London Underground 1938 Stock

The London Underground 1938 Stock is a London Underground tube stock design. A total of 1,121 cars were built by Metro-Cammell and Birmingham RC&W. An additional 173 cars were added to the fleet by the end of 1953, comprising 91 new builds, 76 conversions from Pre-1938 Tube Stock or 1935 Tube Stock, and six unconverted cars of 1935 Tube Stock, and the stock was used on the London Underground until 1988. During their long lives they worked on the Bakerloo, Northern, Piccadilly, East London, Central, and Northern City lines. Ten sets were refurbished and ran on the Isle of Wight as Class 483, making them the oldest passenger rolling stock operating timetabled services on the National Rail network at the time of their withdrawal in January 2021.
The trains represented a major technical advance, as all the electrical equipment was located under the floor for the first time. All previous tube stock had large equipment compartments behind the driving cabs in motor cars, which reduced the space available for passengers by about a third.

Numbers

There were four types of car, one of which was produced in two forms:

Driving Motor – 42 seats, plus 2 tip-up
* 'A' DM – north/west facing; solid centre buffer
* 'D' DM – south/east facing; spring-loaded centre buffer
Non-Driving Motor – 40 seats, no driving or door controls
Special Non-Driving Motor – door controls only
Trailer – 40 seats, no motors or controls

As built, the 1938 Stock was numbered as follows:

'A' DM	'D' DM		NDM	SNDM	T
10012 – 10323 90324 – 90333	11012 – 11323 91324 – 91333		12000 – 12028 92029 – 92058 12059 – 12157 12409 – 12411 12422 – 12446	92447 – 92466	012158 – 012388 092389 – 092408 012412 – 012421 012467 – 012476
322	322	Total	186	20	271

Use on different lines

The 1938 Stock was built as part of the London Passenger Transport Board's New Works Programme 1935–1940. The trains were primarily intended for use on the Northern and Bakerloo lines, with an additional seven trains also being used on the Piccadilly line.
As part of the New Works Programme, the Northern and Central lines were to be extended over London and North Eastern Railway tracks, and because of a joint working agreement between the LPTB and the LNER, it was necessary for a proportion of the Underground fleet to be owned by the LNER. Accordingly, 289 cars of 1938 Stock were designated as LNER owned, and fitted with plates marked "Property of LNER". Although 129 of these were to cover extensions to the Central line, none of them actually worked Central line services: they were mixed with the Northern and Bakerloo line fleets.
Throughout the 1950s and 1960s, the Northern line was worked exclusively by 1938/1949 Stock trains. They were starting to show their age by the late 1960s; the first withdrawals from the Northern line took place in the early 1970s with the introduction of the 1972 Stock trains.
In the mid-1970s, the 1972 Stock cars began to be used on the Bakerloo line in addition to 1938 Stock. The 1972 Stock cars were intended for eventual use on the Jubilee line, thereafter the remaining section of the Bakerloo line continued to be served exclusively by 1938 Stock cars until the 1980s. The Bakerloo line trains received an "Extra Heavy Overhaul" to keep them in service long after their intended withdrawal date. The Bakerloo line was thus the last line to be operated solely by 1938 Stock trains.
The Piccadilly line's few 1938 Stock trains operated alongside 1959 Stock for much of their lives. They were replaced by London Underground 1973 Stock, with the 1959 Stock being transferred to the Northern line, replacing other 1938 Stock trains.
During the 1970s, the short East London Line was worked by 1938 Stock trains, replacing trains of Q Stock. Single 1938 Stock trailer carriages were also inserted into 1960 Stock trains in the mid-1980s; these were used on the Woodford–Hainault and Epping–Ongar sections of the Central line. In addition, unit 10177 worked the Epping–Ongar shuttle between November 1957 and June 1960.
With the 1959 Stock approaching life-expiry, five ex-Bakerloo line trains of 1938 Stock were given a further overhaul in the mid-1980s. These were then used on the Northern line for a further two years; the last day of passenger service was on 19 May 1988. They were then sold for further use on the Isle of Wight.

Nine-car trains

As part of the New Works Programme of 1935–1940, there were plans to operate nine-car trains of 1938 stock on the Northern line. These cars were originally numbered differently from the other cars, the first digit '1' being replaced by a '9'.
The formation for a nine-car train would have been DM + NDM + SNDM + T + NDM + T + SNDM + NDM + DM.
With the scaling back of the planned extensions for the Northern and Bakerloo lines, and the need to order further stock to balance the fleet, cars were renumbered in the early 1950s.
The DMs, trailers, as well as twenty-eight of the thirty NDMs had the '9' replaced by a '1', the DMs becoming 10324-10333 and 11324-11333, the trailers 012389-012408, and the NDMs 12029-12054 and 12056-12057.
NDMs 92055 and 92058 were rebuilt into Uncoupling Non-Driving Motors along with all twenty SNDMs. The twenty two cars rebuilt into UNDMs were renumbered 30000-30021.

1935/1949 Stock

So successful was the 1938 Stock that, when, in 1948, additional cars were needed, 91 almost identical cars were built, 70 non-driving-motor cars and 21 trailer cars. These were known as 1949 stock and operated with the 1938 stock. They were numbered in the same scheme; the UNDMs were numbered 30022-30045, 31000-31045 and the trailers 012495-012515.
After World War II, the former 1935 stock streamlined DMs were rebuilt into trailers, and included with the 1938 stock, being renumbered 012477-012494.
Before the war, three trailers were built for use with the streamlined DMs. These three cars differed from the 1938 trailers in that they were not equipped with compressors. However, the cars were not delivered until after the war and with the DMs rebuilt the three cars became part of the 1938 stock fleet, being numbered 012412-012414, and fitted with compressors.

Technical

Electrical system

Each motor car is fitted with two series DC motors, one on each of the two bogies and are designed to operate from the 630 volt traction supply. Each motor has an output of approximately 250 horsepower. The controllers and switchgear are operated from a 50 volt auxiliary supply provided by a motor-generator set. This system allows the master controller at one end of the train to simultaneously operate the switchgear on all the motor cars in a similar manner to the system developed by Sprague for the Elevated railway in Chicago, Illinois some 46 years earlier. This same supply is also used to power the train lighting as well as some other auxiliary circuits.

'A' and 'D' motor cars

The motor cars are divided into two distinct types, the 'A' end car and the 'D' end car. Each of the bogies fitted to the two cars is identical. This means that if the two motor cars at the two ends of a train were identical, they would attempt to pull the train in opposite directions. Consequently, the bogies on the 'D' end motor car are installed the other way around from those on the 'A' end causing the two motor cars to move the train in the same direction.
The 'A' and 'D' designation is from the designation of the axles on the two bogies. The 'A' end car has the 'A' axle at the driving cab end of the car with the 'B' axle on the opposite end of the same bogie. The 'C' axle on the second bogie is nearest the driving cab with the 'D' axle closest to the coupled trailer car. The sequence is reversed on the 'D' end motor car. This is also why the alternate car is not designated the logically more obvious 'B' end.
Another mechanical difference between the two types of car is that the 'D' end car has a spring-loaded buffer at the driving cab end whereas the 'A' end car has a solid buffer.
These differences mean that when coupling two train sets together, the 'A' end of one set must be coupled to the 'D' end of the other. Although train sets are not normally split in day-to-day usage, they do have to be split when undergoing major maintenance tasks, such as when the bodies are lifted off of the bogies. This is not a problem on most lines, where all the train sets start and remain the same way around. However, on the Northern line the existence of the Kennington loop, just south of Kennington station, which allows Charing Cross branch trains to depart from its southbound platform and arrive at its northbound platform reverses the complete train once every journey. This means that, on this line, on average, half the trains will be facing in the opposite direction to the remainder. Only sets facing the same way can be coupled together.

Traction control

The 1938 design stock features the standard series/parallel traction control using bridge transition. The control system has an unusual feature. Ordinarily, the driver moves the master controller from 'off' up to 'full series' and then further to the 'full parallel' position when the train will be under full power.
The unusual feature is that once the driver has moved the controller to 'full parallel' and the train has accelerated to the point where the switchgear is actually in full parallel, the driver can then move the master controller back to 'full series'. The traction switchgear will remain in 'full parallel' unless the driver moves the master controller from 'full series' to any position towards 'off'. Many drivers took advantage of this feature because it was more comfortable maintaining the downward pressure on the deadman's handle with the handle at the 6 o'clock position rather than the 9 o'clock position.