Trucks shorting on switches?

[jrbernier]

TenX,

  The Atlas 'Snap Switch' has long plastic frogs, so I do not see even 'wide' wheel treads bridging and causing a short(like with Peco Insulfrog turnouts).  The point end is also quite 'short proof' - the stock rail and the adjacent point rail have the same polarity.  The Atlas turnouts have a very wide gap there as well.

  If you have metal truck sideframes, and metal wheels, maybe an uninsulated rim might be touching the sideframe.  Also if you have older cars with metal frames, you could produce a 'short' if the insulated wheels on one truck are on the right, and the other truck has them on the left.  I had an old 50' gondola with metal wheels/trucks/frame.  I got the trucks turned around and problems started.  The car did not really short out the rails until it ran a few laps and the rubbing of the bolsters finally produced a short circuit through the long metal frame of this plastic car.  I took me all Saturday afternoon to find the car!  

Jim

[Anonymous]

Thanks for the replies. More info about this. All cars have metal wheels, my trains are a mix of old, very old and brand new - it happens with all of them. I think all my cars have metal trucks. The age of the switches on which this is happening range from old to brand new as well. I think that the wheel-bridging-frog scenario is where I'm going to start. I'd actually considered the nail polish option and that's why I posted - to get validation from the excellent resources here, like you guys. THANKS! Will let you know how it turns out.

[selector]

Lots of things need elimination systematically here.  If the trucks are indeed metal, is one side frame journal sufficiently worn that a metal wheel is actually rubbing on the inner side of the sideframe?  Could be cause for a short there if the frame also touches the loco frame...there's more to that, but at least it is a possibility.

I do agree that the chances are excellent for it to be a metal wheel tire actually making contact with two electrically mis-matched rails at the frog-rail separation.  That's the same as having a wire or a coin across those two rails.

[Don Gibson]

it seems to happen when the turnout side of the truck of cars are bridging the points of the switch

It is a short, but 1. all Atlas switches' point rails match polarity with it's stock rails. and 2. few cars today come with metal trucks. Do you have Metal wheels?

If so, are they in gage? There is also the possibility that your short is occuring elsewhere. 6 wheeled trucks seem to have problems over too sharp switches, and Atlas 'Snap' switches are  sharp.

I think that one of your cars is SUSPECT and needs re-gaging the wheels with an NMRA gage. I also think your short is being caused by something else.

What happens when you isolate this car from the rest? Run it back and forth by hand over the trouble spot, with power ON. Turn off the lights at night to see what sparks..

ISOLATE the problem. Is it the car or the switch? - The truck or a wheel? (Could be a coupler problem).

[retsignalmtr]

the metal wheels on your cars and locos are bridging the insulation gap on the frogs of your switches. i have the same problem with my dcc system with atlas as well as peco switches. i never had this happen until i switched to dcc. the dcc systems are very sensitive to shorts and react quickly when they happen. this has happened to me in ho and n scale, at my home layout as well as at my club. it also occurs no matter which way the turnout is thrown or what direction the train is traveling. the insulation gap is too close and i have eliminated the problem by buying some black nail polish and painted some on the frog to widen the gap in the rails on the tail of the frog. you could use regular paint but i think the nail polish is harder.

[KingConrail76]

Use an NMRA gauge to check your Switches and wheelsets for correct track "gauge".

[Anonymous]

I've recently converted to DCC and now have a problem with shorts occuring at (some of) my switches. I've narrowed it down  - it seems to happen when the turnout side of the truck of cars are bridging the points of the switch. I'm talking about Atlas remote Snap-Switches, and it causes my controller to stop the train and reset. Very annoying. At high speeds it doesn't affect anything. I never noticed a problem with this with my DC trains. I did notice that reversing the direction of one of the cars that had a higher incedent of occurence helped reduce this. This was a four-wheeled truck on a Bachmann Spectrum PRR car - the rest of the cars in this makeup have six-wheel trucks. I'd of thought 4 vs 6 would have reduced the risk of this shorting? Anyone know what's happening here?