Re: Ringwood

[David Langley <del@ancc.com.au>]

Notagunzel wrote:

> Tony Gatt wrote:
>
> > Yep, got that bit.. fine with that.. but...
> >
> > I need to know about the triangle things inside the left hand rail. They sit
> > next to the signal and look like they may be some form of detector loop for
> > the passing of wheels. I believe there are some on the Epping line...
> >
> > They look like a plastic "wedge" and sit flat to the sleepers..
>
> These are called 'Pin Point Detectors', and are used within a Jointless
> track circuit.
>
> Jointless tracks have a transmitter at one end, and a receiver at the
> other (rocket science so far), but for varios reasons, a pin point
> detector can be installed within the track, and a seperate track relay
> hanging off it.  This will pick when the track is clear between the
> transmitter and the receiver, even when a train may be between the Pin
> Point Detector and the Receiver.  They are used especially for overlaps,
> level crossings, pedestrian gates etc...

Sorry Tony I've been away for a day or two but Mr G has it in a nutshell. I
believe that Pin Point Detectors are used to ensure a definite end of the
jointless track circuit at level crossings. It would not be handy for the standard
relatively coarse junction between track circuits to exist at level crossings
because it would give rise to erratic operation of the booms etc.

David Langley.

>
>
> Hope this helps. :o)
>
> --
> Mr Notagunzel.
> Trying to avoid the Gunzels.
> notagunzel@bigfoot.com
> (Thinking about doing something more at
> http://www.bigfoot.com/~notagunzel)