Derailments and couplers

Discussion in 'FAQs' started by Roger Phillips, Aug 7, 2001.

  1. Roger Phillips

    Roger Phillips New Member

    I'm a newbie to model railroading and chose n scale because space is limited.
    The rear coupler on my atlas engine derails the car it is pulling when it goes around a 9 inch radius atlas turn by pushing the coupler on the car to the outside of the curve. This causes the outside wheel to ride up and out of the track. The cars will not do this to each other but my engine will always do it to the first car it is pulling. What can be done? (asides from using 11 inch radius turns) :confused: Your help would be greatly appreciated.
  2. Catt

    Catt Guest

    Rodger what couplers are you using? Have you converted to Micro-Trains?
  3. Roger Phillips

    Roger Phillips New Member

    I'm using the stock Rapido(sp) couplers. Will the couplers you mentioned cure this woe?
  4. shamus

    shamus Registered Member

    Hi Rodger and welcome to the gauge,

    Arnold Rapido Knuckle couplers are really too big for N-scale and as Catt suggests, maybe a change to Micro trains is the name of the game. However, the main cause (I think) why you get derailments is the fact that the loco has the coupler body mounted and the cars are bogie mounted causing your problem, what happens - is the loco going around the bend - swings the rear coupler out over the track, - the car behind tries to keep in line but cannot, so de-rails.


    NARA Member #24
  5. Woodie

    Woodie Active Member

    body mounted couplers


    Shamus is right with the "body" mounted V/S "bogie" mounted couplers. They can cause problems like you are experienceing on tight curves.

    I have the same problem with HO. (My curves are too tight). I would not play around with the standard couplers on you loco's or rollingstock, otherwise you end up with locos that only run with specific rollingstock. Look at your curves and see if you can lessen them in anyway.

    However I just use an old 4wheel freightcar that I manipulated the couplers on, and place this car between my loco and the other rollingstock. Sorta like a "buffer" car that is small and has fixed wheels and couplers. This helped lessen the difference between loco and carraiges allowing them to be towed around the sharper curves.

    If there is anyway you can lessen the curve, that would be my suggestion, because the problem will also happen with other loco's that you may want to run on your layout.
  6. universalcabbie

    universalcabbie New Member

    Speaking of this problem, speciffically in HO, my hodge podge of ho cars seem to derail each other quite often due to the variation in there horn type couplers.Plus the uncoupler track doesn't seem to work at all on them, but that's another story. Does the use of the kadee couplers provide any improvement in these type of "coupler derailments" or in coupling and uncoupling. I understand they work by magnetism, but are they relly a great improvement over horn couplers, or not?
  7. yellowlynn

    yellowlynn Member


    Kaydees are by far the best, but I personbally never use them . I've got a couple hundred cars, and frankly, I can't afford to do all of them. And mixing,forget it. I have found that if I have trouble at one coupling, I take that car and end for end it. It is trial and error to find the cause. I have had a 102 car train pulled by one loco, and all the hook and horn couplers worked good. Just make sure the spring is good, the height is right, and they couple good and there should'nt be any problem. I don't do switching and that stuff, so I'm not concerned with uncouplers and such.

  8. Catt

    Catt Guest

    The Kadee /Accurail/McHenry etc couplers in HO have a much wider(taller?) mating surface than the hornhook couplers.Thus they allow more uneveness in coupler height than the hornhooks do ,so they are much more reliable in operation and just plain (IMHO) look better.:)

    The Rapido couplers used in Nscale:( have a very narrow mating surface and by design move up and down to couple.The main problem is they don't always move back to a true horizontal position once coupled,and quite often just simply slide out from under or up and over the mating coupler.

    The earlier Micro-Trains knuckle couplers would do this also.:( The newer ones are redesigned to help prevent this from happening. If your Nscale curves are quite tight(mine are a minimum 18") You can use a longer shank coupler to give a bit more swing to the couplers(this also works for HO).

    Didn't mean to write a book on the subject,but I hope this is useful info to somebody.:)
  9. Drew1125

    Drew1125 Active Member

    I didn't catch whether Roger's loco couplers were body mounted or not.
    It's been my experience with N scale that a lot of the stock Rapido couplers on locos are truck mounted, & are very prone to fouling on steps & pilots when negotiating sharp curves.
    My advice would be to slowly push the loco around the curve, & watch closely to see if the coupler is being obstructed in some way. If this is the case, some careful filing might solve the problem.
    Also check your trackwork to make sure the curve is smooth, & without any kinks.
  10. Roger Phillips

    Roger Phillips New Member

    The couplers on my locos are all body mounted and the description by Shamus of the loco coupler swinging out over the track and causing the cars to derail is accurate. I did notice that the coupler spring on the locos doesn't seem to deflect inward much, if at all, during the turn. Is there a way to lessen the spring action of the coupler on the locos so that I can use the sharper 9 inch curves on my small layout?
  11. Catt

    Catt Guest

    Rodger,What kind of locos are you running? If they are 4 axle you shouldn't be having trouble on 9" curves.If you are using the stock rapidos there is no way to lessen the spring action.Out of curiosity what brand locos are you using.

    One thing you might do and I believe it was already suggested but I'll hit on it again.Make sure that your curves flow ,that is the rails are tight at the joiners and flow smoothly through the curve.

    Be sure you don't have one rail riding on top of a rail joiner instead of in the joiner.(been playing this game for 20 yrs and it still happens to me).

    One more thing ,are you sure your curves are 9"?Is there anyway you can make them larger?Always go for the largest possible curve that you can get .If you are using sectional track could you possibly start into the curve with a larger radius piece?

    Well it looks like I'm writing another book here so I'll quit for now.
  12. shamus

    shamus Registered Member

    I used to run a PA1 in N-scale and all my stock at that time were Arnold Rapido couplers, and ran long coaches around 9" (Hidden) track without de-railments, so I would expect yours to do the same regardless of body/bogie mounted. So check out the coupler itself, see if it is binding or the main spring has shifted off centre. that would also cause problems. Without looking at it myself, that's all I can sugest you do.

    NARA Member #24
  13. Furtak

    Furtak New Member


    Here's my .02 cents worth. I've been running N-Scale for about 5 years now and run pretty tight radius on my layouts as well. I model modules and this is a common practice for me. My first was a 3 1/2 by 5.

    My resolution is two fold. (all you rivet counters should skip to the next thread). I find a car with a higher tolerance for the radius. Then I add some weight to it. I play around with the weight making sure its flat enough as to not raise the center of balance to much. Often this resolves the problem but can become a problem when adding more cars.

    I run all Atlas DCC engines on my layout with body mounted couplers. I take the body off and ever so slightly work the thin piece of brass outward making sure not to pull it out. It's a simple procedure to put it back in but your patience can wear thin. With this slight bend your coupler should almost (and sometimes will) loosely move freely on its own when tipping the engine back and forth. I had an SD-40 that I took the brass and bent it to the extent that the couple almost fell out. I used CM to keep it in place.

    My last recommendation is to run GP units rather than SD's. Most Atlas engines today are being shipped with prototypical couplers. Look underneather the inner box.

    Hope this helps,
  14. Roger Phillips

    Roger Phillips New Member

    I'm running Atlas GP-7's (3) and an Atlas GP-9. Once the locos and cars are into the turn they seem to handle the turn okay. Your suggestion of transitioning from the straight to the 9 inch radius turn with a slightly greater radius could solve my problems. Ill give it a try. Thanks, Roger
  15. Roger Phillips

    Roger Phillips New Member

    What do you mean by a prototypical coupler?
    I see what you mean by the brass tab. The car behind my B&M GP-7 has less derailures than the same car does behind my BN GP-7. The coupler on the B&M is looser which helps with the turns, but it won't return to center automatically when cars are decoupled. I have to verify it's centered when I'm coupling with cars.
  16. Furtak

    Furtak New Member

    When I say "proto-typical" I meaning the AccuMate knuckle couplers which ship with Atlas engines as opposed to the "C-Type" Rapido couplers (I've been cautioned before for using this term, prototypical).

    The trade off to my recommendation with "bending" the brass piece is that you will have to check the center when coupling the cars. I use dental instruments anyhow to assist in my coupling efforts.

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