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Trains Derailing on Switches (Points)

Neville wrote:

“My trains are derailing on the switch frogs and wonder if it has something to do with the old cars I am running… the switch in question is fairly new. The curve into the switch rail is quite tight, and wonder if this could be compounding the problem? Advice please.”

14 Responses to Trains Derailing on Switches (Points)

  • phil johnsonsays:

    You didn’t say what size switch or maker. If this is a Atlas snap switch, it is very tight equal to 18″Radius curve. However, if you are trying to back cars through this tight of a curve with truck mounted couplers, bad combination. Also, if you are trying to run long cars (50’+) the coupler swing wont cooperate. If you can get close to the offending switch watch what the cars do as they roll through. If it is the same cars, then it’s the cars. If it’s different cars then it’s the switch. FYI this is where metal wheels are superior to plastic. Also check your track for in gauge. Wheels also, especially if the same ones are derailing

  • Carl R Branninsays:

    Everything Phil said above plus check to make sure all flanges and points are clear of any ballast or obstructions. The tiniest piece of ballast can derail a ttrain (especially plastic wheels and light cars) in a second.

  • Peter Bayley-Blighsays:

    The wheel depth flange on old cars is greater than on modern ones so it is possible that they ‘lift’ the wagon over the points and de-rail. If going in reverse derailment is most often the result of light weight car connectors getting caught up in each other as they push together.

  • The N-Scale Nerdsays:

    To “see” what’s going on at the switch use the video function on your phone.
    I recently had issues with PECO n-scale turnouts and the flanges of my Con-Cor, U50 loco. Turned out the flangeways at the guard rails and the insulfrog section were just not “deep” enough, so the wheels would come off the regularly. I used a 1mm wide hobby screw-driver to gently shave the guides down. Works like a charm….and at full-speed too!

    Like all the comments above, it doesn’t take much to de-rail. Here’s some more….

    – If you’ve automated the switch, the lever wire might be a bit long catching something.
    – Could also be a coupler catching.
    – I also had a couple of PECO ST-5 and ST-6 switch units which had the minutest burr at the heel of the closure rail which was fixed with a fine rat-tail file.

    A video is worth a thousand words, though.

  • Joe Brandtnersays:

    Check the back to back wheel gauge on the offending cars, especially the older ones that you mentioned. Check the “check gauge” at the frog. That is, is the flangeway too tight? Since you say that the turnout is fairly new, I doubt that it’s the problem. My guess is that the back to bakc wheel gauge on some cars is not correct.

  • geoffsays:

    It’s possible your old cars have wheel flanges that are designed for code 100 track, and the switch being newer has code 80 or 75 track, meaning the rail is a slightly smaller height, causing the wheel flanges to ride up on the frogs. If you can’t get an older switch, you could try getting newer wheels for the cars.

  • Timothy Morloksays:

    You didn’t say what gauge you’r running or the track code. In HO, if you are running older cars with plastic wheels sets on code 83 track, the wheel flanges could be too deep and bounce on the molded tie plates and frogs. On a tight radius frog this would cause the trucks to not follow the guard rails and result in a derailment.

  • Nevillesays:

    thanks all. I tried a couple of newer cars without a problem so I think the old cars wheels flanges are wrong for the track.

  • Tim Coversays:

    Could Be the Ballast on the track, Could Be the Flanges on the truck wheels itself.
    Try different cars with different wheels on the trucks.
    If you have ballast laid down, check the ballast around the switches.

  • David Stokessays:

    Go to your local hobby shop and buy the relevant “gauge”. Test the “switch” clearances – the most important being those relating to the crossing or frog, dirty track and obstructions (ballast in the slots).

    Next check every wheelset on every piece of rolling stock. If any of those wheel sets have 1980s or earlier deep flanged wheels, ditch them. The modern sets need to be concentric on the axle, flanges to RP27 standard, and inline at the correct back to back spacing.
    The National Model Railroad Association standards gauge will help you find these fault. RP27 is the NMRA recommended practice for wheel profiles.

    Next, make sure the couplers can swing sufficiently, without hitting the corners of the wagons. I have this issue with a locomotive on which I retrofitted KD couplers, and it required paring away the back of the stunters steps to gain clearance. I know this sounds daunting, but if railroading is to be fun rather than frustration, it needs doing.

  • Sundaramsays:

    One more possibility. Some times the the moving rails on the points are not aligned with the fixed rails – that is the rails are a bit displaced. In this case the flange hits the protruding rail and derails. It happened in few of my points and I had to adjust them with tweezers.
    Also if you are running Hornby trains on Atlas points you could have a problem Please check the track width at the points and the flange width of the the concerned carriage or freight car

  • Glennsays:

    Neville,
    It sounds like you figured out what the problem is. However, one trick I have learned to use, when there is any type of derailing problem, is to use the video capability of my cell phone. You can watch the video in slo-mo and easily see what is happening. You will know exactly where and what is happening, but you will still have to determine why. Remember you probably need to video from both sides to ensure there isn’t more than one problem. From what you said it may be the flanges. One of the biggest improvements you can make to your rolling stock is to replace plastic wheels, with metal wheels. Glenn

  • Frank Bsays:

    You can buy modern wheelsets (narrow flanges) to replace the old wheels with wide flanges.
    Usually they will just spring into place in the trucks.

  • Arjen Van Der Heydensays:

    I recently had much the same problem. Loco would derail going one way, but not the other. Measured the space between the wheels. Lo and behold, there’s a little difference. Bit of wriggling voila, no more problems. Hope this works for you too.

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