Class 405 4-SUB

The 4-SUB was a long-lived and large class of electric multiple unit (EMU) introduced in the latter days of the Southern Railway and surviving in British Rail service into the early 1980s, where it became known as the Class 405. The new build was augmented by rebuilt 3-SUB EMUs, some of which dated back to the mid-1920s! They were used on suburban services out of London (hence the Alpha code).

Preserved 4732 in latter day BR blue livery

Information
Number built:	740 (185 4-car sets) plus rebuilds
Built:	1940-51
Builder:	SR (later BR) Eastleigh Works
Motor:	4 EE507C electric motors per power car (660-750v DC third rail)
Power:	1, 000 hp (746 kW)
Formation:	DMBS (Driving Motor Second)+TS (Trailer Second)+ TSO (Trailer Second Open)+DMBS

Construction began at Eastleigh in 1940 [1], though the first was not completed until 1941 [2] due to wartime delays. Construction of the 4-SUBs continued until 1951 though full scale production did not begin until the end of the Second World War [3]. Many 3-SUBs were rebuilt in the 1940s, some having earlier "torpedo" style fronts (see 8143) below and others the flat fronts of the 4-SUBs. Early on 4-SUBs had a mixture of first and third class accommodation though first class was removed from suburban services in the 1940s. In British Railways days they were listed as having second class throughout, though this was just what third class was renamed! The 4-SUBs had a mixture of open and compartment seating [4].

Rebuilt units were withdrawn from the 1950s and all were gone by the end of the 1960s. Withdrawals of the new built units began in the early 1970s and was completed in 1983. A complete four car set has been preserved plus a rebuilt DMBS and a new build trailer.

Preserved 8143, a rebuilt car, at NRM York

Front on view of 4732

[1] Colin J Marsden, Diesel & Electric Multiple Units Recognition (Ian Allan, 2013) p. 308

[2] David Brown, Southern Electric Vol. 1 (Capital Transport, 2010) p. 158

[3] Brian Haresnape & Alec Swain, Third Rail DC Electric Multiple Units (Ian Allan, 1989) p. 21

[4] Colin J Marsden, Electric Multiple Units (Ian Allan, 1982) p. 61