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DCC turnouts

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  • Member since
    February 2005
  • From: Vancouver Island, BC
  • 23,330 posts
Posted by selector on Tuesday, July 10, 2007 8:08 PM

The uncoupling wire that curves down from the front coupler is often a problem right out of the box.  It can snag, and will have a highest probability of doing so on crossings/diamonds.  Might be worth a watch to see.

Not only could your wheels not be spaced properly on one or more axles, but even if they are spaced properly, they may both be displaced toward one end of the axle sufficiently that one flange will pick the rails or guard rails.  Look for wheels that, when both axles (all three?) in the truck are gently pressed to one side, are all lined up.  The wheel position should look like this <=)(=====)(=>, but not this <)(=====)(==>

  • Member since
    December 2002
  • From: Overland Park, KS
  • 343 posts
Posted by dadret on Tuesday, July 10, 2007 7:09 PM
Thanks for the suggestions.  I did some more investigating and I really misstated the problem - the loco is not shorting out, its just derailing as it goes into some, not all, turnouts and a double cross-over and it appears to be limited to the one Proto E8  that I have (I ran my Proto Y-3 2-8-8-2 steam loco across the same parts of the layout with no real problem) and I didn't see any problem with a BLI E7 either.  I'lll check the wheel sets etc and take a good look at my track laying abilities.  Next time I'll do a little more homework before I panic.
  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Tuesday, July 10, 2007 10:26 AM

Your statement that "locos" are shorting out, not just the E8, indicates that you have a wiring problem with the Walthers turnout(s).  Are they actually shorting out and causing your DCC system to shut down, or are they just stalling on the turnouts?

If these are the newer Walthers turnouts and you installed insulated rail joiners anywhere, that is causing a power loss.  No insulated rail joints are necessary with the newer Walthers/Shinohara, Peco, or Atlas "DCC Friendly" turnouts (at least their code 83 products) unless they are entering a reverse loop or you want to be able to turn a siding off and have separate feeder wires beyond the insulated joint.

If you do have insulated rail joints and separate feeder wires, make sure you don't have the polarity of your wires reversed.  Actually, with DCC improper wiring would cause a phase reversal, not polarity reversal, but the result would be the same -- stalling at the frogs.

 

  • Member since
    November 2002
  • From: Colorado
  • 4,075 posts
Posted by fwright on Tuesday, July 10, 2007 9:10 AM

I don't want to sound condescending or patronizing, but there is really little information to give a correct diagnosis, much less identify the fix.

If I were a service advisor writing down your problem, I would identify what you have said as this:

Train stops intermittently while on Walters #8 turnouts.  Happens more frequently with E8 locomotive.  No further information.

Unknowns for diagnosis:

- Is there a short circuit indication, or could the stoppage be a stall?  Intermittent stalls are actually more likely than inconsistent short circuits.

- Does the stoppage happen on all Walters #8 turnouts, on all legs, with all rolling stock?  In other words, is there a combination that will consistently work correctly with even one of your Walters #8 turnouts on at least one leg in at least one direction?  This question helps determine whether the problem is systemic (wiring errors or similar), or isolated to particular turnouts and/or rolling stock.

- What other turnouts do you have, and do have any problems with any turnouts besides the Walters #8s?

- Is the E8 middle wheel set on each truck blind (no flanges) and/or have considerable lateral play?  This would be typically done to allow the E8 to go around sharper curves than would otherwise be needed.

If the problem is truly an intermittent short only on any of your #8 turnouts, and the E8 middle wheel set is as described, then I would hazard a guess that the middle wheel set is bridging 2 rails of opposite polarity near the throat of the frog, or just past the frog point.  Other wheel sets would not be as wide, or have as much play, and so would be less likely to short across where the 2 live rails of opposite polarity are closest.  Or the E8 could have some wheel sets that are wide in gauge.

#8 turnouts would be more susceptible than smaller number turnouts to shorting just outside the frog due to the manufacturer wanting to minimize the length of the dead frog zone.  To minimize the length of the dead frog area, the insulators are place as close to the frog as possible, letting the closure rails be of opposite polarity near the throat, and the frog rails just past the frog point.

To help identify whether and where the short is occuring try coating the rails at the throat with nail polish, and see if the problem goes away.  This is a temporary fix.  Then repeat for the frog rails just beyond the insulators.

Fixes:

1) carefully check the wheel gauge of all wheel sets on any offending loco or car.  Regauge as necessary.

2) On the E8 or other 6 wheel trucks, it may be necessary to restrict the lateral movement of the center axle with washers or the like.  Note that doing this could increase the minimum radius of the car or loco.

3) Check the track gauge of the turnouts.  Ensure it is not narrower than the NMRA minimum at the turnout throat - but you do want it very close to minimum.

4) Check the guard rails for correct distance from frog point.  This is the least likely cause, because if these are not correct, you should be having derailment problems as well.

5) If none of these fixes work, you will have to lengthen the dead zone around the frog by cutting new gaps in the rails.  You should take up the turnout to ensure the turnout wiring still bridges the new larger dead zone when the gaps are completed.

If the problem is/was stalls instead of shorts, chances are the turnout wiring is not working properly.  Factory jumpers, contacts, and wire connections are common failure points.

my thoughts, I've been known to be wrong.  Good luck.

Fred W 

  • Member since
    December 2002
  • From: Overland Park, KS
  • 343 posts
DCC turnouts
Posted by dadret on Tuesday, July 10, 2007 7:56 AM
I know this has been discussed many times and there have been articles in the magazine but I can't find any of them right now.  I have just completed most of my new DCC layout and I have a problem with my locos shorting out when going across my #8 "DCC friendly" Walthers turnouts.  Problem seems worse on my Proto E8 loco for some reason.  I'm using Tortoise switch machines if that makes a difference.  What's the best way to fix this?

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