Are All Scale Speed Motors Interchangeable?

[narrowminded]

OK, here's some mud for the waters.  I think it confirms that they're all the same speed but I just added another twist to the mix.

I have a loco that's apart that needed a motor and I ordered a new one from Atlas.  This was within the last month.  I pulled that box out as it was still apart, not finished.  That motor has the black brush holder end AND the metal case is blackened AND has the very skewed armature as pictured in the center photo.   So now I have examples of the motor on the right, the one in the center but with a black case, and the Ebay version with gray brush holder, five of the more heavily skewed poles as in the center picture, and a bright metal case.

So I took the time to place a target on the flywheels of each and read the RPM's with a digital tachometer.  The results are within 1%. 

The voltage applied to the motors is from a regulated supply and with a measured output of 11.91 volts. Let each run for a minute or so to warm up. The two mounted in locos had the trucks removed and the new Atlas motor was hand held.  So here are the RPM readings:

Atlas in loco frame:  19466 RPM
Ebay in loco frame:  19694 RPM
Atlas in hand:          19651 RPM

Meanwhile, the ultimate test, place all locos on track and run them.  The GP-38 has the Atlas motor it came with and the two SD-35's have the new motors. Performance is excellent and all three are nicely speed matched on straight DC.  I'm calling this project done!

[peteski]

Thank you all for the information about all those various version of motors, and for the English lesson. 

[narrowminded]

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)

Based on this whole exercise where I learned more than I ever wanted to know, I believe they are the same, just different terminology. 

[rrjim1]

Based on this whole exercise where I learned more than I ever wanted to know, I believe they are the same, just different terminology. 

What you have is three scale speed motors. The one you purchased from Atlas is a new version of the scale speed motor. The middle motor will turn almost 30,000 rpms at 12 volts. The difference between the slow speed motor and the fast speed motor is the skewed poles. The skewed poles were suppose to help the motor start sooner with a little less torque. IMO it never worked that great and probably the reason Atlas went to the scale speed motor. 

Some of the scale speed motors have the poles skewed a little more. Better picture.
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[peteski]

What you have is three scale speed motors. The one you purchased from Atlas is a new version of the scale speed motor. The middle motor will turn almost 30,000 rpms at 12 volts. The difference between the slow speed motor and the fast speed motor is the skewed poles. The skewed poles were suppose to help the motor start sooner with a little more torque. IMO it never worked that great and probably the reason Atlas went to the scale speed motor. 

Some of the scale speed motors have the poles skewed a little more. Better picture.

The main reason for using skewed pole armature is to minimize cogging.

So rrjim1, really how many different types of motors Atlas usede at some time or another in their split-frame N scale locos?  Originally you showed a photo of 4 types, and the 5th motor you are now showing (gray bell, silver body, and very skewed poles) looks just like the cheap eBay motors.  Call me confused.

[narrowminded]

Here are decent pictures of the motors I purchased and have assembled into Atlas locos with the addition of flywheels graciously sent from @rrjim1 .  The performance on straight DC matches very nicely with other Atlas locos I own.  Thanks again, Jim!

They show a little evidence of less than optimum storage.  The evidence is primarily a slight bit of oxidation on the PB contact strips, evident in the photos, and as I would expect if stored for some time.  It ain't much but is the only critique with any merit.  The shell, motor shafts, and all other components have no corrosion or evidence of any issues.  I don't know of anything else I can add at this point.  Enjoy!


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The rub marks on the PB strip are from me handling this motor, trying to grip and get a rigged target in place to get an RPM reading without flywheels attached.  As received they didn't have those marks.

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[rrjim1]

The main reason for using skewed pole armature is to minimize cogging.

So rrjim1, really how many different types of motors Atlas usede at some time or another in their split-frame N scale locos?  Originally you showed a photo of 4 types, and the 5th motor you are now showing (gray bell, silver body, and very skewed poles) looks just like the cheap eBay motors.  Call me confused.

Should have been less torque = smoother start, instead of more torque. Early hadn't had my coffee yet!   The picture I posted was a little poor. That motor still has skewed poles but not as much as the middle motor. Toy motors, poor manufacturing?

And yet another version - the armature.

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[peteski]

Should have been less torque = smoother start, instead of more torque. Early hadn't had my coffee yet!   The picture I posted was a little poor. That motor still has skewed poles but not as much as the middle motor. Toy motors, poor manufacturing?

And yet another version - the armature.

Now you have me confused and repeating what your un-caffeinated post stated.    I meant to say that motor's rotor has skewed poles (not the armature).    Armature is the part of the motor that doesn't rotate.

It would be very helpful if someone would show *ALL* the various version of the motors, with clear descriptions and clear photos.

[Missaberoad]

That isn't exactly accurate... The armature can be part of the rotor or the stator... On Atlas/Kato style Motors the armature is part of the rotor...

Skewed armature is an accurate discription in this case...

[rrjim1]

Now you have me confused and repeating what your un-caffeinated post stated.    I meant to say that motor's rotor has skewed poles (not the armature).    Armature is the part of the motor that doesn't rotate.

It would be very helpful if someone would show *ALL* the various version of the motors, with clear descriptions and clear photos.

Now you have me confused! The armature is made up of the commutator, poles, and shaft and does rotate. The poles part of the armature have the skewed poles. The (-) was to refer to minus the armature, meaning there isn't a armature in the motor!   

[nickelplate759]

There's a good explanation here: https://en.wikipedia.org/wiki/Armature_(electrical)

The Armature is the part that carries the electrical current (e.g. the windings).  Some motor designs (although not the ones we use in N scale trains) have the windings in the non-moving part of the motor.

[peteski]

There's a good explanation here: https://en.wikipedia.org/wiki/Armature_(electrical)

The Armature is the part that carries the electrical current (e.g. the windings).  Some motor designs (although not the ones we use in N scale trains) have the windings in the non-moving part of the motor.

The rotor-less photo rrjim1 posted made me more confused.  I thought that the rotating part of our model train DC permanent-magnet motors is called a rotor. But, as the above explanation shows, it can be called armature.  Also, the armature can be either rotating or stationary part of a motor.    At least the non-rotating part of the motor is always called stator. 

[rrjim1]

The rotor-less photo rrjim1 posted made me more confused.  I thought that the rotating part of our model train DC permanent-magnet motors is called a rotor. But, as the above explanation shows, it can be called armature.  Also, the armature can be either rotating or stationary part of a motor.    At least the non-rotating part of the motor is always called stator. 

I have never heard anyone call the armature in this type of DC motor a rotor. I have rebuild starter motors, rewound armatures, tested armatures, ordered armatures, and brushes for DC motors. 

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[DKS]

A rotor is essentially everything that comprises the moving parts of the motor, which may or may not include the armature, so the terms are not synonyms. All motors contain a rotor, regardless of whether the armature is stationary or moving.

https://en.wikipedia.org/wiki/Rotor_(electric)

 

[rrjim1]

A rotor is essentially everything that comprises the moving parts of the motor, which may or may not include the armature, so the terms are not synonyms. All motors contain a rotor, regardless of whether the armature is stationary or moving.

https://en.wikipedia.org/wiki/Rotor_(electric)

Like I stated no one that I know calls the armature a rotor for this type of DC motor. When one orders parts its a armature. AC motors, and alternators have a rotors.

  https://en.wikipedia.org/wiki/DC_motor