"MIG" wrote

I don't think they Central Line has any normal trips all round the
loop, but the presence of a large depot could result in it going in
from one end and then back into service from the other. They managed
to avoid this with the 1962 stock and then seemed to abandon the
principle some time in the 1980s, so they started facing in all
directions towards the end of their life. And it presumably matters
less with 1992 stock.

For many years the Hainault to Woodford line only had a shuttle service,
with short formations which, AIUI, were normally kept to this service. It
was converted to ATO as a trial for the Victoria Line - did use of ATO stop
after the experimental phase, or did it continue?

Peter

On 25 Feb, 12:41, "Peter Masson" wrote:
"MIG" wrote

I don't think they Central Line has any normal trips all round the
loop, but the presence of a large depot could result in it going in
from one end and then back into service from the other. *They managed
to avoid this with the 1962 stock and then seemed to abandon the
principle some time in the 1980s, so they started facing in all
directions towards the end of their life. *And it presumably matters
less with 1992 stock.

For many years the Hainault to Woodford line only had a shuttle service,
with short formations which, AIUI, were normally kept to this service.

Yes, mostly single units of two 1960 stock motors with two standard
stock trailers, then later one 1938 stock trailer. But at any given
time there would also be one 1967 stock unit shared with the Victoria
Line, which always seemed to be one of the later batch (xx62 to xx79 I
think) for the Brixton Extension. I wonder if there were minor detail
differences that stopped them using the others on the Central?

But even with the shuttle pattern, there were several journeys from/to
Grange Hill via Woodford at either end of each rush hour, which were
full length 1962 stock. These didn't use ATO, so there was dual
signalling. The large depot is between Hainault and Grange hill
stations and trains entered and left service in both directions for
the rush hours. They would be facing in opposite directions.

It
was converted to ATO as a trial for the Victoria Line - did use of ATO stop
after the experimental phase, or did it continue?

The thing I am not sure of the timing of is the demise of the 1962
stock and the beginning of the current service pattern.

It could be that ATO was abandoned for the whole loop to be taken over
by 1962 stock for a while, and then reintroduced (presumably a very
different kind of control) for the 1992 stock.

But it certainly used ATO until it ceased running as a shuttle.

On 22 Feb, 19:19, Charles Ellson wrote:
On Thu, 21 Feb 2008 16:05:57 -0800 (PST), MIG

wrote:
On Feb 22, 12:00*am, "John Salmon" wrote:
"Charles Ellson" wrote

Reversal can also happen with C stock that doesn't stay on the same
line service all day (i.e. Circle Wimbleware or Circle
Hammersmith and City).

That would not reverse them, unless they go 'off route' to run direct
from Aldgate East to Tower Hill, or Gloucester Road to Earls Court.

C stock always had universal couplers though, so that must have been
the assumption.

With the amount of traffic via the relevant junctions it can be
reasonably anticipated that the occasional points failure is going to
result in trains being sent the wrong way on some occasions thus
making handed coupling an undesirable feature WRT the possibility of
it not being impossible that at the same time a train could fail and
require the coupling of a following train for assistance. This leads
onto the question of whether or not C and D stock can assist each
other but if they can't then it still reduces the need for a coupling
adaptor if the following train is the same type.

I would assume not. D stock has different A and D couplers and C
stock has universal couplers.

The first twenty D stock units had cabs at both ends so that they
could work either end of a train without being reversed, and the
subsequent 130 or so had a cab at one end. There's two units in a
train.

I was thinking of reasons why the C stock wouldn't have lined-up
diagrams. Firstly, east and west would be reversed on opposite sides
of the Circle anyway, without reversing the train.

Secondly, a C stock train is made of three single-ended units. Two of
them have to face outwards (therefore in opposite directions) and the
middle one can face either way. It would seem to be very complicated
to have half the middle units only able to face one way as well as the
end ones.

You would either have to have two different arrangements, and the
middle units not line up the same way in depots (if that mattered), or
else have all the middle units face the same way, in which case two
thirds of units would have one kind of diagram and one third the
other, and only one third of cabs would be usable at one end.

In article , R.C. Payne
writes
I can see that something like points failure can cause odd moves, but
in normal service, I though the Tower Hill - Whitechapel, and the Earls
Court - Gloucester Road sides of the respective triangles only see D
stock, not C stock, which would prevent reversals in normal service

That's true for most of the day, but there are scheduled C stock
workings over the Tower Hill to Whitechapel section: at one time, the
last Inner Rail circle train of the day went via Whitechapel rather than
direct just to turn the unit round (otherwise the C stock ends up with
asymmetric wheel wear).

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