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Freight car trucks shorting DCC system.

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  • Member since
    January 2014
  • From: Moneta, VA USA
  • 1,175 posts
Freight car trucks shorting DCC system.
Posted by gdelmoro on Friday, March 27, 2020 6:57 AM

Ok here's one Ive never seen before. Some of you know I'm building a new layout. As part of the build I test track for electrical and track quality as I build each section.  Recently, I completed the main yard section and part of the mainline and tested multiple types of locomotives on all track sections. This being my 4th layout my primary objectives are bulletproof trakwork and wiring.

All locomotives ran flawlessly on all curves, switches and separate CB protected sections. Great! 

Let's add some rolling stock and run forwards and backward on all track and through switches. All good. Make the train longer and see if it's all good.

Yard SHORT?? What happened? After spending several hours checking wiring, looking for debris on tracks, Did i leave some metal tool somewhere? Nothing. Finally I took everything off and replaced each locomotive and rolling stock one at a tme.

As it turned out there were 3 cars that caused the short and the yard breaker to trip. Hmmm? Let's try these on the main, same thing! Finally I took the trucks off and tested the individual trucks (Kadee with Kadee or Intermountain metal wheels). I found 3 trucks that consistently shorted the track. A continuity test across the wheels intermittently caused a week beep from the meter. But not all the time.

I replaced the tucks and all is well.

Has anybody had this happen? Is it something that happens over time? Strange that these cars were running on the old layout without any problems.  Is it the wheels? The trucks? I'd love to find out.

Gary

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Posted by mbinsewi on Friday, March 27, 2020 7:34 AM

The continuity test, you did this on indiviual wheel sets after removing them from the trucks?

I've been using IM sets, no problems yet, and I also have some rolling stock with the P2K sets, and no problems, and a few Kadee sets, no problems.

Mike.

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Posted by rrinker on Friday, March 27, 2020 8:03 AM

IM wheels are all metal, insulated at the axles. If you have one wheelset with the insulator on the left, and the other wheelset int he same truck with the insulator on the right, with the metal Kadee trucks, you have a short. Both insulators on a given truck need to be on the same side.

This doesn't happen with plastic trucks and IM wheels, or metal trucks and P2K wheels. But IM wheels and metal trucks - check the insulators.

                                   --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 mbinsewi on Friday, March 27, 2020 8:09 AM

I don't have any metal trucks.  Evidently Gary does.

Mike.

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Posted by BigDaddy on Friday, March 27, 2020 8:23 AM

If wheelsets weren't insulated, it would be a short on DCC and DC even with plastic trucks.  I agree with Randy.

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by mbinsewi on Friday, March 27, 2020 8:33 AM

I'll have to take a look at some of the old Athearn and Bachmann passenger cars I have, with the little incandescent bulb that sits in the middle.

I remember the wheel sets, one truck with insulated wheels on one (+) side, and the other truck, the insulated wheels on the  (-) side. 

Of course that was for DC.

Mike.

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Posted by rws1225 on Friday, March 27, 2020 8:33 AM

Something similar happened to me.  Plastic truck, Intermountain wheels and a metal underframe.  Wheels were touching underframe occasionally causing the short; about two days of taking all the cars off the layout and putting them back one by one several times before the culprit showed itself.

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Posted by mbinsewi on Friday, March 27, 2020 8:36 AM

So, are all Kadee trucks metal?  I've never used them, only the couplers.

Mike.

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Posted by richhotrain on Friday, March 27, 2020 8:43 AM

gdelmoro

Has anybody had this happen? Is it something that happens over time? Strange that these cars were running on the old layout without any problems.  Is it the wheels? The trucks? I'd love to find out. 

It is strange that these cars were running on the old layout but not on the new layout. How can this be explained?

Rich

Alton Junction

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Posted by floridaflyer on Friday, March 27, 2020 8:51 AM

I believe that on the im wheels, one wheel is insulated with a sleeve, but the metal axle is not. With a metal truck a short would occur as the axle is not insulated. will admit I'm no expert. 

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Posted by rrinker on Friday, March 27, 2020 9:19 AM

richhotrain

 

 
gdelmoro

Has anybody had this happen? Is it something that happens over time? Strange that these cars were running on the old layout without any problems.  Is it the wheels? The trucks? I'd love to find out. 

 

 

It is strange that these cars were running on the old layout but not on the new layout. How can this be explained?

 

Rich

 

 Either the wheelsets were changed, or these cars ALSO have a metal underframe and one truck got swiveled around in the move.

                                --Randy

 


Modeling the Reading Railroad in the 1950's

 

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

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Friday, March 27, 2020 9:32 AM

It is strange that these cars were running on the old layout but not on the new layout. How can this be explained? 

rrinker
Either the wheelsets were changed, or these cars ALSO have a metal underframe and one truck got swiveled around in the move. 

Yeah. C'mon Gary, tell us the whole story.   Laugh

Rich

Alton Junction

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Posted by gdelmoro on Friday, March 27, 2020 10:29 AM

 Wow now that's service! Thanks tor the replies.

It is possible that the wheels were rotated accidentally since I checked all cars for weight and gauge before I put them on this layout.  I will reinsert them in the truck and report hat happens.

I don't think either car has a metal underframe but. Will confirm.

The trucks are metal

I knew you guys ould have some good ideas.  I'll report back later this afternoon.

Gary

  • Member since
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Posted by mbinsewi on Friday, March 27, 2020 10:38 AM

Ahh...there's a start, metal trucks.

Mike.

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Posted by rrinker on Friday, March 27, 2020 11:40 AM

mbinsewi

Ahh...there's a start, metal trucks.

Mike.

 

He said Kadee trucks in the initial post. Your post got in before mine, but I know Kadee trucks are metal. Big Smile

If the underframe is not metal, than the issue is confined to a single truck. If a wheelset was removed to adjust the gauge, or just to check, it's a simple matter to put it back in with the insulator on the wrong side. When most cars have plastic trucks, you probably don't even not which side the insulator is on, because it doesn't matter. But then you hit some with metal trucks...

 

                            --Randy

 


Modeling the Reading Railroad in the 1950's

 

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

  • Member since
    January 2014
  • From: Moneta, VA USA
  • 1,175 posts
Posted by gdelmoro on Friday, March 27, 2020 1:06 PM

Ok I figured it out! The insulated wheels were on opposite sides Embarrassed Just kidding.

once again thanks Randy, Rich and others for the replies.

I must have inadvertently flipped them when I was cleaning and checking gauge. For some reason I didn't even consider it.

Regards

Gary

Gary

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