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What is the
|Type of Stock||Line||
Number of Trains and (Cars)
|1967 Tube Stock||Victoria||
43 x 8 (344)
|1972 Tube Stock||Bakerloo||
36 x 7 (252)
|1973 Tube Stock||Piccadilly||
86.5 x 6 (519)
|1992 Tube Stock||Central||
85 x 8 (680)
|1992 Tube Stock||Waterloo & City||
5 x 4 (20)
|1996 Tube Stock||Jubilee||
59 x 6 (354)
|1995 Tube Stock||Northern||
106 x 6 (636)
|Total tube cars||
|A Stock||Metropolitan & East London||
56.5 x 8 (452)
|C Stock||Circle, Hammersmith & City & District||
46 x 6 (276)
|Metro-Cammell||1969-71 & 1977-79||RFS|
75 x 6 (450)
|Total surface cars||
|Total all cars||
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Passenger cars built for London Underground since the mid-1950s have aluminium bodies with steel or aluminium underframes. Most Underground cars have mixed steel and aluminium underframes. Until the 1990s, cars were unpainted, because this reduced both capital and maintenance costs. However, the onset of the graffiti problem, which first appeared in London on an A Stock car in August 1984 and the poor appearance of the unpainted bodies where graffiti had been cleaned off, led to the return of the painted car. Experiments with painted cars started in 1988 on the A Stock and later on some tube cars. The paint used is the two-pack variety and is more or less graffiti resistant. The unfortunate side effect of the painting policy has been that the cars show dirt more readily and tube cars, in particular, appear to suffer from a body skin static problem, causing dust to adhere to the paint surface. This does not seem to be so much of a problem on the painted sub-surface stocks.
Various types of car are used in various formations to give the type of train required for each line. A group of cars formed into a self-contained set is called a unit. Trains are normally formed with one, two or three units, each unit comprising two or more cars semi-permanently coupled together. Units are provided with automatic couplers at their outer ends to allow rapid make-up of trains.
There are three basic types of car; a driving motor car, a non-driving motor car and a trailer car. A driving motor car has a cab and is equipped with traction motors. A non-driving motor car has the motors but no cab, while the trailer has neither motors nor cab. Some non-driving motor cars and trailer cars are positioned at the coupling ends of units and are equipped with a small control cabinet at the outer end to allow the unit to be uncoupled and driven from that end in depots. It saves the space lost and the expense of providing a full driving cab at a little-used middle-of-the-train position.
In order to allow tube cars to fit inside the small diameter tube tunnels they are 750mm lower in height than surface stock cars. This means that the floor height is only 600mm above rail level instead of 975mm. This restricts the size and layout of underfloor equipment and, because of this, originally all tube trains had motor cars with special equipment compartments behind the driver's cabs. By the mid-1930s designs had progressed to allow the main items of equipment to go under the floor. This removed the need for equipment compartments and gave up to 15% more passenger space per train. Four experimental trains of this new type were introduced in 1936 and the production version, known as the 1938 Tube Stock, comprised over 1100 cars and was the mainstay of Northern and Bakerloo Line services until the late 1970s. The last of these trains was withdrawn from the Underground in 1988 but a few were converted for working the Isle of Wight services of Network SouthEast and are still in use there. An excellent website describing the operation and maintenance of these trains can be found at the Isle of Wight Railway pages.
In spite of the improvements allowing the equipment to be positioned under the car floor, one problem has remained to this day. Wheels cannot yet be made small enough to fit completely below the floor. Tube cars are therefore designed with openings in the underframes to allow clearances for the wheels. Inside the cars, these openings are covered by longitudinal seating. This means that the position of these seats is fixed and excludes the provision of doors in these areas. However, experiments are being conducted to try to find an acceptable design of small-wheeled bogie. A concept known as the "Space Train", including small wheels, has been put forward by London Underground. This is intended as a replacement for the 1967 Tube Stock on the Victoria Line. However, the design and building of such a train will be a long and expensive process and it is doubtful whether, under the present proposals for privatisation of the Underground's infrastructure and rolling stock, a company would be prepared to take the risk of developing such a train.
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In 1932, a new system was devised to identify the orientation of cars and units and it has been used ever since. It was necessary because it was not possible to couple cars which faced in the wrong direction. There was insufficient room to accommodate duplicate sets of jumper cables and hoses between tube cars so only one set was provided. If a car or train became turned, it could not be coupled to the rest of the fleet on that line. See also Coupling, Handing & UNDMs.
The identification system was based on the car axles and wheels. Each car has four axles, lettered A, B, C, and D. The car end nearest the A axle is called the "A" end and the other end, near the D axle, is termed the "D" end. This system ensures that the units are correctly orientated for coupling. The following drawing shows how the identification works.
Fig 3: Diagram of vehicle orientation system used on London Underground rolling stock.
Cars with a driver's cab or controls situated at the 'A' end are referred to as 'A' cars and cars with cabs at the 'D' end are 'D' cars. Cars are normally coupled 'A' end to 'D' end throughout the train and all cars normally face in the same direction unless the line has a loop - like the Northern Line at Kennington or the Piccadilly Line at Heathrow. A triangle of lines - as exists on the Circle Line at Aldgate and at Watford on the Metropolitan Line, will also cause trains to be turned. Fleets like the C Stock, were designed for turning by duplicating all the electrical connections across the automatic couplers. The 1972 Tube Stock was designed so that a 3-car unit would couple either way round to a 4-car unit.
Car sides are numbered 1 and 2 so that wheel identification is simplified. The A axle will therefore have two wheels, Al and A2, the B axle, B1 and B2 and so on along the car. Doors are themselves provided with a letter identification system as well.
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The oldest group of tube stock is the 1967/72 type. The 1967 Tube Stock was introduced for the opening of the Victoria Line with automatic train operation (ATO). Although the car body was to the same general dimensions as the earlier tube stocks, there were a number of differences in style and layout such as wrap-round cab windows, double-glazed passenger windows and the provision of all-longitudinal seats in the trailer cars. Cabs were not provided with side doors for safety reasons.
Fig 4: 1967 Tube Stock in original unpainted condition at Northumberland Park Depot. This is the only place where this stock is normally seen in the open as the whole of the Victoria Line in in tunnel.
Click on the image for the full size view.
The 1972 Stocks, consisting of two versions known as MkI and MkII, were 7-car versions of the 8-car 1967 Stock. They were designed to operate on manually driven lines with a possible future conversion to automatic operation in mind. They never had this fitted but the MkII stock is now working on the Bakerloo Line under One-Person Operation with manual driving. The Mark I version has been disbanded but some cars have been used to supplement the Victoria and Bakerloo fleets following suitable conversion.
Click on the image for the full size view and description.
A feature of London Underground tube car design is the tapering of the car ends. In order to maximise the available length and stay within the gauge envelope on the many sharp curves on the system, car ends have an inward taper beyond the end doors. On the tube stocks built after 1972, this is particularly visible because the cars are 1500 mm longer than older cars. These stocks were designed so that a 6-car train could replace a 7-car train and provide almost the same capacity. This was done because the Piccadilly and Northern Lines have short platforms at some tunnel stations requiring the driver to stop a 7-car older type train with his cab and the rear cab in the tunnel. For the proposed OPO system this was not workable since the driver could not see the platform during stops. The shorter train with longer cars proved to be the answer and had the added advantage of reducing unit costs.
Surface stock has neither the size nor space problems of tube stock. The three types are however quite different in design. The oldest of the current types is the A stock. This was built for the Metropolitan main line services to Uxbridge, Watford and Amersham (in two batches known as the A60 and A62 Stocks) and is designed to provide for the longer distance passenger. All seating is transverse and high-backed and double doors are provided at two positions on motor cars and three positions on trailer cars. This contrasts sharply with the four sets of double doors provided on the high-capacity C69 and C77 stocks built for the very heavily trafficked Circle and Hammersmith lines. This stock (universally referred to as C Stock) is also used on the District Line between Edgware Road, Olympia and Wimbledon.
The bulk of the District Line service is provided by the latest surface stock, the D78 Stock, known as D Stock. This took the long car design first introduced on the 1973 Stock and applied it to a surface stock. In doing so, a flat-sided design was produced with a slightly narrower section than earlier stocks. The narrower section was to allow the longer body to fit the sharp curves found around the system at places like Mansion House. Each car has four large single leaf doors on each side and a combination of longitudinal and transverse seating.
A unique feature of the D Stock is that it has tube stock sized wheels. Traditionally, surface stock has always had 1067mm wheels, whereas tube stock has 790mm wheels. In an attempt to reduce the number of different types of wheelsets in use on the system, the D Stock has the same type of wheels as the 1973 Tube Stock.
The D Stock also saw the introduction of a new type of bogie. It is of welded steel, box frame construction and is in the form of an "H" with a rigid bolster. There are no headstocks. A similar type, but modified for use under tube cars was produced for the 1983 tube stock (now withdrawn). All other stocks have riveted steel bogie frames and rubber suspensions of various types. The H frame design has not been a success. The poor quality of LU track has led to cracking in the bogie frames and some derailments due to the stiffness of the frame. The D Stock bogies are being replaced by new bogies similar to those supplied by Adtranz for the new Northern Line 1995 Tube Stock. These bogies have flexible frames designed to overcome the dreadful state of LU trackwork.
Perhaps worthy of mention are the two most recently withdrawn types of stock, the 1959 Tube Stock and the 1983 Tube Stock. The 1959 Tube Stock was withdrawn from the Northern Line in January 2000 after almost 40 years of operation (with its sister stock the 1962 Stock) at various times on the Central, Piccadilly, Bakerloo and Northern Lines.
The 1983 Tube Stock was built for the Jubilee Line in two batches and was basically a tube version of the D Stock. However, it incorporated a number of innovations to London Underground train design and these were all conspicuously unsuccessful. The first was the traction equipment with an electrically driven camshaft system built by Kiepe and the next was the motor alternators by Mawdsley. The braking control was an analogue system by Westinghouse. The door design, also based on the D Stock, has a single large door where tube cars usually had double doors. As traffic levels improved during the early 1990s, these doors were found to restrict car loading times. Even the bogies were a disaster, a design similar to the ill-fated D Stock bogie.
The 1983 stock was originally intended to be converted for use on the Jubilee Line extension. The fleet of 33 trains was to be increased to 59 trains by taking a 3-car unit an adding three new cars. However, the cost of replacing all the equipment and of converting the single doors to double doors was only 10% cheaper than building a whole new fleet. When the 1996 Tube Stock arrived, the 1983 Stock was withdrawn and 10 trains are being stored under a plan to refurbish them for use on the Piccadilly Line. What the PPP proposals will do for this plan remains to be seen.
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The 1990s have seen the appearance of new tube stocks on three lines. The first was the 1992 tube stock built by BREL (now Adtranz) for the Central Line. The order was preceded by three prototype tube trains known as the 1986 tube stock which were used to try out various technical and design ideas prior to the ordering of the main batch. They were tested in passenger service on the Jubilee Line from May 1988 until August 1989. The 85 eight-car production trains are each made up of four two-car sets. Some of these have driver's cabs at one end for use at the outer ends of the 8-car train but there are shunting control positions at the ends of every 2-car set. The cars have the solid state electric traction control system known as GTO chopper control with DC traction motors and every axle is motored. Regenerative braking is provided to save energy. An additional 20 cars were built for the former BR Waterloo & City Line and these have now been taken over by the Central Line as part of the package to transfer ownership of the W & C from Railtrack to London Underground. It has been proposed that they should be used on the Central Line to supplement the existing fleet, which has been somewhat unreliable. Various options for the W & C have included using older tube cars like the redundant 1983 Stock or surplus 1972 Stock. The whole issue is being reviewed under the PPP bidding process.
The second and third batches of cars were both built by Alstom and are very similar in design. The trains are formed of six-car sets composed of two 3-car units. The end cars of each unit are powered while the centre car is a trailer. This gives four powered cars in a 6-car train. The first order was for 59 trains for the Jubilee Line, known as the 1996 Tube Stock, to replace the 1983 Stock cars on the existing line and to provide the extra trains needed for the extension opened in 1998. The other batch was for 106 trains for the Northern Line and are known as the 1995 Tube Stock. For some inexplicable reason, the Jubilee Line trains were delivered first but the Northern Line trains are dated a year earlier by the stock type.
The main difference between the two batches is the bogies, which are a conventional welded, rigid frame design for the Jubilee Line but which have the flexible frame system designed by Adtranz on the Northern Line fleet. The Northern Line bogies also have air suspension. The traction equipment is also different. They both have 3-phase AC drives but the Jubilee Line 1996 Stock has GTO choppers while the Northern Line has IGBT technology (Insulated Gate Bi-polar Transistor) for its inverters. The GTO choppers on the Jubilee Line are a lot noisier than the Northern Line stock. You can hear the familiar GTO "gear changing" - they aren't gears but they sound like them.
A striking feature of the three new stocks is the doors. Outside mounted doors instead of internally fitted ones are a new feature and are emphasised by the application of red, part of the red, white and blue corporate livery. Windows are provided in the car ends to improve passenger perception of security.
On the new trains, the driver has in-cab CCTV allowing viewing of the station platforms during approach and departure as well as during the station stop and, in addition to conventional public address, there is a "talk-back" facility, so passengers can communicate with the driver in an emergency. There are also be automatic, digitised speech announcements at stations.
The three types of new tube cars are shown below:
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The compressed air supply is provided by electrically driven compressors which automatically maintain the pressure at between 75 and 90 lb/in2 on most stocks. Somewhat higher pressures to 120 lb/in2 have been adopted on some stocks in recent years. The compressors, between two and four per train depending on the length, are driven by the 630-volt traction supply and are usually (but not always) mounted under the trailer cars. Compressor control is synchronised to ensure all compressors operate together.
Most compressors are of the two-stage 3-cylinder reciprocating type. The compressed air output is passed through cooling pipes to a main reservoir on each car and to a pipe (known as the Main Line) running the length of the train. There are special drain valves on the reservoirs to allow water and oil to escape without loss of air pressure. The Main Line pipe is connected between cars by flexible hoses which can be isolated by cocks at either end of the unit.
On each car of the train, the air supply is passed through a filter and then distributed to the equipment on the car as required. A supply is required for brakes, doors, traction control, whistle and the window wiper. Air is also used for the operation of automatic couplers between units and, on the C Stock and the new tube stocks, for the car body suspension. Each item of equipment can be isolated from the main supply if necessary and, in the case of door, control and air suspension equipment, individual storage reservoirs are provided.
As air pressure is essential for train movement, cars of units may be isolated by means of the cocks provided at the unit ends so that defective vehicles can be moved by the use of the equipment on the rest of the train. An innovation on the D Stock was the introduction of automatic flow cut-off valves at the car ends and the duplication of the inter-car connecting pipes which combine to prevent the loss of pressure in one pipe from disabling the train.
The traditional way to provide the 50 volts dc required for traction control, compressor control and other control circuits was to fit a number of motor generators on the train. Motor generators are driven by the 630 volt traction supply and, on stock built since 1960, have a 230 volt AC output which is passed to a transformer and used to supply 115 volts AC for car lighting and 60 volts ac to a rectifier to give 50 volts dc for the battery charging system and control circuits. Batteries are provided for emergency lighting and control systems. The new stocks of the 1990s have an electronic auxiliary supply system known as a converter.
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All Underground passenger trains are fitted with air operated sliding doors worked from control panels at the train operator's position. Originally doors were operated by a guard on the rear car but, from 1984, conversion of all lines to One Person Operation (OPO) was started and was completed on the Northern Line in January 2000. Following some highly publicised incidents of doors opening on the wrong side of trains, which occurred after OPO was introduced, all lines have been fitted with "Correct Side Door Enable" (CSDE) which is a transmission based train docking system. It detects the train is correctly located in the platform berth and only allows door open activation on the platform side of the train. It was gradually introduced over the system from 1993.
Some additional facilities to improve door service have been provided on modern stocks. The loss of car heating at terminal stations while trains are awaiting departure time has always been a concern and the C Stock was the first to be equipped with a "selective close" facility which allowed all the doors except one pair to be closed to retain interior heat. Stock introduced since 1978 has passenger door control. This allows passengers to open only those doors which they need to use, a further way of reducing heat losses at stations. "Open" buttons at each doorway are illuminated by the crew as the train stops at the platform to indicate that the doors can be opened. They are closed by the crew and the system deactivated to allow the train to be started safely. It appears to have been abandoned at the time of writing.
Train doors are air operated and electrically controlled. Door operators are normally located at floor level, since there is little space at the top level on the tube car body. Pocket doors were always traditionally used on London Underground but the tube stocks supplied for the Central Line (1992), the Jubilee Line (1996) and the Northern Line (1995) have externally mounted doors. Fears that bodyside cleaning would deteriorate with the use of outside hung doors appear to be unfounded.
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The traction system used on the majority of Underground trains is based on that first tried out on one of the 1935 experimental tube trains. Each motor car is provided with a complete set of power equipment. It is connected, through a cut-out switch to enable a defective equipment to be isolated, to a multi-core control cable running the length of the train. The control cable is connected to a master controller in each cab and to the control cabinet on shunting cars so that all the traction equipment on the train can be operated from any position.
Series-parallel traction control using resistances was standard up to the 1990s. Resistance switching is achieved by the use of cam-operated contactors, the camshaft being driven by an air-operated, oil-damped engine. This system is known as the PCM (Pneumatic Camshaft Mechanism). All stocks so fitted use camshafts on each motor car, except for the 1967/72 tube stocks and C surface stocks which use a separate camshaft for series and parallel notching. The two camshaft system was introduced because of the more complex equipment required for rheostatic braking, which was introduced to Underground rolling stock at the same time. A larger single camshaft is used on the motoring and braking circuits of stock built since 1973. The 1992 and 1996 tube stocks have modern electronically controlled power systems known as chopper control and the 1995 Tube Stock has IGBT traction control. The 1995-6 stocks use 3-phase AC traction motors.
Fault isolation is regarded as an essential part of LU's train operating philosophy. In the event of a fault on the control cable for example, it can be divided at the point where the units making up the train couple. It is then possible for the driver to operate the equipment on the good unit to move itself and its defective partner to a depot. On stocks built from 1967 the driver can operate this fault isolation system from the leading cab. From the 1973 stock onwards two control cables are provided so that half the equipments are controlled by one cable and half by the other. No separate fault isolation system is needed on these stocks.
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All Underground trains have two braking systems, the service brake for normal use and the emergency brake. The emergency brake is provided to allow the train to be stopped if anything goes wrong with the service brake or if an unsafe situation arises. Standard features on Underground rolling stock are a driver's safety device, which takes the form of the famous deadman's handle on most stocks, and the tripcock, which applies the emergency brake if the train overruns a danger signal.
Older stocks used a system whereby the emergency brake is applied if a passenger alarm handle is operated in the car. Frequent misuse and the difficulty of obtaining assistance if a train stopped between stations has led to a policy whereby all stocks are equipped with an electronic passenger emergency alarm which alerts the driver but does not stop the train between stations. This allows more rapid assistance because platform access is available, prevents the danger of trains being stopped in tunnels where there is smoke and allows outside help to reach the train more quickly.
The emergency brake was traditionally pneumatically controlled through the train-length brake pipe and provided air-operated friction brakes acting on the wheel treads. Service braking was also controlled in this way until the introduction of electro-pneumatic control in the late 1920s. All Underground stock now has e.p. controlled service braking and, since 1967, new stocks have been provided with rheostatic braking on motor cars. From 1973, new stock had electrical control of emergency braking provided in place of the rather vulnerable brake pipe.
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During 1989 a series of trial modernisation schemes was carried out on various types of Underground rolling stock to determine the best way of refurbishing trains to comply with the new safety standards which have been adopted on the system following the Kings Cross station fire in 1987. A number of different types of cars were selected to test methods of replacing interior finishes with new fire resistant materials, to determine ways of improving security, to improve the passenger alarm systems and to provide graffiti-resistant external finishes.
Production versions of refurbished trains began entering service on the Circle and Hammersmith, Victoria and Bakerloo Lines in 1991 and further refurbishment projects were carried out on the 1972 Tube Stock of the Northern Line, the A Stock on the Metropolitan Line and the 1973 Tube Stock on the Piccadilly Line. The Northern Line work was stopped after only three trains were done because of the decision to order a new fleet (the 1995 Tube Stock). The Piccadilly Line refurbishment of 1973 Tube Stock, the last of the current projects, has just been completed. The D Stock remains as the only example of LU stock with unpainted body exteriors and its original interior.
The interiors of all the refurbished trains have been remodelled with new ceilings and lighting, revised draught screen and end bulkhead profiles and, on the C Stock and 1973 Tube Stock, a completely new seating layout. New seating has been installed on all trains with a moquette pattern based on the line colour and car exteriors are painted in the corporate red, white and dark blue. Fire-retardant, low smoke emission rubber flooring, special fire-resistant interior panelling, the new passenger alarm system, driver to passenger communication and improved braking control to give a smoother ride is being provided. The opportunity has also been taken to make some engineering modifications to ease maintenance tasks and improve reliability.
The C stock has being provided with new gears to reduce noise and new bogie frames to replace the originals, which had signs of the stress of many years of running over poor track. End windows have been cut into the A and C Stock cars to improve passengers' perception of security by making it possible to see into the next car. This was not possible on the 1967/72 series of cars for structural reasons.
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Numbering, Sizes and Measurements - A page showing the car body dimensions and
numbering systems of the various types of trains used on London Underground, plus a list
of destinstions available on trains.
|C Stock -
The surface stock trains used on the Circle and Hammersmith & City Lines, plus the
District's Edgware Road ro Wimbledon services.
- The District Line's main fleet of trains.
|1973 Tube Stock - The Piccadilly Line's fleet
|1967 Tube Stock - The Victoria
Line's fleet designed specially for ATO
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