Train Formations

[Deleted]

1) I notice Bakerloo trains are made of a unit of 4 with DMs at each end with and extra 3 added on. Why is this?

2) Every so often I’ll see a 1992 stock train made up of a unit of 4 with two DMs at each end with a normal “half unit” added on for a total of 3 DMs.

3) What are the different delivery methods of stock for each line? I know for example W&C are craned in, and SSR are delivered by rail I’m presuming at Ruislip? But what about other lines, and where are they delivered to?

Thanks!

<<superteacher: Thread title amended for clarity.>>

[norbitonflyer]

Many trains on the Underground are made up of two or more shorter units coupled together. This means that a fault on one car only puts out of action the other cars in that unit, and the good unit(s) can be kept running if another good unit is available to replace the casualty. (i.e two faulty trains only means one train lost from service, because you can make one good train out of the two faulty ones)

Bakerloo trains (1972 stock) are made up of a three-car unit and a four-car unit. They were originally built for the Northern Line, where trains can end up back-to-front thanks to the Kennington loop. In order to keep flexibility regardless of which way round it is, the cabless end of a three-car unit could couple to either end of a four car unit. Thus either end of a four car unit could be at the end of a train, so both ends needed cabs. On the Bakerloo there is no way a train can be turned round, so the middle cabs are redundant and many of them have had equipment removed to be used as spares.

Central line trains (1992 stock) are actually made up of four two-car units. Some units have a cab at one end, others are cabless. Again, because of the Hainault Loop, trains can end up either way round, and any unit can couple either way round to any other. A cabless unit can obviously only be coupled as one of the middle two units in the train, but a cabbed unit can be marshalled in any position. Because of this extra flexibility, slightly more cabbed units were built than cabless ones, and the surplus cabbed units can sometimes be seen in the middle of trains. It also means that a unit with a fault in the cab equipment (a missing windscreen wiper or damaged driver's seat, for example) can still be used whilst awaiting repair. There is, of course, a small loss of passenger space in a train so formed, as well as one fewer passenger door each side.

You can see the same thing on the Piccadilly Line, whose six-car trains are each made up of two three-car units, some of which are "double ended". One double-ender also operated the Aldwych shuttle when that was a thing. Middle cabs were the norm in all older surface and Tube stocks, and single 4-car units of some stocks were occasoinally used, for instance to Ongar and to Chesham.

More modern stock may still be made up of two units, but they are single-ended so it is not so obvious where the join is.

[North End]

Mar 23, 2018 13:48:53 GMT @endstone said:

1) I notice Bakerloo trains are made of a unit of 4 with DMs at each end with and extra 3 added on. Why is this?

2) Every so often I’ll see a 1992 stock train made up of a unit of 4 with two DMs at each end with a normal “half unit” added on for a total of 3 DMs.

3) What are the different delivery methods of stock for each line? I know for example W&C are craned in, and SSR are delivered by rail I’m presuming at Ruislip? But what about other lines, and where are they delivered to?

Thanks!

1) The 72 stock was originally built for the Northern Line, where trains may become turned via the Kennington loop. The design allowed trains to be made up with the 4-car being joined to the non-driving end of the 3-car, giving additional options depending on the orientation of the units. Over time this fell into disuse as it wasn't considered worth the expense of fitting additional equipment to three cabs per 7-car train where two could suffice.

2) There are more driving units of 92 stock in order to provide some additional flexibility. Therefore at any one time and handful of trains will be made up with a cab somewhere in the middle.

3) There is no set procedure as such. For the Northern the 95 stock was delivered to Ruislip and was transferred to the Northern by rail, however the outgoing 59/72 stock some left by road direct from Morden Depot whilst others went by rail via Ruislip. Likewise, for the Victoria Line the 67 stock left via Acton Works, however the 09 stock is out of gauge for the rest of the underground so can only go by road to/from Northumberland Park. S stock has arrived by rail, normally via Amersham and Neasden, but the A stock left via Northwood Siding. For the Jubilee the 83 stock left by road direct from Neasden, although many units were stored in various locations and left in various ways - often with some difficulty after the length of time stored! The 96 stock varied as some units were initially delivered to Neasden (via Ruislip) whilst others went direct to Stratford Market Depot - presumably by road.

Most depots have the ability to send or receive cars by road, but whether this option is chosen depends on circumstances. Golders Green Depot would likely be very tight for this, not sure if this depot has ever sent/received cars by road?

[Deleted]

Thanks for the replies! Biggest thing that stands out to me is the way units are referred to as “wrong way round.” Why does this matter if there are cabs on either end? And how would a 3 car unit be turned to be attached to either end of a 4 car?

[Deleted]

Mar 23, 2018 16:23:01 GMT @endstone said:

Thanks for the replies! Biggest thing that stands out to me is the way units are referred to as “wrong way round.” Why does this matter if there are cabs on either end? And how would a 3 car unit be turned to be attached to either end of a 4 car?

Many older stock had couplers which were handed. They only worked one way round. Also connections for auxiliaries and stuff, sockets only on one side, that kind of thing. Cars on those trains had a very real and concrete wrong and right way around. On other stock, I suppose it's more convention, which way round they were when they were produced. Most of the modern stocks are semi-permanently coupled in very fixed formations anyway.

A 3 car unit could be turned in service by going round the Kennington loop an odd number of times. When you then uncouple it from that unit it'll be one way around. It may not be the right way around for the single-ended 4 car unit you happen to have in the depot. So what do you do? You order double-ended units instead of single-ended ones. Then every way is the right way.

[North End]

Mar 23, 2018 16:23:01 GMT @endstone said:

Thanks for the replies! Biggest thing that stands out to me is the way units are referred to as “wrong way round.” Why does this matter if there are cabs on either end? And how would a 3 car unit be turned to be attached to either end of a 4 car?

Because the couplers have the connections arranged horizontally as there isn't sufficient space on a Tube train to have them arranged vertically. This means that when a train is turned round and attempts to couple to one which is still facing the original way the connections don't align. There's a solution to this which is to duplicate all the connections, but this adds extra expense, extra complexity, and extra chance of failure - so is avoided where possible.

The idea with the 72 stock was that the three-car unit wouldn't be turned, just that the 4-car would attach to the UNDM car and whichever cab was at the outer end would then be the driving one. Not necessary on the Bakerloo Line because there's no opportunity for the trains to become turned, and in practice the arrangement fell into disuse on the Northern due to the cost of installing two sets of new equipment in the units when extra equipment was added over the years.

Note that every train on the Bakerloo is technically wrong-way round, as by convention the 32XX units should face north. However, the Bakerloo works like this because Stonebridge Park Depot faces south, and it allows the majority of shunting movements in the depot to be carried out from a 33XX car which has a full cab. If the trains were right way round then there would be a lot more shunting from the 34XX UNDM cars which don't have a full cab, which is less desirable for obvious reasons.

[norbitonflyer]

Mar 23, 2018 17:04:15 GMT North End said:

Note that every train on the Bakerloo is technically wrong-way round, as by convention the 32XX units should face north. However, the Bakerloo works like this because Stonebridge Park Depot faces south, and it allows the majority of shunting movements in the depot to be carried out from a 33XX car which has a full cab. If the trains were right way round then there would be a lot more shunting from the 34XX UNDM cars which don't have a full cab, which is less desirable for obvious reasons.

Didn't the "wrong way round" convention originally arise because of the practice of detaching single-cabbed units of 1938 stock at Watford Junction in the off peak, and working them to Croxley Green depot? This was a long way to drive using just a shunters panel. Hence the trains were turned the other way round so they could be driven from the cab.

[norbitonflyer]

Mar 23, 2018 16:56:55 GMT tut said:

So what do you do? You order double-ended units instead of single-ended ones. Then every way is the right way.

"Double ended" in this context meaning ambidextrous, I assume - since all 4-car 1972 stock units are double-cabbed and all 3-car single cabbed.

[MoreToJack]

Mar 23, 2018 17:13:37 GMT norbitonflyer said:

since all 4-car 1972 stock units are double-cabbed

In true LT tradition... not quite! One 4-car 1972Mk2TS unit is composed of one DM and one UNDM, rather than the more usual two DMs. The reason for such is reproduced below, from a previous thread (worded much better than I could manage!)

May 20, 2016 17:15:10 GMT phoenixcronin said:

3539 was scrapped, along with 4539, after a collision at Harrow and Wealdstone on the 29th of March 1994. 3249 and 4249 were also scrapped after a collision at Piccadilly Circus on the 22nd of April 1994.

3299-4299-4399-3399 is therefore a unique unit as the 33xx car is an UNDM instead of a DM. The unit is in fact made of 3357-4357-4257,which lost its DM 3257 in a derailment at Piccadilly Circus on the 3rd of December 1996. The remaining 3 cars where "turned", and along with a spare UNDM 3439, was made into a 4 car unit and then renumbered.

[Deleted]

Mar 23, 2018 17:13:37 GMT norbitonflyer said:

Mar 23, 2018 16:56:55 GMT tut said:

So what do you do? You order double-ended units instead of single-ended ones. Then every way is the right way.

"Double ended" in this context meaning ambidextrous, I assume - since all 4-car 1972 stock units are double-cabbed and all 3-car single cabbed.

Ah, what I meant was, the reason why you would order 4-car units with a cab at both ends is so that whichever way round the 3-car single cabbed unit happens to be, you can get a cab at both ends of the train when coupling up to your 4-car unit without having to run either unit round the loop. So let's say your 3-car unit happens to be south facing, you would need a single-ended 4-car unit to be north facing. With a double-ended 4-car it don't matter.

That's what I meant anyway! I think I'm right I'm too tired to trust anything I write right now

[countryman]

As far as I know, this all goes back a very long way. On the Central line, Standard (pre 1938) driving cars were west facing (A) end or east facing (D) end cars. This meant that you had to have an A car at one end and a D car at the other end, and within reason you could theoretically have any DM or trailers you required between. When the 38 stock came along, this was in set 3 and 4 car sets. All of the 4 car sets had 2 DMs. one NDM and a trailer. Some 3 car sets had 2 DMs and a trailer, some had 1 DM, 1 trailer and 1 UNDM (iirc Uncoupling non-driving motor).

According to my trusty Ian Allen book, on the Northern Line the 4 car units ran at the north end with the A car to the north, the 3 car units at the south end, with the UNDM facing north. On the Bakerloo the 3 car unit was at the north end with the D end UNDM facing south> I assume from this that LT built both A and D end NDMs which meant that it would not be possible to easily switch a unit between Northern and Bakerloo!On the Piccadilly the units ran with the 3 car unit at the west end, an A car leading.

When it came to 59 stock there were no UNDMs, and the units still ran with A end to the west, but the units were switched round with the 4 car unit at the west end and the 3 car at the east. I've no idea why! Then on the 62 stock on the Central Line, again it was A cars at the west, although the units could be used at either end of the train so all cabs could be used. (my book does mark many 38 stock and 59 sock DMs as 'middle'). I travelled to school every day on the Central line from 1964 to 1971, and I never saw a reversed train on the west end of the line, despite it being easy to do round the Hainault loop.

I certainly don't propose to comment much on District/Met/Circle stock, other than to say that the A60 and A62 stock had A and D plates on the DMs with A to the north, I did at least once see (iirc) a train coupled A to A, or perhaps D to D. If I am incorrect please forgive it as a senior moment!

[norbitonflyer]

If I recall correctly, the true 1938 stock included no UNDMs - they were built as part of the additional 1949 stock.

On some lines with 3- and 4-car units, the DMs that would be usually to be found at the end of a train (i.e west end of 4-car, east end of 3-car) only had emergency couplers. (The middle cabs could be used if the train ran as a single unit e.g on the East London, Ongar and Aldwych shuttles). Some cabs were identified as "middle" because they had been rendered unusable, either because some part had failed, or parts had been robbed to repair other cabs, or because they had not been upgraded (e.g for OPO conversion), and could hence only be used in the middle of trains after that.

Because of the Watford triangle, A stock could get reversed and thus was designed to couple either way round (A-D, A-A or D-D). Although in normal service it would appear that couldn't happen with C stock, certain workings ran by the "wrong" side of the Minories or Kensington triangles, (thus switching identity from Circle to H&C or "Wimbleware") specifically to turn them round. Thus was done to even out wheel wear on the Circle Line trains. C stock was all of one type, (single ended 2-car units, formed into six car trains, in which the middle unit could be either way round).

D stock could not be turned round, and thus had conventional handed couplings. A few "double enders" were included in the fleet, mainly for operating flexibility although they proved useful on the East London line during a temporary shortage of A stock during OPO conversion. The cabs of double enders had autocouplings, to couple to the UNDM of a single ender, but the can ends of single enders only had emergency couplers.

the 1973 stock has essentially the same layout as the D stock. When it was built there was no way it could get turned round in service, but after the T4 loop opened that ceased to be the case and at any one time half the fleet have the A end at the west and the other half have D end to the west.

[countryman]

Mar 24, 2018 14:02:30 GMT norbitonflyer said:

On some lines with 3- and 4-car units, the DMs that would be usually to be found at the end of a train (i.e west end of 4-car, east end of 3-car) only had emergency couplers.  

Does this apply to tube stock? I know it applied to R stock. I believe the A end cars were like this, the D end DM had an auto, and the UNDM at the east end of the 4 car units, and east end DM and west end UNDMs of 2 car units had auto couplers. Not sure what happened when reformed later. As for Q stock??

[norbitonflyer]

The R stock reforms did not affect the DMs or UNDMs - it simply involved transferring intermediate NDMs from some four car units (making them three car) and adding them to other four car units (making them five car). Thus instead of having 6-car (2+4) or 8 car (2+2=4) trains, they could all be seven car (2+5 or 2+2+3)

Not sure if all Tube stock had emergency-only couplers at ends which would never be formed in the middle in normal service, but the DMs of 3-car 1972 stock and single-ended 1973 stock do, as it is only the other (UNDM) end which will ever couple to anything.

Q stock, (and standard stock, and all older stocks) were not formed in units (with permanent couplings between cars) but the cars could be marshalled any way you liked. MTTMMTTM was normal for Q stock. Standard stock was usually M-T-T-M+CT-T-M but had many variations - a common one was marshalling a control trailer where a normal trailer could have been - in fact some of trailers in the IOW stock were actually control trailers with the cabs disabled. I read somewhere that on the Bakerloo two of the three DMs needed in a 7 car train would be marshalled together at the north end, to maximise the passenger space at the south end of the train which got busier because of where station entrances were on that line

[zbang]

Nice to see it's all so simple . I was expecting a "but if it's Wednesday or Thursday" somewhere in there.

(Off to the maps looking for loops and triangles.)

[Chris M]

carto.metro.free.fr/cartes/metro-tram-london/index.php is a good map to look at for that

[zbang]

Yep, its my go-to map. Downside is that it's a bit large to open on some portable devices.

[superteacher]

Posts about stopping in protected manual have been moved to the thread below:

districtdavesforum.co.uk/thread/29414/

[norbitonflyer]

Mar 23, 2018 16:56:55 GMT tut said:

Mar 23, 2018 16:23:01 GMT @endstone said:

Thanks for the replies! Biggest thing that stands out to me is the way units are referred to as “wrong way round.” Why does this matter if there are cabs on either end?

Many older stock had couplers which were handed. They only worked one way round. Also connections for auxiliaries and stuff, sockets only on one side, that kind of thing.

This is very easily seen on Standard stock. here is a D-end
www.trainweb.org/tubeprune/Standard%20Stock%20Photos.htm
Note the positions of the three square box-like structures low down on the cab front - two on the driver's side and one under the destination plate. These house various connections needed to work the cars together.

And here is an A end
www.flickr.com/photos/norfolkboy1/17562823116/in/photostream/

It should be evident that coupling two A ends or two D ends together would be problematic.

On the main line the problem was solved either by duplicating the connections in each side, or by arranging them vertically in the middle of the cab front. Space is too limited for this on Tube stock, and since on most lines it could never by turned round anyway the asymmetric solutoin was simpler and cheaper. Assymetric coupling arrangements could also include, for example, a plug on one car engaging a socket in the other.

At least two lines made use of the fact trains were locked into facing one way to provide assymetric electric current delivery systems. The GN&C had a four-rail system with the positive rail on one side and the negative on the other (no centre rail). The C&SLR had an off-centre live rail - this was necessary because the tiny dimensions of the trains left inadequate clearance below the centre couplings for a live rail.

[domh245]

Off Topic, but how did they couple the cars together? Is that thing in the middle some sort of coupler, or were the chains and hooks used (or both!)

[Dstock7080]

Under the buffer beam is a Ward coupler.
Trains could be driven together but required a long pole to uncouple.

[domh245]

Interesting, it does make me wonder what the chains and hooks are for then? Redundancy?

[fish7373]

Mar 26, 2018 14:20:39 GMT domh245 said:

Interesting, it does make me wonder what the chains and hooks are for then? Redundancy?

NO they are safty chains just incase there is a break away or the ward coupler comes apart that`s what the chains are for.

[philthetube]

On the S stock there are no electrical connections so no problem if emergency coupling is needed, a emergency communication cable between two trains can be fit if needed, with older stocks if two arrived the wrong way round, it could happen on the northern or the met because of Kennington loop or the Watford north curve, it was necessary to stick bits of cardboard over the electrical connections to prevent the contacting. cardboard pices with clips were provided for this but it was often considered easier to use overhead adverts from in the train.

[fish7373]

Called press pans for the studs on auto couupler.

[metman]

To my knowledge on the SSL handing (ie dedicated ends) came in during 1927 with the District K (later Q27) stock. Prior to this district stock could be coupled either way round. New technology such as the introduction of the EP brake in 1928 on the F stock made it harder to duplicate all the connections as there were more of them!

The Met had a different approach with city and country ends to its early multiple units. The Saloon and compartment stock driving motors and driving trailers were handed however the trailers were not and could be coupled either way round. This was partly I assume due to only being Westinghouse braked.

The A stock lost its ability to couple A-A and D-D with OPO conversion as one set of studs on the coupler were used and this created middle cabs that could not be used in passenger service (although they were used to drive from when turning trips were required to Watford and back!).