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The British Railways BR Standard Class 9F 2-10-0 is a class of steam locomotive designed for British Railways by Robert Riddles. The Class 9F were the last in a series of standardised locomotive classes designed for British Railways during the 1950s, and were intended for use on fast, heavy freight trains over long distances. It was one of the most the most powerful locomotive types ever constructed in Britain, and successfully performed its intended duties. From time to time in the 1950s, the class worked passenger trains with great success, indicating the versatility of the design, sometime considered to represent the ultimate in British steam development. Several variants were constructed for experimentation purposes, in an effort to reduce costs and maintenance, although these met with varying degrees of success. The total number built was 251, with production being shared between Swindon and Crewe Works with the last, 92220 Evening Star, constituting the final steam locomotive to be built by British Railways in 1960. Withdrawals began in 1964, with the final locomotives removed from service in 1967. Several examples have survived into the preservation era in varying states of repair, including Evening Star.

Background
The British Transport Commission had proposed that the existing steam locomotive fleet be replaced by both diesel and electric traction. However the board of British Railways, which wanted the railways to be completely electrified, ignored the BTC and ordered a new fleet of 'standard' steam locomotive designs as an interim motive power solution ahead of electrification. Freight was well catered for in terms of locomotive availability after nationalisation in 1948, with a number of heavy freight locomotives built to aid the war effort forming part of British Railways' inheritance. This consisted of 666 LMS 8F class 2-8-0 and numerous Robert Riddles designed WD Austerity 2-8-0s and WD Austerity 2-10-0s.

It was the Eastern Region's Motive Power officer, L. P. Parker, who made the case for a new design of powerful freight locomotive, able to shift heavy loads at fast speeds in round trips between distant destinations within the eight-hour shift of the footplate crew. Riddles took up the challenge, initially designing a 2-8-2 locomotive, but settled upon the 2-10-0 wheel arrangement for the increased traction and lower axle load that five coupled axles can provide. The resultant design became one of the most successful locomotive classes ever constructed in Britain.

Design features
The 9F was designed to operate freight trains of up to 900 tons (914 tonnes) at 35 mph (56 km/h) with maximum fuel efficiency. The original proposal was for a boiler from the BR Standard Class 7 Britannia 4-6-2, adapting it to a 2-8-2 wheel arrangement, but Riddles eventually settled upon a 2-10-0 type because it had been successfully utilised on some of his previous Austerity locomotives. By distributing the adhesive weight over five axles gave a maximum axle load of only 15 tons, 10 cwt. However, in order to clear the rear coupled wheels the grate had to be set higher, thus reducing firebox volume. There were many problems associated with locomotives of such a long wheelbase, but these were solved by the design team through a series of compromises. The driving wheels were 5' 0" in diameter, and the centre driving wheels were without flanges, whilst those on the second and fourth coupled wheels were reduced in depth. This enabled the locomotive to round curves of a radius as small as 400'.

Variations
The 9F was used as a proving ground for a variety of technical innovations intended to provide improvements in efficiency, power or cost.

Franco-Crosti boiler
92020-92029 were built in 1955 with the Franco-Crosti boiler which incorporated a combustion gas feed water preheater that recuperated low-grade residual heat. In the 9F version, this took the form of a single cylindrical water drum running along the underside the main boiler barrel; the standard chimney at the front was only used during lighting up, in normal working the gases went through firetubes inside the preheater drum that led to a second smokebox situated beneath the boiler from which there emerged a chimney on the right-hand side, just forward of the firebox. In the event, the experiment did not deliver the hoped-for benefits and efficiency was not increased sufficiently to justify the cost and complexity. Moreover conditions were unpleasant on the footplate in a cross-wind, this in spite the later provision of a small deflector plate forward of the chimney. These problems led to the subsequent removal of the preheater drum, although the locomotives did retain the original main smokebox and kept their distinctive look.

Mechanical stoker and blastpipe variation
92165-92167 were built with a mechanical stoker, which was a helical screw that conveyed coal from the tender to the firebox. The stoker made higher steaming rates possible, and it was hoped that mechanical stoking might enable the burning of low-grade coal. It was relatively inefficient, and the locomotives used in this trial were rebuilt to the normal configuration. Simply supplying more low grade coal than a fireman could do by hand did not provide efficient burning.

92250 was built with a Giesl ejector in which the exhaust steam was divided between seven nozzles arranged in a row on the locomotive's longitudinal axis and directed into a narrow fan-shaped ejector that more intimately mixed it with the smokebox gases than is the case of an ordinary chimney. This offered the same level of draught for a reduced level of exhaust back-pressure or, alternatively, increased draught with no performance loss elsewhere. Again, great claims were made as to the potential benefits, and 92250 retained the variant chimney until withdrawal, though no benefit was noticeable.

The only modification which did deliver any noticeable benefit, albeit a marginal one, was the fitting of all 9Fs from 92178 onwards with double blastpipes and chimneys. This allowed the engines to steam slightly more freely and thus generate higher power ranges.

Construction history
The class was introduced in 1954, and designed at Brighton works. 251 locomotives were built at Swindon and Crewe, numbered 92000-92250. Many lasted only a few years in service before withdrawal when steam traction ended on the mainline in Britain. The last was constructed at Swindon in 1960, and was given the name and number of 92220 Evening Star. The locomotive was the 999th standard to be constructed, and ultimately became the last steam locomotive to be built by British Railways. To mark this, a competition was run within the Western Region of British Railways for an apt name to mark the occasion.

Operational details
The 9F turned out to be the best of the standard designs, and one of the finest steam locomotive designs ever designed in Britain in terms of its capacity to haul heavy loads over long distances. It was highly effective at its designed purpose, hauling heavy, fast freight trains, and was used all over the British railway network. This was exemplified when in 1983, preserved engine 92203 Black Prince set the record for the heaviest train ever hauled by a steam locomotive in Britain, when it started a 2,162-ton train at a Foster Yeoman quarry in Somerset, UK.

The 9F also proved its worth as a passenger locomotive, adept at fast running despite its small driving wheels, and for a time was a frequent sight on the Somerset and Dorset Railway. On one occasion, a 9F was set to haul an express passenger train from Grantham to King's Cross. An enthusiast aboard the train timed the run and noted that twice the speed exceeded 90mph. Evidently, the driver was afterwards told that he was only supposed to keep time, "not break the bloody sound barrier!" He replied that the engine had no speedometer, and that it ran so smoothly at high speeds that he just let it run as fast as felt safe. Nor was this the only instance of 9Fs reaching high speeds. However, concerns that with plain bearings the high rotational speeds involved in fast running could cause excessive wear and tear to the running gear prompted the British Railways management to stop the utilisation of 9Fs on express passenger trains

Livery and numbering
After nationalisation, freight locomotives were given plain, BR Freight Black without lining of any description. The BR crest was located on the tender side. Given the BR power classification 9F, the locomotives were numbered in the 92xxx series, between 92000 and 92250. Due to the status of the last locomotive constructed at Swindon, 92220 Evening Star was turned out in British Railways Brunswick Green livery, which was usually reserved for prestigious express passenger locomotives.

Preservation
Nine 9F locomotives have survived, with seven of them being rescued form Dai Woodham's scarapyard in Barry, South Wales. The other two were preserved upon withdrawal, with 92220 Evening Star reserved for the National Collection, and 92203 steaming into preservation on the Longmoor Military Railway when purchased by the noted artist and conservationist, David Shepherd in 1967. The full list of the preserved locomotives are: 92134, 92203 Black Prince, 92207, 92212, 92214, 92219, 92220 Evening Star, 92240 and 92245.

In fiction
An example of this type of locomotive can be seen on the Thomas the Tank Engine and Friends TV Series. The character's name is Murdoch the Heavy Goods Engine, who, despite his size and strength, enjoys peace and quiet.

Recommended reading

 * Cox, E. S.: British Railways Standard Locomotives (Ian Allan: London, 1966)
 * H.C.B. Rogers, Riddles and the 9Fs (Ian Allan, 1982)