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| Car | Weight | Seats | Equipment | ||||||
| DM | 27.4 tons | 44 | Cab | Shoes | Traction Package | Emergency coupler¹ | Motor Alternator | Batteries | |
| T | 18.4 tons² | 48 | Fan MA | Compressor | |||||
| UNDM | 26.1 tons | 48 | Shunting controller | Shoes | Traction Package | Auto coupler | Motor Alternator | Batteries | |
| ¹Auto-coupler on double-ended DM cars. ²Trailer in double-ended unit weighs 19.04 tons | |||||||||
Each car has four doorways on each side with a single leaf sliding door at each position. The doorway opening is smaller than the traditional London Underground double doorway. This was done to save money on door equipment but it means that the doorway is 1067mm (3ft 6ins) wide instead of 1372mm (4ft 6ins). This slows the loading of the cars at busy stations. At the time the stock was built, passenger numbers were declining on the Underground and were about 65% of the level today. Nowadays, double doors would be more efficient.
One very visible modification of the D Stock,
which has also been applied to other lines, is the provision of inter-car safety barriers
(Click on the image for the full size view and description.). These first appeared
on the Piccadilly Line in 1997 and were a response to the occasional accidents where
passengers - usually those suffering from the effects of alcohol or drugs - have fallen
between cars. The barriers are made of black canvas and are hung on brackets fitted
to the outer corners of the car body. They are coupled between cars on sprung
attachments to allow transition on curves without creating a gap or tearing. They
have become a maintenance problem.
The D Stock has been fitted with new bogies (Click on the
image for the full size view and description.) supplied by Adtranz (now Bombardier)
of Derby. These bogies are the flexible frame design also supplied for the 1995 Tube
Stock on the Northern Line. The original bogies were of an H frame design with
welded box members and were a constant source of trouble because of fractures and
derailments. The problem with them was because LU track is not properly maintained
and the construction of the bogie was too rigid to handle the track deformations which
often occur around the system. There were a number of derailments caused by wheel
unloading on critical sections of track. It is hoped that the new bogies will remove
this risk.
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D
Stock Cab Control Desk
Click on the image for the full size view and labels.
The D Stock cab arrangement was a completely new design for London Underground. It resulted from a suggestion by a driver that the existing controls were poorly laid out and induced fatigue. The desk was arranged so that gauges were easily readable, the power/brake controller was operated by the right hand, heat did not get into the driver's eyes and the telephone handset was easily operated. Any driver on the District Line will quickly tell you that the D Stock cab layout is a lot better than that of the C Stock, which is also used on sections of the District.
D Stock nearside control panel
Click on the image for the full size view and description.
At the outer end of each UNDM car, there is a shunting control cabinet which is used to allow the unit to be driven from the non-driving end at reduced speed in the depot. The cabinet contains a set of miniaturised controls for selection of direction speed and braking. There is also a whistle and an air gauge. The cabinet is normally kept locked behind a panel on the left side of the car end panel.
D
Stock shunting controls. These are similar to the original set up provided on the
1973 Tube Stock. Of course, the ''73 panel has been replaced to allow an end
window to be inserted as part of the refurbishment design.
Click on the image for the full size view and description.
There have been some modifications to the stock since it entered service. When the trains first entered service, they were fitted with a forced ventilation system which was powered by fans mounted in the roof behind two long ventilator channels. A special Fan Motor Alternator was provided on each trailer to drive them at 230 volts AC. The fans were supposed to recirculate air inside the cars and it was calculated that this would provide sufficient ventilation to give a comfortable temperature inside the cars. During the first summer of operation (1980), it quickly became apparent that this was not the case. The interiors of cars became uncomfortably hot and stuffy, the problem being exacerbated by the use of passenger door control. Passengers only open the doors required by them to enter or leave the car so, along the outer sections of line, some cars could run for several stations without any of the doors being opened. In sunny weather, the interior temperature could rise to uncomfortable levels.
D Stock offside control panel
Click on the image for the full size view and description.
The first modification was the introduction of a POGO switch. This was a Passenger Open/Guards Open switch which allowed trains to operate with the passenger door opening facility withdrawn. The doors would all open under the control of the guard when he operated the passenger open buttons in the cab. This helped to cool down cars in the summer months. Passenger open was restored in the winter. The second was a new ventilation system and opening windows at some positions along each car. The ventilation grilles along the car ceiling were reversed and a new type of fan fitted. Car 7108 was delivered from the builders in June 1982 with these modifications as a trial and it was decided to modify the whole fleet. The unit with car 7108 was returned to Metro-Cammell and all three cars (7108-17108-8108) were modified, together with the last unit to be built (8129-17129-7129) which was delivered in June 1983, exactly four years after the first unit was delivered to Ruislip. The modifications to the fleet were completed in January 1985.
Shortly after the trains entered service, there were complaints about the lack of external grab handles to assist passengers boarding and alighting. LU was against providing these at the time because they disrupted the cleaning process as a train passed through the automatic washing machine. However, handles were added at one doorway on each side of each car. However, they had to be removed in 1990, after cases of hooligans being killed when they tried to hang onto the handles while the train was moving.
D
Stock offside rear cab wall
Click on the image for the full size view and description.
The original set up for the trains was for two-person operation. The guard occupied the rear cab and controlled the doors from there. The trains were converted to OPO in 1985. The conversion consisted of minor switching modifications to the trains but required the installation of train radio and mirrors and CCTV cameras on stations.
3-car D Stock double-ended units provided the service on the East London Line between April 1985 and May 1987. They became available because of the reductions in service introduced all over the Underground in the mid-1980s. Their use on the ELL allowed the release of A Stock for conversion to OPO. The D Stock was also converted at this time and the units on the ELL began OPO in service from May 1985.
D Stock entering Tower Hill bay road on a Wimbledon reverser.
Click on the image for the full size view.
The door controls include Passenger Door Control (PDC) and Selective Reopen. With passenger door control, the train operator can release the door controls so that passengers can open the door where they located while other doors remain closed. It was popular with passengers during the winter but the poor ventilation of the D Stock made the inside of cars unpleasant at times, so PDC was not used during the summer. Selective Reopen allows the train operator to reopen the doors on a car where a door has failed to close, without opening the doors on other cars. This allows an obstruction to be cleared without the risk of further delay due to other passengers attempting to board the train. At present, PDC is not used because there have been some incidents of misuse by passengers.
The cab has a
Train Management System (click on the image on the left for full size view and
description) which monitors the operation of the essential equipment on the
train. The TMS box is mounted to the right of the end door and angled so that the
display can be seen by the driver. The TMS has a failure display light for each
car. If an item of equipment fails on that car, the car light is illuminated
together with a light to indicate which item of equipment. There are also isolating
switches provided to allow the defective equipment to be switched out of operation.
The TMS was fitted as part of a programme of engineering improvements carried out on the D Stock during the years 1995-96. The TMS replaced an earlier version of monitoring system called a Train Equipment Panel. During the programme the trains were also equipped with "Correct Side Door Enable" (CSDE), to prevent the train doors being opened on the wrong side of the train.
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The D Stock is equipped with DC traction motors using a single, pneumatically driven camshaft for resistance control. The traction circuit is arranged in a classic series-parallel configuration with weak field control. Each of the two motor cars in a 3-car unit has four motors, giving 66% axles motored. The two motors on one bogie are permanently connected in series. The D Stock motors are type LT 118, built by Brush and drive the axle through a gear ratio of 17:75. The low voltage traction control circuits are duplicated and arranged so that one set of control circuits operates one motor car whilst the other set operates the other motor car. This set-up ensures that a low voltage control circuit failure will not disable the train. Only 50% of control will be lost.
Equipment schematic of D Stock showing
simplified layout of systems.
Click on the image for the full size view and description.
Each 3-car unit has a single Westinghouse 3HC43 air compressor, except for the double ended units which have two compressors. LU has a rule which requires that trains must only be allowed to operate in service with two functioning compressors. The double-ended D Stock units can therefore be used as a 3-car train, as they were on the East London Line. Every car has a main reservoir supplied through the main line pipe. Flow cut-off valves are provided each side of the intermediate semi permanent couplers on each unit. The valves ensure that air pressure is preserved on each car even if the hose bursts.
Each motor car has a motor alternator (MA) providing 230 volts AC at 850Hz for auxiliary services. The two MAs on a 3-car unit supply half the lighting on the unit, arranged so that all the lights down one side of the train are fed from one end and the other half from the other end. This means that only 50% of the car lights are lost when the motor car supplying the MA passes over a current rail gap. The MA recharges the battery on each motor car at 50 volts DC and supplies the control circuits at that voltage. The D Stock also has an additional motor alternator supplying 230 volts at 50Hz for the unit's saloon ventilation fans. This machine is mounted under the trailer car and runs when required by the temperature setting of the ventilation equipment.
D Stock at Ealing Common depot.
Click on the image for the full size view and description.
The D Stock is equipped with three braking systems - a spring applied parking brake, the Westcode electro-pneumatic brake and a dynamic brake. The spring applied parking brake is automatic. It will apply blocks to the motored axles if there is no brake cylinder air and main reservoir pressure falls below a pre-set level. The only snag with it is that if main reservoir air is lost on a car or unit, the cars with SAPB applied have to be dragged with brakes applied. The wheels will turn but you shouldn't go too fast for fear of overheating them.
The Westcode brake is an electrically controlled pneumatic 7-step brake system. Only four steps are used on LU versions of the brake but the pneumatics are controlled by a 7-step relay valve on each car. Using a combination of three control wires, the valve can provide seven levels of braking according to the wires which are de-energised. If all wires are de-energised, or control supply voltage is lost, full emergency braking is called for. The brake operates in conjunction with the dynamic brake. The traction motors are used as generators to provide a rheostatic brake the train. The energy produced is dispersed as heat in on-board resistors. A blending system allows the rheostatic brake to provide the required level of braking on the motor cars with the Westcode air brake acting on trailers as necessary. When the train reaches about 20 mi/h, the rheostatic brake starts to fade and the air brake takes over to provide the full braking effort required.
D Stock at Olympia
Click on the image for the full size view and description.
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D Stock lifted in Ealing Common Depot
Click on the image for the full size view and description.
The D Stock is now London Underground's most reliable stock, occasionally reaching 35,000 kms between service failures during some months. The average yearly performance is close to 19,000 kms between failures but it is improving. The difference is due to wild swings in the monthly performance. The good performance is partly a result of the age of the stock, now 20 years, which is considered mature, partly because it is well understood by the operators and maintainers and partly because it has had a number of modifications to get better reliability. It is also a design which had much of the equipment first tried on the Piccadilly Line, where it went through a shakedown period before modified versions were supplied for use on the D Stock.
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Since February 2002, more and more D Stock trains have been appearing in service with a new moquette. It looks to Tubeprune as if it was designed by a pizza chef. What do you think? Photos by District Dave.
General view of the new seat
covering in D Stock
Click on the image for the full size view.
Close up of the new moquette in D
Stock
Click on the image for the full size view.
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D Stock trailer car 8008 in trial repainting as seen
at Ealing Common earlier this year. Photo by Ray Bennett.
Click on the image for the full size view.
The D Stock is the only stock in passenger use on LU which has not been repainted into the corporate red, white and blue. The stock was not part of the refurbishment programme in the early 1990s because it was considered not old enough to be done until after the rest of the fleet. Since the completion of the rest of the fleet, money has not been available to do the work.
Over the last two years, a 3-car unit (7008 - 17008 - 8008) has been going through a trial refurbishment at Acton Works. The result was shown to the public at Wimbledon at the end of January and the unit entered service a few weeks later.
The three cars have been repainted in the corporate colours and one car, the trailer has been internally refinished with new upholstery and some cosmetic work. The result - incorporating some District green and the new pizza flavoured upholstery - is pretty dreadful. Tubeprune hopes that a professional designer will be called in to do a decent design before the refurbishment of the rest of the stock.
It is strongly rumoured that work on the rest of the fleet will start after the PPP contracts have been signed and that it will be carried out at Ilford.
To the Top of this Page or to the Home Page This page corrected 23 August 2002 Copyright © Tubeprune 2001, 2002. If you have comments or if you would like to use any part of this site for publishing or commercial reasons, please e-mail me |
