HISTORY OF THE U CLASS
The U class of 1928 was produced in response to the operating department’s needs for a two cylindered tender engine for semi-fast and cross country services. This need had latterly been met on the Southern Railway by the 2-6-4T K class “River” tanks, though they were somewhat limited by their water capacity, and parts were already on order for more of the class. This order was instead converted to produce the U class 2-6-0, and following a series of serious derailments with the K class, culminating in the Sevenoaks accident, the decision was taken to convert the entire class to Us. A total of fifty engines was completed inclusive of the twenty K class conversions.
Although originated from the K class the U class also had many parts in common with the earlier N class and their appearance was similar. The U class had six feet diameter drivers as befitting its passenger status, and a boiler pressure of 200lb psi providing a tractive effort of 23,866 lb at 85 percent of boiler pressure. The total weight of engine and tender in working condition was 102 tons 16 cwt.
The K class conversions were identifiable by a lower running plate leading to larger splashers, double spectacles to the cab front and cab side cutaways which extended into the curved part of the roof. They also retained their original numbers although they lost their names.
A three cylindered version of the class – the U1 class – was also built between 1928 to 1931 with one, A890, being a conversion of the solitary three cylindered K1 class 2-6-4T.
As originally built the class had piston tail rods, tapered chimneys and smokebox snifting valves. As with the N class the tail rods and snifting valves were removed and new chimneys of the U1 pattern fitted. Short smoke deflectors were fitted, as with all Maunsell Moguls, from 1933. The class either hauled 3500 gallon capacity tenders with straight sides or larger 4000 gallon tenders with turned in tops to their sides. A few number also received new frames with a gentler curve between the buffer beam and smokebox.
NºA629 was for two years fitted with an experimental pulverised fuel burner of German design. This was not a success and was abandoned after it was found there was no fuel saving and that powdered coal was potentially explosive. In 1948 two of the class, 1625 and 1797, were experimentally operated as oil burners. Further members of the class were designated for conversion before the experiment was abandoned.
Although perhaps an unsung and unglamorous class the Us performed well doing exactly what they were designed to do. The first withdrawal was in 1962 with the final withdrawals being in 1966.
Four Us have been preserved though all are not currently in working condition. 1618 and 1638 are owned by the Maunsell Locomotive Society and are based at the Bluebell Railway, with 31625 and 31806 based on the Mid-Hants Railway.