SR U1 Class

Infobox Locomotive
powertype=Steam
name = SR U1 Class Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0711007438]


caption =
designer = Richard Maunsell
builder = SR Ashford/Eastleigh Works
builddate = 1928–1931
totalproduction = 20
whytetype = 2-6-0
gauge = RailGauge|ussg
leadingsize = 3 ft 1 in (0.94 m)
driversize = 6 ft (1.83 m)
length = 57 ft 10 in (17.4 m)
weight = 107 tons 14 cwt (109.4 tonnes)
fueltype = coal
fuelc

waterc

cylindersize = 16 in × 28 in (40.6 cm × 71.1 cm)
boilerpressure = 200 lbf/in² (1,378 kPa)
tractiveeffort = 25,387 lbf (112.92 kN) The SR U1 Class was a class of 2-6-0 steam locomotives. They were a three cylinder development of the U Class. Designed by Richard Maunsell, they were utilised on the Southern Railway. None have survived into preservation.

Background

The Southern Railway U Class of moguls, which had initially been a series of rebuilds from the infamous K Class 2-6-4Ts of 1913, spawned a further development in the Southern Mogul concept, the U1 Class. This was to be a three-cylinder design that was to be utilised on semi-fast passenger duties.

Construction details

In order to further the potential of the Southern 2-6-0, Maunsell rebuilt the remaining K Class 2-6-4T number A890 "River Frome," to the new three cylinder tender engine design in 1928. Herring, Peter: "Classic British Steam Locomotives" (Abbeydale Press: London, 2000) Section "U Class" ISBN 1861470576 Pages 120-121] This was an attempt to increase both the power and efficiency of the basic design and as a result, the U1 Class of Southern Moguls was unveiled. Herring, Peter: "Classic British Steam Locomotives" (Abbeydale Press: London, 2000) Section "U Class" ISBN 1-86147-057-6 Pages 120-121]

The rebuilding involved the removal of the side water tanks, the rear coal bunker and the trailing axles. A 3500 gallon capacity tender was added, sporting straight sides.Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8] The locomotive utilised Holcroft middle valve gear and two Walschaerts outside gear, though the former proved troublesome and was substituted for the latter in the interests of standardization and ease of repair.

20 further locomotives were ordered in due course from a range of standard parts that were available, and these were constructed at Eastleigh.These differed visibly differed from the K Class rebild in that they had a 4000 gallon tender with inward sloping raves as per the N Class.Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8] Maunsell once again intended for the U1 Class to have high route availability, and the three cylinder layout enabled smaller outside cylinders to be incorporated.Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8]

The K Class rebuild had N Class-style double spectacle plates rather than the single incorporated on as-built U1 versions. The cabside cutaways were also cut into the roof, whilst the running plate alongside the boiler was lower set and stepped towards the front with larger splashers; an arrangement that was reminiscent of the U Class rebuilds. Later builds of the U1 Class had a flatter top to the dome covers than those seen on the K Class rebuild.Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8]

The U1 Class as originally designed had smokebox snifting valves, once again a feature seen on the N class. Steps towards the front were relocated ahead of the cylinders on production locomotives, rather than behind as on the K Class rebuild.Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8] Smoke deflectors were fitted from 1933, as with most of the locomotives designed by Maunsell.Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8]

Livery and numbering

Southern

The entire class, from construction in 1928, was outshopped in Maunsell lined SR Olive Green with yellow markings and 'Southern' on the tender.

During the Second World War, the U Class was outshopped in wartime black livery with Bulleid's "Sunshine Yellow" lettering.

The class was initially numbered in the Southern's post-grouping parlance from A890–A900 for the first eleven constructed, changing to 1890–1910 during the 1930s, when the rest of the class was constructed.

Post-1948 (nationalisation)

The class was absorbed by British Railways in 1948, and were given the BR Power classification 4P3F. 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.

Numbering was in line with the BR standard numbering system, in the series 31890–31910.Ian Allan ABC of British Railways Locomotives, winter 1958–59 edition]

Operational details and preservation

The U1 Class was a reliable and economical design, and proved to be more than capable of attaining speeds in excess of 70mph, and has excellent traction and acceleration characteristics. Their high route availability meant that their use was spread throughout the Southern network, and were especially useful on Central Section trains to Portsmouth and Southampton until replaced by Schools Class V locomotives. Crews praised their abilities to achieve what they were designed to do, though they represent one of the rather more unglamourous classes of passenger locomotive. Herring, Peter: "Classic British Steam Locomotives" (Abbeydale Press: London, 2000) Section "U Class" ISBN 1-86147-057-6 Pages 120-121]

Several trials were made by the Southern to check route availability of the class, ans as a result, they were a regular fixture on the restricted Tonbridge to Hastings route alongside their N1 cousins.Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8] They worked troop trains along this route during the war, proving their worth as rugged locomotives. A trial on the Somerset and Dorset proved that the class were not good on gradients, and were thus kept on the Central and Eastern Sections.Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8]

The U1 Class members working on the Hastings route were subjected to excess flange wear due to the tight turns. This was another factor that precluded them from working West of Exeter. From 1955, some of the class received new chimneys of the BR Standard Class 4 variety and newer cylinders. [ Southern E-Group (2004) [http://www.semgonline.com/steam/u1class1.html] Retrieved 19 June 2007. For information on BR modifications.] Withdrawals began in 1962 as part of the BR Modernisation Plan, and all had been struck off the locomotive register by 1963. None have survived.

References

Further reading

*Ian Allan ABC of British Railways Locomotives, winter 1962/3 edition

External links

* [http://www.semgonline.com/steam/u1class1.html SEMG]
* http://www.railuk.co.uk/steam/getsteamclass.php?item=U-1