| NER Class R LNER Class D20 | |||||||||||||||||||||||||||||||||||||||||||||||||||||
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 1907-built Class R No. 2387, at Gateshead in 1954 | |||||||||||||||||||||||||||||||||||||||||||||||||||||
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TheNER Class R (laterLNER Class D20) was a class of4-4-0steam locomotive designed byWilson Worsdell for theNorth Eastern Railway (NER). Sixty locomotives were built atGateshead works between 1899 and 1907.[1] They proved highly successful on express passenger services and were noted for their exceptional reliability.[2] The class passed to theLondon and North Eastern Railway (LNER) at the1923 Grouping, being classified D20, and subsequently toBritish Railways in 1948.[3] The last was withdrawn in 1957 and none were preserved.[4]
At the end of the 19th century, theEast Coast Main Line was experiencing steady traffic growth, resulting in increases in the weight of passenger trains.[5] TheGreat Northern Railway (GNR), the NER's southern partner on the East Coast route, responded by introducing its firstAtlantic locomotives (GNR Class C1) from 1898.[6] In response, the NER proposed an enlarged 4-4-0 design in 1898, which resulted in Wilson Worsdell's Class R.[7]
The NER had also experimented with4-6-0 locomotives for express work, building theClass S from 1899. However, these steamed poorly due to their small and shallow grates, and the 4-4-0s of Class R quickly proved superior for express passenger duties.[8]
The Class R incorporated design features that Wilson Worsdell had used on previous locomotives such as theClass M1 (LNER D17), but also included several new developments to promote better running.[9] The cylinders were 19 inches (480 mm) in diameter with a 26 inches (660 mm) stroke.[10]Stephenson valve gear was retained, but the locomotives were equipped with newly developed outside admissionpiston valves fitted below the cylinders.[9] A slide valve version was contemplated but the piston valves proved so successful that it was never built.[11]
The boiler pressure was set at 200 pounds per square inch (1,400 kPa), with the diameter increased to 4 feet 9 inches (1.45 m) and the firebox lengthened to 7 feet (2.1 m).[11] At the time of introduction, this represented the largest boiler built by the NER.[2] All of the original boilers were fitted withRamsbottom safety valves in a polished brass trumpet cover.[12] All D20 boilers built after 1916 were fitted with two Ross pop safety valves instead.[12]
The locomotives were dual-fitted withWestinghouse air brake cylinders for both the engine and train, and a vacuum ejector for alternative train braking.[13]
All sixty Class R locomotives were built at Gateshead works in six batches.[14] The initial batch of ten was built in 1899, immediately followed by two further batches of ten each in 1900–1901.[15] After a gap of five years, three additional batches of ten each were built in 1906–1907.[15]
The final Class R to be built, No. 1235, was fitted with an experimental Sistertonsuperheater in an extended smokebox.[16] This was trialled with adynamometer car in 1908 and again in April 1909, but the Sisterton design proved unsuccessful and was removed shortly afterwards.[16]
Following successful superheating trials byVincent Raven on hisClass Z (LNER C7) Atlantics, NER management accepted superheating and moved to fit it across their express locomotive fleet.[17] The D20s first received superheaters in 1912, with the majority fitted withSchmidt superheaters, though seven receivedRobinson superheaters instead.[12] Only two locomotives remained unsuperheated at the 1923 Grouping; these were eventually superheated in 1925 and 1929.[12] From 1930, the LNER-standard Robinson superheaters became the norm for replacements.[13] The fitting of superheaters required the smokebox to be extended by approximately 1 foot (0.30 m).[18]
It was standard NER practice to reduce boiler pressure when fitting a superheater; accordingly, the working pressure was reduced to 160 pounds per square inch (1,100 kPa).[19]
The Class R proved to be a great success on express passenger services and were noted for their reliability.[2] The first locomotive, No. 2011, was put to work on a demanding double schedule with two crews, working fromNewcastle toEdinburgh andLeeds every day for six days a week.[20] This was maintained with hardly any breaks for two years. No. 2011 accumulated 284,182 miles by the time it received its first general overhaul in March 1903.[20] The remainder of the first batch was operated by single crews but still averaged 163,000 miles before their first general overhauls.[20]
During this early period, the D20s operated the main express passenger services between York, Leeds, Newcastle, and Edinburgh.[8] After 1903, they shared these services with theClass V (LNER C6) Atlantics.[21] When further locomotives were required in 1906, the NER chose to build more D20s rather than the more recent C6 design, a testament to the class's capabilities.[22]
By the 1923 Grouping, theRaven C7 Atlantics were working most of the main express services on the NER network, but 54 D20s remained allocated to main line sheds.[23] During 1924 and 1925, D20s were occasionally seen in the southern sections of the LNER network, hauling excursions to theBritish Empire Exhibition viaKings Cross.[23]
The class saw two significant reductions in status during the 1920s.[24] The first came with the widespread introduction ofGresley A1 Pacifics, which displaced the C7 Atlantics from their express duties to lesser main line services then occupied by the D20s.[24] This was followed by the introduction of theGresley D49 Hunt/Shire 4-4-0s.[24] These changes led to widespread movement of the D20s away from main line sheds to secondary duties.[24]
By 1935, the D20s were allocated at York (10), Starbeck (8), Tweedmouth (6), Darlington (5), West Hartlepool (4), Scarborough (4), Heaton (3), Gateshead (3), Neville Hill (3), Selby (2), Botanic Gardens Hull (1), Blaydon (1), and Stockton (1).[24]
Rather than withdrawing the ageing class, the LNER decided to modernise these capable locomotives.[13] The boiler design was modified in 1934–1935 to use a single plate barrel instead of the original three-ring design, with sixteen extra tubes added to the boiler, providing an additional 87 square feet (8.1 m2) of heating surface.[13]
No. 2020 became the first D20 to receive more extensive modifications in 1936.[25] The piston valves were moved above the cylinders and increased in size to 10 inches (250 mm) diameter, while the valve travel was increased to 6 inches (150 mm).[13] No. 2020 was also converted to left-hand drive and had its Westinghouse pump removed.[13] These rebuilt locomotives were classified D20/2, while the unrebuilt locomotives were reclassified D20/1.[3]
The modification programme stalled untilEdward Thompson became the LNER'sChief Mechanical Engineer in 1941.[15] Only three D20/2s were completed in total.[15]
At the 1923 Grouping, the sixty Class R locomotives were classified D20 by the LNER.[3] Forty-six D20/1 and three D20/2 locomotives passed toBritish Railways in 1948 and were numbered 62340–62397 (with gaps).[26]
The first D20 was withdrawn in 1943.[27] By the time of nationalisation in 1948, 49 locomotives remained in service.[26] The final allocations included Starbeck (10), Selby (9), Alnmouth (7), Botanic Gardens (5), Tweedmouth (3), Blaydon (3), Northallerton (3), West Hartlepool (3), Bridlington (3), Stockton (2), Duns (1), and York (1).[27] The last D20 was withdrawn in 1957 and none were preserved.[4]
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