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SR Maunsell U1 class 2-6-0

photograph by Alan Robinson

U1 Class N°31905 pictured at Nine Elms shed on the 25th October 1961

The U1 class is the three cylinder derivative of the U class. The first member of the class results from the rebuilding at Ashford in 1928 of the sole three cylindered K1 "River" class 2-6-4T locomotive N°A890 River Frome. This rebuilding to 2-6-0 with tender format was carried out as part of the programme to rebuild the other two cylinder K class "River" tanks to the U class. Its original number was retained (but the name dropped), ot was matched with a 3500 gallon flat-sided tender and re-designated U1 class. The locomotive originally retained its Holcroft conjugated valve gear on its middle cylinder but this continued to be troublesome and was later converted to Walschaerts to conform with the remainder of the class.

The conversion proved to be a success, particularly in regard to acceleration and smooth running, so a further twenty were built from scratch drawing on, as with other Maunsell classes, a range of standard parts. This batch was built at Eastleigh in 1931 and numbered A891-A900 (renumbered to 31891-31900 under British Railways) and 1901-1910 (31901-31910). They were fitted with three sets of Walschaerts valve gear from new and had 4000 gallon tenders with turned-in tops. The three cylinders were of 16in diameter 28in stroke compared to the 19in diameter cylinders on the U class. The resulting reduction in overall width of the engine gave the U1 class a wider route availability that the U class and they were cleared to run on the Hastings line. The driving wheels were 6 ft in diameter as befits a passenger engine. Tractive effort at 85 percent boiler pressure was 25,387 lb. The K1 conversion was identifiable (as with K class conversions) by the side cab cutaway extending into the roof and the front steps being behind the cylinders, although these were later removed and new footsteps fitted in front of the cylinders. The running plate was straight on the new-builds, stepped up at the front on the rebuilds, the new-builds always had their front footsteps ahead of the cylinders and their steam dome had a flatter top. As with the U class the rebuild had larger splashers above the driving wheels.

The U1 class proved to be swift free runners capable of hauling heavy loads. The official speed limit of the class was 70mph and since they were mostly used on semi-fast passenger services they did not get much opportunity to push the limit, though it is recorded that given the chance much faster runs were made. A891-900 were allocated to Fratton from new for working the main Portsmouth line services where they coped well. When displaced by the arrival of the more powerful Schools (V) class they moved to the Eastern section to join the rest of the class. During the war they served well on the Hastings line troop trains, although the continually curving nature of the line led to excessive flange wear. For this reason the class was not a success west of Exeter where they were tried for a short while. The U1 class therefore became a principally Eastern and Central section locomotive. Despite intended to be a passenger engine they also worked freight turns thus somewhat blurring the line between them and the mixed traffic N/N1 classes. In later days a member of the class was tried on the Somerset and Dorset but it did not cope as well as larger types.

Minor modifications happened throughout their lives. As with other Maunsell Moguls smoke deflectors were added in the mid 1930s and due to the high running plate they were of reduced height. Also as with the other Moguls their smokebox snifting valves were removed. Some of the class received new cylinders in 1954, and although unlike other Maunsell classes major front end alterations were not made some did have BR standard blastpipes fitted. The entire class of 21 was withdrawn between 1962 and 1963 and unfortunately none is preserved.

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  • U1 Class
    An unidentified U1 photographed at Hooley during 1935.
    Photograph: Mike Morant collection.
  • 31906
    N°31906 running through a pristine Norbury station with a fast service in the mid-1950s.
    Photograph by by Mike Morant.
  • 31893
    N°31893 with a down Ramsgate train at Newington on 13th June 1959.
    Photograph: Mike Morant collection.
  • 31908
    Nine Elms
    The high running plate and short depth smoke deflectors can be seen clearly in both this front end view of N°31908 at Nine Elms on 25th October 1961 and the photograph of N°31905 above.
    Photograph by Alan Robinson.

Technical Details

Driving Wheel:
Pony Wheel:
Total Weight:
Water Capacity:
Cylinders (3):
Boiler Pressure:
Tractive Effort:
Coal Capacity:
Power Classification:
6 ft 0 ins
3 ft 1 ins
57 ft 91/8 ins
107 tons 14 cwt
4,000 gals
16 in x 28 in
200 lb sq in
25,387 lb
5 ton 0 cwt


Converted "River Class" 2-6-4T
SR N° Later SR N° BR N° Converted by Date Withdrawn
A890 1890 31890 Ashford Jun 1928 Jun 1963
New build U1 Class 2-6-0s
SR N° Later SR N° BR N° Built by Date Withdrawn
A891 1891 31891 Eastleigh Jan 1931 Apr 1963
A892 1892 31892 Eastleigh Jan 1931 Nov 1962
A893 1893 31893 Eastleigh Feb 1931 Dec 1962
A894 1894 31894 Eastleigh Feb 1931 Dec 1962
A895 1895 31895 Eastleigh Mar 1931 Dec 1962
A896 1896 31896 Eastleigh Mar 1931 Dec 1962
A897 1897 31897 Eastleigh Mar 1931 Nov 1962
A898 1898 31898 Eastleigh Apr 1931 Dec 1962
A899 1899 31899 Eastleigh Apr 1931 Dec 1962
A900 1900 31900 Eastleigh May 1931 Dec 1962
1901 - 31901 Eastleigh Jun 1931 Jun 1963
1902 - 31902 Eastleigh Jul 1931 Nov 1962
1903 - 31903 Eastleigh Jul 1931 Dec 1962
1904 - 31904 Eastleigh Jul 1931 Nov 1962
1905 - 31905 Eastleigh Aug 1931 Dec 1962
1906 - 31906 Eastleigh Sep 1931 Dec 1962
1907 - 31907 Eastleigh Sep 1931 Dec 1962
1908 - 31908 Eastleigh Oct 1931 Dec 1962
1909 - 31909 Eastleigh Oct 1931 Dec 1962
1910 - 31910 Eastleigh Nov 1931 Dec 1962

This page was last updated 14 November 2011

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