LNER Class A4

The London and North Eastern Railway Class A4 is a class of streamlined 4-6-2 steam locomotive, designed by H.N. Gresley in 1935. One of the class, 4468 Mallard, holds the record as the fastest steam locomotive in the world.

Overview

Gresley introduced the LNER Class A4 locomotives in 1935 to be integrated into a new streamlined train called the Silver Jubilee that was to run between London King's Cross and Newcastle. The new service was named in celebration of King George V's 25th year of reign.

During a visit to Germany in 1933, Gresley had been inspired by the high-speed, streamlined "Flying Hamburger" diesel multiple unit trains, and indeed the LNER had considered purchasing similar trains for use from London to Newcastle. However, the diesel units of the time did not have the desired passenger carrying capacity and the capital investment in the new technology was prohibitive.

Gresley was sure that steam could do the job equally well and with a decent fare-paying load behind the locomotive and so, following trials in 1935 with one of Gresley's A3 Pacifics No.2750 Papyrus, which recorded a new maximum of 108mph and completed the journey in under four hours, the LNER authorised Gresley to produce a streamlined development of the A3. Initially four locomotives were built, all with the word 'silver' as part of their names, the first being 2509 Silver Link; the others being 2510 Quicksilver, 2511 Silver King and 2512 Silver Fox. During a press run to publicise the service, Silver Link twice achieved a speed of 112.5 mph, breaking the British speed record and sustained an average of 100 mph for 43 miles on end.

Following the commercial success of the Silver Jubilee train, other streamlined services were introduced; the Coronation (London-Edinburgh, July 1937) West Riding Limited (Bradford & Leeds-London & return, November 1937) for which more A4s were specially built. It should also be noted that in August 1936 the Silver Jubilee train on the descent of Stoke bank headed by 2512 Silver Fox achieved a maximum of 113mph then the highest speed ever attained in Britain with an ordinary passenger train.

Design

The A4 pacifics (with the 4-6-2 wheel arrangement) were designed for high-speed passenger services. The application of internal streamlining to the steam circuit, higher boiler pressure and the extension of the firebox to form a combustion chamber all contributed to a more efficient locomotive than the A3, consumption of coal and water being reduced. A further improvement to the design was the fitting of a Kylchap double-chimney first introduced on 4468 Mallard, built in March 1938. This device improved the free-steaming capabilities of the locomotives further, and the final three locomotives of the class (4901 Capercaillie, 4902 Seagull and 4903 Peregrine) were also fitted with the Kylchap exhaust from new, and eventually the rest of the class acquired it in the late 1950s.

This class of locomotive was also noted for its streamlined design, which not only improved its aerodynamics, thus increasing its speed capabilities, but also created an updraught to lift smoke away from the driver's vision, a problem inherent in the earlier A3 design. The distinctive design made it a particularly attractive subject for artists, photographers and film-makers. The A4 Class locomotives were known affectionately by train spotters as "streaks".

The streamlining side skirts (valances) that were designed by Oliver Bulleid to aerofoil shape, and fitted to all the A4 locomotives, were removed during the Second World War to improve access to the valve gear for maintenance and were not replaced. This apart, the A4 was one of very few streamlined steam locomotive designs in the world to retain its casing throughout its existence.

World Record

On July 3 1938 4468 Mallard; the first of the class to enter service with the Kylchap exhaust, set a world speed record of , pulling six coaches and a dynamometer car.

Although the dynamometer car indicated a top speed of ), Sir Nigel Gresley never accepted this as the record-breaking maximum. He claimed this speed could only have been attained over a few yards, though he was comfortable that the German speed record of had been surpassed .

At the end of the record attempt, the middle big end (part of the motion for the inside cylinder) was found to have run hot, the bearing metal having melted, which meant that the locomotive had to stop at Peterborough rather than continue on to London. Deficiencies in the setup of the Gresley-Holcroft derived motion meant that the inside cylinder of the A4 did more work at high speed than the two outside cylinders, and this overloading was mostly responsible for the failure. However, given that the driving wheels went through 500 revolutions per minute at its full speed, this is perhaps forgivable.

Post-war history

Although newer Pacifics had been introduced since the war, and the fact that the streamlined trains were never reinstated, the A4s continued on top link duties, notable on the London to Edinburgh services.

Improved methods of aligning the Gresley conjugated valve gear in the 1950s led to tighter tolerances for the bearings used within it and consequently to almost total eradication of the overloading of the middle cylinder. History repeated itself with the inside big end being replaced by one of the Great Western type, after which there was no more trouble, provided maintenance routines were respected.

The wholesale application of double Kylchap chimneys to the entire class was entirely due to the persistence of P.N. Townend, the Assistant Motive Power Superintendent at King's Cross from 1956. He at first met with considerable resistance from higher authority. When permission was eventually given, it was found that the economy obtained over the single chimney A4s was from 6-7 pound of coal per mile, which more than justified the expense of the conversion .

These improvements led to greatly increased availability.

Locomotive Data

The first four locomotives included the word 'silver' in their names, because they were intended to haul the 'Silver Jubilee' train. The next batch of A4s were named after birds, particularly those that were fast flyers; Gresley being a keen ornithologist. Five (4488 - 4492) were named after Commonwealth countries to haul the new Anglo-Scottish 'Coronation' train and three (4495 - 4497); intended to haul the new 'West Riding Limited' received names with 'golden' in the title, these being connected to the wool trade: Golden Fleece and Golden Shuttle, although Golden Plover's link was a little more tenuous.

A4 No.4498 was the hundredth Gresley Pacific to be built and someone had the idea of naming it after the designer himself, which was a nice gesture. Unfortunately however this did start a rash of renamings of other A4s, usually of directors of the LNER and many of the more obscure bird names (and a few of the better ones: Kestrel, Osprey for example) were exchanged for somewhat less inspiring names.

One locomotive was withdrawn after a German bombing raid on York in 1942 during the Second World War - No.4469 Sir Ralph Wedgewood, which at the time had been overhauled and was based at Gateshead. It was running local trains to run her in, and was stabled in York North Shed (now the NRM) where it suffered a direct hit. However, its tender survived and was later coupled to a Thompson A2/1.

The first four withdrawals were: 60014 Silver Link, 60028 Walter K Whigham, 60003 Andrew K. McCosh & 60030 Golden Fleece. The rest of the class was withdrawn over the 1962-66 period; the last five engines in service were: 60004 William Whitelaw, 60007 Sir Nigel Gresley, 60009 Union Of South Africa, 60019 Bittern & 60024 Kingfisher, these last two named being the final two to go in September 1966

Preservation

A total of six A4s have survived to preservation, making them more numerous in preservation than any other LNER class. Two of these are in North America; 60010 Dominion of Canada in the Canadian Railway Museum and 60008 Dwight D Eisenhower in the American National Railroad Museum.

In popular culture

A4s have appeared numerous times in popular culture:

• The 1954 British Transport Film Elizabethan Express follows the post-war revival of non-stop London to Edinburgh runs. It stars A4 No.60017 Silver Fox, and features footage of the water trough and corridor tender in use.
• The 1959 version of The Thirty-Nine Steps features colour photography of A4 No.60010 Dominion of Canada in the brunswick green livery.
• Carry on Regardless of 1961 parodied this scene, briefly featuring another A4.
• More recently, a stylised animated A4 is seen in the opening titles of the early David Suchet Poirot adaptations. This is undoubtedly based on the original art deco posters for the Silver Jubilee service.
• A similar animated A4 was seen in the opening credits of the ITV programme The South Bank Show, in which it is seen at the head of a Pullman train racing beneath Marilyn Monroe's skirts. This appears to be inspired by an art deco poster for the Coronation Scot.
• Two steam engines of this type, Mallard and Spencer, have appeared in the Thomas the Tank Engine books and TV Series, originated by the Rev. W. Awdry. Mallard is alluded to in the book "Gordon the High Speed Engine" by Christopher Awdry as one of Gordon's "Doncaster cousins" who did 126 miles an hour, before actually appearing in the later book "Thomas and the Great Railway Show." Spencer, who bears a strong resemblance to Silver Link, appears occasionally in the TV series (so far three appearances), and is portrayed as a rather snooty character.
• The locomotive 2509 Silver Link appears in an early scene in the Will Hay film, Oh! Mr. Porter, in which Hay accidentally ruins its naming ceremony.
• A painting of 22 Mallard by Paul Gribble appears on the cover of the 1993 Blur album Modern Life is Rubbish.
• The locomotive appears in the various versions of the computer game, Transport Tycoon and its sequel Chris Sawyer's Locomotion.
• The A4 Class has also appeared in all the computer games in the Railroad Tycoon series, apart from the Deluxe edition.
• An A4 appears in an animated Irn-Bru Christmas 2006 advert, a parody of The Snowman, where it is seen passing over Glenfinnan Viaduct, despite the fact that the class is too heavy for the West Highland Line
• Mallard appears in an animated Yorkshire Tea advert.
• An A4 appears in the BBC comedy Dads Army episode The Royal Train in British Railways livery despite the series being set in World War 2.

Other notable A4s

• LNER 4469 Sir Ralph Wedgwood
• LNER 2509 Silver Link

References