The Unique British Railways standard class 8P 4-6-2 Pacific tender steam locomotive no. 71000 Duke of Gloucester was built to replace LMS class 8P Pacific no. 46202 Princess Anne, which was destroyed in the Harrow and Wealdstone rail disaster of 1952. Only the prototype was constructed, designed at Derby Works under the oversight of R. A. Riddles and built at Crewe Works in 1954.
The design was based on the BR Standard class 7 but it was not possible to increase the power output with two-cylinders so Riddles had to reluctantly introduce a third cylinder between the frames. To avoid difficulties in maintaining the inside cylinder’s valve gear, rotary cam-driven British Caprotti gear with poppet valves was fitted instead of conventional Walschaerts gear. The locomotive was coal fired and used a BR1E tender (replaced with a BR1J in 1958).
During construction a standard GWR double chimney was fitted which was too small for the pressure created by the exhaust, leading to poor draughting. It was also discovered during restoration that the fire grate air inlet dampers were smaller than shown on the drawings. These errors led to poor steam production and no further examples were built, furthermore, no effort was made to improve performance as the modernisation plan was coming into circulation. As a result ‘the Duke’ spent it’s short service life hauling boat trains on the undemanding route between Crewe and Holyhead.
The locomotive was Withdrawn in 1962, only 8 years after construction, it’s outside cylinders were removed for display at the Science Museum and the rest of the engine sent for scrap. The Duke languished in Woodham’s Scrapyard, Barry Island until 1974 when it was purchased for preservation. During restoration, the Kylchap exhaust system, recommended for use with Caprotti valve gear was fitted and the fire grate air inlet dampers were enlarged to the correct size. The Duke of Gloucester is now more powerful and reliable than it ever was during British Railways ownership.
BR Standard class 8P 4-6-2 specification
Length: 67 ft 8 in (20.62 m)
Width: 9 ft 0 in (2.74 m)
Height: 13 ft 0½ in (3.98m)
Gauge: 4 ft 8½ in (1.435m)
Driving wheel dia: 6 ft 2 in (1 880mm)
Boiler Pressure: 250 psi (1.72 MPa)
Cylinders: 18 x 28 in (457 x 711mm)
Loco weight: 101 tons 5 cwt (102.875 tonnes)
Tractive effort: 39,080 lbf (173.8 kN)
Last updated: 02/11/11