BR standard class 8P
| BR standard class 8P | |
|---|---|
.jpg) No. 71000 Duke of Gloucester
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| Numbering: | 71000 (TOPS: 98802) |
| Number: | 1 |
| Manufacturer: | BR Crewe Works |
| Year of construction (s): | 1954 |
| Type : | 2'C1 'h3 |
| Gauge : | 1435 mm ( standard gauge ) |
| Length over buffers: | 20,635 mm |
| Service mass: | 102.9 t |
| Friction mass: | 67.1 t |
| Wheel set mass : | 22.4 t |
| Indexed performance : | > 2,300 kW |
| Driving wheel diameter: | 1,880 mm |
| Impeller diameter front: | 1,016 mm |
| Rear wheel diameter: | 1,067 mm |
| Control type : | Caprotti |
| Number of cylinders: | 3 |
| Cylinder diameter: | 457 mm |
| Piston stroke: | 711 mm |
| Boiler overpressure: | 172.3 N / cm² |
| Grate area: | 4.51 m² |
| Radiant heating surface: | 21.0 m² |
| Tubular heating surface: | 210.3 m² |
| Superheater area : | 62.9 m² |
| Service weight of the tender: | Type BR1E: 56.4 t Type BR1J: 54.6 t |
| Water supply: | Type BR1E: 21.5 m². Type BR1J: 19.7 m² |
| Fuel supply: | 10 t |
The unique piece of the British Railways (BR) standard class 8P is a steam locomotive with a 2'C1 '( Pacific ) wheel arrangement and a three-cylinder engine. What is unusual about the locomotive, which was built in 1954, is its development history: During construction, certain points were deviated from the plans, so that the performance was unsatisfactory and the class was not expanded. During the restoration the defects were identified and corrected, and the machine is now considered the most powerful steam locomotive ever run in Britain.
Emergence
According to the ideas of its designer Robert Riddles , the BR's Chief Mechanical Engineer , the new locomotive was to become the new standard for high-performance express train locomotives. The construction of a prototype was initially rejected by the railway administration because there were enough locomotives of this performance class available. Only when the Princess Anne (Princess Royal Class) had to be retired after the serious accident at Harrow & Wealdstone station in October 1952, the construction was approved.
technology
The standard class 8P was an enlarged further development of the standard class 7MT . With a two-cylinder engine, the planned performance would have required a cylinder diameter that would have violated the narrow clearance profile of the BR, which is why a third cylinder had to be provided. The inner cylinder worked on the first coupling axle, the outer cylinder on the middle one.
The control of the three-cylinder locomotives built by Gresley , in which the movement of the inner slide was derived from that of the two outer slide with the help of a lever mechanism, had proven to be problematic, which is why the 8P was equipped with a Caprotti valve control, which was already used on 30 locomotives the standard class 5MT had been used. This type of control system , which originated in Italy, worked with rotating cams that were driven by cardan shafts. It enabled independent control of the steam inlet and outlet, which promised greater efficiency of the engine.
The locomotive was equipped with two different three-axle tenders , a type BR1E until 1958, then a BR1J. They were equipped with a steam-powered coal pusher.
designation
The BR steam locomotives were divided into power classes, which consisted of a number (0 to 9) and a letter for the purpose. 8P designates a locomotive of the second highest performance class 8 for passenger trains (P stands for passenger ).
Class 8P also included some series that the BR had taken over from its predecessor railways, such as the LMS locomotives of the Princess Royal Class and the LNER class A4 , which is why the term “standard class” is used to differentiate. Often the designation is also given without a P ("Standard Class 8") because there were no other BR standard locomotives of this performance class.
The locomotive was given the track number 71000 and the name Duke of Gloucester . The TOPS number assigned after the restoration is 98802, but the 71000 is still written on the locomotive.
Use and retirement
The locomotive was unpopular with the staff because the steam output of its boiler was felt to be inadequate - further examples of the class were therefore not built. There were also no serious attempts to remedy the deficiency because the BR had already decided at the time of commissioning to completely replace its steam locomotives with diesel and electric locomotives.
The Duke of Gloucester was used on the less demanding North Wales Coast Line between Crewe and Holyhead and retired in 1962.
Consideration was given to handing the locomotive over to the National Railway Museum in York, but in the end only one cylinder with the unusual Caprotti control was considered worth preserving and exhibited in the Science Museum in London. For reasons of balance, the second outer cylinder was also removed and the locomotive was to be scrapped.
restoration
The locomotive was bought by Dai Woodham, whose family ran the Barry junkyard known for rescuing more than 200 steam locomotives. The Duke of Gloucester accidentally ended up in the wrong scrap yard first; but this error was corrected and the machine arrived in Barry in 1967.
It was bought by railroad enthusiasts in 1974 and a 71000 Preservation Society was formed which was converted into the 71000 Duke of Gloucester Steam Locomotive Trust in 1977 .
The restoration was initially considered an "impossible dream" and took 13 years. Many missing parts, especially the Caprotti control, had to be newly procured or manufactured. Because one of the outer cylinders was in the museum and the other had also been dismantled and scrapped, these had to be rebuilt as well - the biggest challenge in this project due to the unusual control. In contrast to the original design, nodular cast iron was used instead of steel. A replacement also had to be found for the missing tender.
During the restoration the original defects of the locomotive were identified and corrected. This concerned two points in particular:
- The chimney and blowpipe were too small compared to other locomotives of this size. In addition, instead of the Kylchap suction system recommended by the manufacturer of the Caprotti control, a standard version was installed against the will of Riddles.
- The air flaps on the ashtray had not been built according to the drawings and were too small in cross-section, which hindered the air supply to the fire.
The success of these corrections was already evident during the first test drives: the boiler was now able to deliver 30% more steam, and the Duke of Gloucester is now considered the most powerful steam locomotive that has ever driven in Great Britain. In comparative runs in which a 430 t train was pulled up an incline, it was clearly superior to the Sir Nigel Gresley ( LNER Class A4 ) and Duchess of Hamilton ( LMS Coronation Class ) locomotives .
The locomotive has the necessary safety equipment for operation on main lines and is regularly used in front of special trains, whereby, due to its performance, it can also travel on routes that other steam locomotives were closed to for decades. In order to be able to drive with modern cars, it has been equipped with a compressed air brake in addition to the original suction air brake .
The Duke of Gloucester is now based in Bury on the East Lancashire Railway .
Web links
- The Duke of Gloucester - Extensive information on the locomotive (English)
- 71000 Steam Locomotive Trust (English)