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Bit of a strange one - only one loco shorting out on 3-way turnout?

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  • Member since
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Bit of a strange one - only one loco shorting out on 3-way turnout?
Posted by tbdanny on Thursday, September 07, 2017 5:36 AM

During my last operating session, I discovered that my diesel locomotive was shorting out when it tried to cross the 3-way turnout I have on my layout. Every other loco works fine over that turnout, and the diesel works fine over every other turnout.  As such, I'm a bit stuck on where to start looking for the cause of the issue.

The diesel is an Athearn mechanism controlled by a TSU-1100 decoder.  For the turnout, I use a Tam Valley Depot dual frog juicer to control the polarity of the various frogs.  The shorts happen regardless of how the 3-way turnout is set.

The only thing I've noticed is that the wheels on the diesel are a bit dirty, even though it still runs.  Other than that, I'm stumped and would appreciate any advice.

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

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Posted by rrinker on Thursday, September 07, 2017 7:31 AM

 Since it's an Athearn mechanism - is this a newer style one with the internal bearings or an old one with metal sideframes and outside bearings? If the latter, perhaps the sideframe manages to touch somewhere? Or if the newer style, maybe the internal metal sideplate is coming into contact with the rail somewhere?

 Does it short no matter what speed? If so, your best bet is to get it to crawl as sloow as possible and carefully watch it, focusing only on one area of the truck at a time, and see exactly what is touching when a short happens.

                                    --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by richhotrain on Thursday, September 07, 2017 7:35 AM

One of the wheelsets has to be out of gauge on that loco and it is striking rails of opposite polarity as the rails converge on that 3-way.

The same thing has happened to me. I use clear nail polish on the converging rails.

What brand of 3-way turnout?

Rich

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Posted by tbdanny on Thursday, September 07, 2017 1:59 PM

Randy,

It's one of the newer style mechanisms.  I've got a Dunkirk running on one of the older mechanisms, and that goes through the 3-way without any issues.  I'll give it a creep test and check for the plate, as it does short at any speed.

Rich,

I'll check the gauge on the wheels, too.

EDIT:

The 3-way turnout is the Peco HO scale code 100 one.

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

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Posted by BigDaddy on Thursday, September 07, 2017 3:29 PM

If none of that works, check out the post with the photo in this thread.

http://cs.trains.com/mrr/f/744/p/257023/2878678.aspx#2878678

 

Henry

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Posted by Mark R. on Thursday, September 07, 2017 4:57 PM

I always have to question the terminology .... does it short out, or does it stall ? Big difference in the diagnosis.

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

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Posted by richhotrain on Thursday, September 07, 2017 5:35 PM

Mark R.

I always have to question the terminology .... does it short out, or does it stall ? Big difference in the diagnosis.

Mark.

 

Assuming that it is a short, is it a momentary short as opposed to a dead short?

The red circle on the Peco Code 100 3-way turnout is tightest clearance on the turnout between two rails of opposite polarity. Check there for a momentary short.

The blue circles have more clearance but still tight between two rails of opposite polarity. Check those two spots as well.

Rich

 

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Posted by tbdanny on Thursday, September 07, 2017 7:59 PM

I've checked the wheels, and they seem to be in gauge, although one axle seems to be a little tight in the slots in the NMRA gauge.  Here's a video of what happens when it hits the turnout:

If you listen carefully, you can hear the sound of the decoder resetting and starting up again, just over the buzzing.  When this occurs, one of the tail lights under the layout is lit - this is my short-circuit protection.

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

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Posted by richhotrain on Friday, September 08, 2017 12:53 AM

All indications are that the wheelset is shorting the turnout. When I mention the word "tight", I don't mean to suggest that the wheel is wedged in the turnout but rather that the rails of opposite polarity are so close that the offending wheel is touching both rails simultaneously, causing the short.

Apply some clear nail polish in the area circled in red in my diagram, not much just enough where those two rails converge.

Rich

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Posted by xdford on Friday, September 08, 2017 3:27 AM

Out of interest, does it do exactly the same when the loco is turned around or another Athearn chassis is run over it? It may be that the truck (bogie to we Aussies) does not quite have enough swing when changing direction. Rich is right about the insulation as well... I found nail polish wore quite quickly so I am playing with some ACC (super glue to us) painted on as an insulator which seems to work better for me at least...

Good Luck

Cheers from Melbourne

Trevor 

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Posted by BMMECNYC on Friday, September 08, 2017 6:04 PM

richhotrain

All indications are that the wheelset is shorting the turnout. When I mention the word "tight", I don't mean to suggest that the wheel is wedged in the turnout but rather that the rails of opposite polarity are so close that the offending wheel is touching both rails simultaneously, causing the short.

Apply some clear nail polish in the area circled in red in my diagram, not much just enough where those two rails converge.

Rich

 

A more permanent solution could take one of three forms:

1. treat the frog like an electrofrog turnout, gap and power separately (if power is required)

2. Using a small triangular file, remove material on both rails from non flange side so that the code 110 rp25 wheel does not make contact.

3. use semi-scale wheels (code 88).  This makes bridging between the rails as described by Rich impossible.

 

Also note that some locomotives have hot sideframes, which can also make incidental contact with the diverging route on the turnout.  

This does not occur with the code 83 turnouts, or on the very newest code 100 turnouts.

Rule 108: In case of doubt or uncertainty, the safe course must be taken.
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Posted by tbdanny on Friday, September 08, 2017 6:23 PM

BMMECNYC

1. treat the frog like an electrofrog turnout, gap and power separately (if power is required)

Do you mean cutting gaps in it?  It's already an electrofrog turnout, with the dual frog juicer sorting out the polarity.

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

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Posted by richhotrain on Friday, September 08, 2017 6:46 PM

Have you ruled out the wheel bridging the two rails of opposite polarity?

Rich

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Posted by rrinker on Friday, September 08, 2017 7:33 PM

 Electrofrogs shouldn't have that problem. The two 'legs' of each frog are electrically the same. There's no narrow bit of insulation as with an insulfrog, where touching boooth sides of that insulation at the same time does cause a short.

                        --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by tbdanny on Saturday, September 09, 2017 12:00 AM

Thank-you to everyone who's provided advice.  I've done a bit of poking around, and I think I've found what the problem is.

I took one of the axles out of the diesel and rolled it along the turnout, pushing it with my finger.  What I found was that at the points circled in the picture above, the back of the wheel was contacting the rail of the opposite polarity, causing a short.  These crossovers don't occur in regular turnouts, hence no short circuits there.

Based on this discussion, I think I have three options:

1) File down the the pinch points so that there's a bit more width.  This may affect the rails and the tracking/running of the other trains.

2) Apply clear nailpolish to the points in question.

3) Replace the wheels on the diesel with the code 88 replacements sets from NWSL.  It's currently got their code 110 sets on it, as I figured I should match the original wheels.  However, I'm not 100% sure this will fix the issue.

Thoughts?

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

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Posted by richhotrain on Saturday, September 09, 2017 5:33 AM

As I mentioned in an earlier reply, clear nail polish is the easiest solution. Give it a try and see if that solves your problem. Just do a small area so you don't create a dead zone.

Rich

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Posted by rrinker on Saturday, September 09, 2017 12:53 PM

 The back of the wheel touching usually means the back to back gauge of the wheels is too tight.

 Do not file out the space indicated, you will destroy the tracking through the frog. 

Shorting at the top 2 makes no sense if you have a Frog Juicer powering the frogs (you are using two different Forg Juicer outputs, right?). All rails in the red circle on the top two should be the same polarity at any given time as that is all part of the frog assembly. Did you cut the jumpers, if the 3 way even has them, connecting the frog to the point rails? On a regular Electrofrog turnout with a Frog Juicer this isn't strictly required. There is a gap in each rail that meets at that frog, on the point side, and then you need insulated joiners on the diverging frog rails at the other end. All of that is powered by the Froog Juicer, so there's no way the rails coming in to the frog from the point side should have different polarities.

                                                --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by tbdanny on Saturday, September 09, 2017 1:08 PM

Randy,

I didn't have track power on when I was doing the testing.  I just noticed that that was where the wheel backs managed to touch both rails.  When I test-run the diesel itself, it doesn't get past the first one.  I've also checked the gauge on the wheels with my NMRA HO scale gauge.

As for the 3-way itself, I didn't make any modifications to it prior to installation, and still haven't.  All I did was install it, then connect the two wires coming off the sides to the frog juicers.

I'll try nailpolish on the lower one and see if that works.

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

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Posted by Redvdub1 on Saturday, September 09, 2017 7:19 PM

clear nail polish does work on typical frog shorting..you coat the top of the railhead in the divergent railheads.  This sounds like a short between the back of the wheel and the vertical side of the opposing rail...I don't think nail polish will work either at all or for very long.  You need something more viscous...we use JB weld for these shorts...after applying take a narrow file and smooth off the JB weld.  The frog rail spacings are (hopefully) on the high end of the spec. and a little artfully placed JB weld will not compromise the required spacing below the min.  works for us.good luck.

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Posted by richhotrain on Sunday, September 10, 2017 4:44 AM

I have three Walthers Shinohara Code 83  3-way turnouts laid end-to-end at the entrance to my passenger coach yard. I had problems with all three turnouts shorting where the rails converge beyond the first frog.

Since the clear nail polish proved not to be a permanent solution, I wound up cutting tiny, narrow strips of masking tape and placing the strips over the converging end of one rail on each turnout. That worked and the strips are still in place four years later. You cannot even see that there are small strips of masking tape on the rails.

Rich

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Posted by tbdanny on Sunday, September 10, 2017 5:14 AM

Rich,

Was that just regular masking tape, or some sort of heavy-duty one?

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

  • Member since
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  • From: Dearborn Station
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Posted by richhotrain on Sunday, September 10, 2017 5:21 AM

tbdanny

Rich,

Was that just regular masking tape, or some sort of heavy-duty one?

 

Regular masking tape.  Beige or tan in color.

What I did was to use an Exacto knife to cut small thin strips right on the roll of masking tape and then apply the small strips to the rail. It is the sides of the rails that come into contact with the wheels so you really don't even need the tape on the top of the rails.

Rich

Alton Junction

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Posted by tbdanny on Sunday, September 10, 2017 5:28 AM

Rich,

Sounds like a plan Smile.  I could even paint it with the paint I used for the rails themselves.  Thank-you.

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

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Posted by richhotrain on Sunday, September 10, 2017 5:32 AM

tbdanny

Rich,

Sounds like a plan Smile.  I could even paint it with the paint I used for the rails themselves.  Thank-you.

 

Glad to be of help. Yes, even painting the sides of the rails will do it. You might need to cover the very ends of the tops of the rails where they converge, but it doesn't take much.

Rich

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Posted by BMMECNYC on Sunday, September 10, 2017 8:23 AM

tbdanny

 

 
BMMECNYC

1. treat the frog like an electrofrog turnout, gap and power separately (if power is required)

 

 

Do you mean cutting gaps in it?  It's already an electrofrog turnout, with the dual frog juicer sorting out the polarity.

 

No.  I was assuming based on the photo posted that you had the insulfrog version.  Since you have the electrofrog, their should already be the appropriate gaps to prevent shorting.  Their may be some jumpers on the back that need to be cut.  If you havent balasted yet, and your turnout is nailed down, this might be a more permanent solution.

My sugestion for filing was again based on the turnout being an insulfrog.  With the older runs of these turnouts (insulfrogs) there is a tendancy for wide tread wheels to bridge the two rails at the frog just beyond the piece of plastic where the rails come together.  This is not applicable to the electrofrog.

Code 88 wheels wont fix the problem you are having.

Rule 108: In case of doubt or uncertainty, the safe course must be taken.

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