Standard stock is the title of a variety of rolling stock which was used on the deep-level underground railways and was constructed between 1923 and 1934. These stocks shared the same characteristics but with some variances between them, these are also referred to as 1923 tube stock or pre-1938 stock. The majority of these stocks where constructed to replace the 1906 or gated stock and to provide additional trains to the railway extensions constructed between 1920 and the early 1930s. The carriages where formed of motor carriages, which had a drivers cabin behind was a 'switch compartment' which occupied approximately one-third of the length of the carriage, a trailer and control trailers, there was a drivers cabin but no motor. The entire fleet had air-operated sliding doors, however earlier models had a manual hinged door which opened inwards for the train guards.

1922 stock - Prototype carriages

Six experimental carriages where delivered in February 1923, for evaluation purposes in anticipation of large stock numbers being ordered. The experimental fleet consisted of five trailers and one control trailer, where marshalled between the French constructed 1906 or gate stock driving motors. The Piccadilly line on 3 February 1923 hosted a demonstration for the press, with the new carriages and the French motor carriages where transferred to the Charing Cross Euston and Hampstead Railway (CCEHR) and entered service during August. The motor carriages where from a batch of twenty which had been converted to work with the 1920 stock and as a part of their refurbishment where equip with air-operated doors. The motors and carriages formed an inaugural train on the Charing Cross Euston and Hampstead Railway (CCEHR) extension from Golders Green to Hendon Central, opening on 19 November 1923.

The carriages where constructed with a partial specification, ensure that every carriage is able to seat 48 and two sets of air-operated doors on either side had an opening of 1.4m (4.5ft). Externally the cars looked the same, however other than the specification every builder managed to design the interiors in their own designs. The control trailers used where designed by the Underground Electric Railway Companies of London (UECL), this stock became known as the 1922 or completion stock and is considered a part of the Standard stock fleet.

1923 to 1925 Production stock

The first fleet of standard stock was constructed for use on the Charing Cross Euston and Hampstead Railway (CCEHR) and City and South London Railway (CSLR) which where currently being amalgamated in addition to incorporating extensions the Charing Cross Euston and Hampstead Railway (CCEHR) extension from Golders Green to Edgware, ad the City and South London Railway (CSLR) extension from Clapham Common to Morden. Three manufactuors where commitioned to constuct 191 carriages to form five-carriage trains.

The City and South London Railway (CSLR) had been constructed with a 3.2m (10.5ft) tunnel diameter which was too small for the new stock and had previously used small electric locomotives to haul carriages before its closure for rebuilding during 1923. The works had been completed by 1925.

The majority of the batch was fitted with equipment from Metropolitan-Vickers which consisted of electro-magnetic contractors being arranged to manage the acceleration of the train automatically without switching to a parallel connection of the motors hauled by bridging them rather than open-circuiting them. There where two motors that had equipment from the General Electric Co (GEC) and worked similarly further to being required to work with the Metropolitan-Vickers equipment. The vehicles all used a C-type door operating engine, however this proved to be a poor design.

In 1924 a further 127 carriages where ordered with most of the equipment being provided by the General Electric Co (GEC), these used WT54 motors, with the Metropolitan-Vickers using MW152 motors, although these where theoretically interchangeable they where kept in pairs. The 1924 batch where equip with D-type door engine, reclassified DL-type after minor modifications had been completed these proved more resilient to their predecessors and this was adopted for future builds of standard stock.

Delivery of the carriages was not easy because there where no direct railway links to another railway from the HECCR. The bodies and bogies had to be delivered by road to Morden or Golders Green depots where two gantries had been erected. A traction engine was delivered with the bodies and would be positioned below the gantries, the engine could then be lifted and the road wheels removed and a steam crane would be used to place the bogies on the track. When the bodies and bogies had been united, the steam engine would remove the complete carriage, ready for the next carriage to be completed.

In 1925 an additional 120 carriages of both equipment was ordered to help manage the opening of Kennington Junction and to lengthen the trains from five-carriages to seven-carriages from 1926. The motor carriages would have 30 seats whereas the trailers would seat 48, the control trailers had a cabin at one end, however there was no switch compartment, and had four fewer seats.

There was a crew of three, a motorman, a front conductor and a rear guard; the guard would signal to the conductor that the train was ready to depart and this would be relayed to the motorman by the conductor. After the use of air-operated doors had proved successful, modifications where made to fit a telephone to enable the guard and motorman to communicate, the re-routing of a starting bell to enable the guard to be located at the rear of the train rather than the front. These modifications allowed for the reduction of the train crew to two, and had been completed by 1927.

1926 and 1927 builds

The new trains where superior to the previous 1906 or gated stock and showed the inadequacies to convert large numbers of the stock to enable air-operated doors and these plans had been largely abandoned. An order was placed with the Metropolitan Carriage Wagon and Finance for a further 112 carriages in 1926 with an additional 170 carriages following in 1927. This enabled the train length to be increased to seven-cars and more trains to operate.

A second order in 1927 with the Metropolitan Carriage Wagon and Finance for 136 additional carriages, however the control equipment would be supplied by British Thompson-Houston, because their equipment generally proved more reliable and previous batches where modified to change the main contractors and replace the existing equipment with British Thompson-Houston equipment. Metropolitan-Vickers provided their own motors however the standard stock was constructed by other manufacturers and used General Electric Co motors. The carriages where inter-operational between the manufacturers and traction control, which is where the title standard stock is derived from.

The 1926 build used a Y bogie with 91cm (36 in) wheel diameters, and the 1927 build used a Z bogie with 100cm (40in) wheel diameters. These differences required modifications to the WT54 motors, supplied by the General Electric Co and became known as WT54A motors, and the gearing had to be modified so the carriages where able to be hauled with either wheel dimensions. The trials of a 'loudaphone' system where the motorman and the train guard could communicate lead to them being fitted to the earlier stocks.

The Central line, during this time, had been converted to use air-operated doors by the Union Construction Co based in Feltham. A plan was formulated to convert the 1906 or gate stock, operating on the Bakerloo and Piccadilly lines, to install air-operated doors, however an analysis showed the cost of constructing new carriages was slightly more expensive than converting and an order for 182 carriages was placed. These became known as the 1927 Feltham stock, although the door-plates carried the date 1928 and had not been delivered until 1929 and 1930. The lightweight construction caused problems as the stock aged, and the seat risers and body bolsters began to develop fractures.

The stock constructed by Metropolitan Carriage Wagon and Finance with the British Thompson-Houston equipment, which had allowed the 1906 or gate stock to be withdrawn from the Piccadilly line in June 1929 followed by the Bakerloo line on 1 January 1930.

1929 and 1930 builds

An order was placed with the Union Construction Co in 1929 for an additional 53 carriages to enable the 1920 stock to be transferred from the Piccadilly line to the Bakerloo line because they where unsuitable to be used in the open sections of the Piccadilly line extensions. A further two motor carriages and four trailers which had additional features to be tested was commissioned in 1930. These where the last carriages that where constructed by the Union Construction Co because political pressure resulted in its closure in 1932.

The new trailers where an additional 0.61m (2ft) longer and the motor carriages where an additional 0.30m (1ft), this was achieved by tapering the one or both ends with prevented them from fouling the structure of gauge curves. Two trailers had their central doors widened from 1.37m (4ft 6in) to 1.57m (5ft 2in), with the other two remaining trailers keeping their central doors however, the seating capacity was reduced from 48 to 40 to allow for an additional single-leaf door at either end of the carriage. The position of the guards door control panel was altered although this proved to be unsatisfactory and was removed from subsequent builds.

The extensions to the Piccadilly line where above ground therefore heaters had to be added, the use of British materials during their construction was for publicity because there was an industrial depression at the time, these became known as 'all British' trains and operated on the Piccadilly and Northern lines. The transfer between the two lines was aided by the construction of a junction just outside Kings Cross St Pancras station in 1927. The Northern line had heavier traffic which would help in assessing the effectiveness of the new features on the trains.

An additional 62 carriages where produced by Metropolitan-Cammell, formed by the Metropolitan Carriage Wagon and Finance, and where intended for delivery on the Bakerloo line, which would replace the 1920 or Watford Joint stock which where still relatively new but required higher crew numbers and had to wait longer at stations because it was equip with swing doors. Problems with the swing doors where highlighted when a fatal accident occured when a passenger got cought in one and the door interlock did not detect it.

This build was not constructed to be compatible with other builds because these had been fitted with electro-pneumatic breaking system in addition to the Westinghouse air-break. This control was accommodated by an additional 10-core control jumper, with the previous builds gradually altered to allow for additional cables which was largely completed by 1936. The motor carriages which operated on the Bakerloo line with Cammell Laird 1920 stock trailers which where not fitted with electro-pneumatic break wiring until they where withdrawn in 1938.

1931 and 1934 builds

Government aid in 1929 enable further extensions to the Piccadilly line, a northwards extension to Cockfosters and westwards from Hammersmith to Acton Town over tracks which where parallel to the District line however not shared with the line. The railway would be increased from a running distance of 13.7km (8.5 miles) to 64km (40 miles) therefore the railway needed additional rolling stock. The improvements that where tested in with the 1930 build where incorporated into the design in addition to further features.

An order was placed with Metropolitan-Cammell for an additional 145 motor carriages and 130 trailer carriages where commissioned from two builders. The trailer carriages had 12 doors each, two sets of double doors and a single-leaf door at either ends of the carriage on both sides. The electro-pneumatic breaks where fitted to enable a higher running speed, which had been tested on the Northern line and had demonstrated that the same service levels could be achieved with fewer trains.

After the formation of the London Transport Passenger Board (LTPB), a small final batch of Standard stock was commissioned from Metropolitan-Cammell in 1934 and consisted of 26 motor carriages, these where in response to the Piccadilly line being extended further from South Harrow to Uxbridge which required an additional eight seven-carriage trains. This was achieved by using the new motor carriages in conjunction with reshuffling some stock between the lines.

These where similar to the 1931 build, however they came equip with some minor changes. Roller bearings had been used for the first time on the 1931 build and ten of the new carriages where fitted with roller bearing axle boxes to reduce the maintenance that was needed with white metal bearings.

Allocation

When the final batch of carriages had been delivered the standard stock was operating on the Bakerloo, Northern and Piccadilly lines.

Northern 724 carriages, 336 motor, 243 trailer, 145 control trailer

The Northern line had a total of 724 carriages comprising of 1923, 1924, 1925 and 1926 builds, supplemented with 62% of the 1927 Metropolitan build and 13 1927-Feltham carriages.

The Piccadilly line had a total of 509 carriages, comprising of 1927 Metropolitan and 1927-Feltham stock, with an experimental 1930 Feltham train, the reminder of the service comprised of 1931 and 1934 builds.

The Bakerloo line service comprised of some 1927-Feltham and 1927 Metropolitan builds, supplemented by four carriages from the 1929-Feltham build and 1930 Metropolitan build. There was a total of 198 carriages in its fleet comprising of 82 motor carriages, 62 trailers and 54 control trailers. To increase the number of trains there where also an additional 20 trailers and 20 control trailers which where supplied from the 1920 stock.

The Underground network between 1935 and 1940 benefited from a scheme called the New Works Programme which invested £40 million, this included a series of extensions to the Northern and Central lines along with new trains, called the 1938 stock, in May 1938. The new 1938 stock was intended to be used on the Northern line and displaced the standard stock to be used on the Central line which was still using its original 1900/1903 stock. Furthermore some of the displaced stock was used on the Northern City line, running between Moorgate and Finsbury Park over the Highbury branch, and the Bakerloo line to allow for the trains to be extended to seven-carriages. There where 82 control trailers which where converted to trailers and 21 driving motors altered from 'A' to 'D' carriages because the seven-carriage trains on the Bakerloo and Central lines had a three-carriage until at the opposite end to the Northern line.

Previously served by surface stock, the Northern City line was modified for use with Standard stock, furthermore there was no standard agreement for the third and fourth rails which supplied power to the carriages and where modified to the same configuration as the Northern line during its refurbishment. The use of control trailers had produced disruption to services and had largely been discontinued during the 1930s, a standard three-carriage train consisted of a driving motor, a trailer and a control trailer (DM-T-CT) and only had one compressor on the motor carriage, however if this failed the train would be standard whereas the standard configuration of a four-carriage train on the network had two motor carriages, configured (DM-T-T-DM) had two compressors. While off peak services on the Northern City line consisted of a driving motor and a trailer, these two-carriage trains remained in service until October 1964.

Use on the Central line

Standard stock began to replace the 1900/1903 stock on the Central line in the autumn 1938 and this had been largely completed by mid 1939. However, the trains had to be modified, because the Central line used a three-rail system with the central conductor rail supplying power and was not converted to the four-rail system until mid 1940, once this upgrade had been completed the trains where converted back to a four-rail system.

The extensions to West Ruislip, Epping and Hainault where under construction and would require additional trains, however the outbreak of the Second World War postponed the opening of these extensions. As a result carriages where stored across the network, nearly 200 carriages where stored in the partially constructed Hainault depot, but this was requisitioned by the US Army Transportation Corps and these carriages had to be moved to open sidings. Other carriages where stored in the sidings at Edgware, Golders Green, Highgate, Morden, Neasden and Stanmore with some also being stored in deport where there was spare capacity. Some of the motor carriages where painted grey and used for engineering tasks with others being used as 'Tube Refreshment Specials' which supplied food and drink to people who where sheltering on the stations platforms from air raids.

When the war was finished, the Central line extensions opened reaching: Stratford on 4 December 1946, Newbury Park and Woodford on 14 December 1947, West Ruislip, Loughton and Hainault on 21 November 1948 and Epping on 25 September 1949.

After being stored in the open-air storage for six years had lead to the stock deteriorate and a programme of heavy refurbishment began, which included replacing the wrapped window frames, the corroded equipment as required and a complete rewiring on many carriages. The stations had been extended before the outbreak of the war and where able to accommodate eight-carriage services, however these where restricted because the depot at White City had not been altered and a six-carriage service began. In November 1947 some seven-carriage services began operating, with an eight-carriage service beginning in January 1948. However, the refurbishment of the carriages was poor and a full eight-carriage services was not achieved before additional stock became available from other lines, following the delivery of the 1959 stock to the Piccadilly line.

The eight-carriage service was formed of two four-carriage units consisting of two driving motors and two trailers (DM-T-T-DM). This was not an ideal arrangement because the middle of the trains did not have passenger doors for about 15m (50ft) which was cared by the switch cabins behind the driving motors. To alleviate this problem, a four-carriage unit was split with two carriages being placed at either end of the other unit, this formation from 1961 became (DM-T x DM-T-T-DM x T-DM) and reduced loading times during peak periods.

The eight-carriage service was short lived on the Central line, with the standard stock being withdrawn less than three years later.

Disposal

The standard stock was replaced with the 1938 stock on the Bakerloo line and the changeover had been completed on 23 May 1947, except for a batch of 1927 built trailers, referred to as '58 trailers' depicting the number of units rather than the standard years which is used on the London Underground network for rolling stock, where converted for use with the new stock on the Bakerloo line.

On the Piccadilly line, the standard stock was replaced with the 1959 stock, which enabled the first full-scale withdrawal and scrappage of the Standard stock, however some carriages in a better condition where transferred to the Central line to allow for additional carriages for the planned increase in carriages per trains. The last passenger service of standard stock on the Piccadilly line ran in July 1964.

The Central line was planned to be upgraded to the 1960 stock which was a prototype batch to replace the Standard stock. However, the service on the Central line was intensive and the carriages, now between 30 and 40 years old, where unable to cope. An electrical fire on a train made a solution or replacement for the stock more urgent. This resulted in the 1959 stock, after 19 trains being delivered to the Piccadilly line, being diverted to the Central line to provide 57 new trains. These where not adequate to provide an eight-carriage service on the Central line and an additional 57 non-driving motor carriages where ordered becoming the first carriages of the 1962 stock. The last passenger service of standard stock on the Central line ran in June 1963.

The last service of Standard stock in passenger service on the Northern City line ran in November 1966.

Various carriages where used as departmental vehicles, 16 where used as ballast carriages and four as pilot motor carriages and lasted until 1978. The motor carriage 3327 was displayed in the Science Museum in London for many years before being returned to the London Transport Museum in 1996.

Manufacturers

The Standard stock is used to describe six experimental rolling stocks which where constructed by five manufacturers in 1923 and a further 18 batches of production carriages, constructed by six manufacturers between 1923 and 1934, totalling 1460 vehicles. This became an iconic stock for the London Underground which was partly due to the Trade Facilities Act 1921, which was a governmental incentive in the aftermath of the First World War to fund schemes that would create employment, partally in the construction, steel and manufacturing sectors. The London Underground network benefited from a £5 million investment scheme further to funding extensions to the Northern line and financed the construction of over 1,100 standard stock carriages between 1922 and 1930.

Experimental Rolling Stock

Production Rolling Stock

Preservation

Four carriages are owned by the London Transport Museum who have formed these into a four-carriage unit consisting of, DM 3370, DM 3693, CT 5279 and T 7296 which is currently in their Acton depot and awaiting restoration.

Various carriages which where preserved have now been scrapped: