Turning problems with SD75

newtoscale Jan 31, 2011

  1. newtoscale

    newtoscale Permanently dispatched

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    I have a friend who has an AZL SD75I and he is experiencing problems with this unit taking right curves. He says it seems to be binding somewhere. This problem only occurs when running around curves to the right yet it runs just fine on left curves. He says when he watches the engine carefully, as soon as it enters any right curve it stops. The motor keeps going, but it won't move unless helped.
    He has tried it both forward and backward but there is no difference. When he uses it in consit with other engines, this problem doesn't occur whether it is in the lead or following. Only by itself does it do this. He says he has checked all possible causes for this and can't find anything. I've suggested that he might want to order a couple of new truck assemblies from Z Scale Monster and see if that has any effect. Beyond that I can't offer any suggestions as to what to try. I have never had this problem with my 75's. Can anyone offer any suggestions?

    Thanks

    Ken
     
  2. henrikH

    henrikH TrainBoard Member

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    I had a similar problem with my SD70.. The wheels where way out of gauge! I have fixed it now, but i can still only pull 4-10 cars before it start's to slip..
     
  3. shamoo737

    shamoo737 Staff Member TrainBoard Supporter

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    AZL's six wheel axles like perfectly smooth track. Any irregularity in the track work will cause it to traction. The problem is the blind axle doesnt have enough give on them and lift the driving wheels of the track. I have drill the wheel wipers go give it more give with some success in the SD70, but they work really well on the brass engines.
     
  4. ztrack

    ztrack TrainBoard Supporter Advertiser

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    First and foremost, has he completely ruled out a track problem. What radius track is the loco running on? Is it 195mm and above? Does the loco stop at at the same spot on track? It could be a track issue. If you are running the loco clockwise, and it binds going into the curve, turn the loco around. This will rule out the 'right' 'left' issue as the same trucks are now turning left and not right. But if it is binding at the same spot, the track may be a bit out of gauge. Shameless plug, but see this issue of Ztrack for our 'Don't blame the loco' article for tips on correcting this issue.

    If the track is ruled out, I suggest also checking the swing of the trucks. The metal tabs that extend from the truck to the chassis can actually act like a spring if they are not seated properly or have become slightly bent. The truck may swing more freely to the left, but not the right. If this happens, try reseating the truck. I also have gently forced the truck to turn into the direction where there is resistance. This can help correct the issues with the tab.

    A new set of trucks may cure the problem, but I would rule out other factors before going to that expense. Are the other locos SD70s? This would also be a good comparison since you can test can compare against like locos. I have even swapped out trucks between locos to troubleshoot a bad truck or seating issue.

    Rob
     
  5. newtoscale

    newtoscale Permanently dispatched

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    Rob:

    As far as I know, the engine has the same turning problem on all radius if tracks from 15 to 45 degree. I don't know about anything less then 15. He has tried the engine in both directions turning to the right. Same problem. Traction doesn't seem to be a problem as it runs well on straights and left curves. He has run this engine in consists with GP35's and 9's. It doesn't seem to have a problem doing this. It is only when it is by itself, and I should mention, it doesn't matter if it is pulling a load or not.
    As for the other things you mention, I will pass this on and see what he has to say.
    Thanks
    K
     
  6. ztrack

    ztrack TrainBoard Supporter Advertiser

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    K,

    The one thing that stands out in your post is the the GP35 and GP9 are four axle locos and can take tighter track work. What I suspect is that there is a slight gauge issue (track, wheelsets, or combo of both) which is causing the loco to bind in a particular spot. The reason you don't see this when run in tandem is that the 2nd loco pushes (or pulls) the SD70s through the trouble spot.

    If you friend has an extra loop of track, 195mm or above, then test run the SD70 on it. Is it still binding? This will give you a good indicator if it is track or locomotive.

    Rob
     
  7. newtoscale

    newtoscale Permanently dispatched

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    Hi Rob.

    My friend has tried this engine on his test track which has several left and right curves of varying degrees. The problem persists. Now I have advised him to check the contacts from the trucks to the chassis to determine if they are out of alignment. I will pass on to him this info about checking the gauge of the wheelsets. I don't know if he has a track/wheel gauge or not, but he can sort that out.
    I have 3 SD75's which I most of the time run together but sometimes I combine them with my GP9's and 35's and I've never experienced this problem so I couldn't help him out in this regard.
    Thanks for you help though and I will pass this on.
    Ken
     
  8. newtoscale

    newtoscale Permanently dispatched

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    Well my friend has tried everything suggested and still the binding on curves to the right takes place. It is indeed puzzling. Short of sending it back to AZL, which they don't seem to want to accept and do repairs, I'm at a loss as to what to suggest to him. It is most odd that this one engine binds when going around right curves in either direction. It just dosn't make sense, at least to me. He is frustrated beyond belief. I'm am going to suggest to him again, that if he hasn't already done so, he should get himself a wheel/track gauge and recheck the wheel sets and track.
    There has to be a logical explanation for this.
     
  9. ztrack

    ztrack TrainBoard Supporter Advertiser

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    I am not sure where you got your information about returns to AZL. I am the guy he would be returning it to. We are the global distributor for AZL. But I won't accept returns until we are clear that all other options have been addressed. Do this. You state you have SD70s. Have you tried running yours on his layout? This will determine immediately if the problem is track or loco related.

    Rob
     
  10. DSZ&N

    DSZ&N TrainBoard Member

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    Never had a problem returning anything to AZL Rob was very helpful. Just remember he is one man juggling a lot of stuff. When ever I've had a problem he makes suggestions if they don't work he'll take a look at it and try to resolve it. I've learned a lot from his suggestions along the way and have always ended up very happy.

    Dave
     
  11. ddechamp71

    ddechamp71 TrainBoard Member

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    Hi, I guess the issue has been described above far better than me but that looks like a problem of gauge. I guess now AZL stuff is gauged following Micro-Trains specifications (as there is still no NMRA leading data to deal with Z scale). My first AZL locos were out of these and I had to check and adjust axle gauge, especially the iddler center axle on every C truck, in order to have good performances on curves and turnouts.

    Hope this helps,

    Dom
     
  12. newtoscale

    newtoscale Permanently dispatched

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    I can't run my SD's on his layout because he lives in Europe. But it would have been and interesting test though.
    The return thing to AZL is based on my own experience. I wanted to return an engine to AZL because I couldn't get it to run properly after cleaning. Of course I didn't go directly to AZL, I went through a third party and everytime I asked about sending it back, I was ignored. So I simply gave up. I took the engine to one of the train shops here in the city, and even though they don't stock z scale (or order it for anyone) I practically begged them to cop a boo at it and try to get it working. Fortunately for me, they were able to fix the problem but it cost me large because they have never worked on Z scale before. Long story short, it's working as well as the other two and I'm a happy camper again.
     
  13. newtoscale

    newtoscale Permanently dispatched

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    I passed on the most recent suggestions to my friend and I haven't heard anything back so I don't know if the engine is working properly or not. He did, however tell me some time ago that he installed MTL couplers on this engine along with the snowplow on both ends of the unit, so it begs the question, are these maybe slightly out of alignment and catching on the track joints? He said no but I have to wonder.
     

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