The Standard Stock title was applied to a variety of Tube stock built between 1923 and 1934, all of which shared the same basic characteristics, but with some detailed differences. This design is sometimes referred to as 1923 Tube Stock, 1923 Stock, or Pre 1938 Stock. Most of the Standard Stock was built to replace the first generation of "Gate Stock" Tube trains or to provide additional trains for extensions built in the 1920s and early 1930s. Standard Stock cars consisted of motor cars, with a driver's cab, behind which was a "switch compartment" occupying approximately one-third of the length of the car, plus trailer cars and "control trailers", with a driving cab but no motor. All were equipped with air operated sliding doors. The guard's door on the earlier trains was a manually operated, inward-opening hinged door.
1922 Stock prototype cars
For evaluation purposes, in anticipation of the large number of cars that were to be built over the next several years, six experimental cars were ordered and had been delivered by February 1923. There were five trailers and one control trailer, which were marshalled between French-built "Gate Stock" driving motor cars. A demonstration for the press took place on the Piccadilly line in February 1923, after which the new cars and the French motor cars were moved by road to the Hampstead Line, entering service in August. The French motor cars were part of a batch of 20 which had been rebuilt with air-operated doors, to allow them to work with the 1920 Stock, the first batch of vehicles built with air doors. The trailers and French motor cars formed the inaugural train on the Hampstead Line extension from Golders Green to Hendon when it opened on 19 November 1923.
The builders were given a partial specification, which ensured that each car would have 48 seats and two sets of air-operated double doors on each side, providing an opening which was wide. Beyond these basic guidelines, each builder was allowed to build a trailer car to its own design, although externally, they looked very similar. The control trailer was designed by the Underground Electric Railways. The stock became known as the 1922 Stock or Competition Stock and was considered part of the Standard stock fleet.
Production stock
The earliest Standard Stock was built for use on the Hampstead tube, which was extended from Golders Green to Edgware and from Clapham Common to Morden in 1923, as well as incorporating the City and South London Railway, which had been rebuilt with larger tunnels. 191 cars were ordered from three manufacturers in 1923, which were formed into five-car trains. The City and South London Railway had been built with tunnels which were only in diameter, and had used small electric locomotives to haul trailer cars, until it closed for rebuilding in 1923. The reconstruction was completed in 1925, and 69 of the new vehicles were owned by them, while the rest were owned by the London Electric Railway Company.
In a departure from previous practice, where all traction control equipment had been supplied by British Thomson-Houston (BTH), most of the batch were fitted with equipment by Metropolitan-Vickers, which consisted of electro-magnetic contactors arranged to manage the acceleration of the train automatically, with switching from series to parallel connection of the motors handled by bridging them rather than open-circuiting them. Two motor cars had equipment by General Electric Co (GEC), which worked similarly, and was required to work in multiple with the Metropolitan-Vickers equipment. All the vehicles used a C-type door operating engine, which proved to be a poor design.
Another 127 cars were ordered in 1924, with most of the motor cars and some of the control trailers using GEC equipment. Cars with GEC controls used WT54 motors. Those with Metropolitan-Vickers equipment used MV152 motors, and although they were interchangeable in theory, in practice they were always kept in pairs. The 1924 cars were fitted with a D-type door engine. This was reclassified as a DL-type after a minor modification had to be made. It proved much more resilient than the earlier C-type, and was used on all Standard Stock until 1931.
Delivery of the cars was not easy, as the Hampstead Line did not have a mainline railway connection to any other line. The bodies and bogies were delivered by road, and two large gantries were erected at both the Morden and Golders Green depots. A traction engine would arrive at the site with the body, and would position it below the gantries. It would then be raised so that the road wheels could be removed, and a steam crane would position the bogies onto the track. Once the body and bogies were united, a steam engine would remove the complete car, to allow the next one to be assembled.
A further 120 cars were ordered in 1925, with both types of equipment, to cope with the opening of the junction at Kennington and the lengthening of trains to six cars and from 1926, seven cars. Motor cars seated 30 passengers, while trailers had 48 seats. Control trailers had a cab at one end, but no switch compartment, and so seated 44. Trains initially had a crew of three, consisting of a motorman, a front conductor, and a rear guard. The guard signalled the conductor that the train was ready to go, and the conductor signalled the motorman.
Once the use of air-operated doors had proved to be successful, modifications were made to enable a train to be operated by a crew of two. Changes included the fitting of a telephone, so that the guard and motorman could communicate, interlocks to ensure that all doors were closed, and the re-routing of the starting bell, so that it could be operated by a guard at the rear of the train, rather than the conductor at the front. These changes were completed by 1927, allowing the reduction of the train crew.
1926 and 1927 builds The superior nature of the new trains helped to show up the inadequacies of plans to convert large numbers of gate stock cars to have air doors, and they were largely abandoned. Another 112 cars, all fitted with GEC equipment, were ordered from Metropolitan Carriage Wagon and Finance in 1926. An order for 170 cars followed on in 1927. This enabled trains to be increased to seven cars, and more trains to be operated. A second order was placed with MCWF in 1927, for 136 more cars.
The traction control equipment was supplied by British Thomson-Houston. Their equipment generally proved to be more reliable, and previous batches of Standard Stock were modified so that the main contactors could be replaced with BTH equipment. BTH continued to be the preferred supplier for this equipment for the next 35 years. Metropolitan-Vickers supplied their own motors. Standard Stock built by other manufacturers used GEC motors. The inter-operability of cars from several manufacturers with three types of traction control was the reason that they were called Standard Stock.
The 1927 builds used a 'Z' bogie, instead of the previous 'Y' bogie, which had wheels of diameter, as opposed to . This required a modification to the WT54 motors, supplied by GEC, which were then known as WT54A motors. The gearing was altered so that cars with either size of wheels remained compatible. Trials with the 'loudaphone' system by which the guard and motorman could communicate on this stock resulted in it being retro-fitted to the earlier stock.
During this period, many of the Gate Stock cars on the Central line had been converted to air-door operation by the Union Construction Co., which was based at Feltham. Plans were briefly formulated to convert the Gate Stock on the Piccadilly and Bakerloo lines, but analysis showed that the cost of building a new car was only slightly more than the cost of converting an old one, and so an order for 182 new cars was placed. They were known as the 1927 Feltham Stock. Their door plates carried the date 1928, and they were not delivered until 1929 and 1930. The lightweight construction caused problems in later years, when the seat risers and body bolsters developed fractures. With the batch of cars built by MCWF and fitted with BTH equipment, these vehicles enabled Gate Stock to be withdrawn from the Piccadilly line in June 1929, and from the Bakerloo line on 1 January 1930.
1929 and 1930 builds Another 53 cars were ordered from the Union Construction Co. in 1929, to enable the remaining 1920 Stock cars, which had air doors but were not really suitable for operation on the open sections of the Piccadilly line, to be transferred to the Bakerloo line. An extra train of two motor cars and four trailers was ordered in 1930, to test several new features. They were the last cars to be built by the Union Construction Co., for it was closed as a result of political pressure in 1932. The new motor cars were longer, and the trailers were longer. This was achieved by tapering one or both ends, to prevent them fouling the structure gauge on curves. On two of the trailers, the centre door openings were widened from to . On the other two, the width of the centre doors was not altered, but the seating capacity was reduced from 48 to 40, to allow the provision of an additional single-leaf door at both ends of the car. The position of the guard's door control panel was altered, although this was not found to be satisfactory, and was dropped from subsequent builds.
Because of the Piccadilly extensions, which were above ground, heaters were fitted, and the use of British materials in its construction was used for publicity purposes, at a time when there was an industrial depression. It became known as the 'All British' train, and operated on the Piccadilly and Northern lines. Transfer between the two was aided by the construction of a junction at Kings Cross in 1927. The Northern line offered heavier traffic, with which to assess the effectiveness of the new features. 62 production cars were ordered from Metropolitan-Cammell, which was formed from the Metropolitan Carriage Wagon and Finance Co. and Cammell Laird at this time, for delivery to the Bakerloo line. They replaced the Watford Joint Stock, which although relatively new, needed a larger crew and had to stop for longer at stations, because of its swing doors. Problems with the swing doors were highlighted by a fatal accident in which a passenger got caught in them, but the door interlock did not detect it.
This build was not initially compatible with other builds, because it was fitted with an electro-pneumatic braking system, as well as the Westinghouse air brake. To accommodate its control, an extra 10-core control jumper was fitted. Previous builds of Standard Stock were gradually altered to include the extra wires, a process which was largely completed by 1936. Standard Stock motor cars which were running on the Bakerloo line with Cammell Laird 1920 Stock trailers were not fitted with the electro-pneumatic brake wiring until the trailers were withdrawn in 1938.
1931 and 1934 builds In 1929, government aid enabled plans for extensions to the Piccadilly line northwards to Cockfosters and westwards from Hammersmith to Acton Town, on tracks which were parallel to the District line but not shared with it, to come to fruition. The length of the line increased from to , and so more trains were needed. The improvements made for the 1930 build were incorporated into the design, as well as some new features. 145 motor cars were ordered from Metropolitan-Cammell, and 130 trailer cars were shared between two builders. All trailer cars had 12 doors, with two sets of double doors and a single-leaf door at both ends on each side. Electro-pneumatic brakes were fitted, as was a weak-field control, which enabled higher speed running and had been tested on the 1930 build. Its use on the Northern line had demonstrated that the same service intervals could be maintained with four fewer trains.