Atlas SD24

[atsfrules]

I recently purchased 3 Atlas SD24 locos with NCE DCC.  I do not have a layout but do run them occasionally on a loop of Unitrak.  One of the locos will run fine on the straight sections but stall on the super elevated curves.  Has anyone else had this issue and what is the fix?  Any suggestions is appreciated.  Jerold

[AKNscale]

The first thing I would do is clean the loco out and relube it properly if you haven’t already(I do this with all new Atlas locos as they’re always severely over lubricated). Next, for your issue, check your frame halves to make sure they’re level(loco doesn’t wobble on straight track). Also check the contact strips for the trucks(make sure they aren’t loose in the frame halves.

That’s where I would start.

[atsfrules]

Thanks, I will see what I can find.  One thing I did find is that when running and leaning right on the curve everything runs fine, but leaning left they will stutter or stop completely and the headlight goes out temporarily.  Somehow they are losing contact.  Is this common for this loco as I find it odd to be doing the same thing on all three locos.

[Point353]

Also make certain that the contact strips are riding on top of the tabs on the trucks and have not slipped off to the side.

[AKNscale]

I do not know how common it is for these locos in particular but I’ve had quite a few different locos with problems just like this.

[woodone]

If all locomotives are doing this? Are they all doing it at the same location on your layout? Might be some faulty track or track work!

[nscalbitz]

The first thing I would do is clean the loco out and relube it properly if you haven’t already(I do this with all new Atlas locos as they’re always severely over lubricated). Next, for your issue, check your frame halves to make sure they’re level(loco doesn’t wobble on straight track). Also check the contact strips for the trucks(make sure they aren’t loose in the frame halves.

That’s where I would start.

Loosen the half-frames and retighten to exact same tension/ setting. If they dont match, look for a skew or binding in the threads.
regards davew

[atsfrules]

Thanks for all the help, when I can get a chance I will do some looking.  As far as the track goes, this was one of the first things I thought of but it is Kato Unitrak, double mainline.  The curves are super elevated, so when the loco goes into the corner and leans right on the elevation it runs fine, leans left and wants to stall.  FYI, Kato locos run just fine through the same track work.

Jerold

[tehachapifan]

How abrupt is the transition to the super-elevation? Could some wheels actually be lifting off the tracks? If not that, could the loco(s) lean over enough in the curves that the contact strips separate from the truck tabs?

[carlso]

Jerold,

By no means am I an expert here but let me through out another thought. I think everyone who has responded will admit that Atlas has/has had problems with decoders fitting loosely in the grooves that they slide into. I believe that there was especially an issue with NCE decoders. Not flaming here folks, just trying to come up with another idea.

I have not seen the KATO elevated 2 track pieces so I do not have any idea about how abruptly the elevation begins. You say your KATO's have no problem but that is no surprise to me. So my question is : is it possible that when your faltering locos enter the elevation there is enough torque to cause the decoder to lift and break contact with the grooves on one side. Try physically turning the locos around and enter the elevation opposite of what you have been doing and see if in fact the same thing happens. Take the shells off so you can use a magnifying glass to watch the decoder action in the elevated curve.

Just my 2 cents, have fun,
Carl

[atsfrules]

Thanks for all the help.  The track does come with transition curves into the elevated curve so there is a nice easy transition.  My guess is it does have something to do with the lean as when leaning to the right it runs fine but leaning left is when the stall occurs.  It will black out and then the light comes back on and will then sometimes start moving again or just does this stop and go action.  I'm not that familiar with Atlas locos, can someone tell me the best way to remove the shell from this loco?  Thanks, Jerold

[AKNscale]

If it’s anything like almost any other Atlas loco, hold it by the fuel tank then grab it by the dynamic brakes and wiggle it side to side until it slides off. When they’re new they’ll fight quite a bit. With what you’re describing, I would think the contact strips should be the first thing you should look at actually, then check that the frame halves are level.

If the board was “loose” I’d think that the connection problems would be constant, not just turning one way.

[MK]

If that doesn't work, try this.

[coosvalley]

Some of the SD24/26's had a slipping drive shaft problem, that may be what's happening too. I'd tell you how to fix it but I have not fixed mine yet