Kato and Atlas autoracks

[peteski]

. . .
 The Atlas cars rumble when they run through them but at least they stay on track.

I was under the impression that all the grade crossings would have their top surfaces slight below the railhead level (so no part of the wheel tread would contact the grade crossing parts). What part of the wheel is contacting the grade crossing to make the rumbling sound?  Also why larger diameter wheels do not have a problem (the wheel's diameter should be irrelevant when it comes to contacting anything at or below railhead).

Or the flangeways are your problem (since flanges would be the only part of a wheel that extends below railhead)?

[MetroRedLine]

I was under the impression that all the grade crossings would have their top surfaces slight below the railhead level (so no part of the wheel tread would contact the grade crossing parts). What part of the wheel is contacting the grade crossing to make the rumbling sound?  Also why larger diameter wheels do not have a problem (the wheel's diameter should be irrelevant when it comes to contacting anything at or below railhead).

Or the flangeways are your problem (since flanges would be the only part of a wheel that extends below railhead)?

Apparently the grade crossing plates against the outside part of the rails were uneven in some areas. The larger wheels could tolerate them just fine so I didn't have an issue but these 28"s because of the narrower tread were more sensitive. When I removed the grade crossing plates, I used process of elimination and found out that the flangeways were not an issue, and nor was the plate that's between the rails.

The rumble might also be due to some CA residue that made its way onto the rail tops. Since the plates are nearly level to the track, I'd probably have to protect them with painter's tape or Tamiya masking tape to scrape them off (and them re-gleam the railhead).

[peteski]

Apparently the grade crossing plates against the outside part of the rails were uneven in some areas. The larger wheels could tolerate them just fine so I didn't have an issue but these 28"s because of the narrower tread were more sensitive. When I removed the grade crossing plates, I used process of elimination and found out that the flangeways were not an issue, and nor was the plate that's between the rails.

The rumble might also be due to some CA residue that made its way onto the rail tops. Since the plates are nearly level to the track, I'd probably have to protect them with painter's tape or Tamiya masking tape to scrape them off (and them re-gleam the railhead).

If anything, it seems to me that the narrower tread would not protrude past the outside of the rail tops as much as wider wheels.  "Sensitivity" should have nothing to do with it. It still doesn't seem to make sense to me why 28" wheels would be more affected by the grade crossing's surface being too close to the top of the railhead than larger diameter wheels.

Either way, in N scale, the goal for grade crossings is to all parts slightly below the railhead's top  (even by just 0.010") to prevent wheels from contacting the crossing's surface.

The important thing is that  you have resolved the problem of that noisy grade crossing.

[MetroRedLine]

If anything, it seems to me that the narrower tread would not protrude past the outside of the rail tops as much as wider wheels.  "Sensitivity" should have nothing to do with it. It still doesn't seem to make sense to me why 28" wheels would be more affected by the grade crossing's surface being too close to the top of the railhead than larger diameter wheels.

Either way, in N scale, the goal for grade crossings is to all parts slightly below the railhead's top  (even by just 0.010") to prevent wheels from contacting the crossing's surface.

The important thing is that  you have resolved the problem of that noisy grade crossing.

Okay, I figured it out. I forgot to add that because the stock model came with 33" wheels, and thus had trucks made for 33" wheels. By putting 28" wheels, the bottoms of the truck sideframes are lowered considerably to where they barely clear the railtops (see photo). So the derailment was most likely caused by the bottom of the sideframe being guided by the grade crossing plates and the rumbling is caused by any irregularities on the track surface (spot CA residue). The rumbling doesn't happen on the primary main, which has the same kind of grade crossing.

I might have to sand the bottom of the sideframes to allow more clearance.

[turbowhiz]

Those racks prototypically are riding on 33" wheels anyhow, so you might want to reconsider the whole 28" wheel idea if its mechanically causing grief.

[peteski]

Okay, I figured it out. I forgot to add that because the stock model came with 33" wheels, and thus had trucks made for 33" wheels. By putting 28" wheels, the bottoms of the truck sideframes are lowered considerably to where they barely clear the railtops (see photo). So the derailment was most likely caused by the bottom of the sideframe being guided by the grade crossing plates and the rumbling is caused by any irregularities on the track surface (spot CA residue). The rumbling doesn't happen on the primary main, which has the same kind of grade crossing.

I might have to sand the bottom of the sideframes to allow more clearance.

Well, that could explain the problem.

[MetroRedLine]

Those racks prototypically are riding on 33" wheels anyhow, so you might want to reconsider the whole 28" wheel idea if its mechanically causing grief.

I have researched the wheel size numerous times and the Thrall articulated bi-level auto rack introduced in 1997 rides on 28" wheels.

Car data: http://www.trainweb.org/nwrp/ttx/bttx880387data.htm

You might have gotten it confused with the larger Greenbrier Auto-Max articulated auto rack car - And yes, those do use 33" wheels.

[turbowhiz]

I have researched the wheel size numerous times and the Thrall articulated bi-level auto rack introduced in 1997 rides on 28" wheels.

Car data: http://www.trainweb.org/nwrp/ttx/bttx880387data.htm

You might have gotten it confused with the larger Greenbrier Auto-Max articulated auto rack car - And yes, those do use 33" wheels.

I've researched it too, and based on my own photographic library research, rather then just a google search, I've concluded they're definitely 33". Don't trust random internet "Facts", they're very often dubious, possibly including this post. However, if you study the photographic record of these cars in detail, I'm pretty sure you'll come to the same conclusion. I'll suggest exactly the opposite to what you've stated regarding articulated auto racks wheels is in fact what is prototypical, in clear evidence (to me at least) here:





(The automax is stenciled for 28" wheels, which won't show up in the lower res post here I don't think)

[sundowner]

Automax are 33” on the articulated truck and 28” or 33” depending on the car.

Tralls bi-level are 33” on all three trucks.

I think this was discuss here when the FVM 28” wheels came out.

https://www.therailwire.net/forum/index.php?topic=27497.msg283686#msg283686