ONLY my Paragon 3 GP9 derails at a turnout in the trailing point direction. The Atlas 2F & 2R (RS-1) and 282 Mikado do not. Something is lifting the rear wheels causing the 1st wheel set to jump over the rail. The turnout is a double curve Code 100 Atlas. I found that there was a bump as the wheels transverse do the frog so I filed the roadbed in that area down. And ran a wheel set over with no bump up. Still derails. PS: Wheelsets on loco and track in gage.
I just saw a youtube video where the space between the guard rail was too narrow and caused the wheels pop up. It was Atlas but not all turnouts had the problem.
A GP-9 has 4 axles
Must be talking SD9?
The plastic Atlas frog can have a slight protrusion above the adjacent rail level. If you take off some of the roadbed, then the whole switch goes down, but it doesn’t do anything to smooth the issue with the frog not mating with the rail. IIRC, the issue is solved by filing down the plastic to match the rail. There’s some other stuff that people do with the frog to correct its issues, but I don’t have any Atlas track so no direct experience with fixing that.
That is not unusual for one locomotive to derail on a turnout when all of the other locomotives on the layout do not derail on that same turnout. It is a clear indication that the problem is on the locomotive rather than the turnout. It could be that one of the wheelsets is not perfectly in gauge. Try running it through the turnout at the slowest speed to see where it is derailing. Look for the offending wheelset. Or, better yet, push it manually through the turnout and look for the offending wheelset. Does it only derail in forward motion or also in reverse?
Rich
I sure that helps answer the question.
It can also bee that the truck does not track correctly, that is it will not turn far enough to track. It could be a bur on the king post, could be a truck detail catching on a body detail, could be a wire inside of the carbody catching the truck.
Not all derailments can be charged to the track department.
The various departments on realroads fight tooth and nail with each other to proove that it was not their department that caused the derailment. Usually when a train is on the ground, some degree of fault lies in several departments.
The flangeway of the Atlas Track could be too narrow (or too wide), but a truck with sufficient movement can laugh it off, while one constrained by a burr cannot.
ROAR
I suspect that this is a BLI SD9 locomotive. What size are the Atlas turnouts? Snap-Switch turnouts have a continuous curve through them. Customline turnouts diverge at an angle through the frog area(like a real turnout). That SD9 may have a clearance issue and one of the trucks is hanging up. A friend had a motor to truck wire that was the issue. I am sorta concerned about that ‘double curve’ turnout - are you describing a ‘wye’ turnout? Jim
I was thinking it might be an S-curve, where the two diverging routes from two turnouts are attached to each other. These can be difficult for longer cars and engines to navigate, because the front half of the engine body is turning one way while the back half is turning the other. If these are Snap-Switches with very tight curves, the engine simply might not be able to take such turns.
I wonder if he is referring to a Peco Code 100 double curve turnout, or as most of us might call it, a curved turnout.
Rich
WOW Thanks for all their posts. I’ll try to answer al the questions here.
I saw that YouTube video and did that but it didn’t make a difference.
Yes sorry SD9
When I run the NMRA gage flat side over the tracks everything is flat.
My first thought was it is the locomotive also and I checked the wheel guage and they were all perfect. The track is in gage also.
I need to check the trucks I guess to see if they are tracking correctly or if there is a burr on the king post but I don’t know how to do that.
Turnouts are Atlas snap switch #8? Double Curve installed on a 24" curve. Not a wye.
He might have an older Atlas 274 or 275 curved turnouts. I had one Proto 2000 PA that didn’t like the Atlas 275 no matter what I did to remedy the problem.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
I once had a similar situation and the frustration and found the truck was derailing before it got to the turnout.
Worth checking it out if you haven’t already.
Good luck
Bob
Yes it’s at least 20 yrs old. Curved turnouts are on left mainline in photo
Looks like photo didn’t load.
Trouble-shooting this kind of issue is hard enough when you are right there on the scene. Trying to be helpful from a distance – nearly impossible. It would be interesting to know if this 6 axle locomotive is the most challenging piece of rolling stock our friend has. Would a six axle passenger car or flat car also derail for example? He mentions other rolling stock that has no problems but frankly there can be so much “slop” built into some engines and cars that they are nearly derailment proof. This particular engine might suffer just because it has fewer compromises with scale tolerances.
I have not seen one in a long time but guys used to make track troubleshooting cars out of clear plexiglass with trucks mounted on them - push or pull the thing through the troublesome spot and look from above to see if there were hitches or hesitations even if no derailment could at least pinpoint the trouble spot, a spot that in turn could derail other stuff. Some guys deliberately used the worst tracking trucks they could find for theirs, just to make it a torture test for their track and roadbed.
It might be the trackwork including a minute kink leading into the turnout that one truck forgives but the other does not. Or a minute bump in the roadbed. It might be that the engine is underweighted over that particular truck that derails – does putting some lead on the roof over that truck help, or does pushing down with your finger help?
Another cause of problems, and not easy to solve, is lack of side play (and verticle play for that matter) in the wheels and axles. It is after all asking alot for a six axle truck to go through even generous model railroad curves. Something may be binding including electric pickup (not that familiar with Paragon / BLI).
Dave Nelson
Hmm. Not unusual to have derailments at or near turnouts. Since two of your locomotives make it thru and only one derails the problem is PROBABLY with the locomotive. BTW a GP9 is a four axle locomotive, whereas you say the derailing locomotive is six axles. Presumably the locomotive is something other than a GP9? At any rate, six axle diesels are more troublesome than four axle diesels on turnouts and curves due to the longer wheelbase. Things to check, lowflying stuff on the locomotive catching on the rails. Insufficient truck swing, the truck[s] are catching on something. Too deep flanges hitting spikes. spile heads, or bits of crud stuck inbetween the guard rails and the stock rails. A bit of crud stuck to a wheel tread somewhere. Flangeways not deep enough to clear the flanges. I can remember deepening flangeways with a hacksaw blade on one troublesome turnout. Rough spots one the track. Turnout points need filing to feel smooth to the touch. Kinks in the track or rail joiners not properly seated. Insufficient sideplay in the locomotive wheels, a six axle locomotive needs some sideplay in the middle axle.
Get some extra light on the turnout and run the problem locomotive thru it slowly, both directions, with the turnout set both ways. Look for something wrong.
Good luck. Model railroading is fun. 
Link worked, here’s his picture
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
Surely not. That looks like a photo of a painting. If there is real track in there, you must have used a diffusion filter.
Some people might not want to log into Dropbox if they don’t have an account.
What I am seeing is a painting of a double track main curving clockwise toward a town. The 1st turnout on the outer track is curved, and it is followed by another that I can’t really see, but from the tracks appearing afterwards, it must be there.
I think the track gurus are going to need a close up picture of the turnouts in question.
Photobucket is more forum friendly for posting pics. Not the most user friendly but an account is free. See Otte’s sticky post.
