| GWR 6400 and 7400 Classes | |
|---|---|
| 6400 Class No. 6412 arrives at Sheringham, North Norfolk Railway, August 1999 | |
| Power type | Steam |
| Designer | Collett |
| Builder | GWR 6400 and 30 7400; BR 20 7400 |
| Build date | 6400, 1932 (40) 7400, 1936 (30), 1948 (10), 1950 (10) |
| Total produced | 6400, 40 7400, 50 |
| Configuration | 0-6-0PT |
| Gauge | 4 ft 8 1⁄2 in (1,435 mm) |
| Driver diameter | 4 ft 7 1⁄2 in (1.410 m) |
| Locomotive weight | 6400: 45.6 long tons (46.3 t), 7400: 45.45 long tons (46.18 t) |
| Fuel type | coal |
| Boiler pressure | 6400: 165 psi (1.14 MPa) 7400: 180 psi (1.2 MPa) |
| Cylinders | two inside |
| Cylinder size | 161⁄2 × 24 in (420 × 610 mm) |
| Tractive effort | 6400: 16,510 lbf (73.4 kN) 7400: 18,010 lbf (80.1 kN) |
| Class | 6400: 2P 7400: 2F |
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 very similar but had no push-pull (autotrain) apparatus, but did have 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 64xx and 74xx classes was the join between the bunker and cab side. The 64xx had an arc whereas the later class was at right angles.
Both classes were closely related to the 1930 GWR 5400 Class and 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' 7½" 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 1930's that also had 4' 7½" wheels and 24" stroke cylinders (and by then pannier tanks and full cabs). Strictly speaking this class was from the "larger" group of tank engines with longer wheel bases and 17" or 17½" diameter cylinders that eventually evolved into the 94xx of 1947.
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The smaller wheels of the 64xx's permitted operation in hillier locations than the 5400 Class and allocations were initially to the South Wales valleys.
Engines of class 6400 worked on many of the ex-GWR branch lines in Devon and Cornwall until the early 1960s, when the lines closed or diesel multiple units took over services. Number 6430 was a regular engine on the old Tavistock South branch line and would often run with two autocoaches. No. 6412 was based at Gloucester loco shed and operated the last 'Chalford Shuttle' autotrain service between Gloucester and Chalford in 1962.[1]
There were 40 locomotives in the 6400 Class, numbered 6400-6439[2] and 50 locomotives in the 7400 Class, numbered 7400-7449[2]
Three of the 6400 Class have survived to preservation:
A 64xx Class loco (no. 6412) was the title character of the British 1970s TV series The Flockton Flyer, which was filmed on the West Somerset Railway where the preserved locomotive was based. (No. 6412 was relocated to the South Devon Railway in 2009.)
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