Are All Scale Speed Motors Interchangeable?

[peteski]

That's what I wanted to hear that the motor would not turn faster than 12,000 rpms. I could not see any indication that they are balanced like an Atlas motor?   I don't really need any but for that price I went ahead and ordered some any way.

Like I have mentioned earlier, the technical specs for many of the eBay items from Chinese vendors are way out in the left field.

[Kentuckian]

I just completed a totally unscientific survey of my Atlas GP7/9 collection. I looked at nine units bought over a period of several years. Three of them have the old high speed motors, and all of these were packed in the old white vacuum formed plastic tray, not foam. The ones packed in foam, regardless of if it was white or gray, all had the slower motors.

High speed plastic tray:





YMMV, past performance is no guarantee of future results, etc.

[narrowminded]

I received two sets of flywheels from @rrjim1, assembled them to a pair of motors and installed in two locos.  As all investigative data suggested and now test running confirms, they are perfect replacements in all ways for Atlas Scale speed motors.  Thanks, Jim.   And thanks to all for your helpful suggestions and information.

I will profer the theory that the motors on Ebay are actually part of what is being liquidated from the failed Chinese contract builder.  I don't know that but it's a theory that makes sense, viewing from afar.   

[peteski]

I received two sets of flywheels from @rrjim1, assembled them to a pair of motors and installed in two locos.  As all investigative data suggested and now test running confirms, they are perfect replacements in all ways for Atlas Scale speed motors.  Thanks, Jim.   And thanks to all for your helpful suggestions and information.

I will profer the theory that the motors on Ebay are actually part of what is being liquidated from the failed Chinese contract builder.  I don't know that but it's a theory that makes sense, viewing from afar.   

Could you clarify?  Are the motors on which you installed the flywheels those motors with gray plastic end bells from eBay seller?

Also, what is "profer". A word I have not seen before. After after almost 40 years  in U.S., still learning English.

Plus, we still don't know what is the difference between slow-speed and scale-speed motors. 

[CRL]

Profer definition is - to put forth or before : bring forth or out.

[narrowminded]

Could you clarify?  Are the motors on which you installed the flywheels those motors with gray plastic end bells from eBay seller?

Yes.

Also, what is "profer". A word I have not seen before. After after almost 40 years  in U.S., still learning English.

You've obviously done pretty well with your English.   You made me look up profer where I found it can also be spelled with two f's.  Apparently it is used more in the legal profession these days.  For me, it's further evidence of misspent youth without a TV but with a well worn library card.  I have no other idea how such a word made it into my bag of tricks.

Plus, we still don't know what is the difference between slow-speed and scale-speed motors. 

I'm only aware of two different speed motors with these physical dimensions.  The older faster one and the newer slower one.   I would consider slow-speed and scale-speed to be  synonyms and would understand either one to be the newer, slower motor.  If there are variants beyond that it would be new to me.

[mmagliaro]

This is positively maddening.   

So... Atlas definitely used the term "slow speed" motor.   You can find that term in their description of the classic GP-35, for example:
https://shop.atlasrr.com/c-736-n722.aspx

According to Spookshow's loco review website, the 2006 class GP-35 was the first to get the "slow speed" motor.

Whether the "slow speed' and "scale speed" motors were different, or were just different terminology used by Atlas to refer to the motor, has been an argument of debate on numerous forums (just do a web search on "Atlas scale speed motor" and you'll see)

Has anybody from Atlas ever clarified this, and am I just so overwhelmed with posts on this subject that I missed it?  They would be the ones who know for sure.

[MK]

Maybe we can ask @Atlas Paul ?

[rrjim1]

Here is a link that shows some Atlas chassis. The first one has the slow speed motor with black end bell. The second one has the scale speed motor with gray end bell. The third is the latest version of the scale speed motor. I have found three different motors of this type in Atlas locos, high speed, slow speed and scale speed.
 I have been on a search to make my old locos run as well as my newer locos. My original RS3s and RS11, with a crappy high speed motor, high gears and traction tires were IMO terrible. Now with the gears from the U25B, no traction tires, and a scale speed motor they run IMO great.

http://www.spookshow.net/loco/atlasgp3840.html

 

[MK]

Here is a link that shows some Atlas chassis. The first one has the slow speed motor with black end bell.

You mean high speed?

[rrjim1]

You mean high speed?

No that's the slow speed Atlas motor, the high speed motor came in the first Atlas locos with this type of motor. The chassis with the high speed motor has the sold frame chassis were you can't see the motor.  If you call all the motors the same how would you tell the difference?

[rrjim1]

From left to right fast, slow, scale.
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[u18b]

From left to right fast, slow, scale.

Notice other difference not mentioned.

The motor in the middle is skewed (the gap in the poles is slanted).    The motor on the right has straight poles.

If I was picking the very best (other factors equal) , I'd want skewed.

[rrjim1]

Notice other difference not mentioned.

The motor in the middle is skewed (the gap in the poles is slanted).    The motor on the right has straight poles.

If I was picking the very best (other factors equal) , I'd want skewed.

The motor on the right, (scale speed) does have skewed poles, just not as much as the middle one. I will take the one on the right, it's by far the better motor for my locos.   

[narrowminded]

The motors I installed the flywheels on and then installed in two SD-35's are skewed as the motor in the center of the picture but have gray brush holder ends.  Another newer unit that has the original motor in it has the gray brush end with the straighter poles as pictured to the right.  The are very slightly skewed but nowhere near the same amount as the center one or the ones I used with the gray brush ends.  So maybe there is a third configuration.  I may get out the tachometer and try to get a reading of these two different motors' speeds at 12 volts.