Doesn't like curves

qquake2k Sep 2, 2018

  1. qquake2k

    qquake2k TrainBoard Member

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    I just got this Trix (from Germany) Fairbanks Morse diesel. For some reason I can't figure out, it slows down in the curves. It has a short wheelbase, and the curves are 249mm (9-3/4") radius. I have a longer Tomix DE10 that I run on the same track with no problem. And I have a longer Atlas RS3 that I run on tighter 216mm (8-9/16") curves , and it doesn't slow down. I'm perplexed.

     

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  2. Hardcoaler

    Hardcoaler TrainBoard Member

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    It's been a long time since I've opened my FM up, but the Trix Fs could be helped on curves by slightly loosening the screw that holds the worm gear retainer plate on top of each truck. Allowing a smidge of extra space seems to help.
     
  3. CarlH

    CarlH TrainBoard Member

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    This is only a guess, but I wonder if being on a curve is impairing the electrical connectivity from the wheel through the trucks to the chassis.

    There is only one Minitrix model of a Fairbanks Morse diesel in Spookshow's directory of N scale locomotives, so my guess is you have this one: http://www.spookshow.net/loco/h1244.html

    I have a Minitrix F9 from the same era. Mine has the same horizontal metal pins which are visible slightly below the worm gears in the Spookshow pictures of your model with the body removed. (These pins keep the truck connected to the chassis, when the body is in place). My guess is that the trucks on your FM have the same design as on my F9. My F9 has a single thin flexible metal contact arm (copper?) attached to each truck which rubs against a metal plate on the underside of the chassis, near the fuel tank in the middle. If the thin flexible metal contact arm attached to a truck gets bent, it will not make contact with the metal plate on the underside of the chassis, and you will not get electrical pickup from that truck. When you enter a curve, particularly one as sharp as 9 3/4 inches, the contact arm will be in contact with a different part of the metal plate on the underside of the chassis.

    If this is an electrical connectivity problem (see hardcoaler's post - it might not be), then you should assume that you are losing some electrical connectivity from both trucks when your loco slows down, because if you were getting completely unimpaired electrical pickup from just one truck, you probably would not notice any slowdown.

    I suggest you look at the metal plate on the underside of the chassis to see if it is worn or dirty. You should be able to inspect this metal plate without taking anything apart. The simplest case to remedy will be if this plate is merely dirty. You can remove a truck to enable that cleaning of the metal plate to be done safely. It is also possible that the thin flexible metal contact arm attached to one or both trucks might need to be adjusted, but this is a delicate operation so I would first see if you can remedy the situation just be cleaning the metal plate on the underside of the chassis.
     
  4. BarstowRick

    BarstowRick TrainBoard Supporter

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    I hate to see US have to re-learn lessons from the past.
    Curves: The widest curves are the best curves. I think I said that before, yep, I did. As we learned from our past experiences the 9 3/4 curves are way to tight for anything we run in N Scale. Absurd that someone early on thought they could cut 18" curves in half for N Scale. Widen or push those curves out and you'll be delighted with the results.

    Some guys have good results tinkering with the locomotive. My advise is leave the darned thing alone and push out the curves. That is if you have room for it.

    Funny but I use the old HO curvatures of 15" for my minimum curves and 18" up to 24" for my main lines. Hey, I'm happy. Everything you can find on the market will run well on it and the best part LOOK GOOD!!!!
     
  5. BarstowRick

    BarstowRick TrainBoard Supporter

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    Yes and No. Confused? You are asking the locomotive to twist and turn internally and most of them don't like that. Yes, connectivity can suffer because some of the electrical contacts are pushed to the max and will disconnect.

    Again my two cents and I take change.
     
  6. Hardcoaler

    Hardcoaler TrainBoard Member

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    I'd like wider radius curves, but my space just won't allow it. :( Oh well, I've made do for many years.
     
    WM183 likes this.
  7. qquake2k

    qquake2k TrainBoard Member

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    Unfortunately, we don't all have the luxury of enough space for wider curves. Following Rick's advice, I wouldn't be able to run anything. As I said before, my longer RS3 runs just fine on tighter 216mm curves. That leads me to believe that the problem is specifically with the FM loco.

     
  8. Charlie Vlk

    Charlie Vlk February 5, 2023 In Memoriam

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    The MiniTrix stuff was designed for 7 1/2” curves. Check for a dirty collector plate or bent/ dirty wheel wipers.
    Charlie Vlk
     
  9. brokemoto

    brokemoto TrainBoard Member

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    You do not state where you got the thing, but, as this thing has been out of production for years, I would assume that you acquired it used. Dirt is Ogre Numero Uno when it comes to problems with N scale power. Dust devils tend to accumulate in the wheels, especially where contact wipers are involved. Grease can end up many places where it inhibits electrical contact. Excess lubrication tends to attract more dirt, hair and other things that inhibit electrical contact and the mechanism, even. I have acquired more than one used locomotive that the previous owner had over lubricated.

    I would go with what Carl H and Charlie stated about the dirt as well as what Hardcoaler stated about loosening the screw. In most cases, screw loosening helps steam locomotives, but, I have seen one or two diseasels that it has helped.

    Do make sure that the trucks are pivotting properly. If not, they could be climbing the curves, which will cause a loss of electrical contact.

    That old TRIX FM is really not the best power out there. If you are on a tight budget, there are some yard goats out there that are far better and can be had for decent prices on FeePay or from certain e-Tailers.
     
  10. tehachapifan

    tehachapifan TrainBoard Member

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    if the problem was dirty electrical contacts, I would expect to see some light flickering during the slowdowns. it appears they do not in the video which leads me to believe it might be something else.
     
  11. mtntrainman

    mtntrainman TrainBoard Supporter

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    Have you checked wheel gauge on all axles ? I have one 4 axle diesel that did the same as yours is doing and i checked the wheel gauge. I cant remember if they where to tight or to loose..but since adjusting them it goes through the Unitrack curves just fine now JMHO

    *I'll even take a stab that its a wheel gauge issue with the truck under the long hood ;) *
     
    Last edited: Sep 3, 2018
  12. SLSF Freak

    SLSF Freak Staff Member TrainBoard Supporter

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    Can you take the shell off and show us a close up picture of the insides? Depending on how old this thing is, and who owned it previously, it could be crammed full of several years worth of oiled up lint gunking up the works. My guess is either dirt or wheel gauge. The unit on Spookshow's site has a good pic of the innards which seems pretty clean. Maybe use that as a guide to see how yours compares (especially around the worm gears).
     
  13. qquake2k

    qquake2k TrainBoard Member

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    It looks pretty clean to me. But it does run better with the shell off. What could cause that? And I didn't see any truck screws to loosen. Where are they?

     

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  14. BarstowRick

    BarstowRick TrainBoard Supporter

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    I would agree there is something wrong with the locomotive in question. Most likely the electrical contacts. Truck screws? Who uhh-err there's none on mine? However, mine are much later runs.

    I didn't start out using larger radius curves and learned the hard way. You know the school of hark knocks and lessons learned.
    It's ok to start out right where you are and to experience for yourself the joys and down falls of operating trains in any scale.

    Get that layout built enjoy all you can about it. You won't regret starting where you do and after all look at all the fun you are going to have. I did not say sarcastically. I had hours of fun with my early layouts. Seriously! And know you will to.

    Get'r done as Larry the Cable Guy says.
     
    Last edited: Sep 4, 2018
  15. 4-4-0

    4-4-0 TrainBoard Member

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    the trucks will fell off if you remove the pin, the small copperwire that goes under the black cover with Trix make the electrical connection, you have to remove the black cover and inspect the connection pad .
     
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  16. SP-Wolf

    SP-Wolf TrainBoard Supporter

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    Before I converted mine to a Bachmann mechanism, I had hard wired from the truck to the body contact board (I have some very flexible wire). That made a huge difference.

    Wolf
     
  17. BarstowRick

    BarstowRick TrainBoard Supporter

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    I've been converting my Mini-Trix to Kato Mechanism's. You can't beat the performance.
     
  18. Mr. Trainiac

    Mr. Trainiac TrainBoard Member

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    I doubt the issue is electrical. If it slows down only on curves, it sounds like something rubbing internally when the trucks turn. If it was electrical, there is either contact or no contact. I don't think reducing the surface area of the parts in contact would slow it down. Doing that would just result in more electrical resistance. The current would still be flowing.
     
  19. mr magnolia

    mr magnolia TrainBoard Member

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    The old (96?) Atlas GP40 is noted in Spookshow notes as having occasional individual models that show this same behaviour, slowing extremely on bends, both small and medium radius.

    My FEC model is one of those - I’ve had it apart and back together and swapped around umpteen times. No changes can I make to performance.
    It does seem to work better without the shell. Sometimes.

    It is, as Spookshow notes, ‘unexplained’ and mines mainly does yard duty with no bends as a consequence. I bought mine used as you seem to have done.

    No help for you in these words, but a shared experience though!
    Donald


    Sent from my iPhone using Tapatalk Pro
     
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  20. Inkaneer

    Inkaneer TrainBoard Member

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    In the video the light appears to stay lit the whole time so I would doubt it is an electrical contact problem. My guess would be either a bind in the drive mechanism or increased friction. Try running the engine upside down in a cradle keeping the trucks straight then turn the trucks as if the locomotive was entering a curve. Is there any decrease in wheel rotation or increase in sound? If the answer is no then there might be another thing at play here. Check the wheel flanges. You photos show some very large flanges and these could be the culprit on sharp curves.
     

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