GWR 3031 Class “Dean Single”

Description

The Great Western Railway Class 3031 or more commonly known as the “Dean Single” were a group of 4-2-2 Single locomotives designed by William Dean and built between 1891 and 1899 for use on top link expresses.

The first locomotives of this class were built between April and August 1891 as eight broad gauge convertible 2 – 2 – 2 engines, numbers 3021 to 3028 and ran in this configuration until the end of Broad Gauge working in May 1892. Another 22 locomotives were built as standard gauge 2 – 2 – 2’s in late 1891 and early 1982, numbered 3029-30 and 3001 to 3020, with 3021-8 being converted to standard gauge in mid 1892. With a driving wheel of 7 feet 8½ inches, the boiler diameter was restricted to just 4 feet 3 inches, which required a boiler length of 11 feet 6 inches in order to provide sufficient heating surfaces for efficient steaming. With this barrel length, the engines were very heavy on the leading wheels and unsteady at speed. Unfortunately, on the 16th of September 1893, the leading axle of number 3021 Wigmore Castle broke inside Box Tunnel causing the train to derail. Between March and December 1894, all thirty members had their frames lengthened to accommodate a leading bogie altering the design to a 4 – 2 – 2 configuration. In addition the cylinder diameter was reduced from 20 to 19 inches, decreasing the tractive effort from 14,115 to 12,200 pounds. The underhung trailing springs were at first retained on the rebuilds until transfer above the platform occurred between 1895 and 1897.

As Wigmore Castle was being rebuilt, the first locomotive to be built new as a 4 – 2 – 2, number 3031 Achilles was also outshopped. The class were then officially known as the 3031 Achilles class, but are frequently known as the 3001 class or ‘Dean Singles’. The rest of the class appeared in batches until the last, number 3080 Windsor Castle, was delivered in March 1899.

This was the period when George Churchward was experimenting with various boiler and firebox designs. The first alteration concerned the clackboxes that feed water to the boiler. A complete absence of clackboxes favoured by Dean on the initial engines was soon replaced by enormous brass mountings on the side of the barrel. In turn, these were superseded in 1898 by a much smaller mounting with a vertical feed pipe which gave way to a hidden feed to the bottom of the barrel. In the same year, in common with many classes, thicker tyres were introduced increasing the wheel diameters to 4 feet 1½ inches bogie, 7 feet 9 inches driver and 4 feet 7½ inches trailing.

The class was originally built for working the West of England expresses between London and Newton Abbot via Bristol and for several years they practically monopolised this route. Unfortunately as train loads began to increase from the turn of the century and more 4 – 4 – 0 locomotives were produced, their usefulness relegated them to occasional turn of this traffic until a larger turntable was installed at Wolverhampton Stafford Road shed and the class began working to Birmingham and Wolverhampton from Paddington. In addition, other routes given over to the 4 – 2 – 2s included Worcester to Oxford and Bristol to Taunton.

As just thirty members of the class had been rebuilt (some more than once!), and the difficulty in coping with more modern operating methods showed the weaknesses in the original 4 – 2 – 2 design, the first withdrawals came early in the locomotives lives. The first engines to be withdrawn were numbers 3005 Britannia and 3020 Sultan in February 1908, while the later series of rebuilt locomotives began to disappear in June 1913 with numbers 3018 Glenside and 3048 Majestic. The final ‘Dean Singles’ to be withdrawn were numbers 3050 Royal Sovereign and 3074 ex Princess Helena in December 1915. Contrary to popular belief, Churchward was not anxious to scrap the class but to alter the engines to a 4 – 4 – 0 configuration incorporating the 7 feet 2 inch wheels of the ‘Armstrong’ class, but the problems of altering the frames from a 4 feet 7 inch trailing wheel to a 7 feet 2 inch driving wheel were too great.