Walthers #7 curved turnout problem

Discussion in 'HO Scale Model Trains' started by mentor63, Jun 14, 2008.

  1. mentor63

    mentor63 Member

    This type of thing may have been discussed before, but I can not find it on the Search so I thought I would see I anyone has any thoughts.

    I have several code 83 Walthers #7 curved turnouts on the layout I am working on. They seem to be prone to derailments, but I have generally been able to work out the problem..until now.

    It is layed on flat plywood, attached with adhesive (no pinching nails), seems to be in gauge, has no ballast above the ties, appears to be smooth, etc.. I tested it initially and everything was fine, but now that I have structures in the way it decides to derail all locomotives under power (only when under power) when against the points.

    Cars will roll through smoothly without problems either direction and locos will "slide" through by hand without power against the points, and will go through uneventfully under power with the points.

    I checked the track and loco wheel gauge and they all seem fine. I have run everything from 4-axle switchers to my DD40X, in fact, the DX40 handles it better that the switcher. The front axle on the front truck always jumps to the outside of the turn between the points and the frog and then comes to a stop before the flangeways as if it has encountered an obstacle. Speed does not seem to be a factor. On the DD40X, the wheels still spin under power, but it acts as if it is bottomed out and lifted off the track. I can find nothing physical that would cause this.

    Oh, yes, this is only a problem on the outside (larger-28") curve, the smaller inside curve is fine in both directions with all cars and locos. I am using code 83 flex track soldered to the turnout into and out of this turnout. I live in Colorado (dry) and doubt that humidity is the problem.

    After many hours of trying everything I can think of, this one really has me puzzled. Any ideas? Gary
  2. doctorwayne

    doctorwayne Active Member

    I have a Shinohara curved #7 (I believe that they're the company that makes the Walthers turnouts) that I removed from my layout in order to lengthen a passing siding. The only thing that I can see on it which might cause a problem is that the area at the points-end of the wingrails allows the wheels to drop slightly: in other words, the wheel tread which passes over the frog is momentarily unsupported by the top of the rail. Is there any chance that the trip pins on the couplers are just a tad too low, causing them to catch on the diverging inside rail as the truck passes over this point?
    I just noticed (the turnout is sitting in front of me as I write) that both the wingrails and guardrails seem to sit just a little bit higher than the running rails. Chamfering the tops of the ends might at least eliminate the chance that this is somehow causing the problem - perhaps something on the bottom of the loco truck sideframes or bottom cover plate is striking the high ends. Beyond this, you've got me stumped.

  3. logicman

    logicman Greybeard

    Gary, you say it tested fine, and then you added structures.
    Could this have caused distortion?
    Did you test with switch motors added or not?

    Wood, plywood etc is always prone to warp because
    its moisture content will try to find a balance with its
    environment. That's going to be different humidity
    at the sawmill, storage yard, wholesalers, retailers and your home.
    Always store wood products where they are to be used
    for 2 to 4 weeks before use.

    To test for winding distortion, lay two sticks across the track
    a little distance apart, and sight across the pair.
    Any winding will be obvious.

    Try a flat rule along the track and sight across the track.
    This shows up any vertical distortion.

    Other than checking for distortion arising since build,
    I'm lost.

  4. mentor63

    mentor63 Member

    Thanks for both of your inputs. They give me some more things to consider. I had checked the coupler trip pins and they are in tolerance (above the railhead), and the plywood surface has been in place for over a year. I checked the bottom of each of the locos and found nothing, and since I get the same result with 3 different locos I figure that is a low probability.

    I had noticed the wingrail and guardrail height issue too. It is a left turnout so I suppose if the left wheel on the front axle raised up, due to the higher wingrail, the right wheel on that same axle would not be in contact with the right rail and might be allowed to ride over the right stationary rail. Once it is over the outside of the rail I suppose the bottoming effect could be expected. I think I will try to pursue that some more.

    I think I will check the guage tolerance in that area again too. The locos seem to exhibit a slight hesitation as they enter the area where the points move. If it is too tight it seems it could cause this result since the outside wheel is the one going over the rail, but since no other cars have a problem it does not seem logical.

    I thought for a while that the joiners used to join the lead-in track and used for the pivot end of the moveable section might be too high, but it does not seem to occur at those locations when I looked closer. Also, I have no clue why being self-propelled (under power) has any effect on it versus when I hand "slide" the locos through the same section of the turnout.

    Well, that is part of the fun of the great hobby! When I succeed in correcting the problem (and one way or another, I know this can be overcome), it will be very satisfying! The layout is almost complete, so I guess I was due for a "showstopper".

    Keep those ideas coming and I will let you know if I work it out. Thanks,

  5. logicman

    logicman Greybeard

    Under power v hand-sliding:

    Could be the motor stalls due to momentary bad pickup or short by wheel.
    This would give a slight motion hiccup or kangaroo effect, perhaps enough,
    with other factors, to cause a de-rail.

    Had these been hornby points, I would have pointed you here
    but that info might help somewhat anyway.

    Keep testing!

  6. mentor63

    mentor63 Member


    That sounds like a good idea to look into too.

    I have thought more about your previous suggestion that there might be some distortion. Due to the location, it will be tough to sight down the track, but it seems to me I did end up having to shim under the ties of one of these turnouts in the past. Maybe I will just do a bit of trail-and-error with shimming.

    Several good things to run down. Thanks again,

  7. logicman

    logicman Greybeard

    Try a hand mirror. :thumb:

    If all these tips fail to work -

    please see my sig.

  8. mentor63

    mentor63 Member

    Well, I rechecked the track and found that the width was a bit wide where the flextrack joins the turnout and the ties were removed at that point for soldering. So I used a nail to move the rail in to the proper wideth and it seemed to work. Everything worked fine for about 30 minutes of testing with all locos, but as I was congratulating mayself, the same problem returned. I think it something to do with the track width, but I am getting frustrated and am going to take a break and think it over some more before returning to it.

    I tried a mirror and that is a good idea, but it doesn't show anything in the way. Thanks, Gary
  9. mentor63

    mentor63 Member

    Well, I rechecked the rail guage all along the turnout and it appeared to be good, so I decided to try adding some random shims under the foam roadbed in several different places, one at a time. Low and behold, when I put a shim under the outside rail at about the pivot point for the moveable tracks, everything worked! I tested all three locos (4 axle switcher, 6-axle, and DD-40X) and they all seem to work now. I suppose I would have to surmise that, even though the turnout was on flat plywood and attached to foam roadbed with a thin film of adhesive, somehow it became distorted slightly. Now we will see if it holds up.

    I will attach a photo of the area. The turnout that was the problem is in the center of the photo, behind the oil tanks and behind the aft end of DD40X. You may be able to see also that there is a second layout level (green fascia) above the area which made it a bit more difficult too.

    Thanks for you inputs and suggestions. They helped to keep me on track. Gary

    Attached Files:

  10. logicman

    logicman Greybeard

    That oil depot looks so realistic!
    I sure hope you're a non-smoker!

    Glad it all worked out for you. :thumb:

    Keep rollin', rollin', rollin'
    though the tracks are swollen ...


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