GWR 6959 Class
|Great Western Railway 6959 Class|
6998 Burton Agnes Hall preserved at Didcot Railway Centre
|Builder||GWR/BR Swindon Works|
|UIC classification||2'C h2|
|Gauge||4 ft 8 1⁄2 in (1,435 mm)|
|3 ft 0 in (0.914 m)|
|Driver diameter||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 ¼ in (19.21 m) over buffers|
|Width||8 ft 11 1⁄2 in (2.73 m)|
|Height||13 ft 2 in (4.01 m)|
|Axle load||19 tons 5 cwt (43,100 lb or 19.5 t)|
|Weight on drivers||57 tons 10 cwt (128,800 lb or 58.4 t)|
|Locomotive weight||75 tons 16 cwt (169,800 lb or 77.0 t) full|
|Tender weight||47 tons 6 cwt (106,000 lb or 48.1 t) full|
|Fuel capacity||6 tons 0 cwt (13,400 lb or 6.1 t)|
|Water capacity||4,000 imp gal (18,000 l; 4,800 US gal)|
|Boiler pressure||225 psi (1.55 MPa)|
|Firegrate area||27.07 sq ft (2.515 m2)|
Tubes and flues
|1,582.60 sq ft (147.028 m2)|
|154.90 sq ft (14.391 m2)|
|Superheater area||295 sq ft (27.4 m2)|
|Cylinder size||18.5 × 30 in (470 × 762 mm)|
|Valve gear||Stephenson, inside|
|Valve type||Piston valves|
|Tractive effort||27,275 lbf (121.33 kN)|
|Railroad(s)||Great Western Railway,
|Power class||GWR: D,
|Axle load class||GWR: Red|
The Modified Halls marked the most radical change to Swindon Works' practice since Churchward's time as chief mechanical engineer. 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 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.
The first of the Modified Halls was outshopped from Swindon in 1944. It carried plain black livery and was unnamed. After the nationalisation or Britain's railways in 1948 British Railways continued construction of this Great Western class until 1950.
Some modified Halls were equipped with a flat, high-sided Hawksworth tenders. Once he became Chief Mechanical Engineer, many earlier locomotives also received these tenders so a Hawksworth tender does not necessarily mean a Hawksworth locomotive.
List of locomotives
- Whitehurst, Brian (1973). Great Western engines, names, numbers, types, classes: 1940 to preservation. Oxford: Oxford Publishing Company. pp. 63–64, 69, 103, 131. ISBN 0-902888-21-8. OCLC 815661.
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