GWR 4900 Class

GWR 4900 Class

Preserved 4953 Pitchford Hall

Type and origin Power type Steam Designer Charles Collett Builder GWR Swindon Works Build date 1928–1943 Total produced 258 (4901 Adderley Hall-6958 Oxburgh Hall) Rebuilder GWR Swindon Works Rebuild date 1924 Number rebuilt 1 (4900 Saint Martin)

Specifications Configuration 4-6-0 UIC class 2'Ch Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Leading dia. 3 ft 0 in (0.914 m) Driver dia. 6 ft 0 in (1.829 m) Minimum curve 8 chains (528 ft; 161 m) normal, 7 chains (462 ft; 141 m) slow Length 63 ft 0 1⁄4 in (19.21 m) over buffers Width 8 ft 11 1⁄4 in (2.724 m) Height 13 ft 3 1⁄4 in (4.045 m) Axle load 18 long tons 19 cwt (42,400 lb or 19.3 t) (21.2 short tons) Adhesive weight 57 long tons 0 cwt (127,700 lb or 57.9 t) (63.8 short tons) Loco weight 75 long tons 0 cwt (168,000 lb or 76.2 t) (84.0 short tons) Tender weight 46 long tons 14 cwt (104,600 lb or 47.4 t) (52.3 short tons) Fuel type Coal Water cap 3,500 imp gal (16,000 l; 4,200 US gal) - 4,000 imp gal (18,000 l; 4,800 US gal) Firebox:  • Firegrate area 27.07 square feet (2.515 m2) Boiler pressure 225 lbf/in2 (1,550 kPa; 15.8 kgf/cm2) Heating surface:  • Tubes and flues 1,686.60 square feet (156.690 m2)  • Firebox 154.78 square feet (14.380 m2) Superheater: ​  • Heating area 262.62 square feet (24.398 m2) Cylinders Two, outside Cylinder size 18.5 in × 30 in (470 mm × 762 mm)

Performance figures Tractive effort 27,275 lbf (121,330 N)

Career Operators GWR » BR Power class GWR: D, BR: 5MT Numbers 4900–4999, 5900–5999, 6900–6958 Official name Hall Axle load class GWR: Red Withdrawn 1941 (4911 Bowden Hall), 1959–1965 (remainder) Preserved 4920, 4930, 4936, 4942, 4953, 4965, 4979, 5900, 5952, 5967, 5972 Disposition Ten preserved or extant, one backdated to GWR Saint Class, remainder scrapped

The Great Western Railway (GWR) 4900 Class or Hall Class is a class of 4-6-0 mixed traffic steam locomotives designed by Charles Collett. A total of 259 were built, numbered 4900–4999, 5900–5999 and 6900–6958. The LMS Stanier Class 5 4-6-0 and LNER Thompson Class B1 both drew heavily on design features of the Hall Class. After nationalisation in 1948, British Railways gave them the power classification 5MT.

By the end of 1923 the GWR was well served with express passenger locomotives of the Saint and Star classes and had recently introduced the Castle Class. However the mixed traffic 2-6-0 locomotives of the 4300 Class were beginning to struggle with the increasing loads. George Jackson Churchward had recognised this with the introduction of the 4700 class 2-8-0 with 5 ft 8 in (1.727 m) driving wheels, intended for express goods and relief passenger trains. However, Collett preferred the idea of a Saint Class with smaller wheels to undertake these duties as this would provide a leading bogie. He therefore rebuilt number 2925 Saint Martin with 6 ft (1.829 m) driving wheels.

The prototype of the new class was rebuilt in 1924 and the cylinders were realigned in relation to the driving axle and a more modern 'Castle'-type cab was fitted. Saint Martin emerged from Swindon in 1924 and embarked on three years of trials. During this period Collett introduced other modifications such a changing the pitch of the taper boiler and adding outside steam pipes.