Intermountain SD40-2

[mu26aeh]

I picked up a Kato SD40-2 a while back from @sundowner a while back.  He has a strip of what I think is painters tape cut to fit length of truck, wide enough to cover the holes in bottom of truck.

[sundowner]

Yes, painters tape. I do this to all of the Kato's that come with the screwless mech to keep out all the fine junk that messes up the work.

[AKNscale]

The other big differences are that the top(big) gear is slanted, not straight, much like the forward gears in a manual transmission and the axle/gear sleeve isn't the full length of the axle so the truck frame actually rides on the axle, not the sleeve.

[Mark5]

The design is so different that the axle gears are totally hidden by the bottom of the gear case.  So the gearing must be different too.  I have also not (yet) taken it apart but the glaring difference is as I said that there are no gears poking through slots in the gear cover - there are no slots!  That in itself signifies a major difference.

Is this discussion about the Atlas S-2 trucks? (thread drift?)

[peteski]

The other big differences are that the top(big) gear is slanted, not straight, much like the forward gears in a manual transmission and the axle/gear sleeve isn't the full length of the axle so the truck frame actually rides on the axle, not the sleeve.

Interesting. Now you made me take mine apart.    It is not quite like that.  The wheelset axles float (do not touch) the gear box walls.  The  truck uses the standard (what Victor Miranda called CAPP) bearings.  Pointed axle ends ride in metal sideframe bearings/pickups, just like most of today's N scale models.  The inner axle design is different but the gear case is not supported by the inner axle.

As far as the slanted teeth go, that is the worm-gear. Most worm gears have slanted teeth to match the slant of the tooth on the worm.  That is normal and considered the best practice.  In some different designs the slant angle is barely imipercivable and some designs have what appears straight-cut teeth on the worm gear (not the best design practice).

This different truck design is due to the fact that this loco does not use the standard split-frame design. The  chassis/frame is a solid 1-piece casting. It uses wires to transfer electricity from the trucks to the circuit board mounted on top of the chassis.

[peteski]

Is this discussion about the Atlas S-2? (thread drift?)

Yup - sure is!   
Don't we fully expect this on TRW?

[Mark5]

Cool, so do the S-2 wheels have a more proto appearance? If so are they swappable as a retro-fit to other "modern" Atlas locos?

[peteski]

Cool, so do the S-2 wheels have a more proto appearance? If so are they swappable as a retro-fit to other "modern" Atlas locos?

Welcome to the thread drift.  No, these will not work in the "standard" Atlas trucks.  The inner axle/gear is totally different.  They do have much nicer lookinig wheel faces thought.

As far as retrofitting goes, those nice and fairly inexpensive Kato wheelsets (which look even better than the S-2 wheels) are almost a drop-in fit into Atlas trucks. The half-axles just need to be pushed in a scoobitch.  This retrofit has been discussed few times on TRW (including retrofitting them into BLI diesels).

[mu26aeh]

Come on !  You're supposed to figure out how to wire this new decoder to allow for flashing ditch lights 

Back to your S-2 thread 

[mu26aeh]

I took the prime mover/start up down to a value of 50 for the volume, much better.

[SkipGear]

So what is the verdict? After all the "it's intermountain, they will screw it up like the tunnel motors...." is there some crow to be eaten? Ours showed up at the shop Saturday and even though I am a steam guy, I picked up a CSX w/sound just because it was too nice to pass up.

[Philip H]

I've been I the "wait and see" camp on these, and so far I'm decently impressed. Might just have to get a KCS grey when they are out.

[sundowner]

So what is the verdict? After all the "it's intermountain, they will screw it up like the tunnel motors...." is there some crow to be eaten? Ours showed up at the shop Saturday and even though I am a steam guy, I picked up a CSX w/sound just because it was too nice to pass up.

That CSX unit has the wrong trucks for the road number, they are suppose to be flexicoil.

[mu26aeh]

That CSX unit has the wrong trucks for the road number, they are suppose to be flexicoil.

Seems like an opportunity for a Shapeways product.  I did find a set that @dcutting did for the early Kato.

This does not bother me though.  I don't know the difference.

[SkipGear]

That CSX unit has the wrong trucks for the road number, they are suppose to be flexicoil.

I'm a steam modeler. I live on compromises and close enoughs. It runs good, looks better and 95% of the people couldn't tell and honestly don't care about the difference in the trucks so it doesn't bother me. If it ever does, I will renumber to a correct version. I know it is something simple that IMR could have done themselves but I'm not going to crucify them over it. There are road names coming that Kato doesn't even have a clue exists and we would never see without IMR doing these. My customers are happy they are here finally.