The Great Western Railway (GWR) 4300 Class is a class of 2-6-0 (mogul) steam locomotives, designed by G.J. Churchward for mixed traffic duties. 342 were built from 1911–1932.
Background
In 1906 Churchward fitted a more powerful Standard No. 4 boiler to his successful 3100 Class 2-6-2T to create the GWR 3150 Class. These showed themselves to be successful locomotives but their weight and water capacity meant that they tended to be restricted to suburban passenger traffic. Churchward was looking forward to the replacement of various of his predecessor’s 2-4-0 classes on secondary duties. In 1911 he therefore designed a tender version of the 3150 class which would be suitable for a wide range of intermediate duties.
Design
The class was ‘a total synthesis of standard parts, using the outside cylinders of the Saint, the wheels of ‘31XX’ 2-6-2 tank and the No. 4 boiler, in its superheated form.’ No prototype was required as the fundamental design had proved itself.
Production series
The locomotives quickly proved themselves to be so useful that they were produced more or less continuously in a series of batches (or lots) over a twelve-year period (1911–1923), sometimes incorporating detailed differences. Two further lots were built in 1925 and 1932 by Churchward's successor, Charles Collett.
Lot 183
The first twenty examples, numbered 4301–4320, were delivered by Swindon Works between June and October 1911. These had inside steam pipes, and were among the first GWR locomotives to be fitted with top feed apparatus. Nos. 4311–4320 had boilers designed to operate at pressure but only 4315 and possibly 4316 ever worked at that pressure.
Lots 193, 194 and 198
Three further batches, totalling a further forty locomotives (4321–4360) were built at Swindon and delivered June 1913 and May 1914, before the onset of the First World War impeded further production. These locomotives (and all subsequent examples) had frames lengthened by at the rear to give better access for maintenance as well as providing more room in the cab.
Lots 202 and 204 to 208
The class proved to be ‘just the type that was needed during the 1914–18 war and were accordingly built in considerable numbers during that period.’ Six batches, totalling one hundred locomotives (numbered 4361–4399, 4300, 5300–5359) were built between May 1915 and September 1918, and a further ten (5360–5369) between January and June 1919. From 1917 detailed changes were made to the design giving better weight distribution between the wheels which were later applied to other members of the class. Eleven examples of the class were transported to France during World War I in the service of the Railway Operating Division of the British Army and these were 5319–5326 and 5328–5330. One survives in preservation.
Lots 209, 211, 212, 216, and 230
The first three of these lots were for seventy locomotives built between June 1919 and July 1921 (Nos. 5370-99 and 6300-6341). Lot 216 was for a further 28 locomotives (6342–6369) but Swindon works was then unable to keep pace with the demand for them and only the first twenty were completed after delay, between March and December 1923. The remainder (6362-6369 and 7320/1) were later built under lot 230 in 1925. 6320 was converted to oil firing between 1947 and the equipment was removed in 1949.
Lots 218 and 222
As Swindon works could not keep pace an order was placed with Robert Stephenson and Company in 1921 for fifty locomotives (Nos. 6370–6399 and 7300–7319). The first 35 of these (Lot 218) were built by the company between April 1921 and January 1922. The remaining fifteen were built at Swindon from parts manufactured by RSH between November 1921 and January 1922. In 1925 Nos. 7300–7304 were modified for better balance and had detail alterations.
Lot 276
In 1932, Collett built a further twenty examples (9300–9319) to a modified design with side window cabs, outside steam pipes and a screw reverse. He also extended the frames, increasing the weight to (), which placed them in the Red band of route availability. After passing into British Railways ownership, these locomotives were modified back to light buffer beam design and were renumbered 7322–7341 between 1956 and 1959.