GWR 6959 Class

Great Western Railway 6959 Class

GWR 4-6-0 Class 6959 No. 6960 'Raveningham Hall' and train at Williton on the West Somerset Railway

Type and origin Power type Steam Builder GWR/BR Swindon Works Build date 1944–1950 Total produced 71 (6959 Peatling Hall-7929 Wyke Hall)

Specifications Configuration 4-6-0 UIC class 2′C h2 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 (530 ft; 160 m) normal, 7 chains (460 ft; 140 m) slow Length 63 ft 0 1⁄4 in (19.21 m) over buffers Width 8 ft 11 1⁄2 in (2.731 m) Height 13 ft 2 in (4.013 m) Axle load 19 long tons 5 cwt (43,100 lb or 19.6 t) (21.6 short tons) Adhesive weight 57 long tons 10 cwt (128,800 lb or 58.4 t) (64.4 short tons) Loco weight 75 long tons 16 cwt (169,800 lb or 77 t) (84.9 short tons) full Tender weight 47 long tons 6 cwt (106,000 lb or 48.1 t) (53.0 short tons) full Fuel type Coal Fuel capacity 6 long tons 0 cwt (13,400 lb or 6.1 t) (5.6 short tons) Water cap 4,000 imp gal (18,000 l; 4,800 US gal) Firebox:  • Firegrate area 27.07 sq ft (2.515 m2) Boiler pressure 225 psi (1.55 MPa) Heating surface:  • Tubes and flues 1,582.60 sq ft (147.028 m2)  • Firebox 154.90 sq ft (14.391 m2) Superheater: ​  • Heating area 295 sq ft (27.4 m2) Cylinders Two, outside Cylinder size 18.5 in × 30 in (470 mm × 762 mm) Valve gear Stephenson, inside Valve type Piston valves

Performance figures Tractive effort 27,275 lbf (121.33 kN)

Career Operators Great Western Railway → British Railways Power class GWR: D, BR: 5MT Numbers 6959–6999, 7900-7929 Axle load class GWR: Red Withdrawn 1963–1965 Disposition Six preserved, remainder scrapped

The Great Western Railway (GWR) 6959 Class or Modified Hall Class is a class of 4-6-0 steam locomotive. They were a development by Frederick Hawksworth of Charles Collett's earlier Hall Class named after English and Welsh country houses.

Although the GWR had been at the forefront of British locomotive development between 1900 and 1930, the 1930s saw a degree of complacency at Swindon reflected in the fact that many designs and production methods had not kept pace with developments elsewhere. This was especially true with the useful GWR 4900 Class, the design of which largely originated in the 1900s and had not fundamentally changed since the mid-1920s.Charles Collett was replaced as the Chief Mechanical Engineer of the Railway by F.W. Hawksworth in 1941 who immediately created a modified version of the design, known as the 'Modified Hall Class'.

The Modified Halls marked the most radical change to Swindon Works' practice since Churchward's time as chief mechanical engineer and was very far from a simple modification of the Hall design. 'Although in outward appearance it looked almost the same, nearly everything about it was new.' Hawksworth's use of plate frames throughout the design was a break with Churchward's practice for 2 cylinder locomotives. The cylinders were cast separately from the smokebox saddle and bolted to the frames on each side. A stiffening brace was inserted between the frames and extended to form the smokebox saddle. The exhaust pipes leading from the cylinders to the blastpipe were incorporated into this assembly.

Additionally, Churchward's bar framed bogie which had been adapted for the original Hall prototype in 1924 was replaced by a plate frame structure with individual springing. There were changes, too, above the running board. Hawksworth decided that the declining quality of coal reaching Great Western depots necessitated a higher degree of superheating. A larger three-row superheater and header regulator were fitted into Swindon No.1 boiler. Improvements were subsequently made to the draughting on some engines, while others were fitted with hopper ashpans.