GWR 6800 Class

Great Western Railway 6800 Class
6833 Calcot Grange at Bristol Temple Meads in British Railways green livery
Type and origin Power type Steam Builder Great Western Railway Build date 1936–1939 Total produced 80
Specifications Configuration: ​  • Whyte 4-6-0  • UIC 2'Ch2 Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Leading dia. 3 ft 0 in (0.914 m) Driver dia. 5 ft 8 in (1.727 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) Width 8 ft 11 1⁄4 in (2.724 m) Height 13 ft 0 in (3.962 m) Axle load 18 long tons 8 cwt (41,200 lb or 18.7 t) (20.6 short tons) Adhesive weight 55 long tons 2 cwt (123,400 lb or 56 t) (61.7 short tons) Loco weight 74 long tons 0 cwt (165,800 lb or 75.2 t) (82.9 short tons) full Fuel type Coal Fuel capacity 7 long tons 0 cwt (15,700 lb or 7.1 t) (7.8 short tons) Water cap 3,500 imp gal (16,000 l; 4,200 US gal) Firebox:  • Firegrate area 27.07 sq ft (2.515 m2) Boiler pressure 225 psi (1.55 MPa) Heating surface:  • Tubes and flues 1,686.60 sq ft (156.690 m2)  • Firebox 154.78 sq ft (14.380 m2) Superheater: ​  • Heating area 4-element: 191.8 sq ft (17.82 m2), 6-element: 253.38 sq ft (23.540 m2) Cylinders Two, outside Cylinder size 18.5 in × 30 in (470 mm × 762 mm)
Performance figures Tractive effort 28,875 lbf (128.44 kN)
Career Operators Great Western Railway, British Railways Power class GWR: D; BR: 5MT Numbers 6800–6879 Axle load class GWR: Red First run 1936 Retired 1960–1965 Disposition All original locomotives scrapped, GWR 6880 Betton Grange being built

The Great Western Railway (GWR) 6800 Class or Grange Class was a mixed traffic class of 4-6-0 steam locomotive, built to replace the GWR 4300 Class 2-6-0. There were 80 in the class, all built at the Swindon works, using some reconditioned parts from withdrawn 4300 Class locomotives .

The GWR locomotive standardisation policy pursued by G.J. Churchward envisaged a range of locomotive classes which would be suitable for the majority of duties, and yet which would share a small number of standard components. Amongst the designs suggested in 1901 was a 4-6-0 with 5-foot-8-inch (1.727 m) diameter driving wheels, and the Standard No. 1 boiler. Although planned in 1901, none were built during Churchward’s lifetime. C.B. Collett, (Churchward’s successor at Swindon Works) rather introduced the Hall class with 6-foot (1.829 m) diameter driving wheels.

The 4300 Class of 2-6-0 tender locomotives had been introduced on the GWR for mixed traffic duties in 1911, and by 1932 there were 342 in service. However, by the mid 1930s some of the earlier examples were in need of attention and the class as a whole was struggling with some of the duties expected of them. Collett therefore revived the Churchward proposal, but modified the design to include a cab and controls to the current style. Between 1936 and 1939, one hundred 4300 Class were taken out of service and replaced by new 4-6-0 locomotives, eighty of which were of the 6800 (or Grange) class, whilst the remaining 20 were of the 7800 (or Manor) class. It had been intended to replace all of the 4300 Class in this way, but the Second World War stopped the programme.

The Granges were effectively a smaller-wheeled version of the GWR Hall Class.

The wheels, valve motion and tenders were taken from the withdrawn engines, reconditioned and then used in the construction of the 100 new locomotives; the components from one old locomotive were spread amongst more than one of the new engines. The cylinders of the Granges were of the same size as those used on the 4300 Class, but the old cylinders could not be re-used because the cylinders and valves shared a common casting, and the new design called for the separation between cylinder and valve centre lines to be increased by 2 ¹⁄₂ inches (64 mm). This was done in order to make the cylinders level with the axles, but still allow the use of the old valve motion parts.