# Short occurs when running over switches



## alroadking (Mar 16, 2011)

I have built my first layout and my track set up is essentially a large loop with two inwardly switching inner loops, so 4 switches. Each time my loco runs over a switch the transformer shorts out. Im running a MTH loco, MTH scale track, and MTH switches. All brand new. This may be a dumb question, but when I put a meter on the track both outside rails act as a ground even though i only have one side grounded to the control... is that correct? or is that the problem i need to figure out? Thanks.


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## gunrunnerjohn (Nov 10, 2010)

The outside rails are grounded through the ties, they should be ground, so that is correct.

I've seen this with O27 switches and Lionel tubular track. In my case, it was the design of the O27 switches and the clearance of the pickups on specific engines.

Does the short occur when you just run the engine alone? Does it happen if the switch is straight, on the curve, or both? You might try slowly pushing it over the switch manually and seeing if you can spot where it's shorting.


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## alroadking (Mar 16, 2011)

Yes it does happen when I just run the engine. It only happens on the curve. It runs great on the straight.


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## gunrunnerjohn (Nov 10, 2010)

Have you tried other engines? How about a picture close up of the switch thrown in the curve position, as well as a picture of the bottom of the engine?


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## alroadking (Mar 16, 2011)

No. I only have the one. I'll try taking the pictures. You think the contacts on the bottom of the train are shorting are spaced in such a way that they are shorting it out. I saw a thread where someone suggested cutting the third rail. Any thought on that or any other suggestions? Thank you.


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## gunrunnerjohn (Nov 10, 2010)

I think we need to see the pictures. Try to use the macro-focus on the camera and get clear close-ups of the engine pickups/wheels and the switch in the problem position.


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## alroadking (Mar 16, 2011)

I will. Thank you for your help.


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## TapRoot (Oct 3, 2010)

I know if my trucks land on a frog going slow enough it will stop, I usually try to use 2 engines for this so one will push/pull the other off the frog


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## tjcruiser (Jan 10, 2010)

Ditto on looking more closely at the loco's leading and trailing trucks. On my prewar locos, these are rather light, and tend to bounce around a bit when going through the switch's frog area.

Try running the loco's motor, only (without shell) or the loco with motor but leading/trailing trucks removed to see if the problem can be isoloated.

It's a hokey solution, but I've fiddled with putting small bits of electrical tape at strategic points on my O27 switches to insulate (electrically) potential areas on the rails and from where the small truck wheels would bounce and cause a short.

TJ


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## novice (Feb 2, 2011)

tjcruiser said:


> It's a hokey solution, but I've fiddled with putting small bits of electrical tape at strategic points on my O27 switches to insulate (electrically) potential areas on the rails and from where the small truck wheels would bounce and cause a short.
> 
> TJ


This solution worked for me on my 027 switches as well. For me it was the Frog that was getting smacked when the engine went over.


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## gunrunnerjohn (Nov 10, 2010)

I had so much trouble with O27 switches that I've abandoned the idea of O27 running, the 022 (O31 gauge) switches are far more trouble-free, and all of my locomotives run through them without issue. I only have a couple of locomotives that will navigate O27 switches without issues.

I'm not familiar with the MTH track and switches, I have only used Lionel tubular track and Fastrack, so that's why I suggested pictures.


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## alroadking (Mar 16, 2011)

*short occurs when running over switches*

Thanks for the advice. I put tape on the middle rail after the switch and that have stopped the shorting. The loco pick-up was hitting both the middle rail and outside rail at the same time. The wierd thing is that i still get sparking at the front guide wheels whe they hit in the v of the turn. Any help would be appreciated, but I will continue to fiddle with the tape. Very good idea, BTW. It helps isolate they problem in a fast and easy way.


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## gunrunnerjohn (Nov 10, 2010)

The sparking on the leading and trailing trucks is a constant issue with some switch/locomotive combinations. You may or may not be able to cure it totally.


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## alroadking (Mar 16, 2011)

*short occurs*

attached are pics. i meant to put them in the last post. Thanks again for your help.


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