BR Standard Class 7

BR Standard Class 7 [1]

Type and origin
Power type Steam
Designer Robert Riddles
Builder BR Crewe Works
Build date January 1951 – September 1954
Total produced 55
Specifications
Configuration 4-6-2
UIC class 2′C1′h2
Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge
Leading dia. 3 ft 0 in (0.914 m)
Driver dia. 6 ft 2 in (1.880 m)
Trailing dia. 3 ft 3 1⁄2 in (1.003 m)
Length 68 ft 9 in (20.96 m)
Width 8 ft 8 3⁄4 in (2.66 m)
Height 13 ft 0 1⁄2 in (3.98 m)
Axle load 20.50 long tons (20.83 t; 22.96 short tons)
Adhesive weight 61.50 long tons (62.49 t; 68.88 short tons)
Loco weight 94.00 long tons (95.51 t; 105.28 short tons)
Tender weight BR1: 49.15 long tons (49.94 t; 55.05 short tons)
BR1A: 52.50 long tons (53.34 t; 58.80 short tons)
BR1D: 54.50 long tons (55.37 t; 61.04 short tons)
Tender type BR1 (40), BR1A (5), or BR1D (10)
Fuel type Coal
Fuel capacity BR1/BR1A: 7.0 long tons (7.1 t; 7.8 short tons)
BR1D: 9.0 long tons (9.1 t; 10.1 short tons)
Water cap BR1 4,250 imp gal (19,300 l; 5,100 US gal)
BR1A: 5,000 imp gal (23,000 l; 6,000 US gal)
BR1D: 4,750 imp gal (21,600 l; 5,700 US gal)
Firebox:
 • Firegrate area		 42 sq ft (3.9 m2)
Boiler BR1
Boiler pressure 250 psi (1.72 MPa)
Heating surface:
 • Tubes and flues		 2,264 sq ft (210.3 m2)
 • Firebox 210 sq ft (20 m2)
Superheater:
 ​
 • Heating area 718 sq ft (66.7 m2)
Cylinders Two, outside
Cylinder size 20 in × 28 in (508 mm × 711 mm)
Performance figures
Tractive effort 32,150 lbf (143.0 kN)
Factor of adh. 4.23
Career
Operators British Railways
Power class 7MT
Numbers 70000–70054
Axle load class Route availability 8
BR (WR): Red
Locale Eastern Region, London Midland Region, Scottish Region, Southern Region, Western Region
Withdrawn June 1965 – August 1968
Disposition Two preserved, remainder scrapped

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 Britannia Class was based on several previous LMS locomotive designs,and also significantly influenced by the Bulleid SR Pacifics, notably in the boiler and rear truck design, 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 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 (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 ageing 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 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.[4]

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, while 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] but unlike the SR Pacifics, the inner firebox was constructed of copper instead of steel, and lacked thermic syphons.[6][7] 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 claimed that "better results could be obtained from a well-designed single chimney than some of the previous double chimney arrangements".[8] The "Britannias" had 6 ft 2 in (1.88 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, yet small enough to allow them to undertake more mundane tasks such as freight haulage.[9]

The design also featured raised running plates above the wheels, which allowed easy access to the inside of the frames for purposes of lubrication.[10] 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.[10] 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.[11] 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] 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.[2] Boiler 'plumbing' was also generally exposed to maintain ease of access. In common with other BR standard designs there was no exhaust injector, as this device was temperamental unless rigorously maintained.[12]

Following experience of occasional cracks appearing near the spring brackets, had one or more further batches of Class 7 Standard Pacifics been built to complete the intended 91 engines,[13] the chassis would have been rearranged to be similar to that used on the solitary BR Standard Class 8 Duke of Gloucester and that drawn up by Derby Drawing Office for the 2nd batch of Class 6 Standard Pacifics. This would have resulted in the locomotive riding on cast steel "sub-frames" carrying the spring brackets.[14] Unlike the smaller BR Standards the exhaust steam manifold within the smokebox saddle (along with the BR Standard Class 6 engines) was an intricate steel casting.[15]

Construction history

Designed at British Railways' Derby Works, the new class was constructed at British Railways' Crewe Works between 1951 and 1954.[16] 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.[17] 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.[18]

Variations and modifications

70013 Oliver Cromwell at Bressingham, May 2004

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.[19] 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.[18] This was the result of a problem of overheating bearings within the cranks, and difficulty in removing the LNER-type casings.[20] 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] However throughout their service the roller bearings used in remaining cases showed no advantage in reliability or cost.

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.[21]

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, 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 (Longsight) 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.[22]

No. 70045 was fitted with LMS-style oval buffers in the course of repairs after collision damage (see photograph).

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.[23] 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 rather than steps, to improve forward visibility after one of the class was involved in a major derailment.

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 (they had to have a pleasant sound). 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 (largely because they were fed-up with the recently ended war). 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.[24]

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".[18] This set the general theme of the naming process, which featured great Britons, although several deviations from the theme were allowed.[2] 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.[3] The locomotive naming ceremonies were carried out at various railway stations around the British Railways network.[2] No. 70047 was never named.

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.[25] However, negative feedback was received from various operating departments, most notably on the Western Region. The criticism was primarily out of partisan preference for GWR-designed locomotive stock among Western Region staff;[26][27] in particular, the class was 'left-hand drive' in contrast to 'right-hand drive' GWR locomotive and signalling practice, a factor in the Milton rail crash of 1955.[28]

For this reason, the Western Region locomotive depots at Old Oak Common and Plymouth Laira declared that the class was surplus to requirements.[11][27] 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.[11]

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.[29] The Southern Region also had an allocation of seven in May 1953, when all Merchant Navy Class locomotives were temporarily withdrawn for inspection after 35020 "Bibby Line" sheared a crank axle on the central driving wheel.[30]

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.[29] During the mid-1960s overhauls were carried out exclusively at Crewe Works. The first locomotive to be withdrawn from service was number 70007 "Coeur-de-Lion" in 1965, and the entire class was gradually 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 in 1968, at the very end of steam operation in Britain.[29] Subsequently, that locomotive was selected to represent the class in the National Collection. Only 70000 "Britannia", which was privately preserved, saw main line service during the preservation era – until 2008, when 70013 "Oliver Cromwell"'s restoration was completed, and she worked part of the "15 Guinea Special" – a special train run to commemorate the final BR steam working in 1968. 70013 is now to be found operating main line railtours over the Network Rail system.

Table of withdrawals
Year Quantity in
service at
start of year 		Quantity
withdrawn 		Locomotive numbers Notes
1965 55 2 70007/43
1966 53 12 70000–01/17–19/30/36–37/50/52–54
1967 41 40 70002–06/08–12/14–16/20–29/31–35/38–42/44–49/51
1968 1 1 70013

Accidents and incidents

Main article: Milton rail crash

[33]

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 the locomotive being classed as mixed traffic. This was lined in orange and black, and the class was given the power classification 7MT.[34] The "Britannias" were numbered under the new British Railways standard numbering system in the 70xxx series.[35] 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.[36] Towards the end of steam plain green livery was substituted, with the touching-up of existing paintwork being preferred to full aesthetic overhaul.

Preservation

Preserved 7MT 70013 Oliver Cromwell approaching Weybourne on the North Norfolk Railway on 11 March 2010.

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, but she 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 ensuring that the doyen of the class was to survive into the preservation era.[37] 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 returned to steam in May 2008 on the Great Central Railway after the readers of Steam Railway magazine contributed towards its overhaul. In July 2008 it appeared in WCRC's Open Weekend at Steamtown, Carnforth. August saw the locomotive return to the main line. Its first turn was the 1T57 'Fifteen Guinea Special' re-run from Manchester to Carlisle, 40 years after it performed the same duty in 1968. As a result, both preserved members of the class have operated on the mainline in preservation.

After its sale to the Royal Scot Locomotive and General Trust, 70000 was overhauled at Crewe and returned to the main line in 2011 (its 60th anniversary), initially in unlined black without name plates as originally outshopped in 1951 (the plates were first fitted for the Festival of Britain later that year).

For location details of the preserved locomotives, see: List of BR 'Britannia' Class locomotives

Gallery

See also

Footnotes

  1. ↑ Clarke 2006, pp. 80–87
  2. 1 2 3 4 5 6 7 8 9 Herring 2000, pp. 176–177
  3. 1 2 3 4 Langston 2006, p. 65
  4. 1 2 3 4 Langston 2006, p. 60
  5. ↑ Clarke 2006, pp. 12–13
  6. ↑ Bradley 1976, p. 8
  7. ↑ Gilbert & Chancellor 1994, pp. 25–26, 47
  8. ↑ Clarke 2006, p. 13
  9. ↑ Clarke 2006, p. 11
  10. 1 2 Clarke 2006, p. 12
  11. 1 2 3 Nock 1984, p. 198
  12. ↑ Tuplin, W.A. (1971). British Steam since 1900. Pan. p. 149. ISBN 0 330 02721 2.
  13. ↑ http://72010-hengist.org/history.html
  14. ↑ BR drawings including SL/DE/21642, SL/DE/21631 and SL/DE/22042 from the NRM indicate the arrangements used on the Class 8 and the proposed 2nd batch of Class 6s
  15. ↑ Confirmed on original BR drawing SL/DE/19620 sourced from the NRM
  16. ↑ Cox 1966, p. 61.
  17. 1 2 Clarke 2006, p. 22
  18. 1 2 3 Poultney 1951, p. 653
  19. ↑ "Standard locomotives temporarily withdrawn". The Railway Magazine. Vol. 97 no. 608. December 1951. p. 856.
  20. ↑ Epton 2006, p. 41
  21. ↑ Tuplin, W.A. (1971). British Steam since 1900. Pan. p. 151. ISBN 0 330 02721 2.
  22. ↑ Weekes 1975, p. 38.
  23. ↑ Rolt, L.T.C. (1976). Red for Danger. Pan. p. 269. ISBN 978-0-330-29189-7.
  24. ↑ Itinerary dated 8 October 1993, Queen of Scots Train.
  25. ↑ Stephenson 2007, pp. 10–11.
  26. ↑ British Railways Illustrated magazine, Vol 5, IrwellPress. Published September 1996, page 612
  27. 1 2 Derry, Richard. The Book of The Britannia Pacifics, Irwell Press, published 2004 ISBN 1-903266-48-3
  28. ↑ British Railway Disasters 1996, pp. 112–3,114
  29. 1 2 3 Clarke 2006, p. 62
  30. ↑ Stephenson 2007, p. 12.
  31. ↑ "Locomotive failure near Winchfield 23 November 2013" (PDF). Rail Accident Investigation Branch. p. 32. Retrieved 17 June 2014.
  32. ↑ Gerard & Hamilton 1981, pp. 89-94.
  33. ↑ Report on the Derailment which occurred on 20th November 1955 at Milton (near Didcot) in the Western Region British Railways at The Railways Archive.(C) Crown Copyright acknowledged)
  34. ↑ Clarke 2006, pp. 46–48
  35. ↑ Clarke 2006, p. 14
  36. ↑ Clarke 2006, p. 52
  37. ↑ 'How we saved Britannia ' (The Railway Magazine), p.22

References

Further reading

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