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Misha_K

NEM/NMRA Wheel Standards and Track tolerances

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Misha_K

Split off from

 

http://www.jnsforum.com/community/topic/13018-what-did-you-order-or-the-post-deliver-worldwide-models/?do=findComment&comment=190896

 

 

On 2/23/2019 at 1:40 PM, Waisneed said:


Sadly, the locos short out on the Kato single crossovers, anyone got any experience with Fleischmann locos on Unitrack? 

 

 

Yes! I have that exact problem. It only happens on that type of turnout and not just with Fleischmann, but Arnold and Minitrix as well. The problem is that the Europeans adhere to older NEM norms for wheel sizes, so their wheels are wider than on Japanese rolling stock. Unfortunately that means they are wide enough to bridge the gap to the closest rail from the crossing track. This isn't an issue with the double crossover, which is insulated in the middle and isn't an issue with the No.4 turnouts on their own, since they are by default power-routing. On the single crossover, however, since the other track is necesarily powered as well, that means you always have a powered track of opposite polarity right next to the frog, so a German loco or car will short it. I just got my single crossover a couple of weeks ago and have just started messing around with them and my German locos short them every time. I'll have to start playing around with insulating maybe 1mm of the inside track to see if I can get this operationally useable.

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Waisneed
56 minutes ago, Misha_K said:

The problem is that the Europeans adhere to older NEM norms for wheel sizes, so their wheels are wider than on Japanese rolling stock.

 

The difference is quite immense, NEM requires 2.0 - 2.2 mm wide wheels, while NMRA sets the standard at 1.83 mm with.

1mm more insulation should be enough.

 

With my experimentation I found out, that it occurs only on one side also, on the rear side of the power connector lies the problem. Now I just need to finde some insulation tape.

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