BR Standard Class 7
The BR Standard Class 7, otherwise known as the Britannia Class, is a class of "Pacific" type steam locomotive designed under Robert Riddles for use by British Railways for mixed-traffic duties. 55 were constructed between 1951 and 1954. The design employed results from the 1948 locomotive exchanges undertaken in advance of further locomotive classes being constructed. Three batches were constructed at Crewe Works, before the publication of the 1955 Modernisation Plan.
The Britannia Class design was based on best practice from the pre-nationalisation railway companies in terms of operating efficiency and lower maintenance costs; various weight-saving measures also increased the route availability of a Pacific-type locomotive on the British Railways network. The Britannias received a positive reception from their crews, with those regularly operating the locomotives giving them favourable reports as regards performance. However, operation in some areas of the British Railway network returned negative feedback, primarily due to indifferent operation of the locomotive, with its effects on adhering to timetables. They were capable of reaching speeds of up to 90 mph.
The Britannias took their names from great Britons, former Star class locomotives, and Scottish firths. The class remained in service until the last was withdrawn in 1968. Two survived into preservation, the first-of-class, number 70000 Britannia, and 70013 Oliver Cromwell. Number 70000 has hauled mainline excursions and 70013, after a period of display following limited steaming, returned to mainline steam in 2008 for the first time since leaving British Railways ownership. 70000 was returned to the main line in 2011.
Background
Locomotive exchanges were commissioned by the fledgling British Railways during 1948, to compare pre-nationalisation locomotive design across the Big Four railway companies. The research gained from operating the best designs of the GWR, LMS, LNER and Southern railways on different areas of the British Railways network paved the way for several new classes of standardised locomotives intended to replace some of the ageing designs inherited.The new classes were designed by E. S. Cox, under Robert Riddles who had previously designed the WD Austerity 2-8-0 and WD Austerity 2-10-0 locomotives for wartime use. The first design requested by the Railway Executive was for a new express passenger "Pacific" locomotive, designed specifically to reduce maintenance and using the latest available innovations in steam technology from home and abroad. Various labour-saving devices were utilised to produce a simple, standard and effective design, able to produce equivalent power to some of the "Pacifics" that were still available as legacies of the Big Four.
Design features
The design of the "Britannias" was based on best practice from the pre-nationalisation railway companies. For example, they utilised a variation of both boiler and trailing truck 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; but unlike the SR Pacifics, the inner firebox was constructed of copper instead of steel and lacked thermic syphons.The "Britannias" had driving wheels, a compromise for their mixed-traffic role to allow sustained fast running with passenger trains, yet small enough to give sufficient tractive effort for freight haulage.
The largest, only outside, cylinders capable of giving maximum tractive effort whilst staying within the British loading gauge were used for ease of maintenance compared with "inside" cylinders located between the frames of a three- or four-cylindered locomotive. Boiler 'plumbing' was also generally exposed to give ease of access. For ease of maintenance, outside Walschaerts valve gear was used.
A self-cleaning smokebox enabled ash to be ejected through the chimney, reducing the workload of the engine cleaner at the end of a working day. The single chimney was unusual for a "Pacific" type of locomotive, but was chosen because the exhaust dimensions including the blastpipe were designed using work done at the Rugby test plant and 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 design also featured raised running plates above the wheels, which allowed easy access to the inside of the frames for purposes of lubrication.
The "Britannias'" footplate was designed around the requirements of the operating crews, with a mock-up being constructed at Crewe to test ergonomics and usability.
Two injectors were fitted, one on each side of the boiler, securely fixed to the firebox foundation ring to eliminate problems previously experienced with fractured pipework on frame-mounted injectors. The injector on the left of the firebox was a GWR-type live steam injector, that on the right was an 11 mm Davies and Metcalfe exhaust steam injector. These injectors fed the boiler through clack valves of SR design. Unlike the smaller BR Standard locos the exhaust steam manifold within the smokebox saddle was an intricate steel casting.
Construction history
Designed at British Railways' Derby Works, the new class was constructed at British Railways' Crewe Works between 1951 and 1954. The initial order was for 25 locomotives, but such was the demand for the Britannias on the Eastern Region that more were rushed through construction before the teething problems had been ironed out on the prototypes. In total, 55 members of the class were constructed over three batches at Crewe Works, where each was given improvements to improve reliability and efficiency, and to overcome flaws with the original design.- First batch: 70000–70024, constructed between January and October 1951
- Second batch: 70025–70044, constructed between September 1952 and October 1953
- Third batch: 70045–70054, constructed in 1954.
Variations and modifications
An unusual fault with the first engines of the class was fore-and-aft vibration, strong enough to prompt passengers to complain and to cause fire-irons stowed in a longitudinal compartment on top of the tender to work their way forward into the cab. The passengers' complaints were dealt with by reducing the tension in the drawbar spring.
Locomotive tenders were also changed as new, improved designs became available. Some examples of the second batch were equipped with the BR1A tender, which had a higher water capacity of 5,000 gallons. Members of the third batch were equipped with another tender design, the BR1D, which had 9 tons of coal and 4,750 gallons of water, due to the fact that they were intended for use on longer runs in the north of the railway network. This tender design also featured a steam-powered coal pusher, which eliminated the need for crew members to mount the tender to pull forward coal when the locomotive was at a stop.
Nos.70043 and 70044 were delivered with Westinghouse airbrakes fitted alongside the smokebox and with no smoke deflectors. The two locomotives, which looked radically different from the rest of the class, were allocated to Manchester and ran a series of brake trials on the London Midland main line during the mid-1950s. Subsequently, both had the equipment removed and deflectors fitted.
No. 70045 was fitted with LMS-style oval buffers in the course of repairs after collision damage.
On 21 January 1960, the Settle rail crash, which cost the lives of five passengers, was caused when the piston rod, cross-head and connecting rod of No. 70052 came loose and damaged the opposite line as a freight train was approaching. The locomotive of the freight train was derailed towards 70052's train and tore out the sides of three passenger coaches. Part of the slide assembly was redesigned, and was fitted as the locomotives were routinely "shopped".
Western Region based examples had hand/foot holds cut into the smoke deflectors replacing the original handrails after a major derailment, to improve forward visibility. Some of these deflectors subsequently migrated to other members of the class.
Naming
From 1948 until the mid-1950s, the responsibility for recommending names for locomotives on British Railways rested with a Locomotive Naming Committee of three senior railway officers, E. S. Cox, George Dow with Derek Barrie as chairman.The Committee set itself several rules and over the years developed many practices. The names had to be euphonious. Also, their meaning had to be readily apparent to anyone interested, whether railwayman or member of the public. There had to be good publicity value in the names as well as providing good morale for the staff, and the collection of names for a class had to provide some form of class identity. Another rule was not to use names of people who were still alive at the time, and some on the committee had a strong dislike of names or associations with the military. There was a preference for names of heroes and other well-known people. However, slavishly following a single theme to an absurd extent was discouraged.
The name that was to be bestowed on the first class member caused great debate on the committee and the wider executive of British Railways. However noted enthusiast Bishop Eric Treacy suggested the name "Britannia". This set the general theme of the naming process, which featured great Britons, although several deviations from the theme were allowed. These exceptions were allocated to those that operated on the Western Region, which were given names of former Star Class locomotives, and those of the Scottish Region, which were granted the names of the various Scottish firths. The locomotive naming ceremonies were carried out at various railway stations around the British Railways network. No. 70047 was never named.