Two lines share one reversing loop?

[jwhitten]

MisterBeasley

Yes, this will happen sooner or later.  This is probably a good application for some of the DCC-specific detection and signalling systems.  (As long as you're doing this, put in real signals, by the way.  It will be easier to get it all right if you have them as indicator lights while you're installing it, and it will look really neat to see the signals flipping automatically as the trains make their way through the loop.)

 

 

Not to take away from what Mr B said, but an equally good recommendation here would be: Don't be so cheap, spend another $25-30 bucks and get yourself a second loop controller !! It *is* possible to be too cheap! 

 

John

[icemanrulz]

   The lines going out would in fact be close, within 7 inch center to center.  I like the excuse to have lights!  We may just grab a "few more feet" and have two loops.  Then both could have a siding out to the work bench.

[BigG]

 This may be a bit crude, but to simplify the layout, it is just a figure-8 with 1 indeterminate end and the other being the reverse loop. An occupancy detector covering the loop and 2 approach tracks, with its output sent to a relay that is controlled by the same signal that allows a certain track to be active going into the dbl-slip, can be made to kill the other input track until the loop becomes unoccupied. (whew!) The other train will come to an abrupt halt on its approach track, but there will be no collision.

 The details might be fun to figure out, but it sounds plausible.

   Have fun,   George

[MisterBeasley]

cthart

Can you join them with a double-slip switch?

Brilliant!  This is a perfect minimal solution.  If you combine a double-slip with an auto-reverser, it solves the basic automation problem.

You do still have the issue of making sure that a second train can't come along while the first is already in the loop, but the fundamental problem is taken care of.

[cthart]

icemanrulz

I am wondering if or how we can do this?  We are building HO DCC and want tow different lines to go out and back (across the room) but do not have the room for two loop backs.  Is there a way to have the trains share a reversing loop, but end up back on the same track they came in on?  AND can it be automated?

How close together do the lines come in to the loop? Can you join them with a double-slip switch? Or do they come in like on opposite sides of a circle?

Automation would require some detection, but how are you going to protect the loop area given that only a train from 1 line may enter it?

I would probably use switches to set the double-slip or turnouts in appropriate positions. The same switches can be used also to reverse the polarity of the loop, no auto-reverser is then needed.

Regards,

Colin

[MisterBeasley]

Assuming you have two parallel tracks (or roughly so) going out, all you need to do is bring them together with a turnout just before they go into the reverse loop.  To automate the whole thing, you will need an auto-reverse unit.  I believe the Tony's Trains PSX-AR has an option to throw the loop turnout automatically.

That still leaves you with the problem of the turnout that brings the lines together.  You would need some sort of detection circuit up the line a ways.  This could be as simple as a magnetic reed switch if you are throwing an Atlas snap-switch turnout, or something more complicated if you want to get into optical or infrared detection.

This is one case where I would recommend the Cadillac approach rather than the Chevy (or Yugo) approach.  Besides simply throwing the turnout, you should think about stopping trains approaching simultaneously on the other line until the first train gets through the loop.  Yes, this will happen sooner or later.  This is probably a good application for some of the DCC-specific detection and signalling systems.  (As long as you're doing this, put in real signals, by the way.  It will be easier to get it all right if you have them as indicator lights while you're installing it, and it will look really neat to see the signals flipping automatically as the trains make their way through the loop.)

[icemanrulz]

 I am wondering if or how we can do this?  We are building HO DCC and want tow different lines to go out and back (across the room) but do not have the room for two loop backs.  Is there a way to have the trains share a reversing loop, but end up back on the same track they came in on?  AND can it be automated?

Thanks