Re: New questions for rail experts

["chris 'fufas' grace" <chris@transdata.co.nz>]

Michael Kurkowski wrote:
> 
> greg@mpx.com.au (Greg Cantori) wrote in
> <392a7311$0$2628@news01.syd.optusnet.com.au>:
> 
> >1. On each platform there is a blue light called the "guards indicator".
> >   What is its purpose, and why does it turn on and off?
> 
> No idea. We don't have guards down in Melbourne, therefore I am not
> qualified to answer this question.
> 
> >2. On the tracks every 50 metres or so is a metal switch-thing that
> >   is up after a train has passed, then flips down when the train is
> >   a safe distance ahead. Presuming this causes a following train to
> >   brake if it goes over it while up, why doesn't the train that
> >   set it up in the first place get caught when its last carraiges
> >   go over it? (unless of course it's the last carriage that sets it up!)
> 
> This is known as the train stop. It interfaces with the signal and the
> train trip to effectively give a full brake application as a train passes a
> signal at stop. The trip is attached to the bogie of the train and gets
> pushed up in the event of it contacting with a train stop that's positioned
> for "stop". 

And the reason why other bogies on a train don't get tripped is that
only one 
trip cock at a time is switched in, depending on the drivers cab is in
use.

I can't speak for NSW as I can't find my copy of the working
instructions, but
on the London Underground, which has the same system, one of the
duties of a driver taking  a train out of a depot or changing ends at
a terminus is to switch the tripcock in
from the cab he is using and test it. This can become quite involved
when a shunt is involved as he has to do it each time he changes cabs.

One thing I'm not sure about: Are the trainstops always on the same
side of the track
facing the direction of travel? If they are that means that the
leading bogie in each set only has a tripcock on that side which would
mean in an 8 car set that there were only two tripcocks per side.
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