Athearn SD-39 Derailing

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Greg@mnrr

Section Hand
I have mentioned this problem in the Coffee House, but would like to do a separate Thread regarding this problem. The locomotive is an Athearn SD-39, six axle locomotive. At only one point on the layout when the SD-39 is going around a 24 inch radius curve will the front lead wheel set on the front truck derail. It is always in the same spot and only with this locomotive. I've run other six axle locos through this curve for hours without a problem

I've check the trucks' wheel gauge, freedom of motion of the trucks, the track gauge, ballast interference and the wheel sets' play in the trucks. If the locomotive is run back wards through the curve everything is fine.

This problem is really getting to me!!!

Any suggestions?

Thanks.

Greg
 

wheeler1963

Aurora & Portland Owner
Greg, I remember the Blue Box SDP40 had that problem way back when. My only one still does it. Where the middle axle square bearing goes in the truck, the square part in the truck side was cut too low. so the middle axle rides too high. Maybe check that measurement and see if the newer ones still have that problem.
 

Selector

Well-Known Member
My money is on the outer rail being a wee bit too low to keep the flange on that lead axle from staying inside the rail. And that may not be the only problem. Sometimes, on longer rigid frames, it's what's going on in the back that makes the front misbehave. If you have uneven rails, and the frame is twisted upward by the rear truck, the front axle will derail even when the rails there are rather well-positioned.

Incidentally, this is one reason why even a small amount of super-elevation is worth bringing to your roadbed or your tracks. It raises that outer rail some and keeps the flanges inside the rails, even with those minor dips.

It could also be the truck not being able to swing in azimuth sufficiently due to snagging or abutting something like a plastic detail or part of the frame, maybe some flashing where the bolster pivots.
 

NYC_George

Well-Known Member
I had 2 Athearn SD40's with the exact problem on a 24R section of track. I tried everything and finally had a friend bring over some ScaleTrains SD40's to see if the track was the problem. No problem with the ScaleTrains locos. I don't have any idea what the problem with the Athearn's locos were but their now a static display. I gave up. I bought 2 Scale trains GE_C39's and their's no problem and much better locos. If you viewed my 20th Century Limited video notice the first turn you'll see the 2 Athearn's on a track that goes no where and that's where there staying. They won't be aggregating me again.

George
 

Greg@mnrr

Section Hand
I think I'm closer to solving this problem. The locomotive runs fine in reverse through this curve. But today after running the locomotive very slowly it seems to be having a problem at a rail joiner on this section of track. The joiner is installed properly, but I bet there a bit of rail out of gauge that the lead truck is getting hung up on.

Couldn't look further today since I all of sudden I received a hand delivered "To Do List" but first thing tomorrow I'll pursue this idea farther. I think this is it. Now to the repair crew and place them on alert.

Greg

;)
 

Greg@mnrr

Section Hand
Sherman: I installed Code 83 and the thought of a Code 100 jointer did cross my mind while watching the Packers make fools out of the team. Maybe later I'll check and report back later, but tomorrow for sure. I suspected some with the joiner yesterday as I picked at some ballast.

I hate the thought of replacing that joiner with scenery in the way and the ballast. I may just replace an entire length of Code 83 flex-track and be done with the problem I hope.

Maybe I can force the joiner down if there's no solder under the inside of the joiner???

Thanks Sherman.

Greg
 
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santafewillie

Well-Known Member
I thought that I suggested this over in the Coffee Shop, maybe not. Have you tried to adjust the wheel gauge of the center axle to the tight side of the gauge? Leave the outer axles in the center of the gauge or maybe to the outer tolerance.
 

Greg@mnrr

Section Hand
Willie: What's the best way to adjust the wheel gauge? I am having trouble removing the bottom clip of the front truck and already broke a piece near the where the clip slips over a lug. I have on order four replacements. How about a channel lock pliers to gentle move the wheels slightly inwards???

Even if I did install a Code 100 joiner by mistake, all my other six axle locomotives have no problems here nor does a 16 car ore train with its short wheel bases of the ore cars.

Thanks.

Greg
 

santafewillie

Well-Known Member
Willie: What's the best way to adjust the wheel gauge? I am having trouble removing the bottom clip of the front truck and already broke a piece near the where the clip slips over a lug. I have on order four replacements. How about a channel lock pliers to gentle move the wheels slightly inwards???

Even if I did install a Code 100 joiner by mistake, all my other six axle locomotives have no problems here nor does a 16 car ore train with its short wheel bases of the ore cars.

Thanks.

Greg
I've never tried channel locks, but they should work. You posted that the loco is an Athearn, unless the design on that one is different than any of mine, that bottom plate should be easy to remove. If you have replacements on the way, what difference does it make if you manage to break it further?
 

Greg@mnrr

Section Hand
Jerome and Willie: Soon I'll be heading down to the layout and work on that SD-39. I'll try and wiggle the screw driver and pop off the clip. The one problem with about working on this loco is that it has a custom weathering job and I hate to spoil it.

This was a good lesson for me. I never test ran thus locomotive before it was weathered. I've done this before and and one other defective locomotive that I had to repair before running it on the layout.

I have some replacement Proto axles that I could work on tightening the gauge of the lead wheel set. I'll use a piece of brass tubing and slip it over the axle end and gently tap it with a small hammer rather than a channel lock pliers.

I'll keep you posted.

Greg
 
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Greg@mnrr

Section Hand
Still having problems with my spell check. the program will change words and sometimes the words are even mis-spelled. I re-read some previous posts and found this problem.

Or, it will miss mis-spelled words and they don't show up until I do an edit after posting the Thread.

Greg
 

NYC_George

Well-Known Member
There must be a difference between Athearn & Scale Trains SD40 type locos. I was unable to fix the track problem so I bought 2 Scale Trains locos and that fixed the problem. It seems funny that 2 or 3 people having this same problem with Athearn. Somethings up. I think if the track is slightly imperfect Athearn's locos will have problems. Scale Train locos don't seem to have this problem. In any case I removed the LokSound decoders I installed in the Athearns and used them in other locos. Then I put the Athreans on a track that use to be the down lead for my old helix. It's a display track now with no use to the layout. That's where there's staying at least for now. (photo below)
George

stactic_display.jpg
 
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