LNER class A4
| LNER class A4 | |
|---|---|
 "Union of South Africa" locomotive, LNER class A4
|
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| Numbering: | 2509-2512, 4462-4469, 4482-4500, 4900-4903 |
| Number: | 35 |
| Year of construction (s): | 1935-1938 |
| Type : | 2'C1 'h3 |
| Service mass: | 104.6 t |
| Friction mass: | 67.1 t |
| Wheel set mass : | 22.4 t |
| Top speed: | 144.8 km / h (scheduled) 201.2 km / h (record) |
| Indexed performance : | over 1,986 kW |
| Driving wheel diameter: | 2,032 mm |
| Impeller diameter front: | 965 mm |
| Rear wheel diameter: | 1,118 mm |
| Control type : | Gresley |
| Cylinder diameter: | 470 mm |
| Piston stroke: | 660 mm |
| Boiler overpressure: | 17.2 bar |
| Grate area: | 3.83 m² |
| Superheater area : | 69.6 m² |
| Evaporation heating surface: | 239.3 m² |
The class A4 of the British London and North Eastern Railway (LNER) are express steam locomotives with the wheel arrangement 2'C1 '(Pacific) . The 201.2 km / h measured with the Mallard locomotive of this series on July 3, 1938, is still the official world speed record for steam locomotives .
History of origin
Tractors for the "Silver Jubilee"
In 1935 the LNER set up a new express train connection between London and Newcastle upon Tyne , which was introduced on the occasion of the 25th anniversary of King George V's throne under the name "Silver Jubilee".
The use of high-speed diesel locomotives for this particular train was initially discussed. There were concerns, however, because engines that had not yet been tested would have had to be used. However, after the designer Nigel Gresley , who had already emerged with the design of the LNER class A3 , saw an operation with appropriate steam locomotives guaranteed, it was decided in favor of this.
Initially four locomotives were procured that were structurally based on the A3 class. They were clad in a streamlined manner and were designated as Class A4. Like the newly designed wagons on this train, they were also given a silver color scheme. The train was also designed by Sir Nigel Gresley. It consisted of two-part articulated wagons, each with a shared Jakobs bogie .
The locomotives proved themselves right away. Just three weeks after commissioning, the prototype reached a speed of 181 km / h in a test drive with a 235 t train. This trip also covered a 69 km route with an average of 100 mph (161 km / h ).
The “Silver Jubilee” was just as successful as its locomotives , and a further 31 units followed from 1936 to 1938. Initially, these subsequently procured machines - like the A3 and other LNER express train locomotives - had a green color scheme; after the introduction of a blue-painted train called “Coronation”, however, all A4s were repainted accordingly.
numbering
The first four A4 were given the numbers 2509-2512. The vehicles built from 1936 onwards were given the numbers 4462–4469, 4482–4500 and 4900–4903 in three groups.
In 1946 the 34 locomotives (one of which did not survive the war) were given new numbers between 1 and 34, but they were not assigned in the same order as the original numbers. So the number 1 was the original number 4500, while the first A4, the original number 2509, received the number 14.
When the railway companies were nationalized to form British Railways in 1948, the locomotives were given the new operating numbers 60001-60034, although the order was retained this time.
Naming
As is widespread in Great Britain, all locomotives were given proper names on signs attached to the locomotive. The first four locomotives were given names that matched the train name: Silver Link , Quicksilver , Silver King and Silver Fox . The following locomotives were mostly named after bird species.
Fourteen of the machines were renamed over time; in doing so, they were mostly given names of deserving personalities. However, locomotive No. 4498 was named Sir Nigel Gresley in honor of its designer from the start . It was the 100th Pacific locomotive built according to his plans.
The name Sir Ralph Wedgwood (after a longtime head of the LNER) was given twice: in 1939 he received the number 4469, which until then had been called Gadwall . After this locomotive was destroyed in the war, the name was given to No. 4466 in 1944 (until then Herring Gull ).
construction
design type
The A4 is a single-frame steam locomotive with a 2'C1 'wheel arrangement, a design that had proven particularly suitable for express locomotives since the beginning of the 20th century. The boiler was equipped with a superheater for superheated steam operation, the wheel sets were driven by three steam cylinders , with the piston rod of the cylinder placed in the middle under the front smoke chamber driving the first drive axis designed as a crop axis . The outer cylinders worked on the crank pins of the wheels of the second drive axle. A tender was brought along for the supply of fuel and water .
The A4 had the same main dimensions as the A3, but differed from them mainly on the outside in the unmistakable shape of their streamlined cladding. Compared to class A3, some details have also been changed; the A4 has a higher boiler pressure, slightly optimized steam paths with larger valve openings and a combustion chamber .
Due to the higher boiler pressure, the cylinder diameters could be reduced somewhat, which in turn led to a reduction in the masses moved to and fro and thus to increased smoothness. With these measures it was possible to increase the output from around 2,250 hp to over 2,700 hp.
control
Like the A3, the A4 is equipped with the so-called Gresley control , in which the movement of the slide of the inner cylinder is derived from the movements of the outer slide via a linkage in front of the cylinders. This design has the advantage that a poorly accessible third control linkage between the wheels could be dispensed with. On the other hand, there was the disadvantage that the central cylinder received a little more steam than the outer cylinder when the bearings were worn and slightly worn out. At higher speeds, the heavily loaded middle espagnolette bearing on the A4 was therefore more prone to overheating.
Rod and axle bearings
In the meantime, the spherical roller bearings developed by the German FAG Kugelfischer AG had proven to be excellently suited for high wheel speeds such as those intended for the A4 . Due to the tense political situation at that time, however, the English designers decided not to use these German products and installed conventional plain bearings which, however, tended to overheat when driving very quickly. Since such hot runners were often only noticeable after the damage had already occurred, glass tubes with an unpleasant-smelling liquid were installed in small holes in the camps . These should burst at a supercritical temperature, releasing the evaporating liquid. The resulting smell should reach the driver's cab and prompt the engine driver to reduce speed.
tender
Like the A3, the A4 were equipped with a four-axle tender . Its wheel axles were not in bogies , but firmly mounted in the frame. The capacity was 9 tons of coal and 22.7 m³ of water. In principle, the amount of water was not sufficient for the planned long routes, but the tenders provided for this purpose were equipped with a water scooping device , as was the case with earlier LNER locomotives . With this water could be taken up from troughs running lengthways between the rails during the journey .
As with the A3, some tenders were equipped with a "corridor" called a side aisle, which allowed personnel to be changed during the journey and thus also non-stop journeys on the long route between London and Edinburgh . There were a total of seven different types of tenders with and without side aisles for the A4, but they hardly differed from one another externally. The tenders with side aisles were only recognizable by the bellows transition on the back.
The official world record of the Mallard
Record run
The locomotive No. 4468 ( Mallard , English name for mallard ) was the first in the A4 class to be equipped with a performance-enhancing Kylchap suction system with a double chimney. On July 3, 1938, it reached a speed of 125 mph (201.2 km / h) with a train weighing 244 t. Some sources also give 126 mph (202.8 km / h), but even Gresley doubted this value because it was only recorded for a brief moment and was probably just a vibration-induced meter reading. The record of the German 05 002 (200.4 km / h) set two years earlier seemed to be surpassed in any case.
The Mallard had been in service for five months at its record, so it was well run in but not overly worn out. Joseph Duddington, a man known within the LNER for taking calculated risks, was selected as the engine driver , and Thomas Bray was the stoker . The track at Stoke Bank has an incline of 1: 178 to 1: 200. The Mallard ran over the previous hill with six seated cars plus a measuring car at 75 mph (120 km / h) and began to accelerate on the incline.
The speeds at the end of each mile (1.609 km) were recorded as 87½, 96½, 104, 107, 111½, 116 and 119 mph (141, 155, 167, 172, 179, 187 and 192 km / h); the half-mile intermediate values were 120¾, 122½, 123, 124¼ and finally 125 mph (194, 197, 198, 200 and 201 km / h). The speed recorded with an instrument reached an instantaneous maximum value of 126 mph (203 km / h).
Discussion of the record
The record has often been questioned because it was reached on a slightly sloping track , because the locomotive did not survive the record attempt with a hot connecting rod bearing undamaged and because the speed measurements are not beyond any doubt, so that the official speed figures are probably a little too high lie. The German 05 002 , on the other hand, drove its record on a level stretch of road and was apparently not yet at its performance limit while driving; the speed measurements for their record run are reliably documented. The 200.4 km / h of the 05 002 should also have been reached by the Mallard .
There is little doubt that some steam locomotives in the US "unofficially" went faster. The largest and most powerful express steam locomotive of all, the class S1 of the Pennsylvania Railroad (PRR), is said to have reached speeds of up to 227 km / h in the 1940s when entering delays. The speeds of up to 209 km / h claimed for Class A on the Chicago, Milwaukee, St. Paul & Pacific Railroad also appear plausible given the performance and design of these streamlined locomotives.
In the United States, 127.1 mph (205 km / h) is often considered the fastest speed ever reached by a steam locomotive. This should already in 1905 by an Atlantic the E2 class have been the PRR reached. However, experts doubt the PRR's proudly published information at the time because the locomotive would not have been able to calculate the required power.
Post war record
Another A4, the Sir Nigel Gresley , has completed the fastest journey of a British steam locomotive after World War II. On May 23, 1959, it reached a speed of 112 mph (180.3 km / h). In 1972, this performance was just surpassed by the much more modern German 18 201 .
Whereabouts
One of the A4 locomotives, No. 4469 ( Sir Ralph Wedgwood ), was badly damaged by a bomb hit and retired during World War II . The remaining 34 locomotives came to British Railways .
While the streamlined fairings of the German high-speed locomotives were removed after the war in order to simplify maintenance, the A4 kept their fairing except for the removed cover of the engine and the drive wheels. In this form and with a black and green paintwork, they were in use until the 1960s.
The Mallard was taken out of service in 1963 and returned to its original condition, the fairing was completed again and it was again given the blue original paintwork and its LNER number 4468. It first came to the Clapham Railway Museum in London and is now in the National Railway Museum in York . After restoration, Mallard embarked on a short career as a museum locomotive from York on July 9, 1986 , which took her to the branch line from York via Harrogate to Leeds shortly after Easter 1987. The machine is currently inoperable.
Including the Mallard , six A4s survive today, four of them in the UK, three of which are operational. In addition to the Mallard , these are the Sir Nigel Gresley (LNER 4498, BR 60007), the Union of South Africa (LNER 4488, BR 60009) and the Bittern (LNER 4464, BR 60019). The latter two run in the British Railways green livery; the Sir Nigel Gresley is painted blue, but different from the Mallard and with the road number of the BR.
The Dwight D. Eisenhower (LNER 4496, BR 60008) and the Dominion of Canada (LNER 4489, BR 60010) were brought overseas and are in the National Railroad Museum in the USA and in the Canadian Railway Museum . For the exhibition of the A4 in York both came back from North America in 2013, were processed and exhibited.
literature
- Don Hale: Mallard. How the Blue Streak broke the World Record , Aurum Press, London 2011.
- Lars Quadejacob: Three cheers for the mallard! LNER A4 Mallard and DRB 05 in the race for the world record . In: Eisenbahn Kurier 7/2013, pp. 114–119.
- Wilhelm Reuter: record locomotives. The fastest on the rails. 1848 - 1950. 3rd edition. Motorbuch-Verlag, Stuttgart 1992, ISBN 3-87943-582-0 .
Individual evidence
- ↑ A detailed analysis of the documentation of the record runs can be found here: Was German 05 002 The World's Fastest Steam Loco? (English) ( Memento of the original from April 20, 2006 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . See also list of world speed records for rail vehicles .
- ^ "Meeting" of the four locomotives in July 2008
