Bachmann HO Norfolk & Western 4-8-4 Class-J Problem

[napa15]

I've got a problem with a locomotive I got from Bachmann earlier this year and I'd like some opinions as to what some of you experienced modelers might think the problem could be. Before you tell me to contact or send it to the service department, I am. In fact, that's where the engine came from. But, before I send it back there I would like to know what could be causing the issue.

The loco in question is in the thread title and the issue is that it runs fine in a straight line and around curves turning to the right. But, if I try and run it on any curves where the engine turns to the left, the front set of drive wheels get bound up. They somehow come up out of the groove they sit in and get stuck and the engine stops. It seems that is the only drive wheel set that does it, and of course that set of wheels doesn't have the drive gears going to it.

I actually got this loco from the Bachmann service department as a replacement engine for an older (much older) Class J I sent in for repair for THE EXACT same issue. This one a new engine that is DCC equipped, the other is a very old analog engine. I paid the shipping and replacement costs that Bachmann charges for this engine, and now will have to pay new shipping charges to send this engine back to them. My issue now is that I can not locate my receipt they sent back with the engine (the pink (right?) copy they send in the box), I think my wife tossed it out. But, that's my problem for not keeping up with my receipts properly, and I'm not bad talking Bachmann's service department. I've had nothing but positive experiences with them every time I have dealt with them. It is a crazy coincidence though that this loco has the same problem the one I sent in for repair originally did though. I noticed it the day we got it and my son and I put it on the track to run it. But, I was frustrated and we realized it would at least run while turning to the right and my layout is setup so that it can run in that configuration. So, it only gets run every now and then.

Man, sorry to ramble.    Anyway, just been meaning to post on here for thoughts as to what the potential issue could be and if it might even be an issue I could fix on my own.

Thanks.
Chuck

[bobwrgt]

The J likes curves of 22in or more. If you are running on 18in you will have problems.
Have you got a track and wheel gauge?  Check the track and the wheels to see if they are in gauge. Sounds like the track or front wheels are out of gauge.

Bob

[napa15]

Thanks for the reply Bob. I should have thought to include the radius of track I was running the loco on. I am running on 22in radius. It is the Bachmann EZ track. I do not have a track or wheel gauge. I would think that if the thing turns just fine to the right it should turn just fine going to the left. on the same degree of track, right?

[Doneldon]

napa-

Cabbage or wine?

Yes, you would expect that a locomotive would turn to the left or right with equal ease but that isn't always true. Motor torque can affect that a bit, just as with automobiles. More important, undercarriage fixtures may interfere with turning one direction but not the other. That shouldn't happen, of course, but it's possible that something is bent or out of position. Turn your loco over and carefully inspect the underside for things which might be coming into contact with your pilot truck. Good luck.
                                  -- D

P.S. Don't forget the earth's rotation. Perhaps your loco would derail on righthand  curves if you were to move to South America.

[napa15]

Thanks for the reply Doneldon.

I don't believe the pilot truck (if I'm understanding the terminology right that is the pilot trucks - the lone set of 2 wheels by themselves?) are being obstructed by anything. They are tracking along just fine, in either direction. It's the first set of driver wheels that cog up (of the 4 driving wheel set). I have looked before to see if I saw anything that would be obviously an intrusion, but could not see anything. I'll take another closer look. I know all the driving rods are aligned properly and nothing on either side of the loco looks out of alignment there. And for info, when the wheels cog up, or get stuck, I have worked them back free and into place, only to have it happen again. So it is a repeating problem.

[bobwrgt]

Does it derail in the same spot or section of track??
Check the track with a level or straight edge to see if there is a dip on the rails.
If you have a dip the wheels will ride up over the rail .
Usually the outside rail. You may have to shim the outside up just a bit.

Bob

[napa15]

Nah, it's not a rail issue. It's not derailing. I think I may put it on the tracks tonight and let the wheels cog up and take a picture to show what it's doing. The front set of drive wheels actually seem to come out of the groove they sit in a bit, at least one side does (from what I remember). Maybe I'll try and get some close up video of it too. Kind of a strange thing.