LNER Class A4

LNER Class A4
60009 Union of South Africa passing Pinnelhill and Pinnelhill Wood in 1973.
Power type	Steam
Designer	H. N. Gresley
Builder	LNER Doncaster Works
Build date	1935–1938
Total production	35
Configuration	4-6-2
UIC classification	2'C1h
Gauge	4 ft 8+1⁄2 in (1,435 mm)
Leading wheel size	3 ft 2 in (0.965 m)
Driver size	6 ft 8 in (2.032 m)
Trailing wheel size	3 ft 8 in (1.118 m)
Locomotive weight	102 tons 19 cwt (230,600 lb/104.6 t)
Locomotive and tender combined weight	167 tons 2 cwt (374,300 lb/169.8 t)
Fuel type	Coal
Fuel capacity	8 tons 0 cwt (17,900 lb/8.1 t)
Water capacity	5,000 imperial gallons (23,000 l; 6,000 US gal)
Boiler pressure	250 psi (1.72 MPa)
Cylinders	Three
Cylinder size	18.5 in × 26 in (470 mm × 660 mm)
Top speed	90 mph in Regular Service (126.4 mph maximum recorded)
Tractive effort	35,455 lbf (157.71 kN)
Locomotive brakes	Vacuum
Train brakes	Vacuum 60009, 60007 & 60019 have been fitted with Air Brakes[1]
Career	LNER, BR
Class	A4
Power class	BR: 8P6F
Number in class	35
Number	LNER: 2509–2512, 4462–4469, 4482–4500, 4900–4903, LNER 1–34 (not in order), BR: 60001–60034
Nicknames	"Streak"
Withdrawn	1942, 1962–1966
Disposition	6 Preserved

The Class A4 is a class of streamlined 4-6-2 steam locomotive, designed by Nigel Gresley for the London and North Eastern Railway in 1935. Their streamlined design gave them high-speed capability as well as making them instantly recognizable, and one of the class, 4468 Mallard, still holds the record as the fastest steam locomotive in the world. 35 of the class were built to haul passenger express trains on the route from London Kings Cross to the north of England and to Scotland. They remained in service until the early 1960s when they were replaced by diesel locomotives.

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 108 mph and completed the journey in under four hours, the LNER authorised Gresley to produce a streamlined development of the A3.^{[citation needed]} 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 over a distance of 43 miles^[2].

Following the commercial success of the Silver Jubilee train, other streamlined services were introduced: the Coronation (London-Edinburgh, July 1937) and the West Riding Limited (Bradford & Leeds-London & return, November 1937) for which more A4s were specially built. In August 1936 the Silver Jubilee train on the descent of Stoke Bank headed by 2512 Silver Fox achieved a maximum of 113 mph, then the highest speed ever attained in Britain with an ordinary passenger train.^{[citation needed]}

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 both 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 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.^{[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) 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^[3]. 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

Plaque on Mallard in commemoration of breaking the world speed record of 126 mph.

On 3 July 1938 4468 Mallard; the first of the class to enter service with the Kylchap exhaust, set a world speed record of 126 mph (202.8 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, though he was comfortable that the German speed record of 124.5 mph (200.4 km/h) had been surpassed^{[citation needed]}.

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 alignment 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 - indeed on at least one occasion this led to the middle big end wearing to such an extent that the increased piston travel knocked the ends off the middle cylinder^[4] - 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]}

Post-war history

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

Although newer Pacifics had been introduced since the war, and although 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.^{[citation needed]} 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^[5].

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 pounds of coal per mile, which more than justified the expense of the conversion ^[6].

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 bird-watcher. 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.

A rare gathering of three ex-LNER A4 locomotives at Grosmont, North Yorkshire Moors Railway, 60009 Union of South Africa, 60007 Sir Nigel Gresley and 60019 Bittern line up alongside each other

A4 No.4498 was the hundredth Gresley Pacific to be built and someone had the idea of naming it after the designer himself. This did however 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.^{[citation needed]}

One locomotive was withdrawn after a Nazi bombing raid on York in 1942 during the Second World War - No.4469 Sir Ralph Wedgwood, which at the time had been overhauled and was based at Gateshead. It was running local trains to run it in, and was stabled in York North Shed (now the National Railway Museum) 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 and 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 and 60024 Kingfisher, these last two named being the final two to go, in September 1966

Preservation

Some six of these pacific locomotives have been preserved, 4 of them in the U.K and all of those examples have run on the BR Mainlines at some point during their preservation career. Another 2 examples have been preserved in the U.S.A and Canada, rather appropriately due to their namesakes.

Numbers			Name	Current location	Condition	Image
Original	LNER 1946	BR
4464	19	60019	Bittern	Mid Hants Watercress Railway	Approved for mainline use
4468	22	60022	Mallard	National Railway Museum, York	Static display (operational during late 80's for two years)
4488	9	60009	Union of South Africa	Based at Thornton, Fife	Approved for mainline use
4489	10	60010	Dominion of Canada	Canadian Railway Museum	Static display
4496	8	60008	Dwight D Eisenhower	National Railroad Museum, Green Bay, Wisconsin	Static display
4498	7	60007	Sir Nigel Gresley	North Yorkshire Moors Railway	Approved for mainline use

In popular culture

60034 Lord Farringdon at Aberdeen Ferryhill, 1965.

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.
• In The Railway Series of children's books by the Rev W Awdry, the A4 No. 4468 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. Mallard appears as a character in the later book Thomas and the Great Railway Show.
• In the Thomas and Friends TV Series, the A4-based character Spencer, appears occasionally. Spencer bears a strong resemblance to Silver Link and is portrayed as a rather snooty character.
• In the children's series Chuggington, the character of Olwin is based on the A4 class.
• 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). [1].
• Mallard appears in an animated Yorkshire Tea advert.[2]
• An A4 appears in the BBC comedy Dad's Army episode The Royal Train in British Railways livery despite the series being set in World War II.

Notes

References

External links

Wikimedia Commons has media related to: 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