BR Standard Class 7
From Wikipedia, the free encyclopedia
 BR Standard Class 7 70013 Oliver Cromwell |
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| Power type | Steam |
|---|---|
| Designer | Robert Riddles |
| Builder | Designed at BR Derby, constructed at BR Crewe Works |
| Build date | 1951–1954 |
| Total production | 55 |
| Configuration | 4-6-2 (Pacific) |
| Gauge | 4 ft 8½ in (1,435 mm) |
| Leading wheel size | 3 ft 4 in (1.03 m) |
| Driver size | 6 ft 2 in (1.89 m) |
| Trailing wheel size | 3 ft 6 in (1.09 m) |
| Length | 67 ft 8 in (22.5 m) |
| Locomotive weight | 143 tons (145.29 tonnes) |
| Fuel type | coal |
| Fuel capacity | 7 tons (7.11 tonnes) |
| Water capacity | 4,250 imp. gal (19,110 litres) (with BR1 tender) |
| Boiler pressure | 250 lbf/in² (11.97 kPa) |
| Cylinders | 2 |
| Cylinder size | 20 in × 28 in (50.5 cm × 71 cm) |
| Tractive effort | 32,150 lbf (1,539.35 kN) |
| Career | Eastern Region of British Railways, London Midland Region of British Railways, Scottish Region of British Railways, Southern Region of British Railways, Western Region of British Railways |
| Class | 7MT |
| Locale | Great Britain |
The BR Standard Class 7, otherwise known as the Britannia Class, is a class of 4-6-2 Pacific steam locomotive designed by Robert Riddles for use by British Railways for mixed traffic duties. Fifty-five were constructed between 1951 and 1954. The design was a result of 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 Britannias Class was based on several previous locomotive designs, incorporating the best practices in locomotive technology as regards labour-saving and lowering maintenance costs; various weight-saving measures also increased the route availability of a Pacific-type locomotive on the British Railways network.[2] The Britannias received a positive reception from their crews, with those regularly operating the locomotives giving them favourable reports as regards performance.[3] However, trials 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.
The Britannias took their names from great Britons, former Star Class locomotives, and Scottish firths.[3] The class remained in service until the last was withdrawn in 1968. Two survived into preservation, the doyen, number 70000 Britannia, and 70013 Oliver Cromwell. Only number 70000 has seen service on the railway network since 1968.
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[edit] Background
Locomotive exchanges were commissioned by the fledgling British Railways (BR) during 1948, to test the best and worst aspects of locomotive design within the Big Four railway companies that had existed before nationalisation.[4] 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 to be constructed.[4] These new locomotive designs were intended to replace some of the aging designs inherited by British Railways.
The new classes were designed by 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 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.[4]
[edit] Design features
The basic design of the Britannias owed much to LMS building practices, especially when considering Riddles' previous career with the said railway.[4] 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, whilst weight was kept within the margins laid down by the Light Pacifics, all of which were designed by Oliver Bulleid.[2] 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.[5] 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.[2] 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 advocated that "better results could be obtained from a well designed single chimney than some of the previous double chimney arrangements".[6] The Britannias had 6 ft 2 in (1.9 m) driving wheels, a compromise that took into account the intended mixed-traffic role they were designed for.[2] This meant that they were large enough for sustained fast-running with heavy passenger trains in tow, yet small enough to allow them to undertake more mundane tasks such as freight haulage.[7]
The design also featured raised running plates above the wheels, which allowed easy access to the inside of the frames for purposes of lubrication.[8] 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.[8] 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 footplate was designed around the requirements of the operating crews, with a mock-up being constructed at Crewe to test ergonomics and usability.[9] 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.[2] This meant that all the valve gear was on the outside, eliminating the problems encountered when operating three or four-cylindered locomotives, with poor access to the inside cylinders located between the frames.[2] Boiler 'plumbing' was also generally exposed to maintain ease of access.
[edit] Construction history
Designed at British Railways' Derby Works, the new class was constructed at British Railways' Crewe Works between 1951 and 1954.[10] 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.[11] 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:[12]
- 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.[11]
[edit] Variations and modifications
Problems with the class were experienced immediately, with the first 25 locomotives being withdrawn in October 1951 after several complaints were received from crews regarding the driving wheels shifting on their axles.[13] They were subsequently modified, and released back into revenue-earning service. Initially, the return cranks on the main driving wheels were of LNER block-type, as seen on Arthur Peppercorn's A1s and A2s, but this was changed to the simpler LMS four-stud fitting.[12] This was due to a problem of overheating bearings within the cranks, and difficulty in removing the LNER-type casings.[14] 70035–70039 were built with roller bearings on the leading and trailing coupled axles only and plain bearings on the remaining axles, whilst 70040–70049 were built with plain bearings throughout.[2] Throughout service, the roller bearings used in remaining cases showed no advantage in reliability or cost.
Locomotive tenders were also changed as new, improved designs became available. Some examples of the second batch (70025–70029) were equipped with the BR1A tender, which had a higher water capacity of 5,000 gallons. Members of the third batch (70045–70054) were equipped with another tender design, that of 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.
[edit] Naming the locomotives
The name that was to be bestowed on the first class member caused great debate amongst the executive within British Railways, however, noted enthusiast and Bishop Eric Treacy suggested the name Britannia.[12] This set the general theme of the naming process, which featured great Britons, although several deviations from the theme were undertaken.[2] This lay with 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.[3] The locomotive naming ceremonies were carried out at various railway stations around the British Railways network.[2] No. 70047 was never named.
[edit] Operational details
The class was well liked by crews in most regions of British Railways, with especially glowing reports from those operating them from Stratford depot on the Eastern Region, where its lower weight and high power transformed motive power over the restricted East Anglian lines.[15] However, negative feedback was received from various operating departments, most notably on the Western Region, primarily out of preference for GWR-designed locomotive stock, and as such, Old Oak Common and Plymouth Laira depots declared that the class was surplus to requirements.[9] However, Cardiff Canton depot displayed its liking for the class despite being part of the former GWR empire, and managed to obtain good results on South Wales passenger traffic.[9]
The Midland Region also had favourable reports, but a marked consistency in losing time on the longer runs between Holyhead and Euston was recorded, although all complaints were down to the individual techniques of the operating crews.[3] This was compounded by the irregular allocation of the class to depots all over the network, meaning that few crews ever had a great deal of experience in driving them.[16] The Southern Region also had an allocation of seven in May 1953, when all Merchant Navy Class locomotives had been withdrawn for inspection following 35020 Bibby Line shearing a crank axle on the central driving wheel.[15]
Repairs to the class were undertaken at Crewe, Swindon and Doncaster Works until the financial constraints of the British Railways Modernisation Plan in terms of expenditure on steam began to preclude the regular overhaul of locomotives.[16] During the mid-1960s, overhauls were carried out exclusively by Crewe Works. The first locomotive, number 70007 Coer-de-Lion, was withdrawn from service in 1965, and the entire class was transferred to Carlisle Kingmoor and Glasgow Polmadie depots as steam was displaced by the dieselisation of British Railways. A succession of bulk withdrawals began in 1967, and the last, of number 70013 Oliver Cromwell, took place at the very end of steam operation in Britain, in 1968.[16] Subsequently, that locomotive was selected to represent the class in the National Collection. Only 70000 Britannia, which was privately preserved, has seen mainline service during the preservation era.
[edit] Livery and numbering
The first member of the class was given a livery of plain black without lining; this was changed to the new standard British Railways Brunswick green that was applied to express passenger locomotives after nationalisation, despite being the locomotive being classed as mixed traffic. This was lined in orange and black, and the class was given the power classification 7MT.[17] The Britannias, were numbered under the new British Railways standard numbering system in the 70xxx series.[18] The locomotives were numbered between 70000 and 70054, and featured brass nameplates with an initial black background, followed by red, located on the smoke deflectors.[1] Towards the end of steam, plain green livery was substituted, with the touching-up of existing paintwork being preferred to full aesthetic overhaul.
[edit] Preservation
Two Britannias have survived, the original, number 70000 Britannia and 70013 Oliver Cromwell. Number 70000 was originally selected to represent the class in the embryonic form of the future National Railway Museum, though was ultimately rejected due to the poor mechanical condition the locomotive was in. As a result, 70013 was eventually selected to represent the class for the benefit of future generations. However, 70000 had been purchased privately from British Railways by the Britannia Locomotive Group, therefore also ensuring that the doyen of the class was to survive into the preservation era.[19] Subsequently utilised on mainline railtours, the locomotive was out of use in the late 1990s, requiring work to bring it back to steam; it was eventually sold to Pete Waterman and stored at Crewe. After a spell in storage on the Bressingham Steam Museum in Diss, Norfolk, 70013 was moved to the Great Central Railway (preserved), following an ownership dispute between Bressingham and the National Railway Museum. The locomotive has since been overhauled, and is scheduled to return to steam and mainline use in 2008, the anniversary of the end of steam in Britain, where it will take centre stage.
- For location details of the preserved locomotives, see: List of BR 'Britannia' Class locomotives
[edit] Gallery
 70037 Hereward the Wake (right) with Royal Scot 46115 Scots Guardsman at Carlisle Kingmoor depot, 1964. |
 70015 Apollo at Carlisle, probably 1960. |
[edit] See also
[edit] Footnotes
- ^ a b Clarke, David: Riddles Class 6/7 Standard Pacifics, pp.80–87
- ^ a b c d e f g h i Herring, Peter: Classic British Steam Locomotives, pp. 176–177
- ^ a b c d Langston, Keith: Made in Crewe: 150 Years of Engineering Excellence, p. 65
- ^ a b c d Langston, Keith: Made in Crewe: 150 Years of Engineering Excellence, p. 60
- ^ Clarke, David: Riddles Class 6/7 Standard Pacifics, pp.12–13
- ^ Clarke, David: Riddles Class 6/7 Standard Pacifics, p. 13
- ^ Clarke, David: Riddles Class 6/7 Standard Pacifics, p. 11
- ^ a b Clarke, David: Riddles Class 6/7 Standard Pacifics, p. 12
- ^ a b c Nock, O.S.: British Locomotives of the 20th Century; Volume 2, 1930-1960, p. 198
- ^ Cox, E. S.: British Railways Standard Locomotives, p. 61
- ^ a b Clarke, David: Riddles Class 6/7 Standard Pacifics, p. 22
- ^ a b c Poultney, E.G.: 'Characteristics of the First Standard Locomotives for British Railways' (Engineer), p. 653
- ^ 'Standard locomotives temporarily withdrawn' (Railway Magazine), p. 856
- ^ Epton, R.: 'The power of the Riddles 'Britannia' 4-6-2s' (Steam World), p. 41
- ^ a b Stephenson, Brian: BR Standard Steam Locomotives, p. 10–11
- ^ a b c Clarke, David: Riddles Class 6/7 Standard Pacifics, p. 62
- ^ Clarke, David: Riddles Class 6/7 Standard Pacifics, pp. 46–48
- ^ Clarke, David: Riddles Class 6/7 Standard Pacifics, p. 14
- ^ 'How we saved Britannia ' (The Railway Magazine), p.22
[edit] References
- Clarke, David: Riddles Class 6/7 Standard Pacifics (Locomotives in Detail volume 5) (Ian Allan: Hinckley, 2006) ISBN 0711031770
- Cox, E. S.: British Railways Standard Locomotives (Ian Allan: London, 1966)
- Epton, R.: 'The power of the Riddles 'Britannia' 4-6-2s' (Steam World: 2006, 223)
- Herring, Peter: Classic British Steam Locomotives (Abbeydale Press: London, 2000) Section "BR 'Britannia' Class 7" ISBN 1861470576
- 'How we saved Britannia ' (The Railway Magazine: 2007, 1,275), p.22
- Langston, Keith: Made in Crewe: 150 Years of Engineering Excellence (Mortons Media: Horncastle, 2006) ISBN 0955286808
- Nock, O.S.: British Locomotives of the 20th Century; Volume 2, 1930-1960 (Cambridge: Patrick Stephens, 1984)
- Poultney, E.G.: 'Characteristics of the First Standard Locomotives for British Railways' (Engineer: 1951, 191)
- 'Standard locomotives temporarily withdrawn' (Railway Magazine: 1951, 97)
- Stephenson, Brian: BR Standard Steam Locomotives (Hinckley: Ian Allan, 2007) ISBN 9780711012455
[edit] Further reading
- Gilbert, Dr. P. T. (Ed.): A Detailed History Of BR Standard Steam Locomotives Volume 1: Background to Standardisation and Pacific Classes (Railway Correspondence & Travel Society (RCTS): 1994) ISBN 0901115819
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