GWR 4073 Class

GWR 4073 Castle class
4079 Pendennis Castle at Didcot Railway Centre in 2023
Type and origin Power type Steam Designer Charles Collett Builder GWR / BR Swindon Works Order number Lots 224, 232, 234, 280, 295, 296, 303, 310, 317, 324, 357, 367, 375 Build date 1923–1950 Total produced 171
Specifications Configuration: ​  • Whyte 4-6-0  • UIC 2′C h4 Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Leading dia. 3 ft 2 in (0.965 m) Driver dia. 6 ft 8+1⁄2 in (2.045 m) Minimum curve 8 chains (530 ft; 160 m) normal, 7 chains (460 ft; 140 m) slow Length 65 ft 2 in (19.86 m) over buffers Width 8 ft 11 in (2.718 m) Height 13 ft 4+1⁄2 in (4.077 m) Axle load 19 long tons 14 cwt (44,100 lb or 20 t) 22.1 short tons full Adhesive weight 58 long tons 17 cwt (131,800 lb or 59.8 t) 65.9 short tons full Loco weight 79 long tons 17 cwt (178,900 lb or 81.1 t) 89.4 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 Churchward tender: 7 long tons (7.1 t; 7.8 short tons) Collett/Hawksworth tender: 6 long tons (6.1 t; 6.7 short tons) Water cap. Churchward tender: 3,500 imp gal (16,000 L; 4,200 US gal) Collett/Hawksworth tender: 4,000 imp gal (18,000 L; 4,800 US gal) Firebox: ​  • Grate area 29.36 sq ft (2.728 m2) Boiler GWR Standard No. 8[1] Boiler pressure 225 lbf/in2 (1.55 MPa) Heating surface: ​  • Firebox 162.7 sq ft (15.12 m2) (Collett) 163.5 sq ft (15.19 m2) (Hawksworth)  • Tubes 1,857.7 sq ft (172.59 m2) (Collett) 1,799.5 sq ft (167.18 m2) (Hawksworth) Superheater: ​  • Type 14-element "Swindon" (Collett) 21-element (Hawksworth)  • Heating area 262.6 sq ft (24.40 m2) (Collett) 295.0 sq ft (27.41 m2) (Hawksworth) Cylinders Four (two inside, two outside) Cylinder size 16 in × 26 in (406 mm × 660 mm) Valve gear Inside cylinders: Walschaerts Outside cylinders: derived from inside cylinders via rocking bars. Valve type Piston valves
Performance figures Tractive effort 31,625 lbf (140.68 kN)
Career Operators Great Western Railway British Railways Power class GWR: D BR: 7P Numbers 4073–4099; 5000–5099; 7000–7037. Axle load class GWR: Red Locale Great Western Main Line Withdrawn May 1950 to December 1965 Disposition Eight preserved, remainder scrapped

The 4073 or Castle Class are 4-6-0 steam locomotives of the Great Western Railway, built between 1923 and 1950.^[2] They were designed by the railway's Chief Mechanical Engineer, Charles Collett, for working the company's express passenger trains. They could reach speeds of up to 100 mph (160 km/h).^[3]