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I was given a dual Pulmor motor Lionel F3 IC 8580. The engine appears to be in really good shape. Both motors also appeared to be in really good shape.

I ran the engine and heard what I can only describe as a horrific combination of screeching and grinding.

After greasing the worm gear, plastic drive gears and adding a drop or two of oil into the armature port at that the top of each motor, the screeching was no more. But what I did notice was the armature exhibited quite a bit of "float" while spinning (see video below. Sorry for the sideways video.....that was easiest way to record the spinning armature with the engine laying on its side). If you zoom the video you'll see the armature float much better.

I measured the amount of vertical play for each armature. The front motor armature moves vertically .8 mm. The rear motor armature moves .6 mm. Is this normal? I'm wondering since these motors are so clean looking; someone worked on them before and lost/left out a few parts?

This is my first foray into working with older Pulmor motors, so I'm hoping one of you could provide some insight.

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Pullout Motor Video
Last edited by Junior
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Hi Bill...if you're talking "gravity"; I'm embarrassed to say I didn't think of that. I was just focused on creating a video.

Hi WBC...  .01 inch/.254 mm is about 1/128 inch.  WOW! Parts are definitely missing. I will pull the motors apart to see what's missing.

I'm pretty sure thrust washers at the top are missing. I would think I should be able to see them above the commutator.

Here's a pic of the top of the motor with the brush housing pulled up.

20210427_162309

As we guessed....no thrust washers.

I took a look in my "Complete Service Manual for Lionel Trains" book (by K-Line) for that motor and it had the same picture you provided.

1619566787291287972617

But....neither shows thrust washers above the commutator. I'm beginning to think the problem might be below the armature where the bearings are?

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  • 20210427_162309
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This motor style would not need thrust washers under the brush plate. Vertical play should be constrained by the E-clips above and below the bronze bushing. Possibly one or more washers are missing in that area.

It is also possible that you have lateral play, so that the rotating armature is contacting the stationary field. Try turning it with your fingers and see if it scrapes. This could happen if the bushing is worn, or bored oversize; or if the field is assembled slightly rotated with respect to the die cast motor base.

nickaix: I pulled apart one of the motors last night. I didn't notice any lateral play, but didn't specifically check for it either. I will check for that today.

GRJ: I have the Lionel Steel Switcher and seem to recall the instructions for that engine provide steps for adjusting that set screw (which I did do).

The F3 came with the original instructions. I'm guessing those will provide a positive indication whether the engine/motors should (not) have those set screws.

Thank you both for your thoughts on what else I should check.

The 2028-100 motor (used in F3s, GP7/9s, EP5s) has no set screw to adjust armature vertical play. If there is too much vertical play just add additional 671M-23 thrust washers either above or below the armature bushing to adjust it. MPC/LTI/LLC 2028-100 motors were assembled slightly more sloppy than their postwar counterparts. I've seen several locomotives with this motor from the 90's with extra thrust washers from the factory on either side of the thrust bearing (instead of the usual one on each side of the thrust bearing) to adjust the vertical play. Adding extra thrust washers is fine, it won't hurt anything.

Lou1985 & GRJ....

Checked the original Instruction sheet....

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No mention of a set screw at the top motor housing.  I already sent an email to my Parts Guy to confirm he has the Thrust washers, bearings and bushings etc. in stock.

In the meantime, I'll check the motor armature for lateral play.

Thank you so much guys! Your help will allow me to get this engine in tip-top shape in no time.

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nickaix: I checked for lateral movement on the armature. If there is any, I can't really tell. Also, there's no scrape marks on the armature itself.

Everyone: I was fiddling with the armature and the following question came to mind. If I add a thrust washer onto the bottom of the washer/bearing set (just above the worm gear); that will pull the armature down and create more space between the commutator and the brush plate. But that will also center the armature vertical in the field coil.

But if I put add a Thrust washer onto the washer/bearing set just beneath the armature windings that will raise the armature putting the commutator closer to the brush plate and put the armature slightly out of center with the field coil.

Any of you have thoughts on which is more suitable?

Last edited by Junior

This may be a dumb question, but what the heck . . .

Is the purpose of setting the vertical play to cause the brushes to have appropriate pressure  against the commutator?

If Yes, then should one have a new set of brushes in place when setting it?  If No, ignore me.

Brush springs get weaker due to heat.  If you run your engine hard, replacing them can be a good move; certainly cheap.

The very early postwar motors  (2333 etc) had brushes with a very high copper content  (as evidenced by their color).  Does anyone provide such a version today?  I am assuming they have better conductivity then the more common ones available  (could be wrong, of course).

Whining of a motor, for me , has always been a dry interface between the top of the armature and the brushplate (the bushing in the brushplate  and the armature shaft, to be clear).  Very distinctive sound.   Whistle tenders, too.

thanks!

John

Last edited by CPF3

The reason for controlling the clearance in the thrust bearings is to keep the commutator from hitting the under side of the brush holder and to avoid impact loading the thrust bearings. And on early motors, to keep the balls from falling out.

There is no change in the strength of steel due to heat until above about 1100 degrees F.  Unlikely the brush springs run that hot.

Lionel used three different brushes in the post war era. They had carbon brushes, which are black and fairly light; they had copper graphite brush, which is black with a copper cast to them and are heavier; and they used a copper coated brush, which are a copper color, but the copper wears off the contact surface, which is then black.  New brushes are only available in carbon. NOS of the other two types can be found, but are getting rare. Brushes need to have significant resistance to control the current flow when the brush shorts across the commutator slots.

Hi David....I believe your post just answered my question regarding the vertical positioning of the armature/commutator vs. the motor's brush plate.

Sounds like I should add the extra Thrust washer(s) directly above the worm gear. This will pull the armature down, centering the armature in the field coil and providing more space between the commutator and the brush plate.

Hi Nickaix - Yes....and that sound is WAY better than the combination screeching-grinding I heard initially before lubricating it! 🤯

During the lubrication process is when I noticed the amount of vertical movement of the armature.

I didn't see any evidence of the armature scraping on the field coil.

FYI....I ordered a complete set of Thrust washers and all bearings including the sleeve bearing.

Last edited by Junior
@Junior posted:

Hi Pete....

Yeah....I'm thinking the same thing. I think I'm gonna order 8 of the Thrust washers and 4 of the Thrust bearings (just in case they fall apart). Worst case is I'll have extras for my parts inventory .

"just in case they fall apart"

My recommendation would be to double your numbers of how many to get.  Here's my reasoning:

  1. They're relatively cheap

  2. They won't spoil or go bad in your parts drawer

  3. You might someday purchase an engine with the same issue

  4. During reassembly, when one squirts out your grease-covered fingers and flies in a graceful arc to some location that's completely inaccessible ... or completely invisible ... or both, your family won't have to hear those special words sometimes heard in the train room. 


Don't ask me how I know...

Steven J. Serenska

Last edited by Serenska

Ok, if you still have the sound, then I still think you have contact between the stationary field and the rotating armature. That is just the sound I would expect with that. You should not have that sound. The motor should be virtually silent. When you check for contact you have to remember that the armature is going to try its hardest to contact the stationary field in some manner. The motor works because magnetic fields are fighting with each other: things are not going to stay in alignment unless constrained. When you check for contact, try to push the armature as far our of alignment as possible, rotating with your fingers, and see if you can't find a contact point. It need not be a large area, perhaps just a burr somewhere, or a corner. Looking closely at this photo, I see a suspicious shine on the top corner of the armature segment. Looking even closer, I see faint abrasions, not yet through the paint, on its leading edge.

@Junior posted:

20210427_162309

It may be that reducing the vertical play is enough to fix this, since that will also reduce the lateral deviation slightly (imagine the tilted armature shaft as the hypotenuse of a triangle). If it still persists, then I would be looking for an oversized bearing, or else out-of-alignment plates in the stationary field. Some file work might fix the latter problem. Or a hammer (carefully, of course!).

Nickaix....Thanks for all the great symptoms to check for....great stuff!

I will definitely check for all those and see what I find. Parts are on order and should arrive some time next week.

I probably won't post anything until next week. Out-of-Towners are arriving today for the weekend. My Wife LOVES to entertain so... you know.....happy Wife, happy Life! 😁

@nickaix....

The replacement motor parts arrived today. I already disassembled one of the motors and checked for armature "wiggle" with the existing bushing. Yep....there's quite a bit of wiggle.

I slipped a new bushing onto the armature shaft and tried the wiggle test...no wiggle that I can tell.

My question to you (or anyone else following this endeavor ) is; is the armature bushing just a friction fit or is it pressed into the motor housing? I'm hoping a little light "tapping" will free the current bushing from the motor housing.

@Junior

I have not yet needed to replace this particular bearing, but I know that the bearing / sleeve in the similarly-made horizontal motor used on the berkshire chassis is pressed in. Not with a great deal of force. If it were me, I would approach it with a length of wooden dowel and a small hammer.

Maybe someone who has replaced these will chime in, though.

@nickaix, et al .....

The new bearings are in both motors. Bearing replacement went pretty smooth....but ran into one issue.

Neither of the armature shafts would slide all the way through one of the new bearings. The other armature shaft/bearing fit like a glove.

I measured both armature shafts and they measured 3/16 inch.

Needing something of substance to hold onto, I pressed the troublesome bearing into the motor housing, held my breath and drilled out the problematic bearing on my drill press. The bearing slid right onto the armature slicker then snot! Phew!

Bottom line; both motors hum like new....and for open frame motors run very well.

Here's a quick video of the final results....

Thank you all for your help!

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MPC-Lionel Rebuild
Last edited by Junior

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