Why should the speed ("considerable" or otherwise) be a matter of
concern for these arms, but not for the leading one? Unless there is
significant acceleration or deceleration, won't it be more or less the
same speed for all of them?

No, because the trainstop would have been lowered, surely, for the time
when it passes the signal.

On Mon, 18 Jul 2005 09:21:45 GMT someone who may be Chris Tolley
wrote this:-

Why should the speed ("considerable" or otherwise) be a matter of
concern for these arms, but not for the leading one?

One way such systems can fail is if the arm breaks off. This risk is
controlled by not having arms generally not striking trainstops and
so not suffering the fatigue this involves. An arm at the front of
the train will only strike a trainstop on rare occasions.

The higher the speed that an arm strikes the trainstop the more
likely it is to fail. "BR" trains will usually be travelling at high
speed when they first encounter trainstops as they enter the LT
signalled section.


--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E
I will always explain revoked keys, unless the UK government
prevents me by using the RIP Act 2000.

David 'Arsehole' Hansen wrote:

One way such systems can fail is if the arm breaks off. This risk is
controlled by not having arms generally not striking trainstops and
so not suffering the fatigue this involves. An arm at the front of
the train will only strike a trainstop on rare occasions.

The risk is so remote as to be of no concern. One of the benefits of
trip cocks is that they are a very simple system. Adding a system to
retract them would complicate the system, and probably increase the
chances of a wrong-side failure.

If there were any concern regarding this issue the simplest thing would
be to tell drivers to kick them out of the way during preparation.

On 18 Jul 2005 03:49:19 -0700 someone who may be "Chippy"
wrote this:-

David 'Arsehole' Hansen wrote:

Excellent, more personal abuse. Do keep it up as it tells us so much
about you.

The risk is so remote as to be of no concern.

So you claim.


--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E
I will always explain revoked keys, unless the UK government
prevents me by using the RIP Act 2000.

David Hansen wrote:
On 18 Jul 2005 03:49:19 -0700 someone who may be "Chippy"
wrote this:-

David 'Arsehole' Hansen wrote:

Excellent, more personal abuse. Do keep it up as it tells us so much
about you.

It isn't abuse. It is recognition of your status as an Arsehole Club
member.

In message .com,
Chippy writes
David 'Arsehole' Hansen wrote:

One way such systems can fail is if the arm breaks off. This risk is
controlled by not having arms generally not striking trainstops and
so not suffering the fatigue this involves. An arm at the front of
the train will only strike a trainstop on rare occasions.

One of the benefits of
trip cocks is that they are a very simple system.
Aren't they tested on every trip? They certainly used to be.
--
Clive

Two points.
Firstly, LT trains work in the same way and I am not aware that they have
had problems.
Secondly, Once a tripcock is struck it remains in the up position until
it
is reset when the unit is uncoupled so the rear unit tripcock will only be
hit once per period of time that the unit is coupled as the non leading
unit.

The only difference being that the LUL trains will get strike the first
signal they encouter leaving the depot at 10mph whilst the Chiltern units
similiar first experience will be a signal at 75mph!

Andyh

"Chippy" wrote in message
oups.com...
David 'Arsehole' Hansen wrote:

One way such systems can fail is if the arm breaks off. This risk is
controlled by not having arms generally not striking trainstops and
so not suffering the fatigue this involves. An arm at the front of
the train will only strike a trainstop on rare occasions.

The risk is so remote as to be of no concern. One of the benefits of
trip cocks is that they are a very simple system. Adding a system to
retract them would complicate the system, and probably increase the
chances of a wrong-side failure.

If there were any concern regarding this issue the simplest thing would
be to tell drivers to kick them out of the way during preparation.


I don't mean to be rude but that demonstrates a clear lack of understanding
and knowledge about the system!

Firstly the trip arm is not that accessible, secondly the force required
would result in some broken toes, thirdly given that large amount of
coupling and uncoupling Chiltern do often this would need to be done in
platforms at Marylebone and Aylesbury, and forthly the drivers would want a
£5k pay rise for doing it!

Andyh

"John Shelley" wrote in message
...

Two points.
Firstly, LT trains work in the same way and I am not aware that they have
had problems.

LT trains will leave depots at slow speed when the "dead" trips are tripped.

Secondly, Once a tripcock is struck it remains in the up position until
it
is reset when the unit is uncoupled so the rear unit tripcock will only be
hit once per period of time that the unit is coupled as the non leading
unit.

That still leaves the front and rear-most cocks being reset a hell of a lot
of times, and being struck at high-speeds.


--
Ronnie
--
Have a great day...
....Have a Great Central day.
www.greatcentralrailway.com

"David Hansen" wrote in message
...
On 18 Jul 2005 03:49:19 -0700 someone who may be "Chippy"
wrote this:-

David 'Arsehole' Hansen wrote:

Excellent, more personal abuse. Do keep it up as it tells us so much
about you.

At least he's not calling you an asparagus...


--
Ronnie
--
Have a great day...
....Have a Great Central day.
www.greatcentralrailway.com