GWR 2900 Class

Great Western Railway 2900 Saint class

2933 Bibury Court

Type and origin Power type Steam Designer George Jackson Churchward Builder GWR Swindon Works Build date 1902-1913 Total produced 77

Specifications Configuration 4-6-0 (thirteen examples were built as 4-4-2 but rebuilt to 4-6-0 1912/13). UIC class. 2'Ch4 Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Leading dia. 3 ft 2 in (0.965 m) Driver dia. 6 ft 8 1⁄2 in (2.045 m) Trailing dia. 1 ft 1 1⁄2 in (0.343 m) (4-4-2 only) Wheelbase loco: 27 ft 1 in (8.26 m) - 27 ft 7 in (8.41 m) loco & tender: 53 ft 4 3⁄4 in (16.28 m) - 53 ft 10 3⁄4 in (16.43 m) Length 63 ft 0 1⁄4 in (19.21 m) Width 8 ft 11 in (2.718 m) Height 13 ft 3 1⁄2 in (4.051 m) Axle load 18 long tons (18 t; 20 short tons) Loco weight 68.30 long tons (69.40 t; 76.50 short tons) Tender weight 43.15 long tons (43.84 t; 48.33 short tons) Fuel capacity 5 long tons (5.1 t; 5.6 short tons) Water cap 3,500 imp gal (16,000 l; 4,200 US gal) - 4,000 imp gal (18,000 l; 4,800 US gal) Firebox:  • Firegrate area 27.22 sq ft (2.529 m2) Boiler GWR Standard No. 1 (with variations) Boiler pressure 225 psi (1.55 MPa) (production series) Heating surface:  • Tubes and flues 1,485.96 sq ft (138.050 m2)  • Firebox 154.94 sq ft (14.394 m2) Superheater: ​  • Type "Swindon No. 3"  • Heating area 307.52 sq ft (28.570 m2) Cylinders Two, outside Cylinder size 18 in × 30 in (457 mm × 762 mm) - 18 1⁄2 in × 30 in (470 mm × 762 mm) Valve gear Stephenson Valve type 10 inches (254 mm) piston valves (2935 rebuilt with poppet valves)

Performance figures Tractive effort 20,530 lbf (91.32 kN) - 24,395 lbf (108.51 kN)

Career Operators Great Western Railway (until 1947); British Railways (until 1953). Class 2900 or Saint Power class GWR: C BR: 4P Number in class 76 Numbers 2900–2955, 2971-2990, 2998 Axle load class GWR: Red Retired 1924–1953 Disposition One rebuilt as Hall class (2925/4900 Saint Martin) remainder scrapped one Hall is currently being back-dated to 2900 specification

The Great Western Railway 2900 or Saint Class incorporated several series of 2-cylinder passenger steam locomotives designed by George Jackson Churchward and built between 1902 and 1913 with differences in the dimensions. The majority of these were built as 4-6-0 locomotives; but thirteen examples were built as 4-4-2 (but converted to 4-6-0 during 1912/13). They proved to be a successful class which established the design principles for GWR 2-cylinder classes over the next fifty years.

After finally converting the last broad gauge lines in 1892, the Great Western Railway (GWR) began a period of modernization as new cut-off lines shortened its routes to west of England, South Wales and Birmingham. During the first decade of the twentieth century the Chief Mechanical Engineer, George Jackson Churchward, designed or acquired a number of experimental locomotives with different wheel arrangements and boiler designs to help him plan for the future motive power needs of the railway. The first of these was a two-cylinder 4-6-0 locomotive, designed in 1901 whilst Churchward was still the Chief Assistant of his predecessor William Dean.

Between 1902 and 1905 Churchward built and tested three prototype locomotives with detail differences, before using the third as the basis for the production series.

The first prototype was completed at the Swindon Works of the GWR (Lot 132) in February 1902. It was numbered 100 and in June 1902 was named Dean (later William Dean) to mark the latter's retirement. The new design incorporated all of Churchward's current ideas including a domeless parallel boiler, raised Belpaire firebox, 19 in (48.3 cm) diameter outside cylinders with 30 in (76.2 cm) piston stroke, and boiler pressure of 200 psi (1.38 MPa). The piston valves were driven by rocking levers actuated by the expansion link of Stephenson valve gear – this particular design was only used on no. 100. The parallel boiler was later replaced with a taper boiler, and then the first superheated taper boiler in 1910. Churchward had studied American boiler design, but he was also later influenced by continental practice in efficient motion design. From the Société Alsacienne de Constructions Mécaniques (SACM) a de Glehn 4-4-2 compound engine was ordered for comparative trials on the GWR. According to E.C. Poultney, No. 100 was the first 4-6-0 locomotive to have high enough boiler capacity and steam ports large enough to handle the steam flow required by large cylinders: "The engine probably influenced to a large extent the use made of engines of the 4-6-0 type". No.100 was renumbered 2900 in 1912, and was withdrawn from service in 1932.