SR Class Merchant Navy
| Merchant Navy | |
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 Merchant Navy 21C18 "British India Line" 1946 in front of the Bournemouth Belle in London Waterloo station
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| Numbering: | 21C1-21C20 35001-35030 |
| Number: | 30th |
| Manufacturer: | Southern Railways Eastleigh Works |
| Year of construction (s): | 1941-1949 |
| Retirement: | 1964-1967 |
| Axis formula : | 2'C1 'h3 |
| Gauge : | 1435 mm ( standard gauge ) |
| Length over buffers: | 69 ft 8 in (21.23 m) |
| Service mass with tender: | 94.75 long tons (96.3 t) |
| Driving wheel diameter: | 6 ft 2 in (1880 mm) |
| Impeller diameter front: | 3 ft 1 in (940 mm) |
| Rear wheel diameter: | 3 ft 7 in (1092 mm) |
| Number of cylinders: | 3 |
| Cylinder diameter: | 18 in (457 mm) |
| Piston stroke: | 24 in (610 mm) |
| Boiler overpressure: | 280 psi (19.31 bar) reduced to 250 psi (17.24 bar) |
| Grate area: | 48.5 ft² (4.5 m² ) |
| Radiant heating surface: | 275.0 ft² (25.5 m² ) |
| Tubular heating surface: | 2,175.9 ft² (202.1 m² ) |
| Superheater area : | 822.0 ft² (76.4 m² ) |
| Evaporation heating surface: | 3,272.9 ft² (304.1 m² ) |
| Water supply: | 5000 imp gal (22730 l) |
| Fuel supply: | 5.0 long tons (5.1 t) |
The Merchant Navy Class steam locomotives of the British Southern Railway (SR) were procured in several lots from 1941 to 1949 , based on a design by Oliver Bulleid . A total of 30 units of this class were built in the railway's own workshops in Eastleigh . The last ten copies were delivered from 1948 to the state British Railways (BR), in which the SR was absorbed as a result of the Transport Act 1947 . They were officially multi-purpose locomotives, but were mainly used in front of the main express trains of Southern Railways and the Southern Region of British Railways. The machines were gradually withdrawn from 1964, the last hauled express trains until 1967, including the Pullman Express Bournemouth Belle between London Waterloo and Bournemouth . This made them one of the last British Railways express steam locomotives to be used.
history
In order to accelerate its heavy express trains in the south-west of England and the "boat trains" such as the Golden Arrow to the ports on the English Channel , the SR needed new, more powerful locomotives from the mid-1930s. The previously used locomotives with the 2'C wheel arrangement had proven to be inadequate, and many express trains also had to be double-hauled with locomotives with the 2'B wheel arrangement. The new locomotives were supposed to haul express trains weighing up to 600 tons at average travel speeds of up to 70 miles per hour (mph), a requirement that had not been met by the British railways until then. Oliver V. Bulleid, SR's new chief engineer, who had previously been Sir Nigel Gresley's personal assistant at the London and North Eastern Railway (LNER), pursued the goal of not only optimizing previous procedures, but also noticeably further improving the locomotive technology develop. On March 2, 1938, the Rolling Stock Committee gave Southern Bulleid an order to develop a new generation of express train locomotives. Based on the initial considerations for a Pacific , Bulleid initially considered a locomotive with a 1'D1 '( Mikado ) wheel arrangement , as had recently been introduced to LNER with the LNER class P2 , and was involved in its development was. A Mountain with a 2'D1 'wheel arrangement was also considered by Bulleid. In view of the various restrictions of the existing network in terms of weight and length, it finally stayed with a Pacific, which was first introduced to the SR.
The new class designed by him finally received some components and technologies that had not been used in British locomotive construction or were only used in test locomotives. For example, the welded manganese steel fire boxes were new for British locomotives . Most striking to observers was the siding, but the Bulleid not the spirit of the times according to the current line ( "streamline") called, but as "air-smoothed". The drive was also unusual. Bulleid equipped the three-cylinder machines with a new control system developed by him , which was carried out jointly for all three cylinders via chains and was stored in an oil pan within the frame. The new BFB wheel sets, based on American Boxpok wheels , had also not been used before.
The outbreak of World War II meant that in Great Britain only locomotives for freight trains were allowed to be developed and built. Bulleid, however, managed to convince the Ministry of Supply that the new locomotives were designed for "mixed traffic", and the SR was allowed to continue the development and construction. The first new locomotive was finally completed by the railroad's own workshops in Eastleigh in February 1941. It was named "Channel Packet" after SR's own shipping company. All other locomotives also received the names of shipping companies , the whole class was called "Merchant Navy Class" (in German " merchant navy called class"). Originally, the locomotives were to be named after Allied victories in World War II. The name "River Plate" was planned for the first locomotive and a model of the nameplate was created. The critical war situation for the United Kingdom at the time of delivery in 1940/41 - at this time the Battle of Britain was raging - made this no longer seem opportune for the Southern Railway. The name and flag of the respective shipping company as well as the class designation were displayed on large signs on both sides of the locomotive. However, the staff of the Southern called the locomotives somewhat derogatory due to their appearance as “Spam cans”, after the tin cans used in Great Britain for breakfast meat (“Spam”). The term “Packets” was also in use, derived from the name of the first copy as well as the visual impression.
After initial tests with the first two machines, another eight followed by July 1942, which were manufactured in Eastleigh. The boilers were supplied by the North British Locomotive Company in Glasgow . Based on the first experiences with these locomotives, the fairing was slightly changed in the front area and the two prototypes were also adapted accordingly. Most noticeable was the cover across the smoke chamber, which was intended to divert the escaping steam over the boiler and thus outside the field of view of the staff. Narrow smoke deflectors were also attached for this purpose . However, since Bulleid had made maximum use of the clearance profile of the Southern, the continued poor visibility along the boiler cladding remained a permanent problem until the class was converted. Since the prototypes were also heavier than planned, the plans were revised again to stay within the permissible values. The Merchant Navys were still too heavy for many routes on the Southern. Bulleid therefore derived the somewhat lighter Pacifics of the West Country or Battle of Britain class from this class in the following years . In 1944/45 the workshops in Eastleigh built ten more, this time including the boiler. Shortly before the end of independence, the Southern Railways ordered a further ten pieces, but these were not delivered to what is now British Railways until 1948/49. The first 20 machines were given the numbers 21C1 to 21C20 according to the SR designation scheme newly established by Bulleid, while the last ten machines already had BR numbers from the beginning. At BR, the entire class was given the numbers 35001 to 35030.
The new technology initially led to considerable problems. In particular, the chain-driven control and the oil sump, which cannot be permanently sealed, proved to be susceptible, on the one hand to igniting oil and on the other hand to starting difficulties due to oily rails. The machines also required a comparatively high level of maintenance. On the other hand, its efficiency was undisputed, in particular the boiler redesigned by Bulleid proved to be extremely efficient. It therefore also served as the basis for the boiler design of the Pacifics of the BR standard class 7MT ("Britannia" class), which were procured from 1951 . However, the locomotives also had a high consumption of coal.
As the problems with the controls persisted and the closed oil pan made it difficult to maintain, British Railways decided in the mid-1950s to fundamentally rebuild the machines. At this point in time, the machines were expected to have a remaining useful life until 1987. Between 1955 and 1959 the chain-driven internal controls on all 30 locomotives were replaced by conventional Walschaerts controls and the machines lost their eye-catching cladding. In this context, they also received a new smoke chamber . The high boiler pressure had already been reduced. Only the BFB wheelsets were retained as an external feature, otherwise the locomotives were similar to the newer standard Pacifics from BR. The conversion was generally regarded as a success in the professional world, as the locomotives retained their efficiency. At the same time, the ongoing maintenance problems were substantially reduced, and the poor visibility for the locomotive personnel along the fairing, which was repeatedly criticized, was eliminated. The only disadvantage was that due to the new control, the drive wheels had to be equipped with counterweights , which led to somewhat increased loads on the rails. BR continued to use the locomotives on the traditional routes of the former Southern Railway.
In April 1953, the breakage of the drive axle of the 35020 “ Bibby Line ” locomotive at full speed resulted in the platform roof of the train station being damaged by Crewkerne as a result of a brake block coming loose , luckily without any injuries among the waiting passengers. The train also stayed on the tracks. However, the entire class was initially taken out of service in order to examine it for possible further breaks in the axles. After a few weeks, however, they came back into operation after no further breaks or cracks had appeared.
From the end of the 1950s, BR accelerated the conversion to diesel and electric traction, although new steam locomotives were procured until 1960. The Merchant Navys had to give way to the new diesel locomotives earlier than planned. Only a few of the converted locomotives were able to run longer and from 1964 the decommissioning of the machines began, which was completed by 1967. In the west of the Southern Region, part of their routes went to the Western Region, which replaced them there with new diesel-hydraulic locomotives of the later BR classes 42 and 43 ("Warships"). The routes from London to the Channel coast were operated electrically from the early 1960s. The last seven copies still hauled express trains between London Waterloo and Weymouth until July 2, 1967 and were then decommissioned.
technology
Original version
Bulleid integrated various technical innovations, some of which had not been tested before, in the largest and most powerful locomotives on the Southern Railway. During construction, welding technology was used on a large scale for the first time in British locomotive construction.
The frame parts were partly made of conventional sheet metal and partly made of cast steel . Both the front bogie and the outer frame of the trailing axle were also made of cast steel. The new chain-driven internal control developed by Bulleid was stored in a closed oil pan between the frame cheeks. All moving parts were sprayed with lubricating oil via pumps, which should guarantee constant lubrication of all drive parts and protection against contamination. At the same time, the work of the locomotive personnel should be made easier and they should be relieved of manual lubrication. A frame carrier made of cast steel was integrated into the frame , on which the inner cylinder and the control system rested between the front bogie and the drive wheels. However, the sealing of the oil pan could never be completely ensured, so that oil dripping out repeatedly led to dirty rails and the associated start-up problems. Occasionally the oil also caught fire on hot parts of the locomotives and started fires. All three cylinders were controlled by means of the chain drive developed by Bulleid via an auxiliary crankshaft , which was driven by a triple chain from the drive axle , all three cylinders drove the central coupling axle. Bulleid had incorporated experience from the engine development in the automotive industry at the time into the control.
Was carried out in welded technique also consisting of manganese steel produced firebox of the locomotive boiler of the type Belpaire wherein Bulleid the clearance profile of the intended use of the routes Southern Railway ausnützte maximum. The fire box also received two Nicholson thermosyphons , a component from the US locomotive industry, with which the radiant heating surface should be further enlarged in order to utilize the heat radiation to the maximum. The boiler was designed for 280 psi , the highest pressure in British locomotive construction up to that point. It was considered one of the best British locomotive boilers, despite a somewhat high coal consumption. On the other hand, it was very flexible in its performance characteristics and was able to achieve high continuous performance even with poorer coal. After a few years, the boiler pressure was reduced to 250 psi, which proved sufficient. The chimney was in the type Lemaitre as a exhaust installation designed with a plurality of nozzles similar to distributed Kylchap - blowpipe . The smoke chamber was slightly sloped at the top in order to have enough space for the Lemaître induced draft system.
Making the work of the engine driver and stoker easier was a particular concern of Bulleid. The Merchant Navys were the first British locomotive class to receive a steam-powered fire door , which was also designed for the highest possible level of safety. Electric locomotive and driver's cab lighting, including illuminated sight glasses and displays, was also installed for the first time. The locomotives were given a steam generator to generate electricity. The front sides of the driver's cab with the windows in them were designed at an angle to allow a glare-free view to the front. A steam-driven reversal was also intended to make work easier, but this, in conjunction with the chain-driven control, proved to be fragile and difficult to control during operation.
Most noticeable from the outside were the casing of the boiler as well as the new BFB wheel sets, which are similar to the American Boxpok wheels . The abbreviation BFB stands for Bulleid and the manufacturer Firth Brown Steels from Sheffield . In contrast to Boxpok wheels, the BFB wheels were cast in one piece. The outer cladding was deliberately not referred to as streamlined cladding by Bulleid , but as "air-smoothed". On the one hand, it was intended to make the Southern Railway recognizable as a modern transport company, but above all it served to simplify the cleaning of the exterior in washing facilities for passenger coaches . The extremely poor view from the driver's cab along the fairing turned out to be a disadvantage. Since Bulleid had exhausted the clearance profile to the maximum, only narrow viewing slits remained in the driver's cab next to the boiler. The flat surface on the top of the boiler also created a vacuum that pushed the exhaust steam into the driver's field of vision. The latter problem could be resolved with a redesign of the front, in particular an additional cover above the smoke chamber door, and the addition of narrow smoke deflectors only a few centimeters away from the smoke chamber . Since the panels of the cladding were quite thin to save weight, they could easily be damaged. They often got kinks and folds, which also contributed to premature corrosion.
The locomotives received two different types of tenders , which differed mainly in their different water supplies . One version could carry 5000 gallons (approx. 22,700 liters), the other 6000 gallons (approx. 27,300 liters). The supply of coal was 5 tons, a relatively small figure, but it was mostly sufficient for the comparatively short routes of the Southern. The tenders were designed with slightly outwardly curved walls in order to adapt them optically to the passenger coaches of the time and to achieve a closed appearance of a train.
Conversion version
The costly maintenance of the locomotives, especially the Bulleid controls, as well as the poor visibility remained a constant problem for the class. Insufficiently dimensioned drive parts also broke. British Rail therefore decided in the mid-1950s to fundamentally rebuild the locomotives after considerations that they had been discarded in favor of building more "Britannia" Pacifics from the BR new building program. At that time, it was assumed that there would be around 30 more years of use until the second half of the 1980s. The accelerated conversion to diesel locomotives, electrification and the serious cuts in the British railway network by the Beeching ax , however, meant that many of the converted locomotives were only in service for a few years.
While the high-performance boiler remained largely unchanged, apart from a new, no longer sloping smoke chamber - only the oval smoke chamber door was reminiscent of the original design - the exterior and the controls were fundamentally redesigned. The machines lost the high-maintenance Bulleid chain controls , which were replaced by traditional Walschaerts controls for each cylinder. Instead of the external cladding, the machines were given a conventional exterior with boiler cladding and large smoke deflectors, similar to the BR standard locomotives. The BFB wheels were retained, but were given counterweights , as due to the relocation of the control to the outside, a corresponding mass balancing was required, which was not previously necessary for the internal control. Other components such as the ash box , the steam lines to the cylinders, cylinder taps and sand boxes were also replaced, and the steam-driven reversing system was also expanded. The tenders have also been fundamentally rebuilt. The conversion made the machines about two tons heavier.
Coloring
Originally all locomotives were painted in malachite green , the standard colors of Southern for their express tractors. Decorative lines and lettering were done in yellow. Only the machines delivered in 1944/45 were initially given a simple black color as a saving due to the war, but were also painted green after the end of the war. British Railways initially kept the SR color scheme. In the early 1950s, BR replaced the previous color scheme on almost all machines with Express Passenger Blue ; a strong blue. The machines lost this color scheme as early as 1953, since then they have been painted in dark green, the new standard color for express train locomotives. The converted locomotives were also given this color scheme, with the decorative lines in red and the lettering initially in yellow and later in beige.
Preserved locomotives
A total of eleven locomotives of the class were preserved, with most of them initially standing in a scrapyard in Wales for several years before being purchased and restored by railway enthusiasts and museum trains . Some machines have not yet been refurbished and are still in the condition in which they were salvaged from the scrapyard. Several machines were or are operationally used in front of special trains and on museum railways. Since the class was completely rebuilt in the 1950s, no copy remained in the original version of Bulleid. However, there are plans and considerations for several machines to restore them to the original version.
| SR number | BR number | Surname | Year of construction and month | Retirement | current location or location | Status | image | Remarks |
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| 21C5 | 35005 | Canadian Pacific | December 1941 | October 1965 | Mid-Hants Railway | operational, currently under investigation |
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| 21C6 | 35006 | Peninsular & Oriental SN Co. | December 1941 | August 1964 | Gloucestershire Warwickshire Railway | operational |
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| 21C9 | 35009 | Shaw Savill | July 1942 | September 1964 | East Lancashire Railway | not operational, refurbishment planned |
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| 21C10 | 35010 | Blue star | August 1942 | September 1966 | Colne Valley Railway | not operational, refurbishment planned |
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Dismantling in the original version in consideration |
| 21C11 | 35011 | General Steam Navigation | December 1944 | February 1966 | Swindon and Cricklade Railway | in work-up | Dismantling in the original version planned | |
| 21C18 | 35018 | British India Line | May 1945 | August 1964 | Carnforth , West Coast Railways | ready to use |
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| - | 35022 | Holland America Line | October 1948 | May 1966 | Crewe | not operational, refurbishment planned |
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| - | 35025 | Brocklebank Line | November 1948 | September 1964 | Sellinge, Kent | not operational, refurbishment planned | ||
| - | 35027 | Port line | December 1948 | September 1966 | Crewe | not operational, refurbishment planned |
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to 1996 on the Bluebell in use |
| - | 35028 | Clan Line | December 1948 | July 1967 | Stewarts Lane, Battersea | operational |
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only locomotive of the class sold by British Railways in working order |
| - | 35029 | Ellerman Lines | February 1949 | July 1966 | National Railway Museum , York | inoperable |
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Cauldron partially cut open for exhibition purposes |
Individual evidence
- ^ OS Nock: The British Steam Railway Locomotive, Volume 2, 1925–1965 , Ian Allan Ltd., London 1966, p. 171
- ↑ kentrail.org.uk: Bulleid Merchant Navy Class 4-6-2 , accessed May 24, 2019
- ↑ a b c d Bulleid’s Locos: The Background To Bulleid's Revolutionary 'Merchant Navy' Class , accessed on May 10, 2019
- ^ A b c Southern Railways E-Group: Modified Bulleid MN "Merchant Navy" Class 4-6-2 , accessed May 10, 2019
- ↑ kentrail.org.uk: Bulleid Merchant Navy Class 4-6-2 p. 2 , accessed May 25, 2019
- ↑ a b c d e f clan-line.org.uk: The Merchant Navy Class , accessed May 24, 2019
- ↑ www.steamlocomotive.com: Southern 4-6-2 Locomotives in Great_Britain , accessed May 25, 2019
literature
- OS Nock: The British Steam Railway Locomotive, Volume 2, 1925-1965 , Ian Allan Ltd., London 1966
