SR Class 4Sub
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|Southern Railway 4-Sub Units|
Prototype 4-sub Unit 4101 with domed front cab
|Number built||185 new built sets|
|Formation||power car + 2 trailer cars + power car|
|Operator(s)||Southern Railway and British Railways (Southern Region).|
|Maximum speed||75 mph 121 km/h|
|Weight||DMBS - 39–43 long tons (40–44 t)|
|Prime mover(s)||Early units: 4 x 275 hp (205 kW) traction motors
total 1,100 hp (820 kW)
Later units: 4 x 250 hp (190 kW) traction motors
total 1,000 hp (750 kW)
|Braking system(s)||Air (Westinghouse)|
The Southern Railway (SR) and the British Railways (Southern Region) (BR(S)) used the designation Sub to cover a wide variety of electric multiple units that were used on inner-suburban workings in the South London area. The designation ‘Sub’ was first officially used in 1941 to refer to newly built 4-car units. However, during the 1940s large numbers of earlier ‘3-Car Suburban Sets’ were increased to four cars by the addition of an 'Augmentation' trailer, and became part of the 4-Sub category. The SR and BR (S) continued to build or else rebuild 4-car units to slightly different designs which became part of the 4-Sub Class. Many of these later examples survived in passenger use until late 1983, by which time British Rail had allocated to them TOPS Class 405.
3-Car Suburban Sets
In 1923 the Southern Railway inherited 84 3-car suburban electric multiple units from the London and South Western Railway (LSWR), dating from 1914. These could be enhanced by 24 2-car trailer sets coupled between two units, creating 8-car formations. Over the next 18 years the SR acquired a further 516 3-car sets. These were either new; rebuilt from steam stock inherited from the LSWR, the London Brighton and South Coast Railway (LBSCR) and the South Eastern and Chatham Railway; or rebuilt from LBSCR AC multiple units. Some rebuilt units has ‘torpedo style’ front ends, others had the newer, flatter, front ends used on the main-line stock introduced during the early 1930s. They were designated ‘3-Car Suburban Sets’ to differentiate them from main-line units, and were numbered between 1201 and 1800. They are sometimes referred to as ‘3-Sub units’, but this designation does not appear to have been used whilst they were in use.
The 3-car units ultimately proved to be inadequate for most trains and inconvenient as the trailer sets had no driving cabs and so had to be marshaled between two 3-car units. Therefore, many were augmented by the addition of a new trailer car and rebuilt as 4-Sub units between 1942 and 1948. The remainder of the 3-car units were withdrawn. The last 2-car trailer set was withdrawn in September 1948, and the last 3-car formation ran in 1949.
In 1939, following the appointment of Oliver Bulleid as Chief Mechanical Engineer, the SR announced a new welded steel 4-car suburban unit with curved sides, seating six passengers across rather than the normal five. The prototype unit, 4101, was not completed until 1941 due to the advent of the Second World War. This had composite (both First Class and Third Class) seating accommodation in one trailer car and domed cab roofs. A further nine units were built in 1944-5 with Third Class accommodation only. Twenty units were introduced from 1946 with a vertical, ‘slab’ front end, and Third Class accommodation only. The underframes were built at Lancing Carriage Works and the bodies at Eastleigh Works.
As mentioned above, between 1942 and 1948 many 3-Car Suburban Sets were rebuilt and enhanced by the addition of a new 'Augmentation' trailer car to create 4-Sub units. This was done by inserting new steel trailers rather than one of the existing trailer cars. The rebuilt units were renumbered between 4131 and 4249.
BR(S) continued to introduce 4-Sub units, both new and converted from existing units, until 1951.
The usual formation for the newly built units was to have a Driving Motor Brake Third (DMBT) car at each ends, with accommodation for 108 passengers in nine compartments, together with two Trailer Third (TT) cars between with ten or eleven compartments giving a total passenger accommodation for 456 in all four coaches. (After the renaming of 'Third Class' to 'Second Class' in 1956 these became DMBS and TS respectively.) However some of the rebuilds had Trailer Composite (TC) cars. The earlier coaches provided compartments, whereas the post war newly built carriages tended to provide saloon or semi-saloon style accommodation to allow for more standing room. These new 'open' carriages were designated DMBTO or TTO.
Throughout their careers the 4-Sub units were used on the London suburban services of all three divisions of BR (S).
The rebuilt units began to be withdrawn in the late 1950s and all had been withdrawn by the end of the 1960s. Apart from a few accident damaged units, the newly built units began to be withdrawn in 1972, and had all been withdrawn by 1983. Those units surviving in the early 1970s were designated as British Rail Class 405 under the TOPS computer system.
A handful of Sub stock carriages have survived in preservation, thus:
- Driving Motor car number 8143 (formerly of Sub unit 1293, later 4Sub 4308) is in the care of the National Railway Museum, York.
- 4Sub unit number 4732, formed of DMBTO 12795, TT 10239, TTO 12354 and DMBTO 12796, was retained by British Rail after withdrawal from normal passenger service for use on special occasions. It is currently Stored at the Electric Railway Museum, Warwickshire, after spending many years stored in the open at various locations.
- Former Departmental Converted 4 Sub Carriage TT 10400 is stored at a private site.
(current in bold)
|1243||4308||8143||-||-||-||1925 Eastleigh||SR Maunsell Green||National Railway Museum|
|-||4732||12795||12354||10239||12796||1951 Eastleigh||BR Blue||Electric Railway Museum|
|-||-||-||10400||-||-||1951 Eastleigh||Network South East||Finmere|
History of individual units
|989-1200||-||1920–1937||Various||Two-car Sub Trailer sets. Converted from LSWR, SECR and LBSCR steam stock and LBSCR AC electric stock. Disbanded between 1941 and 1948, some cars used to augment 3-car Suburban to 4Sub.|
|1201–1284||3-car Suburban||1914–1917||DMBT+TC+DMBC||Built by London and South Western Railway, their numbers E1-E84, ex-steam stock. Most augmented to 4131-4171 and 4195-4234 series in 1942–1948.|
|1285–1310||3-car Suburban||1925||DMBT+TC+DMBT||Western Section (London to Guildford & Dorking) units, new-build, short frames. Augmented to 4300-4325 series in 1945–1946.|
|1401–1495||3-car Suburban||1925–1926||DMBT+TC+DMBT||Eastern Section units, ex-SECR steam stock. Most augmented to 4431-4594 series in 1946–1949.|
|1496–1524||3-car Suburban||1925||DMBT+TC+DMBT||Eastern Section units, new-build, standard frames. Augmented to 4326-4354 series in 1945–1946.|
|1525–1534||3-car Suburban||1926||DMBT+TC+DMBT||Eastern Section units, ex-SECR steam stock. Most augmented to 4431-4594 series in 1946–1949.|
|1579–1599||3-car Suburban||1932–1937||DMBT+TC+DMBT||Ex-LSWR steam stock. Most augmented to 4401-4594 series.|
|1601–1630||3-car Suburban||1927–1928||DMBT+TC+DMBT||Central Section units, ex-SECR steam stock. Most augmented to 4431-4516 series.|
|1631–1657||3-car Suburban||1928–1929||DMBT+TC+DMBT||Central Section units, ex-LBSCR steam stock. Most augmented to 4517-4614 series.|
|1658–1701||3-car Suburban||1927–1928||DMBT+TC+DMBC||Central Section units, ex-LSWR steam stock. Most augmented to 4172-4194 and 4235-4250 series.|
|1702–1716||3-car Suburban||1928||DMBT+TC+DMBC||Central Section units, ex-LBSCR steam stock. Most augmented to 4517-4614 series.|
|1717–1772||3-car Suburban||1929–1930||DMBT+TC+DMBC||Central Section units, ex-LBSCR AC electric stock. Most augmented to 4517-4579 series.|
|1773–1785||3-car Suburban||1930–1931||DMBT+TC+DMBC||Ex-LSWR steam stock. Most augmented to 4517-4614 series.|
|1786–1796||3-car Suburban||1931–1932||DMBT+TC+DMBT||Ex-LSWR steam stock. Most augmented to 4517-4614 series.|
|1797–1801||3-car Suburban||1932||DMBT+TC+DMBT||Ex-LBSCR steam stock. 1801 later renumbered 1600. Some augmented to 4580-4614 series.|
|4101||4-Sub||1941||DMBT+TT+TC+DMBT||Prototype new-build, steel bodied 4-Sub unit with domed cab roof.|
|4102-4110||4-Sub||1944–1945||DMBT+TT+TT+DMBT||New-build, steel bodied 4-Sub units with domed cab roof.|
|4111-4120||4-Sub||1946||DMBT+TT+TT+DMBT||New-build, steel bodied 4-Sub units with vertical cab roof.|
|4121-4130||4-Sub||1946||DMBTo+TTo+TT+DMBTo||New-build, steel bodied 4-Sub units with vertical cab roof.|
|4131-4171||4-Sub||1942–1948||DMBT+TT+TT+DMBT||Ex-3-car Suburban units, with additional ex-3-car Suburban trailer car.|
|4131-4132||4-Sub||1969||DMBT+TT+TT+DMBT||Second use of unit numbers. Formed from spare steel-bodied Sub cars, including those used in the 7TC unit.|
|4172-4194||4-Sub||1947–1948||DMBT+TT+TT+DMBT||Ex-3-car Suburban units, with steel-bodied Augmentation trailer.|
|4195-4234||4-Sub||1942–1948||DMBT+TT+TT+DMBT||Ex-3-car Suburban units, with additional ex-3-car Suburban trailer car.|
|4235-4249||4-Sub||1947–1949||DMBT+TT+TT+DMBT||Ex-3-car Suburban units, with steel-bodied Augmentation trailer.|
|4250-4257||4-Sub||1942–1948||DMBT+TT+TT+DMBT||Formed from a variety of spare Sub cars.|
|4277-4299||4-Sub||1948–1949||DMBTO+TTO+TT+DMBTO||New build, steel-bodied 4-Sub units.|
|4300-4354||4-Sub||1945–1946||DMBT+TT+TT+DMBT||Ex-3-car Suburban units, with steel-bodied Augementation trailer.|
|4355-4376||4-Sub||1947–1948||DMBT-TT-TT-DMBT||New build, steel-bodied 4-Sub units.|
|4377||4-Sub||1947||DMBT-TTO-TT-DMBT||New build, steel-bodied 4-Sub unit, including prototype full saloon trailer car.|
|4378-4387||4-Sub||1948||DMBTO+TTO+TT+DMBTO||New build, steel-bodied 4-Sub units.|
|4401-4594||4-Sub||1946–1947||DMBT+TT+TT+DMBT||Ex-3-car Suburban units, with steel-bodied Augmentation trailer.|
|4601-4608, 4610/13/14||4-Sub||1947||DMBT+TT+TT+DMBT||First use of unit numbers. Ex-3-car Suburban units, with steel-bodied Augmentation trailer.|
|4601-4607||4-Sub||1950||DMBTO+TT+TT+DMBTO||Second use of unit numbers. New Driving Motor cars formed with trailers built between 1946 and 1948.|
|4617-4620||4-Sub||1972–1976||Formed from spare Sub cars built between 1946 and 1950.|
|4621-4754||4-Sub||1949–1951||DMBTO+TT+TT+DMBTO||Most cars had new bodies on old frames, though some were entirely new build. 4667-4754 included an Augmentation trailer from withdrawn units.|
- Moody 1968, p. 88
- ’’The ABC of Southern Electrics’’ (1943), p.12.
- Moody 1968, p. 137
- Southern E-Group 4-Sub (Class 405) http://www.semgonline.com/gallery/class405_01.html
- The ABC of Southern Electrics. Ian Allan. 1968.
- Marsden, Colin J. (1983). Southern Electric Multiple Units ; 1898 - 1948. Ian Allan. ISBN 0-7110-1253-9.
- Moody, G.T (1968). Southern Electric 1909–1968. Ian Allan.
- Rayner, Bryan; Brown, David (1983). The "4-Sub" Story. Southern Electric Group. ISBN 0-906988-09-8.
- "4-Sub (Class 405)". Southern E-Group. Retrieved November 2013. Check date values in:
- "4-SUB Units - Principle Data". Suburban Electric Railway Association. Retrieved November 2013. Check date values in:
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