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Automating a reverse loop


Del

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I've found a plan I *really* like which incorporates a return loop.

From my reading, I seem to remember that I have to stop the train on the loop, set the route, flick the changeover switch, then restart the train with the controller in the opposite direction.

So, two questions:

i) is it only necessary on a single-track loop? After all, if it's double-track, the train comes out of the loop on a different track to the one it entered, if you see what I mean.

ii) can this process be automated without going to DCC, and without stopping the train?

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Del

 

The easiest way to not have to stop the train is to provide the power feed to the loop and use a suplementary switch (like a Peco PL15) attached to the point that controls access to the loop to switch the feed to the rest of the layout. You can change the point any time that the train is in the loop - but will have to simultaneously stop the train and change the point before you use the loop again. this system works well for a simple terminus to reverse loop layout but could get a bit complicated for a more complex layout. It does mean that everything will just happen without having to worry about doing anything other than change the point.

 

An alternative is to feed the loop via a bridge rectifier which will enable you to reverse the controller (if your controller allows it) and the point while the train is running in the loop. You have to be alert because there is only a small time window for you to do this before the train will short the track when it reaches the end of the loop of you do not complete the switching in time.

 

Without a full diagram it is difficult to see how complex your double track scenario is and how relevant the single track solution will be.

 

Reverse loops have been discussed before so it is worth doing a search to see if there is something of relevance already posted.

 

 

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Many years ago I used to have a return loop on a single track line.

 

The outer rail was fed by the power going through a PL15 that was atached to the point motor. Take power for each outer rail at the toe of the point to either side of the switch and use the common to feed the outer rail of the loop. The inner rail of the loop was connected without breaks to the point thus having the point provide the switching of the middle rail's power source.

 

You'll need to get the PL15 the right way round or you'll feed both rails of the loop with the power from the same feed.

 

Best to stop the train change point and then continue using the new direction on the controller.

 

 

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Here's the setup I'm getting at.

If a train comes in on the red line or the blue line, then am I right that it doesn't cause a short as it comes round the loop, therefore there's no need for any complicated wiring?

 

12q5wy.jpg

 

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Hi

As you're using dc and I assume two controllers - one for each of the input/exit lines, then no switching or other special controls are really needed. Though you can use a DPDT switch to control each of the actual loops rails if wished!

Consider for normal dc operation positive needs to be on the right-hand rails for forward movement.

 

So for dc operation and probably the easiest method is.... fit four insulated rail joiners (IRJs) where shown by the two red lines cutting across the tracks. Two IRJs per track - one in each rail.

 

Operation would then be drive loco/train into the loop in the red direction via controller 1, then preset controller 2 to the correct direction of travel and roughly the same speed setting, then as the loco exits across the IRJs it will pick up its feed from Controller 2.

 

Same thing applies to a controller 1 (red) powered loco entering the loop then going in the blue direction - set controller 2 for direction and speed and allow loco to exit loop under Controller 2.

post-281-127515315219.jpg

 

For DCC operation you would need two Auto Reverse Modules (ARMs), one feeding each loop. Plus 8 IRJs installed to make each loop electrically separate from the rest of the layout. Each ARMs output then feeds its own loop rails.

post-281-127515209437.jpg

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Since you have quite a simple layout this will be the best way to run your trains without having top stop in the loop:-

 

post-7495-127520666359.gif

 

If you have dead frog points there will be no interesting wiring to do do but you will have to make provision for switching the feeds if using a live frog crossing.

 

 

Topologically all that you have is a single track (using Brians diagram from CON1 to CON2) with a slightly fancy passing loop!

 

post-7495-127520746275.gif

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