Jumpin track


N-gager

N-gager

Member
I recieved a Kato Sd90/43mac I'd ordered the other day. Tested it on the layout and I consistantly jumps track on two different curves. None of my other 3 engines have an issue with the layout (Bachman 40ax).
To further confuse, I can find nothing wrong with the track AND this only happens in a clock-wise direction. The Kato runs great otherwise (counter-clockwise w engine turned forward and backward - if that makes sense to you).
Everything on the engine looks good.
I've checked clearance, smoothness, looked for obstructions, even ground down the rail joiners in the suspect area even with the inside rails.
The one section of track IS ballasted but I've checked for problems with clearance. The other curve is not ballasted yet.

What am I missing here????
 
I have an Athearn SD70 that's awfully picky and derails where nothing else does. Never have figured out why except that the wheels fit the rails more tightly and has less "wriggle room" side to side. Makes for a good track tester, because if it'll stay on then anything will. I've never had any problem at all with my SD80/90's, of which I have ten. They're actually really great about practically staying welded to the rails.

When it's derailing going clockwise, is it doing THAT in both forward and reverse? You said it runs fine counter-clockwise in forward and reverse but I wasn't clear on whether it was derailing in both forward and reverse.

If it is derailing in both forward and reverse only going that one direction, then it almost has to be your trackwork, though I'm as stumped as you if you can't find even the slightest variations. It's weird what can cause it, too. I had a spot on one line where I could barely see any deviation at ALL, and the locomotives didn't look like they even noticed it either, but it happened to be right after a curve and for some reason it caused derailments every other time until I straightened it. One wheel of one truck would jump off, so subtly that you didn't even notice until it hit the turnout about two feet further along. And seriously, it was such a minor deviation I wasn't even sure I HAD straightened it until it dried back down and I could test it out.

Other than that, make sure none of your wheels have defects and that the trucks rotate freely in both the yaw and pitch axis and nothing is binding. I've actually run one of my SD90's through a tiny super-sharp Peco ST-6 turnout and some really sharp industrial siding curves just to see if it would do it, and yeah, it does. So unless something's binding up it definitely wouldn't be your curve radius or anything like that.

Once all that is checked out, short of borrowing another SD90 to run over it and see what happens I don't know what you could do except try and exchange it to see if another locomotive does actually do okay.
 
Yes it jumps only in the clockwise direction. Doesn't matter if it's front or rear moving in clockwise direction.
jumps to the outside (left side).

I've closed my eyes and run my finger over alll surfaces of the rails and ties and can't feel any thing wrong. No bumps - all smooth and level.

Not sure about returning unit for exchange. Bought the only one in stock at modeltrainstuff..

Don't know anyone who would have one to borrow from round here. If I can't figure it out I may just have to settle on one direction of travel lol.

MikeOwnby said:
When it's derailing going clockwise, is it doing THAT in both forward and reverse? You said it runs fine counter-clockwise in forward and reverse but I wasn't clear on whether it was derailing in both forward and reverse.

If it is derailing in both forward and reverse only going that one direction, then it almost has to be your trackwork

Once all that is checked out, short of borrowing another SD90 to run over it and see what happens I don't know what you could do except try and exchange it to see if another locomotive does actually do okay.
Click to expand...
 
I had a similar problem where cars and locos were jumping the track but only in one direction. Mine turned out to be a soldered joint on a code 80 to code 55 piece of track had come come loose and allowed the joint to shift just a bit. One rail was slightly shifted inward so when trains came through in that direction it would cause some to jump track.

Hope this helps.
Steve


Sent from my iPhone using Tapatalk
 
Just wanted to make sure...I know you're feeling for irregularities, but make sure you don't have a kink in it at a joint. The photo below is an extreme example (like, REALLY extreme), but it doesn't take anywhere near that much of a kink to start having problems. If your curve isn't a very smooth and constant curve, if it has even a very small angled "kink" in it at a joint, it's going to cause problems with some locomotives. If your curves are done right you shouldn't even be able to tell where the joints are. If you can, you probably need to fix that.

kinkedflextrack.jpg
 
arealgijoe said:
Talk about a BAD joint........... I can not fathom much NOT JUMPING at that juncture.......
Click to expand...

Right? I'm glad I found it to illustrate my point, but if I was the guy who did that I think I'd have been too embarrassed to post the picture of it :D
 
I'd look closer at the loco.........I've had similar issues with big Kato locos and the problem usually comes down to the truck(s) binding on something. Your trucks may be fine turning one way and snagging when turning the other way. A club member had an E5 with similar problems. The front truck was snagging on bodywork. Out of the box, it wouldn't go around 24 inch radius curves without derailing. I have an SD70ACe that I still haven't gotten to work right.........it works with the shell off, but with the shell on the trucks hit various body parts as well as the coupler boxes. Your track may have some minor issues, but since your other locos work I'd look at the loco.
 
Had a similar problem with a HO engine on a curve. The track was in place for a long time, but never really tested with different locos. A four axle unit would "jump" only in one direction, but work fine in the reverse direction.

Only one locomotive derailed on this curve. My informal model railroad group was coming over for a meeting and I knew I needed to find out the problem.

Used a track gauge over the area and found that an area that the gauge was binding at a rail joiner. No matter what I did I couldn't resolve the problem, so I finally replaced a section of track with new flex-track and eliminated the joint on this point of the curve.

This locomotive had one axle where the wheels were a bit tight, but very close in gauge.

It surprising that a little problem causes so many problems.

Thanks.

Greg
 
Mike..........we ALL make boo boos, its part of being human.

Right? I'm glad I found it to illustrate my point, but if I was the guy who did that I think I'd have been too embarrassed to post the picture of it :D

IMO it was a GREAT example, gets the IDEA/CONCEPT across quickly.

I have a turnout/switch that has long been problematic for SOME locos. I replaced it a while back with a brand NEW Atlas.......... still have problems IN the switch.
 
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