GWR 4900 Class

GWR 4900 Class
Preserved 4936 Kinlet Hall
Power type	Steam
Designer	Charles Collett
Builder	GWR Swindon Works
Build date	1928–1943
Total production	259
Configuration	4-6-0
Gauge	1,435 mm (4 ft 8+1⁄2 in)
Leading wheel size	3 ft 0 in (0.91 m)
Driver size	6 ft 0 in (1.83 m)
Minimum curve	8 chains (530 ft; 160 m) normal, 7 chains (460 ft; 140 m) slow
Length	63 feet 0-1/4 inches (19.20 m) over buffers
Width	8 ft 11¼ in (2.72 m)
Height	13 ft 3¼ in (4.04 m)
Axle load	18 tons 19 cwt (42,400 lb/19.2 t)
Weight on drivers	57 tons 0 cwt (127,700 lb/57.9 t)
Locomotive weight	75 tons 0 cwt (168,000 lb/76.2 t)
Tender weight	46 tons 14 cwt (104,600 lb/47.4 t)
Fuel type	Coal
Water capacity	4,000 imp gal (18,000 l; 4,800 US gal)
Boiler pressure	225 lbf/in² (1,550 kPa; 15.8 kgf/cm2)
Fire grate area	27.07 square feet (2.515 m2)
Heating surface: Tubes and flues	1,686.60 square feet (156.690 m2)
Heating surface: Firebox	154.78 square feet (14.380 m2)
Superheater area	262.62 square feet (24.398 m2)
Cylinders	Two, outside
Cylinder size	18.5 in × 30 in (470 mm × 760 mm)
Tractive effort	27,275 lbf (121,330 N)
Career	GWR » BR
Power class	GWR: D, BR: 5MT
Number	4900–4999, 5900–5999, 6900–6958
Official name	Hall
Axle load class	GWR: Red
Withdrawn	1960–1965
Preserved	4920, 4930, 4936, 4942, 4953, 4965, 4979, 5900, 5952, 5967, 5972
Disposition	11 preserved or extant, remainder scrapped

5972 Olton Hall in fictitious red livery for the filming of the Harry Potter films.

The Great Western Railway 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.

Overview

Prototype

The prototype was rebuilt from GWR Saint Class number 2925 Saint Martin in 1924 with smaller driving wheels. Additionally the cylinders were realigned in relation to the driving axle and a more modern 'Castle'-type cab was fitted. The rebuilt Saint Martin emerged from Swindon in 1924 and, renumbered 4900, embarked on three years of trials. During this period Collett introduced other modifications. The pitch of the taper boiler was altered and outside steam pipes were added.

Production

Satisfied with no.4900's performance Collett placed an order with Swindon works and the first of the new two-cylinder Halls entered service in 1928. They differed little from the prototype; the bogie wheel diameter had been reduced by two inches from 3 ft 2 in (0.965 m) to 3 ft 0 in (0.914 m) and the valve setting amended to give an increased travel of 7.5 in (191 mm). The overall weight of the locomotive had increased by 2 tons 10 cwt (5,600 lb/2.5 t) to 75 tons 0 cwt (168,000 lb/76.2 t) but a tractive effort of 27,275 lbf (121.33 kN) compared favourably with the 24,935 lbf (110.92 kN) of the ‘Saint’.

In what amounted to a trial run the first 14 were despatched to the arduous proving grounds of the Cornish main line. However they were so successful here and elsewhere on the GW system that by the time the first production batch of 80 had been completed in 1930 a further 178 were on order. By 1935, 150 were in service and the 259th and last Hall, No. 6958 Oxburgh Hall, was delivered in 1943.

Modified Hall

Collett had been replaced by F.W. Hawksworth in 1941 and Hawksworth created a modified version known as the Modified Hall Class which remained in production until 1950. One of Hawksworth's modifications in changing the design was to equip it better to cope with the low quality coal available during the war. If anything the situation worsened after the war, leading to serious consideration being given to oil firing. Beginning in 1946 with No. 5955 Garth Hall the GWR converted 11 of the class to burn oil. Within four years, however, they had all reverted to coal.

British Railways

All but one of the original Collett Halls entered British Railways service in 1948, the exception being No. 4911 Bowden Hall which took a direct hit during a bombing raid on the Plymouth area in April 1941 and was broken up. Official withdrawals began in 1959 with the prototype Saint Martin. Its accumulated mileage, both in its original form and rebuilt form, was a remarkable 2,092,500 miles.

Preservation

By 1965 the last Hall had been withdrawn from the Western Region without a single one entering the National Collection. Eleven examples of the Hall class have survived to preservation and No. 4942 Maindy Hall is being back-converted into a GWR Saint Class locomotive at Didcot Railway Centre.

List of locomotives

• List of GWR 4900 Class locomotives

In fiction

In the Harry Potter films, No. 5972 Olton Hall is used to pull the Hogwarts Express.

References

• Haresnape, Brian (1978). Collett & Hawksworth Locomotives, A Pictorial History. Ian Allen Ltd. ISBN 0-7110-0869-8. 
• Whitehurst, Brian (1973). Great Western Engines, Names, Numbers, Types and Classes (1940 to Preservation). Oxford Publishing Company. pp. 42–44, 53–55, 62–63. 103, 144. ISBN 0-902888-21-8. 

External links

Wikimedia Commons has media related to: GWR 4900 Class

• Great Western archives - Hall class
• Friends of Locomotive 4930 Hagley Hall