Couplers - body mount - truck mount

Discussion in 'FAQs' started by zeeglen, Jan 1, 2004.

  1. zeeglen

    zeeglen Member

    Am starting this discussion to learn the pros and cons of body mounted vs truck mounted couplers. The benefits of each have always been somewhat mysterious to me and would like to get other's experiences on this. There is some mention in various places in the archives, but as far as i know no thread specifically for this.

    Starting with my own observations:

    Z scale - using MT rolling stock, body mount is the only way to go. The MT cabooses are truck mounted couplers and they get away with it being on the end of the train and so short. But any other piece of rolling stock was doomed to derailment when backed in reverse over turnouts with truck mounted couplers, but worked fine when the original body mount couplers were used.

    N scale - most of my rolling stock is MT truck mounted couplers, sometimes i regret it. While they line up better on 9.75" rad curves the sideways force in reverse can make them derail on turnouts when backing long trains. When i run a Kato SD40-2 (with body mount couplers) on 9.75 inch radius curves, the first car coupled to it must also be a body mounted coupler; otherwise the sideways force on the truck derails a truck mounted coupler boxcar even in the forward direction. I have only two cars with body mount, all the rest are truck mount so have not been able to determine the results of all body mount on sharp curves.

    My tentative conclusion is that body mount is probably the best. But how well does body mount work on 9.75"r curves in N scale or 18"r in HO etc. Is there any other problem (other than re-coupling) with body mount on minimum radius curves caused by the increased sideways swing? Is truck mount better on min radius curves?

    The only problem i've seen (so far) with body mount is at the bottom of a grade where the trip pin (air hose) of a MT body mount coupler can hit the outside rail on a curve or the frog of a turnout and snag unless adjusted to higher than the recommended height (with the locomotive tilted on the grade bottom with little vertical easement the coupler is angled downwards). Truck mounted couplers remain inside the rails and don't have this problem.

    In other words, if i was to change all my N scale rolling stock to body mount, would there be any new problems due to 9.75 inch rad curves?
  2. Russ Bellinis

    Russ Bellinis Active Member

    If you are just pulling a train around a layout, and never backing up, talgo mounted couplers will work fine. In addition they allow you to run a little tighter radius for a given length of car than you could with body mounted couplers. The problem comes when you want to back up and do switching movements. If all of your track is in gauge, all of your wheelsets are in gauge, and you have body mounted couplers, you can back a train all over the layout, through S curves, etc, and not derail. Hook up a train with talgo truck mounted couplers and you can't back it all of the way around a simple oval without pushing cars off the tracks. If you push a talgo truck around any kind of curve, it will want to derail to the outside of the curve. If you need to have the ability to run long passenger cars around a tighter radius than they like, you can body mount the coupler on a pivot and let it swing unimpeded say 160*. If you do that you get all of the advantages of a talgo truck, but without the disadvantages.
  3. 60103

    60103 Pooh Bah

    When I was in N scale (I've said it before -- over 20 years ago!) I tried to get as much body mounted as possible. I know I ran full length passenger cars around 12" radius; not sure if I had anything less. If you're running 80 to 90 footers around 9.75" curves, you might have a problem.
    Truck mounted couplers next to body-mounts on diesels are a problem in any scale with sharp curves.
    The problem with backing is that the trucks are forced at an angle to the track and the flanges catch on any joint that isn't exactly aligned and pushed tight. (It's worst with those HO couplers with sideways spring pressure.) If your flanges are sharp or square rather than round the problem gets worse.
  4. Wayne

    Wayne New Member

    Thanks guys for this thread. I have been thinking on this for some time now.

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