# Problems with a reversing loop



## Ealoftin (Sep 29, 2016)

I am having trouble with a reversing loop. I have an autoreverser working in one end and it seems fine, but when it comes out the train comes out of the loop, it stalls. Keep in mind, the loop is ends on a different turnout, and that I am a newbie and this is my first layout. Any help would be greatly appreciated!


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## Mark VerMurlen (Aug 15, 2015)

A diagram or drawing of your track plan that shows where the blocks boundaries are would help. What type of train(s) are you running? If you have lighted passenger cars, you need to be sure that the entire length of the train will fit within the reversing section. It may also help to know exactly what DCC system you are using and what auto reverser you are using.

Mark


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## Ealoftin (Sep 29, 2016)

Thanks, Mark. I am running DCC (digittrax) systemand this is my first layout. The engine is steam. I will get some pictures up shortly so someone can hopefully help.

Special Ed


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## DonR (Oct 18, 2012)

I agree with Mark. The most likely cause of
your loco stalling when exiting the isolated
section is that something is triggering the
loop controller so that it can't reverse it's
'polarity'.

You can test this theory by running ONLY the
loco through the isolated section. If it continues
without stalling the rear end of the train is
causing the problem.

Lighted cars or cabooses can cause the event,
but so can metal car wheels spanning the gap
over the insulated joiners in each rail.

Can you take a pic of the entire isolated
'reverse loop' and also the train that is
stalling. Show the train stopped over both
insulated joints, entry and exit.

Don


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## Ealoftin (Sep 29, 2016)

Yeah, I will take some pics tonight. I am only running the engine through and think I may have wired something wrong. I keep second-guessing myself and think I may need another reverser somewhere but am just lost. Can you just post pictures fairly easily to the thread? I'll figure it out, hopefully.


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## Lemonhawk (Sep 24, 2013)

Why would a lighted passenger car hinder the reverser? Seems like if the passenger car spanned the isolated block it would only loose power as the trucks would be picking up power from the same side. What I think would be a problem are any metal wheels that have yet to get into the reversing block after the reverser switched. This would cause any metal wheels to short out as they crossed the isolated gap, triggering another unwanted reverse since the isolated gap now has rails of opposite phase, so the metal wheel may actually short while at the gap in the track.


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## Ealoftin (Sep 29, 2016)

Yeah, I will take some pics tonight. I am only running the engine through and think I may have wired something wrong. I keep second-guessing myself and think I may need another reverser somewhere but am just lost. Can you just post pictures fairly easily to the thread? I'll figure it out, hopefully.


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## CTValleyRR (Jul 26, 2014)

Ealoftin said:


> I am having trouble with a reversing loop. I have an autoreverser working in one end and it seems fine, but when it comes out the train comes out of the loop, it stalls.


Spitballing a bit, but I think the clue lies in your description. The autoreverser should cover the ENTIRE reversing loop. Any feeders you have in that loop should be wired through the autoreverser, and the loop should be isolated at BOTH ends.


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## Lemonhawk (Sep 24, 2013)

The longer the entire isolated (both rails) reversed section is the better. The entire train needs to be on the isolated track before it gets to point the triggers the reverser.


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## mesenteria (Oct 29, 2015)

Lemonhawk said:


> The longer the entire isolated (both rails) reversed section is the better. The entire train needs to be on the isolated track before it gets to point the triggers the reverser.


This is only true if any of the metal tires bridge the gaps at the moment of reversal, or if there are electrically active wheel sets astride the gaps in the same frame.

If you cut two (2) sets of gaps at each end of the section of track controlled by the auto-reverser, separated by the length of the longest truck or driver wheelbase, you won't get problems of that nature. This is what DCC Specialties says in the manual for the PSX-AR.

On my last layout, I knew I would be running a coal drag through my reversed section that was longer than the reversed section. I checked the literature, cut the additional gaps at each end, and routinely ran a long coal drag across that segment without so much as a blink.


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## Ealoftin (Sep 29, 2016)

Hmmmmm. CTValleyRR's description of wiring THROUGH the autoreverser gives me pause. So confused.


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## DonR (Oct 18, 2012)

Ealoftin said:


> Yeah, I will take some pics tonight. I am only running the engine through and think I may have wired something wrong. I keep second-guessing myself and think I may need another reverser somewhere but am just lost. Can you just post pictures fairly easily to the thread? I'll figure it out, hopefully.


Since you get the short when running only the loco
through you must have a wiring error.

Check to see that you have the INPUT to the
reverse controller fed by your DCC track bus.
The OUTPUT of the controller goes ONLY
to the isolated track section. 

There can be other possibilities but we can detect
them if you can you provide a
drawing of your layout. The best way to do this
is using RED for the right rail and BLACK for
the left. Any time the RED rail contacts
the BLACK you have a short.

A short reminder of how a reverse loop controller
works: When the loco wheels span the insulated
joiners they create a short, the controller instantly
detects this and reverses phase (polarity). When
the loco continues to the exit the wheels again
span the insulated joiners, another short, and
the controller again reverses polarity to match
the main track. As mentioned lighted cars and
or metal wheels over the insulated joiners at the
same time loco wheels are on the other joiners,
can cause a shut down. 

There are simple ways to protect against the
metal wheel problem. Use a thin styrene
chip over the insulated joiners between the rail ends
that microscopically
rises above the rail head. Or you can simply
put a tiny dot of clear fingernail polish on one
side of the insulated rails so that there can be
no electrical contact by the metal wheels.

Don


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## Ealoftin (Sep 29, 2016)

Trying upload photos of my situation from this damn phone.


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## Bwells (Mar 30, 2014)

I think you may need a certain number of post before being allowed to do so but not sure on the number.


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## Mark VerMurlen (Aug 15, 2015)

Here's a basic diagram for how an auto reverser should be wired:










This is from a larger write up about wiring at http://www.building-your-model-railroad.com/model-railroad-wiring.html.

Its not clear from your earlier posts if you actually have both a DCC command station and an auto reversing module. Some command stations will claim that they do auto reversing, which is correct, but only when used in conjunction with another master command station.

Hope this helps explain how the wiring is supposed to work.

Mark


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## Ealoftin (Sep 29, 2016)

Ok, well I can't seem to post pictures but every single time the problem occurs it is in the same spot and it happens when the two front wheels of my steam engine crosses the gap and the big wheels hit the insulation. Oh, I am using a digittrax system with a separate autoreverser. This seems like it would be the metal wheel issue, no? So, what is styrene? What if the lady has no clear nail polish? But seriously, any help on how to apply this stuff? You guys have been great, so thank you!


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## Mark VerMurlen (Aug 15, 2015)

Are you using the Digitrax AR1 auto reverser? If so, the instruction manual talks about adjusting the current level at which the auto reverser should kick over. See http://www.digitrax.com/static/apps/products/autoreversing/ar1/documents/AR1.pdf. It warns that if the current level is set too high, the command station will shut down before the AR1 switches the phasing. This sounds like what you are experiencing.

I think you need to give us the exact model numbers of the command station and the auto reverser.

Mark


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## Ealoftin (Sep 29, 2016)

Digittrax Zephyr and and AR-1. I have tried to adjust the setting and it still doesn't work.


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## Mark VerMurlen (Aug 15, 2015)

I think the Zephyr is quite sensitive. Looking on the Digitrax website, I found a bulletin about using the AR1 with the Zephyr. Read the recommendation at http://www.digitrax.com/tsd/KB1034/ar1-autoreversing-zephyr-xtra/ and see if that might help.

Mark


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## Ealoftin (Sep 29, 2016)

Nicely done, Mark! I am going to try this in the morning and see if I can avoid the styrene or nail polish. Fingers crossed. Thank you so much!

Ed


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## DonR (Oct 18, 2012)

At first one wonders why, if the Zepher is reacting
before the AR1, the short doesn't appear when
the loco ENTERS the isolated section but does
when the loco EXITS. One answer could be that
the isolated track is 'in phase' with the main and 
thus the AR1 is inactive. When the loco reaches
the EXIT insulated joiners the isolated section is
'out of phase' with the main and thus the short.

Let's hope adjusting as suggested solves the
problem.

If not we'll likely need a drawing of the track plan.

Some had said that you cannot upload photos from
a phone. I use my desktop for that.

You would use the styrene (plastic) chip or nail
polish only to avoid the metal wheel problem on
a long train.

Don


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## Ealoftin (Sep 29, 2016)

Frustrated. I tried to program the Zephyr to fix this situation. No dice. I even move the insulated joiners back in the reversing section to see if that could help. No dice again. Very frustrated. I can't post any pictures for some reason. I am close to giving up.


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## Ealoftin (Sep 29, 2016)

Maybe these attached......


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## Ealoftin (Sep 29, 2016)

And another.


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## mesenteria (Oct 29, 2015)

Hook up a length of track with a gap in it, and power the two halves with different phase...switch the feeders on either side of the gap. You can mock this up inside of ten minutes.

Power the AR from the same terminals as one set of the feeders, and then feed the other side of the gap with feeders from the output terminals on the AR to the tracks on the other side of the gap...if you follow.

Now run a locomotive across the gap. If you get a short, you're either wiring the AR incorrectly or you have a defective AR, assuming no amount of sensitivity adjustment cures the tripping.

BTW, the default for sensitivity should always be maximum setting so that the AR trips first when there's a short. You can back this off experimentally if you wish until you get the system shutting down and beeping because the AR is too slow at stopping the short itself. All it should do, in any case, is to take about 3/1000 second to switch phase which the decoder can't respond to by doing funny things or letting the magic smoke out.


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## Lemonhawk (Sep 24, 2013)

Look carefully at Mark's diagram of how to make a reversing section and see if yours looks like that. Did your Zephyr come with a little track test light? If so put the test light across one of the reverse loop gaps. The tester is nothing more than a bi-color led with a 1K resistor and some alligator clips. I think its described in the Digitrax manual. Here's a picture of it clipped across an isolation gap.







Try the tester at each of the gaps that isolate the reverse loop. If the light is off, your in phase and no action will be taken by the AR controller. When you find a gap that does light the LED then take a screw driver and short out the gap, the AR unit should trigger and the LED should go out. Now if you move to the gap that did not at first light the LED, testing it now should show the LED on. Again if you short out this gap the LED should go out and if you go back to the previous gap the LED should light. 
The little LED tester is a great tool to detect track power and isolate problems. 
You aren't the only one having photo problems as no matter how I rotated this photo it always came out landscape on its side.


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## CTValleyRR (Jul 26, 2014)

Mark VerMurlen said:


> Here's a basic diagram for how an auto reverser should be wired:
> 
> 
> 
> ...


Thank you, Mark. That's exactly where I was going. If you have more than one power feed into the reversing loop, it also needs to come off the right side (in the above diagram) of the AR unit.

Ealoftin -- does your wiring look like that? And is the reversing loop completely isolated at both ends? I think we need to confirm that before going any further. Please don't take that as an insult -- we've all done similar things. When you're having trouble, it pays to double check the obvious.


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## CTValleyRR (Jul 26, 2014)

Ealoftin said:


> Maybe these attached......


Can you show us the OTHER insulated rail joint in the loop?


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## DonR (Oct 18, 2012)

Very sharp pictures. But if you have yet to
solve the problem, we need to have a pic or
drawing showing all of your tracks. Sometimes
when a reverse loop isolated section is involved
there can be a second one lurking nearby.

The easy thing to do is make a simply 
line drawing on a white
piece of paper and take a pic of it. Post that. Not necessary
to be to scale, but it should show all tracks,
turnouts and crossings.

Indicate on the drawing where you have the
insulated joiners. Also put an X where you
have track drops to the DCC buss and a Y where
you have the output of the AR1 connected to
the track.

Don


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## Ealoftin (Sep 29, 2016)

Here is another picture.


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## Ealoftin (Sep 29, 2016)

Next to the screwdriver is the beginning of the reversing section. Next to the rail cutters is the other end of the reversing loop. In the middle is a no reversing section (mainline). It is all a disaster.


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## DonR (Oct 18, 2012)

If your isolated 'reverse loop' is what appears to be a
2nd level starting at the screwdriver going around and
endind at the nippers, that is the longest that I have
ever seen. One of the suggestions will be to shorten
that drastically. Don't do anything yet.

Is that very long isolated section powered entirely
by the AR1? How many track drops to the AR1 output
are there? 

We still need to be able see the entire 
track plan to be able to analyze the problem.
If you could get on a ladder to the right end (as
seen in your last pic) and take your pic it should
include your entire track plan.

I doubt you have a disaster. Most reverser 
problems can be fixed without much ado.

Don


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## Ealoftin (Sep 29, 2016)

View from the ladder!


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## Lemonhawk (Sep 24, 2013)

Since I power the rails on both sides of my frogs, is that also true on these Atlas turnouts? Isn't the rail after the plastic frog dead unless its powered by the rail connected to it. By having isolation right next to the turnout I think you have a long dead rail from that insulated rail joiner to just beyond the plastic frog, and when the engine gets there it will stop. I can't remember it this is the case with those turnouts. That's another reason its nice to make the rail power tester. If this is the case you just need to move the isolation gap further down the rail and power the part between the isolators the turnout with power from the DCC system.


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## Ealoftin (Sep 29, 2016)

Damnit. I don't know. I've tried and tried and tried and now I quit.


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## Ealoftin (Sep 29, 2016)

I went to Home Depot and got a power meter thingy......but I don't know how to use it. My skill set is limited.


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## JerryH (Nov 18, 2012)

Set the meter to read AC volts. You should see about 13 volts between the rails.


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## Ealoftin (Sep 29, 2016)

Can you still have feeder wires within a reversing loop? My loop is obviously way too long. Could that be the problem?


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## fcwilt (Sep 27, 2013)

Ealoftin said:


> Can you still have feeder wires within a reversing loop? My loop is obviously way too long. Could that be the problem?


1. You have to have feeder wires from outputs of the AR unit ONLY.

2. Length is not an issue.


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## Ealoftin (Sep 29, 2016)

So I don't want any feeders to the bus BESIDES the two wires coming from the autoreverser?


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## Lemonhawk (Sep 24, 2013)

The long loop is unlikely to be a problem, even if you only have one feed from the AR1 connected to it. Use the multimeter on its A/C setting and check the voltage from rail A to rail B you should see the 10-15 volts. Check a lot of different spots. Familiarize yourself with what this reading looks like - especially the units multiplier so you don't get confused with volts and milli-volts, like notice what a reading looks like with the probes held in your fingers vs the 10-13 volt reading across the rails. Then check the voltages across the isolated gaps to see where there is a voltage across one of the gaps. Its a reverse loop so the gaps at the screwdriver or the cutters should have a voltage across the gap (test across the gap not rail a to rail b). 
Shorting this gap should cause the meter to read a very low voltage (millivolts to zero), now the gap that you originally read a low voltage should now have a voltage present. Test the section between the plastic frog and the rail form that frog to the insulted gap, test this with a probe on the outside rail and the other probe on the rail between the frog and isolator, this should always show the 10-14 volts that you normally see testing from rail A to rail B.
Don't get frustrated! We will all learn together what the problem is, its just that your the only one close to it.


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## fcwilt (Sep 27, 2013)

Ealoftin said:


> So I don't want any feeders to the bus BESIDES the two wires coming from the autoreverser?


What do you mean by BUS?

The reverse loop track should have insulated rail joiners or gaps in both rails at both ends of the reverse loop.

The outputs of the AR unit should connect to the reverse loop track, one output to each rail.

There should be NO other connections to the reverse loop track.

Frederick


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## Lemonhawk (Sep 24, 2013)

A feed (rail A and rail B) from the AR1 to the track between the screwdriver and the cutters, and you need a feed (rail A and rail B) from the DCC system to the rest of the track as shown in the diagram. Keep things simple until its working.


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## Ealoftin (Sep 29, 2016)

I have wiring supplying power WITHIN the loop. Oops. I will disconnect these in the morning and look at it with fresh eyes. Thanks for the support guys! I have successfully learned to get a reading with the probamajigger so that is a start. The readings I'm getting are in the 10-15 range. Why I attached the feeders from the track within the reversing loop to the main line? Uh, because I ain't the swiftest sort.


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## Lemonhawk (Sep 24, 2013)

Were making progress!


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## Ealoftin (Sep 29, 2016)

Reversing loop problem SOLVED.

Problems: sloppy track work leading to bad connections, putting several attachment to the main power within my reverse loop, general impatience, using inadequate wires, and on and on.

Takeaways: learned how to measure track power in various places, learned that bull in a china shop methodology is not going to get it done, learned more about reversing loops (and that isolated means isolated), learned that I am need to practice soldering and track work (a lot), realized the value in carefully thinking what exactly each connection will accomplish, and on and on. I also learned that my layout design is subpar and once reversed there is no way to turn the engine back around. Not good. But this is all a learning exercise!

To all you guys (or maybe gals) that helped me out with your valuable time, I am really thankful!

I'll be back!

Special Ed


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## Lemonhawk (Sep 24, 2013)

Yes you have to back thru the reverse loop, but you might just have to do that with only the locomotive. Glad you pick up a few useful skill! That what is all about! A year ago I would never have though about making my own turnouts, not I'll never go back to premade ones! You just never know what you find and learn while making a layout. Enjoy the experience and most of all thank you for telling us what you found and how you corrected it:appl:


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## CTValleyRR (Jul 26, 2014)

Called it all the way back in Post #8.

Glad you got it sorted out. Don't worry about roomie mistakes. We've all been there, done that, and gotten enough T-shirts to make rags out of!


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## DonR (Oct 18, 2012)

Fantastic. 

But you still have a very long isolated section. It
should be no longer than your longest lighted
passenger train. The reason for this 'rule' is to
avoid a second train entering the isolated 
section before the first train has cleared. As
we've mentioned, that would cause a short
again. Take your time in doing it but it should
be done before you ballast the tracks.

Don


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## berger (Mar 4, 2015)

*Reverse loop problem with Digitrax*

I have two reverse loops on my layout and had the same problem. You have too change a setting on the Digitrax box.
KB1034: AR1 autoreversing with the Zephyr Xtra

This article was last updated on May 12, 2016, 9:59 a.m. Article | Leave Feedback

When using an AR1 with the Zephyr Xtra, we suggest you change Option Switch 18 to Closed (OPSw18='c'). Option Switch 18 extends the DCS51 booster short circuit shutdown time from 1/8 to 1/2 second. By increasing this Option Switch setting to 1/2 second, this allows the AR1 to change the track polarity before the DCS51 booster reacts to the momentary short caused when the train passes over the reversing section gaps.



To change Option Switch 18, do the following:



Press PROG

Press SWITCH

Press 1

Press 8

Press c (CV-WR, lower right)

Press EXIT


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