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LMS Route: Nuneaton to Birmingham New Street

LMS Route: Birmingham New Street to Tamworth

Saltley Shed: mrsalt1251

British Railways Standard Class 7P 'Britannia class' No 70047 is seen standing in front of No 3 roundhouse

British Railways Standard Class 7P 'Britannia class' No 70047 is seen standing in front of No 3 roundhouse (see above and below). Despite the absence of the smokebox number plate, indicating that it might be a candidate for withdrawal, the locomotive looks reasonably maintained and in a relatively clean condition. The locomotive had worked down to Birmingham on a Carlisle to Washwood Heath Sidings trip and after being serviced would return on the up working of this service. Built at Crewe works in June 1954 No 70047 was never to carry a name and remained in service until July 1967 when it was withdrawn from 12A Kingmoor shed in Carlisle.

This was a class of 4-6-2 Pacific steam locomotive designed by Robert Riddles for use by British Railways for mixed traffic duties with fifty-five being constructed between 1951 and 1954. The basic design of the "Britannias" owed much to LMS building practices, especially when considering Riddles' previous career with the said railway. However, in keeping with the necessity to follow best practice in creating standardised steam locomotives, they utilised a variation of both boiler and trailing wheel of the Merchant Navy Class, while weight was kept within the margins laid down by the Light Pacifics, all of which were designed by Oliver Bulleid. The firebox was also similar in having a rocking grate, which allowed the fire to be rebuilt without stopping the locomotive, removing both ash and clinker on the move. A self-cleaning smokebox was used, which enabled ash to flow into the atmosphere, reducing the workload of the engine cleaner at the end of a working day. A single chimney was placed on top of the smokebox, which was unusual for a "Pacific" type of locomotive. This was because the blastpipe was designed by S.O. Ell at Swindon Works, who claimed that "better results could be obtained from a well-designed single chimney than some of the previous double chimney arrangements".

The "Britannias" had 6 ft 2 inch driving wheels, a compromise that took into account the intended mixed-traffic role they were designed for. This meant that they were large enough for sustained fast running with heavy passenger trains, yet small enough to allow them to undertake more mundane tasks such as freight haulage. The design also featured raised running plates above the wheels, which allowed easy access to the inside of the frames for purposes of lubrication. The lack of wheel splashers on this running plate also reduced the risk of the bearings overheating, by allowing more air to flow around the axles when at speed. Wheel splashers were used on older locomotive designs to box-in the top portion of the driving wheels for aesthetic reasons, and to prevent water and dirt from being thrown at the cab windows. The "Britannnias'" footplate was designed around the requirements of the operating crews, with a mock-up being constructed at Crewe to test ergonomics and usability. For ease of maintenance, availability of spare parts and increased reliability, two sets of Walschaerts valve gear were used, along with the largest cylinders capable of staying within the British loading gauge. The "inside" cylinders located between the frames of a three- or four-cylindered locomotive are difficult to access for maintenance; the two-cylinder design of the Class 7 – with all the valve gear on the outside – avoided these maintenance problems. Boiler 'plumbing' was also generally exposed to maintain ease of access.

Saltley Shed: mrsalt1252