A LOOK INSIDE A PITTMAN MOTOR

Now, that's just plain KOOL. Thanks.

Alex, what's it going in???  What's the diameter and where did you get it (if it's new)?

Hi Bob

My apologies, I should have explained that in my original post. This is an old Pittman that came out of a Lionel Niagara that I'm repairing, there's a huge amount of play between the armature shaft and the bearings, which is screwing up the speed sensor trying to read the magnet on the flywheel. So I'm going to order a new motor. I took this old one apart to see if there was anything I can to to reduce the amount of play , but there's nothing I can do. 

Thanks

Alex 

Alex,

This is the engine we were speaking about on Saturday at TrainStock, correct?. Amazing, your description was right on.

K

Alex, did you clean the motor before taking the pics? If not it looks like its hardly been run.

Pete

That is from the CCII Niagara, they don't run too long. Bad gears - we are working on a solution with Lionel and a whole host to forum members.

Norton posted:

Alex, did you clean the motor before taking the pics? If not it looks like its hardly been run.

Pete

Hi Pete,

I cleaned it up a bit, but there's a huge amount of play between the armature and the bearings, it's the worst I've ever seen.

Alex

You can get new bearings from Pittman, you can also get brushes if you need them.

If there's just end-to-end play, why not add some shims and put it back together?

Alex M posted:

Norton posted:

Alex, did you clean the motor before taking the pics? If not it looks like its hardly been run.

Pete

Hi Pete,

I cleaned it up a bit, but there's a huge amount of play between the armature and the bearings, it's the worst I've ever seen.

Alex

Alex;

Too bad about the bearing play because the armature and the brushes look pretty darn good. I wonder if that one managed to slip through the line without lubrication?

gunrunnerjohn posted:

You can get new bearings from Pittman, you can also get brushes if you need them.

If there's just end-to-end play, why not add some shims and put it back together?

John,

Would love to take the end to end play out of this motor, that would save me from ordering a new one.What kind of shims can i use, i just want to stress this is the worst end to end play I've ever seen. There's more than 3/16 inches of play. In the past I've noticed they develop a bit of play, but not like this one.

Alex

I'd just find some washers that fit over the end of the shaft, sized to just go over the shaft.  Obviously, the smaller the outside diameter, the better.  You can arrange them on whatever end they make sense to align the brushes properly on the commutator and then put it back together.

Alex you can just use washers. You want the ID of the washer to just slide over the shaft. 3/16 is pretty bizarre. Any chance something was preventing the the ends from closing all the way?

Pete

Thanks Pete, and John for this info , i will take up the play with the correct size washers and see if it resolves the issue. Pete the ends were tight to the center section, no play at all.

Alex

Alex, FWIW I have a couple of these same motors. Both have virtually zero end play. Typically when these are new the armature is no more than .030" shorter than the case. Usually less than that. It should only take one or two shims about .010" to eliminate the end play. Thats why I think something else is wrong. The motor case should measure 2.400" when bolted together tight.

Pete

Pete 

Take a look at these few photos ,first one is the measurement of the case. The next two are the shaft from the back. You will see in the picture if I don't pull on the shaft how it's looks. Then in the next picture look at the huge difference of how far in the shaft goes when I pull on it from the opposite side. I also have the same motor here from another engine which has no play at all 

Rod Stewart posted:

Alex M posted:

Norton posted:

Alex, did you clean the motor before taking the pics? If not it looks like its hardly been run.

Pete

Hi Pete,

I cleaned it up a bit, but there's a huge amount of play between the armature and the bearings, it's the worst I've ever seen.

Alex

Alex;

Too bad about the bearing play because the armature and the brushes look pretty darn good. I wonder if that one managed to slip through the line without lubrication?

Hi Rod 

yes I agree with you 

thanks

Alex 

john, my experience with pittman on parts,  you need to order I think it was a 100 each part,, they won't sell  one  or two,  I have a pittman apart,  brushplate is different,  plus its all ball bearing,  I would look for ball bearings for the end pieces,  I get  them out hear at VXB bearing, that is also web site,  VXB.com bearings.

Alex, I measured mine with dial calipers and was within  couple of thousands of 2.400". I read your rule at 2 5/16" which is about 2.312" or .088" shorter. Not what I would have expected. It is also marked 9434F827-R1.

Anyway looking at the armature travel, you should be able to shim it with washers. 

Pete

Nice size motor.

I tried Googling Pittman 9434F827-R1 and got very little info, but everything I saw pointed towards this being a "gearmotor".

Could it be that they took a bunch of gearmotors and removed the gearhead, but didn't change the housing (maybe the housing is longer when used with the gearhead) before they put them in the engines at the factory?

This is a SWAG, just throwing it out there.

Looks like the commutator has been slid up a bit on the shaft, perhaps from an impact.  Look at the wear pattern from the brushes, they have moved down near the edge of the commutator.  I think I'd put most of the shims on the long shaft side to center the brushes on the commutator again.

Pittman's are no doubt heavy duty quality motors. The pictures do not look like this version is designed to accommodate thrust loads.  As for trying the shim method, if you go to a store with a large hardware selection like a True Value or Ace store, you can find miniature metric washers than you can use to take up the play.  Hope that this helps to save what looks like a near new motor.

BTW, the shims should probably go under those grease shields on the armature.

All that's happened is the commutator has been pushed towards the armature as those are 2 separate pieces. Using a jaw puller the commutator can be pulled back into position and all end play eliminated. Pull the commutator until the windings are tight then assemble motor with factory shims. If armature won't spin then tap the armature shaft with a hammer until it spins and end play is correct.

Excessive end play is usually from dropping motor on armature shaft or incorrect pressing on of flywheel, u-joint etc. Have to press against the armature shaft and not the motor housing.

Casey Jones2 posted:

All that's happened is the commutator has been pushed towards the armature as those are 2 separate pieces. Using a jaw puller the commutator can be pulled back into position and all end play eliminated. Pull the commutator until the windings are tight then assemble motor with factory shims. If armature won't spin then tap the armature shaft with a hammer until it spins and end play is correct.

Excessive end play is usually from dropping motor on armature shaft or incorrect pressing on of flywheel, u-joint etc. Have to press against the armature shaft and not the motor housing.

Trying to pull the commutator down will likely result in more issues than simply shimming it at this point.  I agree that it probably happened as the result of a drop or other impact, already said that.  There's no easy way to grab the commutator without damaging the connecting wires.  Since the motor can be made to run quite nicely shimming it, I'd go for the safe option and not risk ruining the motor.  Also, the shims are much easier to do.

There are shim washers at both ends.  I count them when disassembling.  I have actually been successful taking a good armature out of a pittman that had damaged bearing and other issues with the magnet, and putting it in a motor that had a burned armature.

If you have other Pittman motor you can salvage thrust washers from it, or use post war shim and place between the Pittman shims.  If it had them in the first place.

Also lubricate the bearing internally while apart. 

EDIT.  Looking at your picture it is missing shims.  Maybe some one else had this apart before.  Usually 2 to 3 at shaft end, and 1 at brush end. G

GGG posted:

There are shim washers at both ends. 

True, however in this case I believe the object of the exercise is to center the brushes on the commutator that has slipped due to impact or pressure on the shaft.

Hello everyone,

George you're totally correct, some one else worked on this entire engine. To be totally honest it's been a nightmare to say the least. I will never understand why if a person isn't qualified why would they butcher an engine. Let me give all of you the list of things i found when i started on this nightmare, first thing i found was the wrong length screw holding down the mother board. the screw was so long it made a huge grove in the driveshaft, second  the flywheel was crazy glued to the shaft of the motor,third  the speed sensor was installed wrong and there was also crazy glue on it, fourth every screw i needed to remove in this engine was the wrong size and they were also stripped, fifth once i saw how much play there was in the motor shaft and i opened the motor up i found the situation i have now.  Lastly the smoke unit was taken apart and put back together like a mess, also there's more that i found i just can't remember right now.

   George as you and the other guys said there definitely is shims/spacers missing because the butcher was also inside this motor. So i decided to make my own shim/spacer out of nylon, and i must say it worked like a charm.I bench tested the motor for 30 plus minutes and she's runs like new with no enf to end play, it will be a while before i can test this engine on the track because there's lots more to repair on this engine before i can put it back together. 

As always thank you all for the great info and input in this thread. I always say if you want to learn something always search the OGR forum.

Here's a couple of photos of the nylon spacer i made.

Thanks,

Alex

Looks good Alex, onward to the new problems with it.

Could this have been caused by the lack of a TORQUE BRACE...?

(Search my posts about "Torque Brace" and the Niagara on another thread)

This loco has a separate gearbox, which appears to lack a torque brace.  When power is applied, the gearbox will want to rock forward or aft, possibly placing thrust loads on the motor.

Most large steamers going all the way back to the 700E have their gearbox cast into the frame (which is actually an inferior design from a serviceability standpoint.)  However, with a cast-in gearbox, well-placed ball thrust bearings can absorb the thrust load, which means all the motor has to deal with are axial (rotation) loads.  This contributes to smooth operation and durability.

I agree with GRJ, it looks like the commutator slipped down toward the armature, leading to the excessive thrust play you're seeing.  [Note: You can often tell if a Pittman motor was opened up by a user, if the label was cut through.  The label covers the motor body and the end bell, so to disassemble the motor you have to peel or cut the label.]

To prevent the commutator from slipping toward the armature again, it might be necessary to add a torque brace to the gearbox, thus preventing it from rocking toward the motor.  Very nice job on the nylon bushing, you've absorbed most of the slack.  However... if the commutator has already slipped all the way down on its shaft, now when the gearbox rocks toward the motor, there will be a thrust load at the aft end of the motor.  This binding could be observed as high current draw (and slower rpms in the absence of closed-loop speed control.)

I might be way off base with these speculations, because I've never seen one of these Niagaras in person (only the exploded diagrams on Lionel's website, and photos here on the forum.)  But as much as I like the idea of a separate gearbox, if they're not properly anchored to prevent rotation, the loco may not run as well (or be as trouble-free) as one with the typical cast-in gearbox and captive axles.

My $.02, thanks for sharing Alex.  -Ted

Hi Ted,

    Your post is so well put and spot on, I'm already having this problem, The gearbox is now thrusting forward and locking up, this was next on my list to figure out some kind of brace, if you or anyone else have photos of one please post it here.

Thanks,

Alex

And the beat goes on...   I'll bet you regret taking this one on!

I use the barrel w/ magnets to keep my screwdrivers magnetized. 

Another solution to dealing with the gearbox torque is to use a telescoping U joint. That would eliminate any thrust on the motor. This is how Williams has done it. Compare the gearbox and U joint to the Lionel setup. Hopefully if Lionel rereleases their Niagara they will offer something along these lines.

Pete

Glad it worked out Alex.  So that commutator did not move, if it did I would think you would have a bent shaft and bearing issues too.  The shims go on the bearing side of the shields also.  The commutator marks are from the excess thrust causing brushes to rider in different areas of the commutator depending on thrust.  Both fwd, reverse and pulsing depending on load.  I was very happy when I salvage a motor now that they are north of the $70 price.  G

I'm not sure how we determined the commutator didn't move.  Something moved to allow all that slop.

Thanks for posting that photo Pete.  The telescoping U-joint is a good feature.  Not only does it prevent most fore-and-aft movement from affecting the motor, it also creates some forgiveness in fit between the gearbox and the motor or flywheel.  But it looks like the gearbox in your picture DOES have a torque brace.  See the horizontal arm below and to the right of the gearbox, just above the frame?  I would guess the other end of it is anchored to the chassis somewhere between the last pair of drivers.

 I

The Williams Crown Edition steamers were made by Samhongsa / SAMtech, a company with a lot of experience in HO scale brass.  These were excellent designs (although I would replace that 3-pole RS-550 motor with the equivalent 5-pole RS-555 motor.)  IMO this is how a scale steam loco should be built.  If you can graft a brace like the one in Pete's (Norton) picture onto the gearbox in the Lionel Niagara, most of your problems will be solved.

As an aside-- Mike's Train House (Mike's original retail business before he became an importer) sold Williams brass, and one of their employees even offered a service to upgrade the Niagara, FEF, etc., to a Pittman motor.  So they knew about the advantages of a separate gearbox.  Why then, did MTH revert to the cast-in gearbox with captive axles when they began offering scale steam under their own brand name?   Instead of embracing the best accepted engineering principles, and creating a loco with great potential for upgrades and customization, they went back to a prewar toy train design, and set an unfortunate precedent which continues to this day.  What a shame!!  What burns me even more, is that when MTH diversified into HO-scale, those locos DO have a separate gearbox.  Not that it does us any good.  Grrr... 

Looks like the commutator has been slid up a bit on the shaft, perhaps from an impact.  Look at the wear pattern from the brushes, they have moved down near the edge of the commutator.  I think I'd put most of the shims on the long shaft side to center the brushes on the commutator again.

I don't remember what happened, but my son did something to my Dremel motor tool that caused the commutator and windings to move on the shaft. I ordered a new armature assembly from Dremel, and then decided to try to move it back. It worked! I still have the replacement if the need arises.

gunrunnerjohn posted:

I'm not sure how we determined the commutator didn't move.  Something moved to allow all that slop.

How did we determine it did move?   What I saw was there were no thrust washers on the motor.  I think Alex's comment about other issues he found lead him to believe the motor was taken apart.  It is easy for those thrust washers to come off via the magnet when pulling the motor apart.

As a note, it is best to remove the shafted end cap first.  Keeping the brush end cap on.  Push the armature out, vice pulling the brush end cap off.  This allows you to lift the brush to remove, vice pulling them off the commutator.

Ted, the Brass Williams do have a brace and going to the 555 is better if you don't want to go to a pittman.  That is what I did on my N&W J.

Lets not forget that while not a universal slip joint, MTH uses a dogbone that can slide up and down.  The gear box has bearing and thrust washers allowing some play, and any motor thrust (movement of the flywheel) does not effect the worm drive as the dog bone collar just moves.

On articulate the universal drive is used.  So both MTH and Lionel have adapted this type of drive for big steam.  I am not sure why one would be better or worst than the other at this point.  Other than MTH/Lionel doesn't require a third idle gear.   G