GCR Classes 8D and 8E
| GCR Classes 8D and 8E LNER Class C5 |
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| Type and origin | |
|---|---|
| Power type | Steam |
| Designer | John G. Robinson |
| Builder | GCR, at Gorton |
| Build date | 1905–06 |
| Total produced | 4 |
| Specifications | |
|---|---|
| Configuration: |
|
| • Whyte | 4-4-2 |
| • UIC | 2′B1′ n3v, later 2′B1′ h3v |
| Gauge | 4 ft 8 1⁄2 in (1,435 mm) |
| Leading dia. | 3 ft 6 in (1,070 mm) |
| Driver dia. | 6 ft 9 in (2,060 mm) |
| Trailing dia. | 4 ft 3 in (1,300 mm) |
| Wheelbase | 51 ft 10 in (15,800 mm) |
| Length | 61 ft 11 1⁄4 in (18,879 mm) |
| Axle load | 18.5 long tons (18.8 t) |
| Adhesive weight | 37 long tons (38 t) |
| Loco weight | 73.3 long tons (74.5 t) |
| Tender weight | 48.3 long tons (49.1 t) |
| Total weight | 121.6 long tons (123.6 t) |
| Fuel type | Coal |
| Fuel capacity | 6 long tons (6.1 t) |
| Water cap | 4,000 imp gal (18,000 l) |
| Firebox: • Firegrate area |
26.24 sq ft (2.438 m2) |
| Boiler pressure | 180 psi (1.2 MPa) |
| Heating surface | 1,931 sq ft (179.4 m2) |
| • Tubes | 1,778 sq ft (165.2 m2) |
| • Firebox | 153 sq ft (14.2 m2) |
| Cylinders | Three, one inside high-pressure, two outside low-pressure |
| High-pressure cylinder | 19 in × 26 in (483 mm × 660 mm) |
| Low-pressure cylinder | 21 in × 26 in (533 mm × 660 mm) |
| Valve gear | Stephenson |
| Valve type | HP: piston valve, LP: slide valves |
| Train heating | Steam |
| Loco brake | Steam |
| Train brakes | Vacuum |
| Performance figures | |
|---|---|
| Tractive effort | 13,321 lbf (59.25 kN) |
| Career | |
|---|---|
| Operators | |
| Class |
|
| Number in class | 4 |
| Numbers |
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| Nicknames | "Compounds" |
| Axle load class | LNER: RA 7 |
| Withdrawn | 1946–47 |
| Disposition | All scrapped |
GCR Classes 8D and 8E were two pairs of three-cylinder compound steam locomotives of the 4-4-2 wheel arrangement built in 1905 and 1906 for the Great Central Railway.
In 1903, the Great Central Railway (GCR) had given comparative trials to two pairs of two-cylinder express passenger steam locomotives designed by their Chief Mechanical Engineer, John G. Robinson. These were similar in most respects, the main difference being that one pair (class 8B) were of the 4-4-2 wheel arrangement, whereas the other pair (class 8C) were 4-6-0. These trials demonstrated that the 4-4-2 was best for the GCR conditions, and so five more of class 8B were ordered, soon followed by a batch of 12.
Whilst these were under construction, it was decided to compare the merits of these locomotives against a three-cylinder compound of similar size. Accordingly, two compounds of the 4-4-2 wheel arrangement were built: no. 258 in December 1905 followed by no. 259 in February 1906, and these formed Class 8D.
The class 8D locomotives were designed by Robinson according to the principles of Walter M. Smith, in which there were three cylinders: the boiler fed a single high-pressure cylinder placed between the frames, where the steam was partially used; it was then passed to two low-pressure cylinders mounted outside the frames, which extracted the remaining useful work from the steam. The same system had already been tried by Smith's employers, the North Eastern Railway in their class 3CC of 1898, and with great success by the Midland Railway (MR) in their 1000 class of 1902. The GCR engines used the same size cylinders as the MR engines, but were arranged differently. On the MR engines, all three cylinders drove the same axle, but the GCR engines were designed so that the high-pressure cylinder drove the front coupled axle as on the MR engines, whereas the low-pressure cylinders drove the rear coupled axle; the first use of this arrangement in Britain.
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