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Auto Reversing Loop Problems

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Posted by wjstix on Thursday, October 14, 2021 11:59 AM

In my experience, if the AR1 doesn't work no matter how you adjust it, it's because of an error in the wiring of the track / reverse loop. Maybe disconnect all wiring to the reverse loop, then try it make sure it isn't getting power somehow (like a track gap that has closed and is making a connection). Then connect two wires from the reverse loop to the AR1 outputs, and see if you can get it to work. Then add additional feeders and test after each change.

Stix
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Posted by rrebell on Wednesday, October 13, 2021 8:09 PM

gregc

 

 
rrebell
The AR1 is hard to set up right and speed of train will affect how well it works.  The length of track dose not seem to be as important and metal whells on boxcars don't seem to trip it as long as train is moving fast enough.

 

that's not how an auto-reverser should work.

looks like the AR1 can be set to handle a train drawing 6A and would suggest the trip current needs to be higher.   what if the booster can't supply 6A or a circuit breaker limits the current?

sounds like the AR1 needs to trip at a lower current by adjusting the Trip Current Adjuster (TTC), turn counter-clockwise.  2A would probably be more than enough

928

 

On mine the setting will not work right higher or lower on the AR1, thinking of getting the juicer that can act as an auto reverser.

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Posted by richhotrain on Wednesday, October 13, 2021 4:28 PM

Lastspikemike
 
richhotrain 
 
Lastspikemike

You can build as many reversing sections as you wish but it's hard to understand why you would.  

It might be hard to understand if one is building a small, say, 4 x 8 layout, but on larger, more complex layouts it's not hard to understand at all. Think about a dogbone layout with two reversing sections, one on each end. Then think about a double mainline dogbone layout. Now, it's easy to understand why someone, like me, would have four reversing sections.   

 

Well, depends on your control and power systems. I can see the advantage to treating a full double track layout as two independent single track layouts. Then you'd have 6 sections to deal with. Only one section in each track would need to be a reversing section so it would be feasible with DCC to build your suggested layout of a twin track dogbone with only two reversing sections in fact. For DC you'd have better control with four reversing sections but strictly speaking it would not be necessary. A set of SPDT on off block power switches downstream from the DPDT block power connectors would achieve much the same operating options even in DC. 

Not sure why you bring up DC when this is a DCC thread, but whatever.

My layout is not a suggested layout but rather an actual layout. The two reversing end loops connect to a 4-track complex in the middle of the layout in which the two mainlines run parallel to each other, forming four parallel tracks. All four tracks connext through a series of four turnouts and four double slips, permitting trains to change directions from any track.

Lots of luck wiring that up with two auto-reversers.

 

 

 

 

Alton Junction

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Posted by wjstix on Wednesday, October 13, 2021 2:04 PM

gregc
 
richhotrain
Imagine a reverse loop with one ... feeder ... wired to the main bus.

 

your observation could explain the problem

 

trying to get more info from the OP

 

 
That's what I was getting at, because that happened to me. I have a reverse loop with several power feeders connected, at one connection one of the wires got connected to the main power instead the reverse loop's AR1 output. It meant that trains could enter in one direction fine, but when coming out the AR1 started clicking back and forth changing polarity over and over. I guess since it was only one rail, it was enough to mess up the AR1's working properly, but not enough to trip the short circuit breaker on the DCC system, so I didn't think a short was the issue. Took me quite a while to find it; sometimes you just have to disconnect everything and start over.
Stix
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Posted by richhotrain on Wednesday, October 13, 2021 9:19 AM

Lastspikemike

You can build as many reversing sections as you wish but it's hard to understand why you would.

It might be hard to understand if one is building a small, say, 4 x 8 layout, but on larger, more complex layouts it's not hard to understand at all. Think about a dogbone layout with two reversing sections, one on each end. Then think about a double mainline dogbone layout. Now, it's easy to understand why someone, like me, would have four reversing sections.

 

Alton Junction

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Posted by SeeYou190 on Wednesday, October 13, 2021 8:48 AM

BNSFWill
I'm trying to wire a loop that goes around my railyard. I'm using a Digitrax AR1 for this reverse loop but I'm having problems. My train can enter the loop but it will short out when it exits the loop.

Have you tried it with just a single locomotive and no other train cars?

-Kevin

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Posted by richhotrain on Wednesday, October 13, 2021 6:59 AM

CSX Robert
 
richhotrain
Now what DCC user does that? 

Me.

CSX, I am having a hard time believing that a man of your expertise starts out with a DPDT controlling a reversing section, but I will take your word for it that you do. 

I am not trying to brag when I say this, but I successfully set up a complex set of four reversing sections on a double mainline on my current layout in which four turnouts and four double slips are involved, all controlled by four ARs, without so much as a single failure. No DPDT involved.

CSX Robert
 

If it doesn't work with a DPDT switch, then you know there is a problem in the wiring.

True, but that does not necessarily mean that the reversing section is wired wrong. The DPDT can be wired wrong. How many threads have we seen where a DPDT is wired wrong or where the OP on such a thread has no idea how to wire a DPDT?

Rich

Alton Junction

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Posted by gregc on Wednesday, October 13, 2021 6:09 AM

rrebell
The AR1 is hard to set up right and speed of train will affect how well it works.  The length of track dose not seem to be as important and metal whells on boxcars don't seem to trip it as long as train is moving fast enough.

that's not how an auto-reverser should work.

looks like the AR1 can be set to handle a train drawing 6A and would suggest the trip current needs to be higher.   what if the booster can't supply 6A or a circuit breaker limits the current?

sounds like the AR1 needs to trip at a lower current by adjusting the Trip Current Adjuster (TTC), turn counter-clockwise.  2A would probably be more than enough

928

greg - Philadelphia & Reading / Reading

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Posted by rrebell on Tuesday, October 12, 2021 10:57 PM

The real proublem with auto reversers  is they all behave diferently to varius situations. The AR1 is hard to set up right and speed of train will affect how well it works. The length of track dose not seem to be as important and metal whells on boxcars don't seem to trip it as long as train is moving fast enough.

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Posted by CSX Robert on Tuesday, October 12, 2021 9:18 PM

richhotrain
Now what DCC user does that?

Me.

richhotrain
If a reversing section is correctly gapped and wired, the auto reverser will work just fine IF the user takes into account the protocols associated with a particular auto reverser, including the settings for timing and current trip setting and the concern for mixing mechanical relays (e.g., the OP's Digitrax AR1) and solid state circuitry like a circuit breaker upstream

Yet people are often posting on here about their reversing section not workkng properly.

richhotrain
A DPDT takes none of that into account.

Which can be a good thing.  If it doesn't work with a DPDT switch, then you know there is a problem in the wiring.  If it works with a DPDT swicth, but not the autoreverser, then the wiring is correct (as long as it's a heavy enough gauge) and you know to look at other possibilities.

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Posted by gregc on Tuesday, October 12, 2021 7:31 PM

richhotrain
Imagine a reverse loop with one ... feeder ... wired to the main bus.

your observation could explain the problem

trying to get more info from the OP

greg - Philadelphia & Reading / Reading

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Posted by richhotrain on Tuesday, October 12, 2021 6:39 PM

gregc
 
richhotrain
Exactly. Imagine a reverse loop with one set of feeders. 

so ... 

gregc
 
BNSFWill
My train can enter the loop but it will short out when it exits the loop

from either end?  or is there only a problem at one end? 

Not sure if you are asking a question, greg, or just indicating that we agree, which I believe that we do.

Rich

Alton Junction

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Posted by gregc on Tuesday, October 12, 2021 6:36 PM

richhotrain
Exactly. Imagine a reverse loop with one set of feeders.

so ...

gregc
 
BNSFWill
My train can enter the loop but it will short out when it exits the loop

from either end?  or is there only a problem at one end?

669

greg - Philadelphia & Reading / Reading

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Posted by richhotrain on Tuesday, October 12, 2021 6:35 PM

Lastspikemike

Way easier to build a reversing section using the DPDT first and test it for correct operation before inserting the auto reverser in its place. 

Now what DCC user does that?

If a reversing section is correctly gapped and wired, the auto reverser will work just fine IF the user takes into account the protocols associated with a particular auto reverser, including the settings for timing and current trip setting and the concern for mixing mechanical relays (e.g., the OP's Digitrax AR1) and solid state circuitry like a circuit breaker upstream. A DPDT takes none of that into account.

Alton Junction

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Posted by richhotrain on Tuesday, October 12, 2021 6:09 PM

gregc

what if, as you suggested, there's a reverse section feeder wired to the mainline bus?    there would be a permanent short whenever the AR attempted to reverse the polarity at one end but works fine at the other end 

Exactly. Imagine a reverse loop with one set of feeders. That pair of feeders is wired to the main bus. A loco enters the reverse loop on the side where the polarity inside the loop matches the polarity of the adjacent track from which the loco enters the loop. No short, the AR is not triggered. When the loco attempts to exit the loop, the AR is not triggered and a dead short occurs. That is the scenario that the OP describes. So, it could be a wiring issue.

Rich

Alton Junction

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Posted by gregc on Tuesday, October 12, 2021 4:26 PM

richhotrain
 
gregc
BNSFWill
My train can enter the loop but it will short out when it exits the loop 

from either end?  or is there only a problem at one end?

greg - Philadelphia & Reading / Reading

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Posted by richhotrain on Tuesday, October 12, 2021 7:23 AM

gregc
BNSFWill
My train can enter the loop but it will short out when it exits the loop 

from either end?  or is there only a problem at one end?

In any reversing section (loop), the polarity inside the reversing section is always going to match the polarity of the adjacent track on one end of the reversing section and be mismatched with the polarity of the adjacent track on the other end of the reversing section. Those matches and mismatches change each time the AR is triggered.

Rich

Alton Junction

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Posted by richhotrain on Tuesday, October 12, 2021 7:11 AM

gregc

wouldn't a miswired feeder always cause a short?

It would seem so. If a pair of feeders are crossed in a non-reversing section of track, a dead short would occur. But the wiring of a reverse loop can present other issues.

Lucky me, I have never miswired a reversing section (loop) of track. I am always careful to fully isolate the reversing section, keep the feeders in phase, and connect all feeders inside the reversing section to the output side of the AR. But, what happens if a pair of feeders inside the reversing section are inadvertently connected to the main bus feeding power to the input side of the AR? I don't have an answer for that form of miswiring.

Anyhow, I would just urge the OP to confirm that his wiring is correct.

Rich

Alton Junction

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Posted by gregc on Tuesday, October 12, 2021 3:35 AM

wouldn't a miswired feeder always cause a short?

BNSFWill
My train can enter the loop but it will short out when it exits the loop

from either end?  or is there only a problem at one end?

richhotrain
Of course, there is always the possibility that everthing is operating properly, feeders and AR settings, but the entire train is longer than the reversing loop. So, is it?

good question

 

greg - Philadelphia & Reading / Reading

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Posted by richhotrain on Monday, October 11, 2021 11:18 PM

I've never been fond of the "test car" method. Too easy to get confused while running the test car around the layout unless the rails are also color coded in some manner. Better to get a blank sheet of paper and draw the track as two separately colored rails, for example red and blue. Now, you have a permanent visual record of where red meets blue and blue meets red, the point of reverse polarity.

But, in this case, that is not even the issue. If you take the OP's word for it, he already knows where that point of reverse polarity is located, and he has fully isolated the reverse loop. From the OP's description, it sounds like a balloon track running around the yard. So, his issue is likely either a miswired feeder or a faulty setting on the AR1.

Of course, there is always the possibility that everthing is operating properly, feeders and AR settings, but the entire train is longer than the reversing loop. So, is it? Try just running the locomotive through the reverse loop.

The fact that the locomotive does not short upon entering the reverse loop but does short upon exiting the reverse loop is typical of a malfunctioning reverse loop. One end of a reverse loop will always be in phase with the adjacent track, while the other end of the reverse loop will be out of phase with the adjacent track. Why? Because the reversing section itself will have its polarity flipped by the AR unless there is a miswired feeder or a faulty setting on the AR.

If the entrance to the reverse loop is in phase with the adjacent track from which the locomotive is entering the reverse loop, the AR won't even be triggered. The AR will only be trigged upon the locomotive's exit from the reverse loop, so that the polarity inside the reverse loop matches the polarity of the adjacent track to which the locomotive is exiting. Now, the original entry point to the reverse loop will have the mismatched polarity with the adjacent track from which the locomotive is entering the reverse loop. And the exit point will have the matched polarity. That's just how a reverse loop works. Turn the locomotive around and try to enter the reverse loop from the original exit point. What happens then?

Rich

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Posted by ba&prr on Monday, October 11, 2021 9:35 PM

If all your wireing is correct, you can adjust the trip current on the AR1 useing the set screw.  It might be set too high. What DCC system are you usuing?     Joe

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Posted by jjdamnit on Monday, October 11, 2021 8:56 PM

Hello All,

BigDaddy
...when you view things from underneath that layout, as you wire, it's easier to get L & R confused.

That's why most wiring mishaps occur..."Dyslexics 'Untie'!"

If you are running the test car in a previously undetected reverse polarity section, and you see that the "Red" "+" side of the car is over a "Black" "-" track feeder, that might be an indication of a problem.

The shielding colors of wires typically don't change, no matter what angle you view them from.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by BigDaddy on Monday, October 11, 2021 8:32 PM

jjdamnit
A simple way to determine where the track polarity shifts is to take a car and mark one side red and the other side black.

Absolutely true, but when you view things from underneath that layout, as you wire, it's easier to get L & R confused.

One of the worst moments for an anesthisiologist is to look over the "ether screen" and see the surgeon is operating on the wrong side.  Even worse when it happens to be an appendectory.  (yes ththe later really happend, but fortunately not to me)

Henry

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Posted by jjdamnit on Monday, October 11, 2021 5:40 PM

Hello All,

Welcome

A simple way to determine where the track polarity shifts is to take a car and mark one side red and the other side black.

Another option would be to mark one side with a "+" (plus) and the other with a "-" (minus).

You can do this with electrical tape or pieces of colored paper.

As long as you can determine which polarity (side) is which.

This will be your "test car".

Set the car on the tracks with the polarity of the wheels (color coding or plus "+", minus "-") matching the polarity of the track.

Typically Red "+" on the Right, Black "-" on the Left, when the locomotive is facing the forward direction of travel.

Push the car through all your track variations.

If at a point you find the track color coding is opposite the colors on the test car you have reached a "reversing section".

Run the car along until the colors match again. That is the end of the reversing section.

Now you know which specific tracks to double gap and power from the ARU.

Hope this helps.

 

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by BigDaddy on Monday, October 11, 2021 2:37 PM

Is there a circuit breaker upstream from the reversing loop power?  Some circuit breakers trip faster than the AR.

Henry

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Posted by richhotrain on Monday, October 11, 2021 12:51 PM

You indicated that you have fully isolated the reverse loop.

It is possible that the reverse loop or the adjacent track is miswired. You need to to determine if any feeders are crossed or connected improperly. Any feeder inside the reverse loop needs to be connected to the output side of the AR. Any feeder outside the reverse loop needs to be connected to the main bus that feeds power to the input side of the AR.

The usual cause of a train entering a reverse loop without shorting but then shorting upon exit is that the polarities match when entering, but the polarities are mismatched when exiting, indicating a wiring fault. If the wiring checks out, then you need to check the settings on the AR1. It could be a timing issue.

Rich

Alton Junction

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Posted by wjstix on Monday, October 11, 2021 11:37 AM

BNSFWill
My train can enter the loop but it will short out when it exits the loop.

Can the train enter either end of the reverse loop, or just one way? If just one way, it could be you've got a connection to the reverse loop that is hooked up to the main track wiring. Check to be sure all the track connections in the reverse loop are only connected to the AR1 output.

Stix
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Posted by Water Level Route on Monday, October 11, 2021 11:32 AM

Welcome

Tough to tell just what you have going on with the details you provided.  A couple basic questions.  Is your train shorter than the stretch of track you have wired up to the AR1?  You did isolate it with 4 insulated rail joiners, correct?

Give us some more details.  A sketch would be great - be sure to follow the instructions for how to post one.  Hang in there through your initial moderation period.

Welcome to the forums!

Mike

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Auto Reversing Loop Problems
Posted by BNSFWill on Sunday, October 10, 2021 1:53 PM

Hi there,

I'm trying to wire a loop that goes around my railyard. I'm using a Digitrax AR1 for this reverse loop but I'm having problems. My train can enter the loop but it will short out when it exits the loop. I've watched a handful of videos and other online resources but nothing seems to work. I'm hoping someone here can help me or walk me through what I need to do as I'm still relatively new to the hobby.

For context:

My layout is DCC

I've isolated the loop with isolated rail joiners

 

Thanks

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