Metropolitan Railway 1906 Stock (M and N Stock)

The Metropolitan Railway began the electrification of it's lines in the early 1900s, with the first electric services running between Baker Street and Uxbridge in 1905. Electrification gave the Metropolitan Railway a problem however, they were left with a number of nearly new surplus locomotive hauled carriages. In 1906 the Metropolitan Railway began to convert these carriages into electric multiple units [1].

Side view of an M Stock DM [2]

Information for M Stock
Number built:	58 (Carriages)
Built:	1898-1900 (Conversions 1906)
Builder:	Ashbury Railway Carriage & Wagon Company (Conversions) British Thomson-Houston
Motor:	4 GE69 electric motors per power car (600v DC fourth rail)
Power:	1, 600 hp (1, 194 kW)
Formation:	Driving Motor (DM) + Trailer (T) + T + T + T + T + DM

The first conversions were 4-car rakes converted in 1906. They were initially found to be underpowered and were retro-fitted with more powerful motors. These cars, later in 6-car rakes, were known as N Stock and were later used on the Metropolitan Stanmore branch.

Also created were 7-car rakes with GE69 motors [2], two motors apiece on each bogie on the Driving Motor. These M Stock trains were later strengthened to 8-car rakes. Behind the cab in each Driving Motor the former guard and luggage compartment became an equipment area containing switching and other control electrical apparatus which took up about a third of the coach [3].

M Stock on test [2]

GE69 electric motor [2]

Equipment area behind the driver's seat in the cab [2]

[1] Piers Connor, The London Underground Electric Train (Crowood Press, 2015) p. 135
[2] "Converted coaches on the Metropolitan Railway", The Electrician (Oct 12 1906) p. 1004
[3] Oliver Green, The London Underground. An Illustrated History (Ian Allan, 1987) p. 26