GWR 6400 Class

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GWR 6400 and 7400 Classes
6417 at Aberdare (Low Level) in 1954
Type and origin Power type Steam Designer Charles Collett Builder GWR/BR Swindon Works Order number 6400: Lots 277 (part), 294, 300, 305 7400: 307, 371, 380 Build date 6400: 1932 (40) 7400: 1936 (30), 1948 (10), 1950 (10) Total produced 6400: 40 7400: 50
Specifications Configuration: ​  • Whyte 0-6-0PT Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Driver dia. 4 ft 7+1⁄2 in (1.410 m) Length 31 ft 1 in (9.474 m) Width 8 ft 7 in (2.616 m) Height 12 ft 2+15⁄16 in (3.732 m) Loco weight 6400: 45.6 long tons (46.3 t; 51.1 short tons) 7400: 45.45 long tons (46.18 t; 50.90 short tons) Fuel type Coal Fuel capacity 3 long tons 18 cwt (8,700 lb or 4 t) (3.2 short tons) Water cap. 1,100 imp gal (5,000 L; 1,300 US gal) Firebox: ​  • Grate area 16.76 sq ft (1.557 m2) Boiler GWR Standard No. 21[1] Boiler pressure 6400: 165 psi (1.14 MPa) 7400: 180 psi (1.2 MPa) Cylinders two inside Cylinder size 16+1⁄2 in × 24 in (419 mm × 610 mm) Valve gear Stephenson Valve type piston valves
Performance figures Tractive effort 6400: 16,510 lbf (73.4 kN) 7400: 18,010 lbf (80.1 kN)
Career Operators Great Western Railway • British Railways Class GWR 6400 and 7400 Power class 6400: BR 2P 7400: BR 2F Numbers 6400: 6400-6439 7400: 7400-7449 Locale Western Region Withdrawn 1958–1965 Disposition Three 6400s preserved, remainder scrapped. All 7400 locomotives scrapped.

The Great Western Railway (GWR) 6400 Class is a class of 0-6-0 pannier tank steam locomotive introduced by Charles Collett in 1932. All 40 examples were 'auto-fitted' – equipped with the remote-control equipment needed for working autotrains.

The 1936 GWR 7400 Class was a similar class, without the autotrain apparatus, but with a higher boiler pressure of 180 psi, providing a small but useful increase in power. An initial build of 30 in 1936-1937 was added to by British Railways in two batches each of ten locos in 1948 and 1950. These were destined for a short life, the briefest being only nine years. A minor visual difference between the 5400 and earlier 6400, and the later series of 6400, with the 7400 classes was at the join between cab and bunker. The 5400 and early 6400 had an arc whereas the later 6400 and the 7400 class was straight. The early locos also had a lip at the leading edge of the cab roof, whereas the later locos had a plain corner edge.

Both classes were closely related to the 1930 GWR 5400 Class, which was in turn an evolution of both the Armstrong 1874 GWR 850 Class and the Dean 1891 GWR 2021 Class. Thus the basic design was almost sixty years old when new, the 4 ft 7+1⁄2 in (1.410 m) driving wheels being the main distinguishing factor, apart from the more modern profile. There were also superficial similarities with the GWR 645 Class as extant in the 1930s, that also had 4 ft 7+1⁄2 in (1.410 m) wheels and 24 in (610 mm) stroke cylinders (and by then pannier tanks and full cabs).