BR Standard Class 8

Infobox Locomotive
powertype=Steam
name = BR Standard Class 8

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caption = 71000 "Duke of Gloucester" as preserved.
Note the Caprotti valve gear.
designer = Robert Riddles
builder = BR Crewe Works
builddate = 1954
totalproduction = 1
whytetype = 4-6-2 ("Pacific")
gauge = RailGauge|ussg
leadingsize = 3 ft 4 in (1.03 m)
driversize = 6 ft 2 in (1.89 m)
trailingsize = 3 ft 6 in (1.09 m)
length = 67 ft 8 in (22.5 m)
weight = 154 tons 19 cwt (157.43 tonnes)
fueltype = coal
fuelc

waterc

cylindercount = 3
cylindersize = 19 in × 28 in (455mm × 710mm)
boilerpressure = 250 lbf/in² (11.97 kPa)
tractiveeffort = 39,080 lbf (173.836 kN)
railroad= London Midland Region of British Railways
locale=Great Britain
railroadclass=8P|

The BR Standard Class 8 was a class of 4-6-2 "Pacific" steam locomotive designed by Robert Riddles for use by British Railways. Only the prototype was constructed, which was named "Duke of Gloucester". Constructed at Crewe Works in 1954, the "Duke", as it is also referred to, was a replacement for the destroyed Princess Royal Class locomotive number 46202 "Princess Anne", which was involved in the Harrow and Wealdstone rail disaster of 1952.

The "Duke" was based on the BR Standard Class 7 "Britannia" design. It incorporated three sets of modified Caprotti valve gear, relatively new to British locomotive engineering, and more efficient than two sets of Walschaerts or Stephenson valve gear. The "Duke" was regarded as a failure by locomotive crews due to its poor steaming characteristics and its heavy fuel consumption. Trials undertaken by British Railways also returned negative feedback, reporting problems with the poor draughting of the locomotive having an adverse effect on adhering to timetables.

The result was an operational period of only eight years. This unique locomotive was saved from being scrapped at Woodhams' Scrapyard when it was purchased by a group of railway enthusiasts who restored it from scrapyard to as-built condition in 13 years. Since then, modifications have been made to the original design, resulting in one of the most efficient and powerful locomotives ever to run in Britain. [The Duke of Gloucester Locomotive Trust (2007) [http://www.dukeofgloucester.co.uk/ The changes of the locomotive's characteristics] retrieved August 30, 2007] As a result, the "Duke of Gloucester" can frequently be seen on the mainline around Britain.

Background

Riddles had frequently argued the case for the inclusion of a Standard Class 8 "Pacific" into the standard range of locomotives being introduced by British Railways. However, these proposals were rejected by the Railway Executive on the grounds of cost in attempting to develop a form of steam motive power that was not necessarily required for use on Britain's railways, as there were enough class 8 locomotives available for use. However, opportunity came out of adversity when the short-lived rebuild of the The Turbomotive, 46202 "Princess Anne", was destroyed in the Harrow and Wealdstone rail disaster of 1952.Langston, Keith: "Made in Crewe: 150 Years of Engineering Excellence",p. 64 ISBN 0955286808] A gap now existed in the roster for locomotives with 8P power classification, of which the demand was high for the efficient operation of heavy expresses on the West Coast Main Line between London Euston and Scotland.'British Railways prototype class 8 express passenger locomotive' ("Railway Magazine"), p. 490] This presented Riddles with the perfect opportunity to press the case for his new design, a prototype of which was duly authorised for construction.'British Railways prototype class 8 express passenger locomotive' ("Railway Magazine"), p. 491]

Design details

At first, Riddles wished to develop an enlarged version of his Standard Class 7 "Britannias", as the design still featured a two-cylinder layout.Herring, Peter: "Classic British Steam Locomotives", Section: Standard Class 8, pp. 188–189] However, the size of the cylinders in order to achieve the 8P power classification would have put the design over the British loading gauge limit, and so a reluctant reversion to the three-cylinder layout ensued. This reluctance was borne from experience with the Gresley "Pacifics", where the conjugated valve gear was difficult to maintain due to the location of the middle cylinder between the frames. Therefore, an alternative type of valve gear had to be found.

The valve gear that was settled upon was a modified form of Caprotti valve gear, the novel rotary cam-driven British Caprotti valve gear with poppet valves.'B.R. class 8 4-6-2 locomotive No. 71000' ("Locomotive, Railway Carriage and Wagon Review"), p. 88] This was based upon Italian locomotive practice, and allowed the precise control of steam admission to the cylinders, whilst improving exhaust flow and boiler draughting characteristics when compared to the more conventional Walschaerts and Stephenson valve gear. On paper, this was to create a free-steaming, hard-working locomotive capable of hauling heavy loads over long distances, but in practice, fundamental design errors and undetected deviations from the drawings were made during construction, which combined to prevent the locomotive from ever achieving its expected performance during British Railways ownership.'British Railways standard class "8" locomotives' ("Engineer": 1954), pp. 8–19]

The main problem was known even when the locomotive was under construction, as Mr. L.T. Daniels, the representative of the British Caprotti company, recommended the use of the Kylchap blastpipe, which could have coped with the fierce exhaust blasts experienced with the Caprotti system. However, a standard double chimney of the Swindon type had been fabricated in order to cut costs, and had been installed in the smokebox before Riddles could do anything to change this development. As a result, the locomotive would suffer due to the choke area of both chimney and blastpipe being vastly undersized for the pressure created by the exhaust, leading to poor draughting when in everyday use.'British Railways standard 3 cylinder 4-6-2 express passenger steam locomotive No. 71000' ("HMSO, British Transport Commission"), p. 29 ] Further problems regarding the firebox of the locomotive were only discovered during restoration, including a poorly-dimensioned ashpan and dampers that were vastly undersized, strangling the fire of air when operating at speed.'British Railways standard 3 cylinder 4-6-2 express passenger steam locomotive No. 71000' ("HMSO, British Transport Commission"), p. [58] ]

Construction history

The opportunity to create an entire batch of locomotives within the 8P category was declined by the Railway Executive. This was because the design process had been highly expensive and complex, so that when the locomotive emerged from Crewe Works in 1954, it meant that such thoughts had been precluded, especially with the advent of the Modernisation Plan. As a result, 71000 remained the solitary member of a proposed class of Standard 8P locomotives.

Naming the locomotive

Upon emerging from Crewe Works, the locomotive was named the "Duke of Gloucester" in 1954, prior to entering revenue-earning service. As a result, had further locomotives been constructed, they would have belonged to the "Duke" Class, standing alongside the sister locomotives of the "Britannia" and "Clan" Classes. Since then, the locomotive has colloquially been referred to by generations of steam enthusiasts and crews as the "Duke".

Operational details

The "Duke" was highly unpopular with crews, who regarded it as something of a liability due to its poor steam production. Inefficiencies caused by the aforementioned problems regarding the draughting abilities and firebox design meant that no further examples were constructed.Nock, O.S.: 'Performance and efficiency tests on B.R. class 8 locomotive' ("Engineer": 1957, 204), pp. 293–294] The fact that no effort was made to rectify these problems indicates the change in policy regarding steam locomotives, with the Modernisation Plan entering circulation as the 'Duke' entered service. Based for its entire working life at Crewe North depot, the locomotive was utilised in hauling boat trains on the undemanding North Wales Coast Line between Crewe and Holyhead. All of this culminated in the locomotive having a short service life of only eight years, being finally withdrawn from service in 1962. However, the reputation of the locomotive amongst its crews as being a poor steamer was eventually to disappear, but only after it was rescued from a scrapyard during 1974.

Livery and numbering

The livery of the 'Duke' was a continuation of the standard British Railways Brunswick green applied to express passenger locomotives after nationalisation. This was lined in orange and black, whilst the class was granted the power classification 8P.Clarke, David: "Riddles Class 6/7 Standard Pacifics", pp. 82–83] Following on from the 'Britannias,' "Duke" was numbered under the British Railways standard numbering system in the 71xxx series.Clarke, David: "Riddles Class 6/7 Standard Pacifics", p. 82] The 'Duke' was given the number 71000, and featured brass nameplates with a black background, located on the smoke deflectors.Clarke, David: "Riddles Class 6/7 Standard Pacifics", p. 84]

Preservation

After withdrawal, the "Duke" was initially selected for the National Collection, though it was later decided that only the cylinder arrangement was of interest. One of the outside cylinders was removed for display at the Science Museum, whilst the other was removed to restore balance in readiness for scrapping. The locomotive was purchased by Dai Woodham, though was initially sent to the wrong scrapyard. After retrieval, the "Duke" languished for many years in Woodham's Scrapyard at Barry Island, South Wales, before enthusiasts purchased the locomotive in 1974, forming the Duke of Gloucester Steam Locomotive Trust.Langston, Keith: "Made in Crewe: 150 Years of Engineering Excellence",p. 65 ISBN 0955286808] Restoration began in earnest, though with many components missing, the most expensive of which being the Caprotti valve gear, it took 13 years of effort on the part of enthusiasts, with assistance in the guise of sponsorships from industry, to return the locomotive to as-built condition.

Two significant construction errors were discovered during restoration:

* The chimney was too small compared to other locomotives of similar size, resulting in poor boiler draughting at times of high steam demand. [The Duke of Gloucester Locomotive Trust (2007) [http://www.dukeofgloucester.co.uk/ Problems discovered with original features] retrieved August 30, 2007]

* The firebed (grate) air inlet dampers had not been built to the drawings, and were too small, resulting in poor oxygen supply and inefficient combustion. [The Duke of Gloucester Locomotive Trust (2007) [http://www.dukeofgloucester.co.uk/ Problems discovered with original features] retrieved August 30, 2007]

These were corrected, and the opportunity taken to incorporate some other improvements, including the previously recommended Kylchap exhaust system, which has finally unlocked the locomotive's true potential as a powerful express passenger locomotive. When the "Duke" was first allowed to haul a full load on the main line, it became immediately obvious that the boiler was now producing steam at a more efficient rate, and that the re-born "Duke" was unrecognisable from the failure that was experienced under British Railways ownership [The Duke of Gloucester Locomotive Trust (2007) [http://www.dukeofgloucester.co.uk/ The changes of the locomotive's characteristics] retrieved August 30, 2007] With these modifications, the "Duke" is now the most powerful steam locomotive ever to run on Britain's railways past or present, and ironically, is also more powerful than the English Electric Type 4 diesel locomotives which replaced it in service. The locomotive can be regularly seen hauling enthusiasts' special trains around the country.

The "Duke" has held an impeccable operational record for reliability; however on June 9th 2007 the engine operated a railtour from Preston to Carlisle returning via Settle, where, for operational reasons, the locomotive's start position was changed to Carnforth.Hopkins, Danny and Streeter, Tony: 'The Duke's Bad Day' ("Steam Railway Magazine"), p. 89] Little over convert|30|mi|km into the journey, the locomotive was stopped at Penrith with leaking tubes in the firebox, and removed from the train. The engine was then withdrawn for overhaul before a return to service in January 2008. As the locomotive now bears little mechanical resemblance to that which operated under British Railways, it has also been used as a test bed, incorporating several other modifications and innovations. These are intended to investigate how much further the locomotive's performance can be enhanced, therefore raising speculation surrounding the capabilities of an entire batch of Standard class 8 "Pacifics" had history been different.

Gallery

Sound

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Footnotes

References

* 'British Railways standard 3 cylinder 4-6-2 express passenger steam locomotive No. 71000' ("HMSO, British Transport Commission": London, 1957), p. [58] (Performance and efficiency tests, Bulletin No. 15)

*'British Railways standard class "8" locomotives' ("Engineer": 1954, 197, 81)

* 'B.R. class 8 4-6-2 locomotive No. 71000' ("Locomotive, Railway Carriage and Wagon Review": 1954, 60)

* 'British Railways prototype class '8" express passenger locomotive' ("Railway Magazine": 1954, 100)

* Clarke, David: "Riddles Class 6/7 Standard Pacifics (Locomotives in Detail volume 5)" (Ian Allan: Hinckley, 2006) ISBN 0711031770

* Herring, Peter: "Classic British Steam Locomotives" (Abbeydale Press: London, 2000) Section "BR Standard Class 8" ISBN 1861470576

* Hopkins, Danny and Streeter, Tony: 'The Duke's Bad Day' ("Steam Railway Magazine": 2007, 338)

* Langston, Keith: "Made in Crewe: 150 Years of Engineering Excellence" (Mortons Media: Horncastle, 2006), ISBN 0955286808

* Nock, O.S.: 'Performance and efficiency tests on B.R. class 8 locomotive' ("Engineer": 1957, 204)

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 0-901115-81-9

External links

* [http://www.71000trust.com The 71000 Trust website - latest news and photos of the Duke of Gloucester]
* [http://www.dukeofgloucester.co.uk The Duke of Gloucester website - more detail and pictures]
* [http://www.visitcumbria.com/wc/ssphotos4.htm Steam Special along the West Cumbria Coast 24th Feb and 10th March 2007]