[Boston&Maine]

I have not been able to run my trains for a while, so why I waited so long to ask this question is a mystery to me, LOL... Here is the deal... I have a 6-axle MTH diesel... The outer two axles on each truck have flanges on the wheels, but the inner axle on each truck does not... Obviously this allows the train to negotiate tighter turns since the "wheel-base" is shorter...

Anyways, the minimum curve for this particular diesel is an O-42, but I ran it on the next size up, O-54... Sometimes when the train would go around a curve (all my curves were 1/4 a circle), the inner side of the axles that did not have flanges on them slipped down next to the inner side of the rail... This would create a popping sound when the train exited the curve as the wheels were forced back onto the rail, and it just does not seem like it could be any good for the rail or truck...

So my question is, is this normal behavior? Like on my steamer, the axles that do not have flanges are fixed in place, but for some reason on this diesel they have room to move and this allows it to dip below the rail... I am just curious...

 

[T-Man]

It doesn't make sense for the wheel to slip off the inner rail. Check the measurement of the middle wheel set difference or any play. The distance should be wider. Are the center wheels drive wheels? ANother explanation is a compatibility issue with the track.
Also what happens on to the outer wheel?
Also what happens when the engine is turned around going in the opposite direction?

 

[Boston&Maine]

It doesn't make sense for the wheel to slip off the inner rail. Check the measurement of the middle wheel set difference or any play. The distance should be wider.

The wheels measure the same distance apart as the ones with flanges... There is no side-to-side play, but as I said they move up and down... To get an idea, when the train is sitting on rails, the flangeless wheels can not be pushed up any more... When the train is picked up though, the flangless wheels drop down to the point where they are flush with the flanges on the other wheels (what is that, like 1/8 an inch?)...

ANother explanation is a compatibility issue with the track.

I doubt it, MTH train on MTH track...

Also what happens on to the outer wheel?

The wheel on the outer side of the curve stays on the rail...

Also what happens when the engine is turned around going in the opposite direction?

Nothing different, the inside flangeless wheels will sometimes slip below the rails on the inner side of the curve...

 

[T-Man]

The axle must be floating side to side. Being flangeless it should stay on the track but handle a greater width of track to the inside and outside of the wheel. Depending on the position going into the curve.
Perhaps the outer axles are not wide enough? If they are tight within the rails the inner axle should stay on.
Are these your UP beauties?

 

[Boston&Maine]

Are these your UP beauties?

LOL, si Senor...

 

[T-Man]

Try inquiring at MTH. Maybe they had a recall.
I checked OGR they have alot of MTH owners. One discussion was about Mike of MTH visiting Charles RO in Malden. I have yet to go there.

 

[Boston&Maine]

Well, after doing some searching, I have noticed that some of the 6-axles have the flanges on the outer axles on each truck... Some examples:

I checked, and even the newer AC6000's have the setup like mine... These have been in storage for a while, but I think I am going to get them and try to swap the wheels so they are setup like in the pictures above... Maybe this will fix the problem? I do not see what it could hurt :dunno:

 

[Boston&Maine]

These have been in storage for a while, but I think I am going to get them and try to swap the wheels so they are setup like in the pictures above... Maybe this will fix the problem? I do not see what it could hurt :dunno:

This will not work as the problem wheelset is not geared...

Anyways, since I never remember to take pictures of mine, I happened to find a picture of it online... You can see how on the front truck, the inner wheelset's outer wheel is very close to the edge of the rail, if not off the rail... I guess this just boils down to bad design :dunno:

From: http://www.ericstrains.com/modern_trains/mth.php