LNER Class A4

LNER Class A4
60009 Union of South Africa in 1951
Type and origin Power type Steam Designer H. N. Gresley Builder LNER Doncaster Works Build date 1935–1938 Total produced 35
Specifications Configuration: ​  • Whyte 4-6-2  • UIC 2'C1h Gauge 4 ft 8+1⁄2 in (1,435 mm) Leading dia. 3 ft 2 in (0.965 m) Driver dia. 6 ft 8 in (2.032 m) Trailing dia. 3 ft 8 in (1.118 m) Loco weight 102 long tons 19 cwt (230,600 lb or 104.6 t) Total weight 167 long tons 2 cwt (374,300 lb or 169.8 t) Fuel type Coal Fuel capacity 8 long tons 0 cwt (17,900 lb or 8.1 t) Water cap. 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) Loco brake Vacuum Train brakes Vacuum 60009, 60007 & 60019 have been fitted with Air Brakes
Performance figures Tractive effort 35,455 lbf (157.71 kN)
Career Power class BR: 8P6F Number in class 35 Nicknames "Streak" Withdrawn 1942, 1962–1966 Disposition 6 Preserved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 claims the official record as the fastest steam locomotive in the world. 35 of the class were built to haul passenger express trains on the East Coast Main Line 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 Deltic diesel locomotives.

Overview

Gresley introduced the 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 (173.8 km/h), 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 (181.1 km/h), breaking the British speed record and sustained an average of 100 mph (160.9 km/h), over a distance of 43 miles (69.2 km).

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 (181.9 km/h), 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 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. 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

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. Close analysis of the data of the record runs, however, does not confirm his confidence, although the Mallard's speed most probably equalled that of the German BR 05 002. The Mallard record has also been questioned because it reached its maximum speed only on a downhill run and actually failed technically in due course, whereas 05 002's journey was on level grade and the engine did not yet seem to be at its limit.

At the end of Mallard's record attempt, the middle big end (part of the motion for the inside cylinder) was found to have run hot (indicated by the bursting of a heat-sensitive "stink bomb" placed in the bearing for warning purposes), 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 - and this overloading was mostly responsible for the failure.

Post-war history

No. 60034 Lord Faringdon hauling a train at Peterborough railway station in 1959.

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. 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 pounds of coal per mile, which more than justified the expense of the conversion.

These improvements led to greatly increased availability.

Locomotive data

LNER Number (Intermediate Number)	British Railways Number	Doncaster Works number	Original Name (Rename(s))	Entered Service	Withdrawn
2509	60014	1818	Silver Link	7 September 1935	29 December 1962
2510	60015	1819	Quicksilver	21 September 1935	25 April 1963
2511	60016	1821	Silver King	5 November 1935	19 March 1965
2512	60017	1823	Silver Fox	18 December 1935	20 October 1963
4482	60023	1847	Golden Eagle	22 December 1936	30 October 1964
4483 (585)	60024	1848	Kingfisher	26 December 1936	5 September 1966
4484 (586)	60025	1849	Falcon	23 January 1937	20 October 1963
4485 (587)	60026	1850	Kestrel (Miles Beevor from November 1947)	20 March 1937	21 December 1965
4486 (588)	60027	1851	Merlin	13 March 1937	3 September 1965
4487	60028	1852	Sea Eagle (Walter K. Whigham from October 1947)	20 March 1937	29 December 1962
4488	60009	1853	Union of South Africa	29 June 1937	1 June 1966
4489	60010	1854	Dominion of Canada	4 May 1937	29 May 1965
4490	60011	1855	Empire of India	25 June 1937	11 May 1964
4491	60012	1856	Commonwealth of Australia	22 June 1937	20 August 1964
4492	60013	1857	Dominion of New Zealand	27 June 1937	18 April 1963
4493	60029	1858	Woodcock	26 July 1937	20 October 1963
4494	60003	1859	Osprey (Andrew K. McCosh from October 1942)	12 August 1937	29 December 1962
4495	60030	1860	Great Snipe (I) (Golden Fleece from September 1937)	30 August 1937	29 December 1962
4496	60008	1861	Golden Shuttle (Dwight D. Eisenhower from September 1945)	4 September 1937	20 July 1963
4497	60031	1862	Golden Plover	2 October 1937	29 October 1965
4498	60007	1863	Sir Nigel Gresley	30 October 1937	1 February 1966
4462	60004	1864	Great Snipe (II) (William Whitelaw from July 1941)	10 December 1937	17 July 1966
4463	60018	1865	Sparrow Hawk	27 November 1937	19 June 1963
4464	60019	1866	Bittern	18 December 1937	5 September 1966
4465	60020	1867	Guillemot	8 January 1938	20 March 1964
4466 (605)	60006	1868	Herring Gull (Sir Ralph Wedgwood (II) from January 1944)	26 January 1938	3 September 1965
4467	60021	1869	Wild Swan	19 February 1938	20 October 1963
4468	60022	1870	Mallard	3 March 1938	25 April 1963
4469	—	1871	Gadwall (Sir Ralph Wedgwood (I) from March 1939)	30 August 1938	6 June 1942
4499	60002	1872	Pochard (Sir Murrough Wilson from April 1939)	12 April 1938	4 May 1964
4500	60001	1873	Garganey (Sir Ronald Matthews from March 1939)	26 April 1938	12 October 1964
4900	60032	1874	Gannet	17 May 1938	20 October 1963
4901	60005	1875	Capercaillie (Charles H. Newton from September 1942) (Sir Charles Newton from June 1943)	8 June 1938	12 March 1964
4902	60033	1876	Seagull	28 June 1938	29 December 1963
4903	60034	1877	Peregrine (Lord Faringdon from March 1948)	1 July 1938	24 August 1966

The first four locomotives included the word 'silver' in their names, because they were intended to haul the 'Silver Jubilee' train. No 2512 Silver Fox of this batch carried a stainless-steel fox near the centre of the streamline casing on each side, which were made by the Sheffield steelmakers Samuel Fox and Company. 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.

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, four 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 two 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 NB currently running in guise of 4492 'Dominion of New Zealand'
4468	22	60022	Mallard	National Railway Museum, Shildon	Static display (operational during late 1980s for two years)
4488	9	60009	Union of South Africa	Located at Crewe Heritage Centre	Undergoing major overhaul
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

A4s have appeared numerous times in popular culture, both during and after preservation. The class's first film appearance was 2509 Silver Link, which appears in a scene in the Will Hay film, Oh! Mr. Porter, in which Hay accidentally ruins its naming ceremony. Post war, A4 No.60017 Silver Fox features heavily in the 1954 British Transport Film Elizabethan Express, which follows the revival of non-stop London to Edinburgh runs and features footage of the water trough and corridor tender in use. A few years later, the 1959 version of The Thirty-Nine Steps features colour photography of A4 No.60010 Dominion of Canada amongst others in their post-war British Railways Brunswick green livery. This scene was subsequently parodied in the 1961 film Carry on Regardless.

In The Railway Series 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 subsequent television series Thomas and Friends, the A4-based character Spencer, appears occasionally. Spencer bears a strong resemblance to Silver Link and is portrayed as a rather snooty character. Olwin from the children's series, Chuggington, resembles an A4 minus the tender making her a tank engine. A painting of 22 Mallard by Paul Gribble appears on the cover of the 1993 Blur album Modern Life is Rubbish.

Models

The distinctive shape of the A4 has made it an obvious choice for model manufacturers, with examples being made in the majority of the popular scales, including a wooden example for the Brio wooden railway. Notably, one of the first two Hornby Dublo locomotive models produced, in 1938, was an A4, and in 2004 Hornby produced an 'OO'-scale live steam version, that used an electrically-heated boiler to produce steam – not previously possible in such a small model.

References

• Boddy, M.G.; Neve, E.; Yeadon, W.B. (1973). Fry, E.V. (ed.). Part 2A: Tender Engines - Classes A1 to A10. Locomotives of the L.N.E.R. Kenilworth: RCTS. ISBN 0 901115 25 8. {{cite book}}: Invalid |ref=harv (help); Unknown parameter |month= ignored (help)

External links

• 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

Video links

• 1935, Demonstration run of 'Silver Jubilee' to Grantham
• 1944, Retirement of driver Duddington