GWR 3252 Class
3258 King Arthur
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| Type and origin | |
|---|---|
| Power type | Steam |
| Designer | William Dean |
| Builder | GWR Swindon Works |
| Build date | 1895–1899 |
| Specifications | |
|---|---|
| Configuration | 4-4-0 |
| UIC class | 2'B ht |
| Gauge | 4 ft 8 1⁄2 in (1,435 mm) standard gauge |
| Leading dia. | 3 ft 8 in (1.118 m) |
| Driver dia. | 5 ft 8 in (1.727 m) |
| Axle load | 15 long tons 7 cwt (34,400 lb or 15.6 t) (15.6 t; 17.2 short tons) full |
| Loco weight | 46 long tons 0 cwt (103,000 lb or 46.7 t) (46.7 t; 51.5 short tons) full |
| Tender weight | 24 long tons 0 cwt (53,800 lb or 24.4 t) (24.4 t; 26.9 short tons) full |
| Total weight | 70 long tons 0 cwt (156,800 lb or 71.1 t) (71.1 t; 78.4 short tons) full |
| Fuel type | Coal |
| Boiler pressure | 160 lbf/in2 (1.1 MPa) 180 lbf/in2 (1.2 MPa) after refit |
| Heating surface: • Tubes |
1,285.58 sq ft (119.434 m2) |
| • Firebox | 115.27 sq ft (10.709 m2) |
| Cylinders | Two, inside |
| Cylinder size | 18 in × 26 in (457 mm × 660 mm) |
| Valve gear | Stephenson |
| Train brakes | Vacuum |
| Career | |
|---|---|
| Operators | GWR » BR |
| Withdrawn | 1929-1951 |
| Disposition | All scrapped |
The Great Western Railway 3252 or Duke Class were 4-4-0 steam locomotives with outside frames and parallel domed boilers. They were built in five batches between 1895 and 1899 for express passenger train work in Devon and Cornwall. William Dean was their designer, possibly with the collaboration of his assistant, George Jackson Churchward. Four prototype 4-4-0s, of the Armstrong Class, had already been built in 1894.
The outside frames of the Dukes were curved upwards over each pair of driving wheels. Inner and outer frames were 3⁄4 in (19 mm) thick. The first 40 members of the class were fitted with Mansell pattern bogie wheels with wooden centres. The first 25 tenders built also had Mansell pattern wheels, and a shorter than normal wheelbase of 11 ft (3.35 m) so that the locomotives would fit on the smaller turntables then in use west of Newton Abbot. The engine bogie was of a centre-less type designed by Dean.
The majority of the class were fitted with round-topped fireboxes of the same diameter as the boiler. The last four were fitted with Belpaire fireboxes, raised a few inches above the boilers. Eighteen of the Duke class were later rebuilt with domeless tapered boilers and Belpaire fireboxes between October 1906 and January 1909. They were reclassified as members of the Bulldog Class. A further Duke, no. 3273 Armorel, had been fitted with a parallel domeless boiler in February 1902, converting it to a Camel Class locomotive. It was fitted with a Bulldog-type boiler in October 1910. By December 1923 all remaining Dukes had been fitted with flush-topped Belpaire fireboxes and domed boilers pressed to 180 lbf/in2 (1.2 MPa). Duke no. 3258, King Arthur, built August 1895, was fitted with a superheater in December 1896. The rest of the class, with the exception of two locomotives, were fitted with superheaters between August 1911 and September 1946. The class had distinctive long smokeboxes, extended to hold a diaphragm plate and net for spark prevention.
Slide valves were fitted underneath the cylinders, and were driven directly by eccentrics on the leading driving axle through Stephenson valve gear. This position had the advantage that, when the regulator was closed and steam pressure shut off, the valves would drop away from the steam ports, thus reducing wear on the valves and port faces. Dean's earlier designs had used slide valves mounted vertically between the cylinders; the new position allowed an increase in cylinder diameter from 17 in (432 mm) to 20 in (508 mm) in the Armstrong Class. The Dukes had 18 in (457 mm) diameter cylinders, possibly due to permanent way weight restrictions and a reduced supply of steam from the Dukes' smaller boilers.
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Wikipedia