London Underground 1973 Stock

The London Underground 1973 Stock is a type of rolling stock used on the Piccadilly Line. The type was introduced into service in 1975 with the extension of the line to Hatton Cross, followed by a further extension to Heathrow Central in 1977. A total of 86 six-car trains were built.

The trains were built by Metro-Cammell between 1974 and 1977, and were refurbished by Bombardier Transportation between 1996 and 2001. They are some of the oldest trains running on the Underground, and in Britain as a whole, second only to the 1972 Stock running on the Bakerloo Line.

 

 

History

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In the early 1970s London Transport placed an order for a new fleet of trains to replace the 1938 Stock and 1959 Stock vehicles which previously operated on the Piccadilly Line. Built between 1974 and 1977 by Metro Cammell in Birmingham, the first unit entered service on 19 July 1975 and the last was introduced by 1977. The trains featured longer cars and larger door space than the previous units, being designed for airport travellers with luggage.

The order was for 87+1⁄2 6-car trains, made up of 196 driving motor (DM) cars, 175 trailer (T) cars and 154 uncoupling non-driving motor (UNDM) cars. Each train is made up of two 3-car units, and most units are single-ended, formed DM-T-UNDM. There are also 21 double-ended units, formed DM-T-DM, to provide additional flexibility and to operate the Aldwych shuttle (now closed).

 

 

The initial order included two test units equipped with solid state traction equipment and electronic control systems. These were double-ended units 892-692-893 (delivered 1977) and 894-694-895 (delivered 1979), and were known collectively as the ETT (Experimental Tube Train). The first unit was equipped by Westinghouse, the second by GEC. In order to provide additional units for the opening of the Heathrow loop, these units were converted to standard at Acton Works, entering service between 1986 and 1987.

One three-car unit (166-566-366) was damaged during the bombings on 7 July 2005 and subsequently scrapped.

Refurbishment

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From 1996 to 2001, the entire fleet was refurbished by Bombardier Prorail at Horbury railway works. The interior was completely remodelled, with changes including the removal of transverse seating, replacement of the original wooden flooring with new floor material, replacement of straphangers with new grab rails, new enclosures for the ceiling ventilation fans, brighter lighting with new diffusers, installation of car-end windows and new perch seats in the centre of the cars, creating more luggage space for airport passengers.

The original unpainted exterior was painted in London Underground's corporate livery, and a new emergency detrainment system was fitted in the cabs. The external destination blinds were also replaced with LCDs, and these were subsequently replaced with new LED units in 2015.

Interior dot-matrix displays were also introduced around this time, with later refurbished trains having a more compact surrounding than earlier refurbished cars.

The final refurbished unit re-entered service on 10 July 2001.

Technical details

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The 1973 Stock features a robust construction, consisting of a welded steel underframe and a riveted aluminium body frame with aluminium alloy panelling. The exterior was painted in London Underground's corporate red, white, and blue livery during refurbishment.

The bogies of the 1973 Stock are 4-wheel symmetrical plate frame bogies constructed with a combination of welding and riveting. The wheel diameter is 790mm when new and 710mm when worn. The train utilizes London Underground Automatic Wedgelock couplers between units, with semi-permanent bars connecting the cars within each unit.

The traction system of the 1973 Stock includes a G.E.C. Traction pneumatic single camshaft, resistance controller with series/parallel grouping, and two stages of weak field and rheostatic dynamic braking. Each driving motor car is equipped with Brush LT118 axle-hung, nose-suspended motors, operating at 300 volts, with a 17/75 gear ratio. Each driving axle has one motor, and the two motors on each bogie are connected in a permanent series.

 

 

For compressors, the stock uses Westinghouse 3HC43 reciprocating models with integral 630V DC motors. There is one compressor on each single-ended trailer and two on special trailers (double-ended units). The braking system includes a blended rheostatic/friction brake with load control for motor cars and a friction brake with load control for trailer cars, with one friction brake per wheel. The emergency brake system uses friction brakes on all cars, controlled via an energize-to-release Westcode 7-step valve. The service brake operates on steps 3, 4, 5, and 6, while step 7 is used for emergencies. The parking brake is an automatic spring-applied, air-released system.

Auxiliary power is supplied by a G.E.C. Traction type MG3007 Motor-Alternator-Rectifier, with one per motor car. The system includes a nominal 50V lead acid battery with a 77Ah capacity and a Powernetics 6kVA single-phase, 240V, 50Hz static converter to power saloon fans and cab air conditioning, with one per trailer. Main lighting is provided by a 115V, 850Hz supply from the motor alternator, which powers fluorescent tubes via individual inverters. Each driving motor car has 20 fluorescent tubes, while each trailer/UNDM car has 22 tubes. Emergency lighting consists of four battery-fed fluorescent tubes per car, which also form part of the main saloon lighting.

Heating in the 1973 Stock is delivered through panel heaters, each with a capacity of 4.2kW per car. Ventilation is facilitated by seven extractor fans per car, two of which are inverter-fed from the battery, along with manually operated ventilators over the saloon side windows. For passenger information, there are six LED scrolling visual display units per car, semi-automatic audio station announcements, and a passenger alarm system with talkback to the driver.

The doors of the 1973 Stock are pneumatically operated sliding doors, with two double and one single door per side on driving motor cars, and two double and two single doors per side on trailer and UNDM cars. Train protection systems include tripcocks, train stops, and a deadman’s handle. The track gauge is 4 feet 8½ inches (1435mm), and the current system operates on 630V DC using a 3rd and 4th rail with a floating earth configuration.