engine derails on curves


R

RIRRfan

Member
On the same note of the other thread "Cars derai"l...

I bought 2 SD45 from a consignment table. Same make and manufacture.
One is in excellent condition and runs great.
the other is in excellent condition and runs great on straight but as it enters the curve one truck doesn't want to turn. (the same result for both directions)

I can't see anything physically wrong. and can't seem to nail this one down.
Any suggestions?
 
The trucks may be warped. Notorious in Athearn Genesis models. I had one that did it routinely, and I sent it back to Athearn for replacement. No more problems.

Also, check the gauge of the wheels and also make sure there are no burrs on the wheel flanges.

Im sure others can give you some more advice, but speaking from my experience, these are some of the big items to check for.
 
Place the engine on a clean shiny countertop and backlight it well with a strong lamp. Get down with your eyes to where the flanges meet the counter surface and look for light where there shouldn't be between the wheel flanges and the counter. If may not be a twisted truck frame, but a bad axle, flashing on a bolster between the engine frame and the truck, a wire snagging a component of the drive or truck...you'll have to eliminate the obvious, but it usually means partial disassembly.

Also, whenever I have had such problems, also with diesels, and also with Genesis, I find that the outer rail on my curves is as much to blame. I found that, whereas all my other period diesels and steamers of various makes and models were happy with my tracks, the Genesis SD75M's were not. So, I wet the ballast and waited for it to soften (10 minutes) and then gently pried up the outer rails along the place where the engine derailed. I placed the odd sliver of plastic or wood, or cardstock under several ties, tamped down the ballast to force some of it under the ties that didn't have new supports, and then simply waited for the ballast to harden once more. I am talking about raising the tie ends on the outer curve by maybe 1/32" or a bit more.

That seemed to make a difference. I no longer get derailments, and my steamers and period diesels from the transition era don't care either way.

So, I would also have a very determined and considered/objective/critical look at my track levels. Find a worthy straightedge and place it atop the rails just before and over the place where your new diesel derails. Backlight the straightedge and get your eyes down to rail-top level. Do you see light where you had thought there'd be none? There-in lies your troubles.

-Crandell
 
Last edited by a moderator:
Selector said:
Place the engine on a clean shiny countertop and backlight it well with a strong lamp. Get down with your eyes to where the flanges meet the counter surface and look for light where there shouldn't be between any between the wheel flanges and the counter. If may not be a twisted truck frame, but a bad axle, flashing on a bolster between the engine frame and the truck, a wire snagging a component of the drive or truck...you'll have to eliminate the obvious, but it usually means partial disassembly.

Also, whenever I have had such problems, also with diesels, and also with Genesis, I find that the outer rail on my curves is as much to blame. I found that, whereas all my other period diesels and steamers of various makes and models were happy with my tracks, the Genesis SD75M's were not. So, I wet the ballast and waited for it to soften (10 minutes) and then gently pried up the outer rails along the place where the engine derailed. I placed the odd sliver of plastic or wood, or cardstock under several ties, tamped down the ballast to force some of it under the ties that didn't have new supports, and then simply waited for the ballast to harden once more. I am talking about raising the rail tips on the outer curve by maybe 1/32" or a bit more.

That seemed to make a difference. I no longer get derailments, and my steamers and period diesels from the transition era don't care either way.

So, I would also have a very determined and considered/objective/critical look at my track levels. Find a worthy straightedge and place it atop the rails just before and over the place where your new diesel derails. Backlight the straightedge and get your eyes down to rail-top level. Do you see light where you had thought there'd be none? There-in lies your troubles.

-Crandell
Click to expand...

I agree with professor doctor crandell. That is some college grade in-depth lesson
 
Good point on the rails. I haven't checked that yet/ will report as soon as I can.
just finishing up a GP30 in Wisconsin Central colors.
 
Ok, Got a good look at things. test run found where my track had a small rise at the coupler. A little teaking got me past that point. Upon watching the loco run it does not straighten after coming out of the curves.

Only thing I found was who ever had it before me must have had it apart. I found nearly every screw 1-2 turns loose.

After tightening the screws I did another test run. same thing happened.
I turned the loco around and it will not derail when the rear trucks are being pushed.
(Meaning the cab is in the rear position).

So it is atleast usable in a limited way.
I'll keep looking to try and narrow it down.
 
If the truck will turn into the curve, but not return when the tangent is encountered, it suggests strongly to me that you have a snag. Turning at first, the snagging item can be bent or is resistance in the one direction can easily be overcome. But on the return, it stiffens and prevents the traversing of the truck in azimuth. Again, it suggests a wire or more probably some flashing...or a burr. You'll need to remove the truck and look for something that shouldn't be where it is.

-Crandell
 
Selector,
Your right. I found a few burrs where a screw holds the truck through the PCB assembly.
I removed those now it turns more freely.

I also was able to fix a bad spot in one of my curves which still derailed it.

I replaced a couple of my 30 yr old curves. Not sure what the problem was there but new track resolved the last issue for this loco and curves.

I suspect one or both curves are out of guage. I can see where it looks like a straight section on one rail a little ways from the join.

When I started asking for help on this issue the loco derailed on 3 of my 4 corners. (I never even tired the loop).
Now it runs freely.
thanks guys for the ideas.
 
RIRRfan said:
Selector,
Your right. I found a few burrs where a screw holds the truck through the PCB assembly.
I removed those now it turns more freely.

I also was able to fix a bad spot in one of my curves which still derailed it.

I replaced a couple of my 30 yr old curves. Not sure what the problem was there but new track resolved the last issue for this loco and curves.

I suspect one or both curves are out of guage. I can see where it looks like a straight section on one rail a little ways from the join.

When I started asking for help on this issue the loco derailed on 3 of my 4 corners. (I never even tired the loop).
Now it runs freely.
thanks guys for the ideas.
Click to expand...

What type and brand of track was on those curves? A couple of weeks ago in response to another thread I mentioned I've been replacing all of the Peco flex track on my curves for reasons similar to yours. That track was laid down 30 odd years ago just like yours. Interestingly enough in the same areas where I used Atlas flex track it is still as good as the day I laid it down.
So from now on I'll only be using Atlas flex track even though the odds are I won't be around 30 years from now to see the results.

Ahh the ravages of time I guess. LOL

Good to hear you got it straightened out.
 
RIRR Fan, I am very pleased at your success. It is always a best guess, or guesses, in this hobby, and if we managed to net the big one with all the other fish, so much the better. Good for you! :)

-Crandell
 
NH Mike,

I have a couple of Atlas flex track from way back. They adorn my workbench as a test track for coupler heigth and wheel rolling.
Flex track is what I bought new for my layout as all my old flex plastic was brittle.
 
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