class was absorbed by British Railways (BR) in 1948, and was given the BR Power classification 4P3F.[6] Livery was initially as Southern Railway, though with 'British Railways' on the tender, and an 'S' prefix to the Southern number. This was succeeded by the BR mixed traffic lined black livery with red and white lining, and the BR crest on the tender. [6] Numbering was in line with the BR standard numbering system, in the series 31790–31809 for the K Class rebuilds, and 31610–31639 for the rest.[7]
Operational details and preservation
The U Class was a reliable and economical design, and proved to be more than capable of attaining speeds in excess of 70mph.[6] Their high route availability meant that their use was spread throughout the Southern network, and were especially useful on Western Section trains West of Exeter.[4] Their "go anywhere" nature meant that they earned the nickname of 'U-Boats.'[1] Crews praised their abilities to achieve what they were designed to do, though they represent one of the rather more unglamorous classes of passenger locomotive.[1] Several trials were made by the Southern Railway operating department to improve efficiency across their locomotive fleet. U Class number A629 was fitted with an experimental pulverized fuel burner of German design, though was abandoned after they proved unsuccessful.[1] The decision was made on safety considerations, as powdered coal was potentially explosive.[4]
Prior to nationalisation, the class provided an ideal test-bed in response to a Government-backed scheme concerning locomotive fuel arrangements in 1948.[4] Two of the class, numbers 1625 and 1797, were converted as oil burners, though whilst several other members of the class were designated for conversion, the project was abandoned.[1] From 1955, 23 of the class received new chimneys of the BR Standard Class 4 variety and newer cylinders.[6] Withdrawals began in 1962, and all were struck off the locomotive register by 1966, though four have survived. These are (3)1618 and (3)1638, based on the Bluebell Railway, and (3)1806 and (3)1625, based on the Mid-Hants Railway. (3)1806 is the only survivor of the K Class rebuilds.
References
- ^ a b c d e f g h Herring, Peter: Classic British Steam Locomotives (Abbeydale Press: London, 2000) Section "U Class" ISBN 1861470576 Pages 120–121
- ^ a b c d e f g Middlemass, Tom: 'The 'Woolworths' — Woolwich Arsenal's tentative entry into main line locomotive building' (Backtrack: 4, 148–54)
- ^ Casserley, H.C.: 'End of the Maunsell moguls—the Southern maids-of-all-work' (Railway World: 1966, 27), pps. 436–440)
- ^ a b c d e Reynolds, W.J.: The Maunsell moguls (S.R. Railway Magazine: 1943, 89), pps. 155–158, 199–202 and 279–282
- ^ a b c d e f Haresnape, Brian: Maunsell Locomotives - a pictorial history (Ian Allan Ltd, 1977), ISBN 0711007438
- ^ a b c d Longworth, Hugh: British Railway Steam Locomotives: 1948–1968 (Oxford Publishing Company: Oxford, 2005) ISBN 0860935930
- ^ Ian Allan ABC of British Railways Locomotives, winter 1958–59 edition
Further reading
- Ian Allan ABC of British Railways Locomotives, winter 1962–63 edition