GWR 6000 Class 6000 King George V

King George V
GWR No.6000 King George V at STEAM – Museum of the Great Western Railway, Swindon
Type and origin Power type Steam Designer C.B. Collett Builder GWR Swindon Works Build date June 1927
Specifications Leading dia. 3 ft 0 in (0.914 m) Driver dia. 6 ft 6 in (1.981 m) Minimum curve 8 chains (530 ft; 160 m) normal, 7 chains (460 ft; 140 m) slow Length: ​  • Over beams 68 ft 2 in (20.78 m) Width 8 ft 11 1⁄2 in (2.73 m) Height 13 ft 4 3⁄4 in (4.08 m) Axle load 22 long tons 10 cwt (50,400 lb or 22.9 t) full Adhesive weight 67 long tons 10 cwt (151,200 lb or 68.6 t) full Loco weight 89 long tons 0 cwt (199,400 lb or 90.4 t) full Tender weight 46 long tons 14 cwt (104,600 lb or 47.4 t) full Total weight 135 long tons 14 cwt (304,000 lb or 137.9 t) Fuel type Coal Fuel capacity 6 long tons 0 cwt (13,400 lb or 6.1 t) Water cap 4,000 imp gal (18,000 l; 4,800 US gal) Boiler: ​  • Type GWR Number 12 Boiler pressure 250 lbf/in2 (1.72 MPa) Heating surface:  • Tubes 2,008 sq ft (186.5 m2)  • Firebox 194 sq ft (18.0 m2) Superheater: ​  • Heating area 313 sq ft (29.1 m2) Cylinders Four, two inside, two outside Cylinder size 16.25 in × 28 in (413 mm × 711 mm) Valve gear Inside cylinders: Walschaerts Outside cylinders: derived from inside cylinders via rocking bars
Performance figures Tractive effort 40,300 lbf (179.3 kN) original , 39,700 lbf (176.6 kN) after 1st overhaul
Career Operators Great Western Railway/Western Region Class GWR 6000 Class Power class GWR: Special BR: 8P Axle load class GWR: Double Red Current owner National Railway Museum

Great Western Railway (GWR) 6000 Class King George V is a preserved British steam locomotive.

After developing the "new" GWR Star class in the form of the GWR Castle class, Chief mechanical engineer C.B. Collett was faced with the need to develop an even more powerful locomotive to pull 13+ carriage express trains.

Collett successfully argued with the GWR's General Manager, Sir Felix Pole, that had the axle-loading restriction of 19.5 long tons (19,800 kg) of the "Castle" class been increased to the maximum allowable of 22.5 long tons (22,900 kg), an even more powerful locomotive could have been created. Pole agreed to allow Collett to explore such a design, subject to getting tractive effort above 40,000 lbf (180,000 N).

Collett designed the "King" class to the maximum dimensions of the original GWR 7 ft ¹⁄₄ in (2,140 mm) broad-gauge engineering used to develop its mainline, resulting in the largest loading gauge of all the pre-nationalisation railways in the UK, with a maximum height allowance of 13 feet 5 inches (4.09 m). Consequently, this restricted them as to where they could operate under both GWR and British Railways ownership. To accommodate the largest possible boiler, and to conform with Pole's requested tractive effort requirement, the "King" class were equipped with smaller 6 ft 6 in (1.981 m) main driving wheels than the "Castle" class. This resulted in both the GWR's highest-powered locomotive design, but most importantly a higher tractive effort than the "Castle". This combination allowed the "King" class to pull the now required higher-weight 13+ coach express trains from London to Bristol and onwards to the West Country, at a higher-speed timetable average than the "Castle".