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Derailments at Switches

Larry posts this question to readers:

“I recently set my pre-1980s N-gauge train up after it was in a box for fifty-some years. I set up a temporary oval track with no switches and was absolutely amazed and excited that it still works. Now I am working on a permanent layout and purchased some new track pieces including manual switches, all code 80 which matches my old track. My problem is derailments at the switches and I believe the cause, thanks to the tips here, to be the old wheels on my locomotives and rolling stock. I shopped around online to buy new wheels and quickly got lost. My first question is if RP27 the correct standard or should it be RP25? My second question is how can you tell for sure if you are buying wheels made to the correct standard? I see lots of wheels for sale from multiple manufacturers but they don’t have details on specifications. I have all old style couplers as well but am hoping to get away with just replacing the wheels. Thanks in advance for any and all help!

4 Responses to Derailments at Switches

  • Dale says:

    Old equipment was famous for problems at turnouts. Most manufacturers today use RP25 profiles for the wheel sets since it reasonably closely follows prototype flanges design. One area where RP25 differs is the width of the tread. The slightly wider tread makes for a more reliable tracking. While I don’t endorse any particular manufacturer, I found the wheel sets from Fox Valley worked well on my N scale layout. One caution, don’t mix wheels from different manufacturers on a single bogie. Also, be sure to verify that the cars are the correct weight (check the NMRA website) since light cars can be more likely to derail while cars too heavy may not roll well.

  • Larry White says:

    Thanks for the help Dale I appreciate it! Sorry I took so long to respond. I took my track apart to add a stream and a couple of bridges and it took a lot longer than I expected. I purchased some Fox Valley wheels and installed them on 6 of my cars and they are working really well. They didn’t fit all my cars due to the length of the axles so need to do some more research to replace those wheels. I also found this article which is a good history on the topic:
    https://www.trains.com/mrr/beginners/guide-to-n-scale-metal-wheelsets/
    I am still having intermittent derailments on the switches with my locomotive (a Bachmann – 4061 – Locomotive, Diesel, EMD GP40 – Penn Central – 6100 from about 1975) still with its original wheels. These always result in the front wheels of the locomotive going down one switch path and the rear wheels attempting to go down the other switch path. Thanks again!

    • Robert says:

      It sounds to me that one set of wheels is out of gauge. I have had that problem with Athearn diesels. Adjusting the wheel back to back measurement solved the problem.

  • The N-scale Nerd says:

    I used my phone to take a video of what was going on when I had issues at a set of points on my layout and used that to identify my problem. Slowed the vid down at the problem spot and was able to come up with a simple fix.
    Yours maybe a different issue, but you might get a closer look at what’s going on.

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