truck tuning: consistent delrailment on a tight radius

[CRL]

I’m guessing the loco is derailing when moving left to right in the photo above. Your outside rail is not aligned and the rail nearest the upper right corner is presenting a point for the outside wheel to pick.

Either file the point or solder the joint while applying pressure from the outside to make the rails straight through the rail joiner. When you release the pressure, use a file to dress the joint & check the gauge. This might fix your problem.

PS - I also agree with Lee’s comments, but this might fix the problem without relaying the track.

Good luck.

[freedj]

Lee: I would have done that if the curve was only two sections long, but this one was 5 sections long.  Perhapse soldering, gluing, and then cutting expansion joints in the laid track would be a better approach for such a long tight curve.

CRL:  The loco derails when traveling right to left, but I may try your solution anyway!  I could solder both while applying the pressure you talk about and see if that resolves the issue before ripping anything up.

[John]

Agree with Lee .. solder the joints, but on the inside joint, push it outward some, and solder it while it's pushed out ..  something else to try is to push the joiner back, and then widening the gap at the joint slightly .. it looks like you may be deforming the inside rail due to tightness ..

[mmagliaro]

From the photo, I see two things.

1. The whole track looks lifted up in the air off the roadbed, especially on the inside rail side.  It could be photo distortion, but it looks like there is quite a space under the ties there.  I would check that and if anything is "floating" through there, add some spikes to get it all flat.  That might be enough to fix it.  But...

2. The inside rail joint is kinking inward.  That's probably the abrupt change in direction you can feel when you run your finger over it.

I know you said this spot is hard to get to.  But if you can use some PC board ties as you were thinking, you wouldn't have to rip anything out.  Just adding a few soldered PC board ties through that section, soldered while you hold that inner rail INWARD so you get rid of the kink, would really help.  You might even be able to just set a few PC board strips under that inner rail, with the rest of the strip extending INWARD.  Solder them to just that inside rail, then pull them inward and spike them down to "pull" the inner rail more inward to get rid of the kink.

I have had to do this exact thing on a helix that was already buried under a mountain, and it wasn't easy.  But it did work.  I wouldn't rely on just pushing the inner joint into alignment and soldering it.  In my experience, once a joint kinks like that, it will eventually ease inward again, even if it is soldered.

[CRL]

You’ve got a pretty good inward kink on the lower rail also. Probably need to solder that joiner also while applying outward pressure.







Then you’ll probably have to rip it out and replace it.

[strummer]

...the only thing that would make this worse is if it was code 55 rail... 

Good luck and let us know how it goes...

Mark in Oregon

[CRL]

...the only thing that would make this worse is if it was code 55 rail... 

Good luck and let us know how it goes...

Mark in Oregon

Not if it was Peco code 55. This problem wouldn’t be happening.

[freedj]

Oh, it is code 55 rail 

[CRL]

But it’s not Peco code 55 flex.

Peco code 55 doesn’t have that sliding rail that will get out of gauge. The Peco code 55 flex is the easiest track to lay well that I’ve ever worked with and if you use the Peco code 55 rail joiners which are very tight, they help hold the joints straight while they are soldered. I know some don’t like the tie spacing, when ballasted it looks just fine IMHO.





Now let the fireworks begin.

[nkalanaga]

Freedj:  I've also had the "out-of-place pickup strips", and yes, those can sometimes be a pain to find.

As for flash, I had trouble with my MILW "branch", which is basically a 180 degree curve to a hidden storage track.  Diesels ran fine on it.  My Kato EF-57 derailed every time.  The gauge was right, it was NOT at a rail joint, and it derailed in both directions, but always to the outside of the curve.  I could remove the trucks and push them through the curve by hand fine. 

It turned out to be a bit of flash between two spikes, inside the rail web, on the inside of the outer rail, on the ME code 40 track.  Being on the inside, I couldn't see it, and it was below the NMRA gauge pins.  But the Kato flanges, although turned down, were just a little deeper, and hit the flash.  The wheelbase is longer than on diesel trucks, so the lead axle is pressed tighter against the rail, and it would lift just enough to slide up and over the rail.

[mmagliaro]

Looking back at your original photo of that helix area, it doesn't look like the track is hard to get to, at least now.  Do you plan on covering all that up?   Permanently?

Not only would I solder some PC board ties under this problem section to fix it, but I'd slide a few in at every joint in that helix.  You'll thank me later.   It wouldn't surprise me at all to see other joints in that 10" radius eventually give way and have one rail push in or out like this.    A few PC board ties will hold everything in solid alignment. 

[peteski]

Looking back at your original photo of that helix area, it doesn't look like the track is hard to get to, at least now.  Do you plan on covering all that up?   Permanently?

Not only would I solder some PC board ties under this problem section to fix it, but I'd slide a few in at every joint in that helix.  You'll thank me later.   It wouldn't surprise me at all to see other joints in that 10" radius eventually give way and have one rail push in or out like this.    A few PC board ties will hold everything in solid alignment.

I agree with Max.  This is especially important for track that is either hard to get to, or hidden.  It should be made as perfect as possible before it becomes less accessible.  I have seen multiple examples (on the layouts I helped to build and which I operate on) where the trackwork we thought was of sufficient quality (but not absolutely perfect) developed problems later on (sometimes few or even several years) after it was made not easily accessible.  Layout constructed out of wood, plastic, and metal is not a dimensionally stable structure.  It will expand and contract, or even warp when subjected to even small temperature and especially humidity variations.  If the track is imperfect when first laid down, it is almost guaranteed to develop more severe problem in the future.

[freedj]

Not only would I solder some PC board ties under this problem section to fix it, but I'd slide a few in at every joint in that helix.  You'll thank me later.   It wouldn't surprise me at all to see other joints in that 10" radius eventually give way and have one rail push in or out like this.    A few PC board ties will hold everything in solid alignment.

If i solder PCB ties under the joints, don't I loose my expansion joints there?

Right now it's reasonable to access that track, and in the future it will only be slightly less so.  I'll be filling in the space between the two levels with a vertical wall, but the track will always be easy to get to from the top.  I'll just have a bit less finger room on the outside edge of the lower level.  The upper level is wide open right now, but eventually i'll be adding a piece of facia there which will make accessing the outside edge of the upper level a bit harder as well. 

I do want to perfect this piece of track before moving on.

[peteski]

I wonder if you can pre-bend the rails of your flex track to the desired radius in the expansion gap areas?  That way the track would not try to spring back to being straight and keep the desired curvature (even when the expansion gap joiners are not soldered).

[DKS]

Late to this party, but in looking at this photo, the first thing I saw was that the inner rail to the left of the joiner has popped free, or the "spikes" have been sheered off, for at least 6-8 ties.



This has almost certainly ruined the gauge, and I think there will be two effective courses of action.

1. Install several PC board ties (as previously suggested), pull the inner rail away from the outer rail, and solder both. This is about the only way to hold the rail in gauge.

2. Replace this stretch of track.