Metal Wheelset Incompatibility

[jereising]

I searched and couldn't find an answer, so I'm throwing this out to see if I'm the only one with a problem.

The trackwork on my Oakville Sub is fairly decent, I think.  I'm also a fan of BLMA cars.  But as I have stated before, if I'm gonna have a problem, 95% of the time it's with BLMA wheelsets.

I recently brought out my reefer train for an engine change.  Despite it having run well the last time around, this time I was seeing frequent derailments.  This is likely due to the fact that it is in the high sixties temp wise - that's the only difference from the last time out.

The usual fix is to replace the BLMA wheelsets with FVMs of the same width and diameter.  Most of my FVM wheelsets are of the wide variety, although I also have some of the original FVM as well.

But the FVM wides don't like the BLMA trucks one little bit.  The outside of the wheel rubs the inside truck face. 

And now to the question:  Has anyone measured wheel tread width and come up with some sort of reference?

I can see a project looming and I'd just as soon not repeat work if not necessary.

And maybe I'm on a wild goose chase. 

I'd be most interested in comments, and I thank you in advance.

[GaryHinshaw]

I'm not sure I understand your question Jim.  Are you looking for a table of tread widths for the various other brands of metal wheels?

I've had issues with the Trinity reefers being stiff riders, unrelated to the wheel sets.  It seems to be a combination of the trucks being a bit tight and the flanges grazing the floor of the car.  I've had luck reaming the truck bolster hole slightly using a tapered wood pilot bit (I twist it with my fingers, not a power drill, until I've reamed out a few thou of plastic).  I also replace the wheels with narrow tread FVM which have a slightly smaller flange, to avoid rubbing the floor. But you could also add a washer if you don't mind a slightly higher ride.

Not really an answer, but it might help.

[jereising]

That's pretty much what I'm looking for, Gary.

I'd like to be able to put an end to this difficulty - it's GOT to the the wheelsets causing the issue, and the replacements simply won't fit the trucks - the tread is TOO wide.  Maybe it will be just as simple as using the original FVM narrows - if I can find some in my stash.

And actually, the REAL solution would be to get rid of the Atlas switches and handlay.  Except the derailments are not always at switches, seem to almost be at random with the one common being it's always a BLMA wheelset involved.  This particular train has a lot of the original BLMA wheels - I only replace if there's a problem. 

Gonna have to spend some time with the micrometer and NMRA gauge, I guess...

[Englewood]

I seem to recall that the original BLMA wheelsets came with very small flanges which gave me a lot of trouble. I changed them out with FVM wheels which solved the problem. I don't remember if I had any trouble with tight trucks on their reefers, although I think I did on their flat cars. Have you tried the Rapido wheels? I just bought some and they run very well.

[cbroughton67]

I've had similar issues with BLMA wheel sets, in that they are the source of derailments. In my experience, the issue is the wheels are not in-gauge. I had this issue with the BLMA spine cars, and ended up going through every axle on every car to correct the wheel gauge. That seems to be the fix. I have also replaced the wheels on some BLMA cars with FVM wheels. I use the narrow-tread wheels, so the rubbing issues never came up.


Chris

[nkalanaga]

I also had trouble with the BLMA wheels, but in my case they were in gauge.  The problem was that the track gauge was too wide.  "Normal" wheels didn't have any problems, but the narrow treads allowed the BLMA wheels to drop between the rails.  Then, when they came to the end of the wide spot, they were pinched between the rails, and the train derailed.

Fortunately, the main problem area was on a bridge, where I had spiked the rails, rather than soldering them, and regauging the track was easy.  But it took a while to solve, and I was seriously considering replacing the wheels.

[peteski]

And actually, the REAL solution would be to get rid of the Atlas switches and handlay. 

Are Atlas C55 switches not adhering to  NMRA specs?  I thought that properly handlaid switches would have even tighter tolerances.

It might make sense to closely investigate how and where exactly the trucks derail (after checking the gauge of the wheels first of course).

[jereising]

I appreciate everyone's comments.  Nice to know I'm not alone. 

I've checked the gauge on the latest suspects and they were dead on.  Now I'm going to have to check the track gauge where I think the problem may have occurred.  Although I'm using ME track, I know of at least one instance where the gauge went wide on the last six inches...that was with standard ties, while the majority of my track is concrete tie.

And Pete, the problem is not necessarily tied to the Atlas switches...the car usually has a truck on the ground before it gets to the switch, although I do have one area where the switch is suspect.

I'm suspecting the problem may be similar to nkalanaga's and is being exacerbated by the cooler temps. 

I know replacement will work, but I need to find narrower FVMs - I mic'ed tread for an hour this morning and aside from two aberrations, find that most treads on the FVM wheelsets I have are .0725 to .0750, with a goodly number greater than .0750.  Narrower than this would be desirable.

And the project may very well be placed on hold until Matt's new supplier is on line - supposed to be happening real soon...

[nkalanaga]

It may be the temperature, but it could also be humidity.  Has that changed with the seasons?  If your track is on a wood roadbed or base, humidity can have a bigger effect than temperature.

[GaryHinshaw]

Well, I don't have any further advice to add that isn't obvious, but...  Isolating the cause if the problem is necessary before finding a solution.  If your track gauge is too wide in spots, you can either correct the gauge or switch to wider tread wheels that don't rub.  (The latter may require switching trucks too, if the rubbing problem can't be solved with the existing trucks.)  If the problem too small a flange, replacement with original-width FVM wheels should help, when they're available again.  If the problem is something else, then the solution may be something else.  (Okay, at least you didn't have to pay for this advice.    )

But the FVM wides don't like the BLMA trucks one little bit.  The outside of the wheel rubs the inside truck face. 

I'm still not grasping how this can happen: it would require that the axle point barely extend beyond the wheel face, but then these wheels would not work with any truck that required the same axle length.  I find it hard to imagine that Matt would even sell such wheels (but I don't have any and I've never seen any up close).

[larry p mahoning division]

i had the same issue. I use atlas flex track and i also have large radius curves. However the issue is the tolerance for the flex track is larger than the tolerance for the narrow tread width of the wheel sets. I also use all FVM 10-36 wheels and have had absolutely no issues. You can see my layout in N-scale magazine. Jan/Feb 2014 issue. The layout has had a lot of major changes since that issue.

[jereising]

Well, I don't have any further advice to add that isn't obvious, but...  Isolating the cause if the problem is necessary before finding a solution.  If your track gauge is too wide in spots, you can either correct the gauge or switch to wider tread wheels that don't rub.  (The latter may require switching trucks too, if the rubbing problem can't be solved with the existing trucks.)  If the problem too small a flange, replacement with original-width FVM wheels should help, when they're available again.  If the problem is something else, then the solution may be something else.  (Okay, at least you didn't have to pay for this advice.    )

I'm still not grasping how this can happen: it would require that the axle point barely extend beyond the wheel face, but then these wheels would not work with any truck that required the same axle length.  I find it hard to imagine that Matt would even sell such wheels (but I don't have any and I've never seen any up close).

We're on the same page, Gary.
I need some photos to illustrate the issue; and it's not the wheelsets from FVM, it's the BLMA trucks.  The FVM have been flawless everywhere I've used them EXCEPT in a BLMA truck.  Remember, those reefers were the first BLMA car - I strongly suspect some tweaks were made as time went on.  I do recall that the trucks were quite tight originally - some of the wheels wouldn't roll free, and I was told to bend them out a bit, which I did.
 
I doubt humidity is a problem; the subroadbed is spline which is as rigid as it gets - even after being flooded last spring there were no problems and the humidity is kept at a fairly low level year round.

[nkalanaga]

OK, if the humidity is controlled, AND an actual flood didn't hurt the track, humidity isn't your problem!

I doubt that temperature is, either.  If the rail length changed enough to affect the gauge, and the track is that solid, it would have had break the spikes.  You'd have a prototypical sun kink, and those are fairly easy to see.  Larry P probably has the right idea - the gauge tolerance in the track is greater than the tread width will tolerate.  If you can find the wide spots, you might be able to fix them with some spikes on the outside of the rail.

[jereising]

This should illustrate my dilemma:



Treads measure .0625 and .0760

Flanges are .0070 and .0190

The narrow wheelset with low flange is BLMA, and the wide with higher flange is FVM.  And that FVM is NOT the widest I have.

Putting aside temperature and humidity considerations, it is obvious there is a problem.

All I can do is try and find a wheelset with a wider tread (and higher flange than the BLMA.

[GaryHinshaw]

It looks like the flange-to-flange spacing on the top wheel set is quite a bit larger than the bottom one.  How is the gauge maintained on that set?  Are you sure its an FVM?  (I don't see the insulator bushing I'd expect on an FVM.)  Also, does the upper set have a .540" axle?