I have a spur coming off a reverse loop into a yard. The reverse loop has an auto-reverser between the main and the reverse loop. Do I need another between the reverse loop and the spur coming off it?
No you do not need another.
It’s fine to have a reverse loop with attached trackage that floats as part of the loop as a complete sub-system. I’ll assume and talk DCC here,and that your auto reverser is hooked up to the reverse loop, which is gapped (isolated) from the main.
Consider a loco in the yard moving slowly forward doing some switching. If a mainline train then comes through the reverse loop it will trigger the auto reverser to switch the DCC “polarity” when needed (as the loco enters or exits the loop). When the DCC polarity changes, which happens in a fraction of a second, the decoder in the yard loco just as fast changes the use of the incoming signal and uses the juice as needed to keep the loco going forward, since that is still the instruction for that loco’s decoder.
If someone had a truly extensive system branching off the loop, lots of trains operating in the loop and the attached tracks, one might want to add gaps and make the attached trackage its own sub-district with a separate breaker so if a short occurred one would know if it was in the loop vs the attached subsystem. In reality most people let their yards float with the attached loop. If a couple of trains are moving and a short occurs, it’s usually obvious that it’s happening as a loco hits a turnout, etc, so the extra complication of additional breakers is easily skipped.
One more detail. If the yard attached to the loop were to connect back to the mainline (let’s say, at the far end of the yard), then you would have to let the yard float with the main OR with the reversing loop. If floating with the main, you would put isolation gaps at the yard track connected to the turnout at the reversing loop (leaving the yard trackage connected to the mainline). If the yard were to float with the reversing loop, one would put isolation gaps at the
thanks Paul [bow]
If you can submit a drawing of your track plan, we can confirm whether or not you need a second auto-reverser.
Rich
Ok her is the layout. The section I’m talking about is in red. It is powered from a separate bus off a circuit breaker that isolates that section. https://www.dropbox.com/s/ywkstuubsopnl0g/Photo%20Nov%2020%2C%2012%2047%2011%20PM.jpg?dl=0
Another thing I don’t understand is how to wire then reverse loop. I know the autoreverser connects to the main and the reverse loop but the reverse sections are about 10 - 12ft long and the wire on the autoreverser looks like 24ga. It doesn’t seem that it will provide sufficient power to the reverse loop throughout the loop. Should I wire to a terminal strip and then run 18, 20 ga wires from there?
You’ve got at least 3 different threads going about wiring/function issues and it’s like pulling teeth to get a pic of your layout. I don’t do sideways so here it is right side up. I would create sub buses for your reversing loops. Those with more experience that I can comment on your wire guage.
[:$]Thanks Henry, I apologize for any confusion I have caused.