truck tuning: consistent delrailment on a tight radius

[mmagliaro]

Isn't there a pin or something molded into the truck where it inserts into the frame that limits how far is can turn?  Could that not be filed a little bit to let the trucks pivot more?

If the center wheelset axle has flat ends (i.e. no pointy axles sticking out), you can just place the wheelset  between the jaws of a jewelers vise, with an NMRA guage on the flanges to keep an eye on how much you move the wheels inward.  Then give it a gentle squeeze to make the wheels narrower.  You really just want one tiny "ooch" narrower, so go easy (Cap'n Obvious!).  You are obviously on the hairy edge of what that engine can tolerate.  But you might be able to cheat it through that curve by narrowing the center wheelset., as you originally asked about.

Congratulations on setting up an independent test with sectional track to confirm the behavior outside your layout environment.  That was a very good idea.

[Point353]

There may be one more adjustment you have to make.  First, carefully remove the shell from the drive, and put it aside.  Then, using a small jeweler's screwdriver, separate the side frame from the truck.
Now place the truck, the sideframe, and the locomotive drive on a paper towel.
Now take that paper towel out to the driveway, and put it under the tire of your car.  Drive over the locomotive, backing up and repeating the maneuver as often as is necessary, then go to the hobby store and buy another engine.

You might enjoy this YouTube channel: https://www.youtube.com/channel/UCcMDMoNu66_1Hwi5-MeiQgw

[CRL]

If the problem is that the truck isn’t able to swivel enough to one side, narrowing the gauge of the center wheelset won’t correct the issue.

[jjb62556]

Bite the bullet and relay the track right! Your next three wheeled trucked engine will have the same problems.

[mmagliaro]

Bite the bullet and relay the track right! Your next three wheeled trucked engine will have the same problems.

I've been thinking this for a while.
As I look back at the photo of where this problem is, it does certainly look like you could get that lower inside curve out to at least another inch in radius.  The difference between a 10" and 11" radius is huge.  I think you could push the inner/lower track section more out to the outside edge of the wood, and cut some notches in the wooden supports that hold up the upper section to clear the trains.

Broader radii make everything run better.  Patching up one engine makes, well, that one engine run okay.

[Point353]

If the problem is that the truck isn’t able to swivel enough to one side, narrowing the gauge of the center wheelset won’t correct the issue.

If the trucks don't swivel enough, why does the loco derail in only one direction?

[freedj]

Atlas told me that i am "exceeding the limits of the locomotive."  Looks like I won't be getting any support from there.

[freedj]

If the trucks don't swivel enough, why does the loco derail in only one direction?

I am wondering the exact same thing, but i am thinking its the outside wheel sets in the truck that are the problem, not the center one.  If I slightly reduced the gauge there it would allow slightly more miss-alignment between the truck and the track.

[freedj]

As I look back at the photo of where this problem is, it does certainly look like you could get that lower inside curve out to at least another inch in radius.  The difference between a 10" and 11" radius is huge.  I think you could push the inner/lower track section more out to the outside edge of the wood, and cut some notches in the wooden supports that hold up the upper section to clear the trains.

The challenge with this idea is that the current spiral doesn't have enough vertical clearance for the train to go under the upper level except where the bridge is.  I would need to remake the module to accomplish this.

I could possibly cut the upper level flush with the ends of the ties, and notch the supports as you describe, and then relay all the track in the lower loop as close to the outside as possible, but that would only take me up to around a 10.25 or 10.5" radius and I am not sure it would be enough of a difference.

The question is.. is it worth it to remake the module so I can run this loco, and other long wheelbase 6 axel locos.  I have a rs4/5 that is fine on the curves.  I have tried a nice selection of longish rolling stock and so far have not had any problems.

I guess one other possibility is to only put the loco on the layout in the orientation that it can successfully navigate the curve, since I don't have any way to reverse the loco / train on the layout

[alhoop]

Atlas told me that i am "exceeding the limits of the locomotive."  Looks like I won't be getting any support from there.

I hope that is TIC - you really think Atlas should help? WM3798 gave you the right solution in Reply #54 -- take it.
Al

[mmagliaro]

The challenge with this idea is that the current spiral doesn't have enough vertical clearance for the train to go under the upper level except where the bridge is.  I would need to remake the module to accomplish this.

I could possibly cut the upper level flush with the ends of the ties, and notch the supports as you describe, and then relay all the track in the lower loop as close to the outside as possible, but that would only take me up to around a 10.25 or 10.5" radius and I am not sure it would be enough of a difference.

The question is.. is it worth it to remake the module so I can run this loco, and other long wheelbase 6 axel locos.  I have a rs4/5 that is fine on the curves.  I have tried a nice selection of longish rolling stock and so far have not had any problems.

I guess one other possibility is to only put the loco on the layout in the orientation that it can successfully navigate the curve, since I don't have any way to reverse the loco / train on the layout

I guess I don't understand your problem.  I'm only suggesting that you broaden the curvature around the whole lower level by about 1" in radius.  I don't see how that changes where the levels cross over each other at the bridge.

[strummer]

I would need to remake the module to accomplish this.

We're into the 5th page of this discussion, so perhaps a total "remake" is the only answer.

I once bought a bunch of N scale stuff from a local guy, including a small layout with a similar issue. No matter what I did to fix a derailing problem in one spot, it never went away. I ended up pitching everything he had done and started over.

Problem solved.

Mark in Oregon

[nkalanaga]

"I guess one other possibility is to only put the loco on the layout in the orientation that it can successfully navigate the curve, since I don't have any way to reverse the loco / train on the layout "

If it only derails in one orientation, and the layout has no way to change that orientation, that's what I'd do.  Problem solved, and nothing needs to be rebuilt.