Re: Three Position Signalling

["Notagunzel" <notagunzel@bigfoot.com>]

Christopher_Martin GORDON <cmgord@ecr.mu.oz.au> wrote in message
7t8m0v$47q$1@mulga.cs.mu.OZ.AU">news:7t8m0v$47q$1@mulga.cs.mu.OZ.AU...

> : > Also on loops on the BG.

> : > The only way to get the signal off for a movement into no.1 road and not
> : > have the departure signal off is to reverse the points at the far end.
> : > The after the arrival signal is off then the points at the far end are
still
> : > free to move (ie you can move them back).

> : Are you sure? AFAIK once you set up this move the points at the far end are
locked until
> : you either put the home arrival back to stop or the train passes the home
arrival at low
> : speed caution and enters the "yard" area either main or loop.

Hmmm... Doesn't *sound* right, I can't disagree with you, but if it is so, then
it sounds like lazy circuit design.

> Will I think that is true for the standard gauge, but what about the BG loops
> around.  One I can think of is Herns Oak (Between Moe and Morwell).  It is
> controlled from a panel at Morwell and when I was there late one night the
> signaller showed me how to get the main line signal for No.1 road off.  The
> first way was reversing the far end points, then the signal would come off,
> the points still had the "free to move" light and he restored them to normal
> (ie moved the far end points).  I would of thought that these points would be
> locked, but they wern't that is why I got him to restore the points while
> the signal was off.

> : I think you'll find some interlocking here preventing that. This
interlocking is probably
> : in the Office equipment and thus field circuits do not show it but that is
how I
> : understand it would work. It always did when I worked on the system.

Interlocking in office equipment?  Hope it's not vital interlocking. |-)

> Same again, down at Herns Oak.  Once the departure signal for No.1 road was
> off the arrival signal was off, he put back the departure signal and the
> arrival staied off.  After a little while he then had avaibility on the
> points (the ones locked by the departure signal)./

> So on the SG what happens when say the up train is signalled into no.1 road
> (ie arrival is off) and the down train is signalled into no.2 road.  The
> down arrives can you then restore the points and let the up train have a
> clear run through the loop?  Or do you have to wait until the up train
> enters the loop (or you put back the arrival signal).

Both Up & Down Homes will be displaying Caution Low Speed, once the Down is in
clear, the Up end points should be Free.  These can be run, & the Up Departure
Pulled.  Then both xxx/8 & xxx/4 should both display Top Green.

Another point is that the Arrival Home Signals are interlocked with the next
single line section in advance.  So the Arrival Home can only come off if:

A) The points at this end are reverse
B) The points at this end are normal, & the points at the other end is reverse,
or
C) The points at both ends are normal *and* the direction of traffic in the
section in advance has been established as going away.

The idea is to perhaps prevent a head on collision if a train passes an Arrival
signal at Stop.

--
Mr Notagunzel.
Rail Transportation Connoisseur.
notagunzel@bigfoot.com
(Waiting for the next move at http://www.bigfoot.com/~notagunzel)