LNER Class A4

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60034 Lord Farringdon at Aberdeen Ferryhill, 1965.

60027 Merlin at Dundee Tay Bridge, 1965, showing the corridor connection through the tender that allowed crews to be changed on Scotch expresses without stopping.

Another view of 60027 Merlin at Dundee Tay Bridge, 1965. The yellow cabside stripe indicates that she is prohibited from electrified West Coast Main Line south of Crewe, where she is out-of-gauge.

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

[edit] Overview

Sir Nigel Gresley introduced the LNER Class A4 locomotives in 1935 to haul a new train called the Silver Jubilee 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 gave the green light to 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 achieved a speed of 112.5 mph, breaking the British speed record.^{[citation needed]}

[edit] 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 double-exhaust Kylchap blastpipe 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 were fitted with it (by BR) 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.^{[citation needed]} 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) of all the A4 locomotives were removed during the Second World War to improve access to the valve gear for maintenance and were not replaced.

[edit] World Record

Plaque on Mallard in commemoration of breaking the world speed record of 125 mph.

On July 3, 1938 4468 Mallard; the first of the class to enter service with the Kylchap exhaust, set a world speed record of 125 mph (201.2 km/h), pulling six coaches and a dynamometer car.

Although the dynamometer car indicated a top speed of 126 mph (202.8 km/h), Sir Nigel Gresley never accepted this as the record-breaking maximum. He claimed this speed could only have been attained over a few yards (metres), though he was comfortable that the German speed record of 124.5 mph (200.4 km/h) 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.^{[citation needed]}

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.

[edit] Preservation

Preserved 4468 Mallard was returned to steam for the fiftieth anniversary of its record-breaking run in 1988.

60009 Union of South Africa.

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.

[edit] 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 interesting footage of the water trough and corridor tender in use.
• The 1959 version of The Thirty-Nine Steps features some wonderful 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.
• 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 the computer games Railroad Tycoon 2 and Railroad Tycoon 3.

[edit] Other notable A4s

• LNER 4469 Sir Ralph Wedgwood
• LNER 2509 Silver Link

[edit] External links

Wikimedia Commons has media related to:

Preserved LNER Class A4 steam locomotives

• LNER Encyclopedia Page covering the history and development of the LNER A4 Pacifics
• Detailed list of the names, numbers and production dates of LNER A4 locomotives
• Railuk database
• Screenshots from Elizabethan Express