Hi group,

Trivial question, but something that puzzles me when the rubbish collector
has been too thorough and there's no ES left to read:

I've noticed a small black and yellow stripped plate in the cab windows of
Met line trains. Might be in others too, not sure. What are they?

Silly answers are as equally welcome as sensible ones, so if you do know
the real answer, hold back a bit so we can get some wild speculation going


--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

Does it look like this
http://www.trainweb.org/districtdave...d78_stock.html

Fig wrote:

Hi group,

Trivial question, but something that puzzles me when the rubbish collector
has been too thorough and there's no ES left to read:

I've noticed a small black and yellow stripped plate in the cab windows of
Met line trains. Might be in others too, not sure. What are they?

Silly answers are as equally welcome as sensible ones, so if you do know
the real answer, hold back a bit so we can get some wild speculation going


--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

On Fri, 01 Sep 2006 18:49:03 +0100, chunky munky
wrote:

Fig wrote:

I've noticed a small black and yellow stripped plate in the cab windows
of
Met line trains. Might be in others too, not sure. What are they?

Does it look like this
http://www.trainweb.org/districtdave...d78_stock.html

Yes, that's it! But, I'm afraid that after having read all that, I'm still
none the wiser. Will read again and if I still don't get it, I'll stop
worrying about it.

--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

On Fri, 01 Sep 2006 19:09:32 +0100, Fig wrote:

On Fri, 01 Sep 2006 18:49:03 +0100, chunky munky
wrote:

Fig wrote:

I've noticed a small black and yellow stripped plate in the cab windows
of
Met line trains. Might be in others too, not sure. What are they?

Does it look like this
http://www.trainweb.org/districtdave...d78_stock.html

Yes, that's it! But, I'm afraid that after having read all that, I'm still
none the wiser. Will read again and if I still don't get it, I'll stop
worrying about it.

In simple terms the driver has a handle (CTBC) which he pushes forward
to accelerate and pulls back to slow down. This is a very simplistic
explanation as stock vary as to the exact design.

The top speed and level of acceleration are affected by which of the
"flags" are set. They are a form of cruise control to use a car analogy.
If both flags are up then the train is in "turbo" mode ;-)

I'll now await the arrival of various drivers and train managers to make
me look a right idiot.

--
Paul C


Admits to working for London Underground!

The black and yellow plate is called a "Weak Field Switch". It allows
more current to the motors to allow them to go faster. It used to be
fitted to all trains like 38 stock, R stock, Q stock etc as well as the
A stock and was a method of going faster when needed. The idea of it
being visible is that it can be seen by the train controllers and
drivers can get into trouble for using it when not authorised. On the
Met line it is used all the time.

More modern stock since the 60's I don't think have this arrangement.
I've never seen one on a 67 or 72 stock or anything newer.

Ian

Ian Rivett wrote:
The black and yellow plate is called a "Weak Field Switch". It
allows more current to the motors to allow them to go faster. It
used to be fitted to all trains like 38 stock, R stock, Q stock etc
as well as the A stock and was a method of going faster when
needed. The idea of it being visible is that it can be seen by the
train controllers and drivers can get into trouble for using it
when not authorised. On the Met line it is used all the time.

More modern stock since the 60's I don't think have this
arrangement. I've never seen one on a 67 or 72 stock or anything
newer.

They are fitted to D stock (1978) on the District Line, as explained at
http://www.trainweb.org/districtdave...d78_stock.html

--
Richard J.
(to e-mail me, swap uk and yon in address)

On Sat, 02 Sep 2006 10:21:43 +0100, Ian Rivett wrote:


The black and yellow plate is called a "Weak Field Switch". It allows
more current to the motors to allow them to go faster. It used to be
fitted to all trains like 38 stock, R stock, Q stock etc as well as the
A stock and was a method of going faster when needed. The idea of it
being visible is that it can be seen by the train controllers and
drivers can get into trouble for using it when not authorised. On the
Met line it is used all the time.

More modern stock since the 60's I don't think have this arrangement.
I've never seen one on a 67 or 72 stock or anything newer.

Ian

Thanks Ian, all that District line stuff threw me. Will make sure I only
board a train showing a weak field switch in future ;-)

--
Fig
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

On 2 Sep 2006 02:21:43 -0700, "Ian Rivett" wrote:


The black and yellow plate is called a "Weak Field Switch". It allows
more current to the motors to allow them to go faster. It used to be
fitted to all trains like 38 stock, R stock, Q stock etc as well as the
A stock and was a method of going faster when needed. The idea of it
being visible is that it can be seen by the train controllers and
drivers can get into trouble for using it when not authorised. On the
Met line it is used all the time.

When did that change? I thought that the flag switch used to be
lowered between Baker Street and Aldgate, where the higher
acceleration would be needed, and the higher maximum speed irrelevant.

On a related note, my uncle used to drive Circle and H&C services and
he claimed that the A stock used to cause service problems as it was
'slower' than the other stock over the northern part of the Circle. By
'other stock' he meant the CO/CP that was in use at the time.

On Fri, 01 Sep 2006 19:30:03 +0100, Paul Corfield wrote:

I've noticed a small black and yellow stripped plate in the cab windows
of
Met line trains. Might be in others too, not sure. What are they?

Does it look like this
http://www.trainweb.org/districtdave...d78_stock.html

Yes, that's it! But, I'm afraid that after having read all that, I'm still
none the wiser. Will read again and if I still don't get it, I'll stop
worrying about it.

In simple terms the driver has a handle (CTBC) which he pushes forward
to accelerate and pulls back to slow down. This is a very simplistic
explanation as stock vary as to the exact design.

The top speed and level of acceleration are affected by which of the
"flags" are set. They are a form of cruise control to use a car analogy.
If both flags are up then the train is in "turbo" mode ;-)

I'll now await the arrival of various drivers and train managers to make
me look a right idiot.

Perhaps this is a silly question and I'll kick myself when I see the
answer, but why would you want to deliberately restrict the speed of
trains in this way (i.e. beyond that required by line speed limits and
the signalling system)? Is it to do with saving energy?

Surely if the trains travel faster, with the same distance between
each train (which is externally determined by the signalling), you'll
have more trains per hour and therefore higher capacity, as well as
improved journey times.

"asdf" wrote in message
...
On Fri, 01 Sep 2006 19:30:03 +0100, Paul Corfield wrote:

I've noticed a small black and yellow stripped plate in the cab
windows
of
Met line trains. Might be in others too, not sure. What are they?

Perhaps this is a silly question and I'll kick myself when I see the
answer, but why would you want to deliberately restrict the speed of
trains in this way (i.e. beyond that required by line speed limits and
the signalling system)? Is it to do with saving energy?

Surely if the trains travel faster, with the same distance between
each train (which is externally determined by the signalling), you'll
have more trains per hour and therefore higher capacity, as well as
improved journey times.

Weak field was (is?) only supposed to be used on longer open air sections of
line, such as most of the Met main and the Hammersmith to Acton Town section
of the Piccadilly. In tunnel sections and most other open air sections of
line, with stations closer together, you would rarely get the opportunity to
reach weak field speeds before starting to brake for the next station.