Speed issue in Lionel Postwar 681-100 motor

Are you absolutely certain that your commutator plate, brush wells, and brushes are clean?

I had motor on my desk recently that would not run nicely until I used some extra fine emery cloth to clean up the commutator. And I have had motors that needed to have their brush wells burnished with a brass rifle barrel cleaning brush to make good contact with the brushes.

The original bearings on your 681 motor are Oilite oil impregnated bearings. While I don't know what Jeff has available, some of the reproduction motor bearings that I have seen are turned brass. The original bearings would have to be pretty bad for me to replace them with brass ones.

C.W.

Thanks for popping up. The brushes are new and I did clean the commutator with green Scotch Brite and contact cleaner (followed by alcohol). The brush wells were cleaned with contact cleaner on Q-tips. I suppose I could open it back up later and clean that stuff with wet/dry sandpaper to see if it makes a difference.

Yes, I was/am a bit reluctant to swap out the bearings. Doing it mainly because it's something I've never done before and wanted to learn how to do it. But it will be a last resort if nothing else pans out. Doesn't seem to be a lot of possibles as the motor does this even separated from the chassis. 

Roger

The brush wells were cleaned with contact cleaner on Q-tips.

Sometimes that's not good enough.
The tip to use a gun barrel brush is something I picked up here.

I have even gone as far as replacing the brass inserts that are mounted to the diesel brush plate when they were misshapen or damaged.

I did clean the commutator with green Scotch Brite and contact cleaner (followed by alcohol).

I don't know how using a Scotch Brite pad would compare to using fine emery cloth. I try to avoid using emery cloth because it does remove material. But sometimes this cannot be avoided.

I have mentioned before that alcohol will attack the insulation on at least some Lionel armatures. I ruined a few by using alcohol before I realized what was happening. I prefer to use pure mineral spirits.

I think I have a gun brush somewhere. I'll give it a shot.  The green Scotch Brite shines up commutators real well. Much more abrasive than the blue.   Going to take a close look at those brush tubes this afternoon.

Could it be the armature that's not 100%?

Roger

You might also try a pair of shunted brushes. Is the armature original to the motor? Is the armature itself tight on the shaft?

C.W.

I found the brush, so I will give that a shot later. By the way......if you're at York, I'll be helping Jeff again with his booth. Stop by

Roger

Chuck,

Coincidental that you mention those brushes. I've been meaning to order a set from Jeff for quite awhile to see how they work.  Next order

Roger

Chuck,

Yes, the armature appears to be original and it seems tight, although later when I take it apart again, I'll double check that

You might also try a pair of shunted brushes. Is the armature original to the motor? Is the armature itself tight on the shaft?

I overhauled a 2056 that really benefited from installing a pair of shunted brushes. With non-shunted brushes it ran poorly and the brush holders quickly got very hot. The shunted brushes resolved the issue.

I stocked up on them during the last Lionel factory parts sale.

If it runs faster in forward as you posted I would count myself as lucky. Most times they run faster in reverse. I tune my motors by rotating the brushes in the brush holders while the motor is running in the forward direction. Use a super light touch while doing this. I listen to the sound of the motor. The better / faster it runs - the nicer the sound. I don't care if it runs slower in reverse. Note that if you take the brushes out, they have to be adjusted again. Sometimes trading brushes from one brush holder to the other makes a big difference. Shunted brushes, once soldered in, can not be adjusted. Shunted brushes do compensate for poor tolerances in modern versions of postwar motors. A whole other story.

Is it possible that the commutator slots have a lip on one edge and a ramp on the other? That would cause the brushes to drag in one direction and run smoothly in the other direction.

BigO,

The motor runs slower in the forward direction. When I get one that goes slower in reverse, I ignore it as I don't run engines fast in reverse. And to be fair, this one is not "slow", it's just that there's a difference in speed and I don't think there should be. 

RoyBoy,

I looked at the faces of the commutator under my big illuminated magnifier and it/they appear flat.

C.W.,

I just cleaned out the brush tubes with the gun barrel brush till it shines. Recleaned the commutator surfaces. No change. Also......Jeff sent me Oil Lite bearings. We'll see if that makes a difference. 

I also did some ohm tests....connected the faces of the commutator and got 1.3ohms for each combination.  

We seem to be narrowing down the possibilities here, but so far, no luck

Roger

Most of my experience is with larger motors, but some may apply to Lionel motors.  The commutator should not be polished, it should be chocolate brown.  A commutator that is a raw copper color is wearing the copper.  The brushes are probably too hard.  A commutator that is black has carbon on it.  The brushes are probably too soft and are leaving carbon on the commutator.  If a commutator is chocolate brown it should be cleaned with a solvent and not sanded.  

If the commutator face is not smooth it should be sanded using very fine garnet paper.  The harder abrasives, like aluminum oxide, will embed into the copper and increase brush wear. The method I use is I have a very flat steel plate with an 1/8" clearance hole drilled in it. Punch a 1/8" hole in the sheet of garnet paper, line the holes up, and put the armature shaft through the holes.  Rotating the armature will sand the commutator face keeping it flat and square with the shaft.

On larger dual direction motors some times there is a problem with wear on the sides of the brush box and on the sides of the brushes. This allow the brushes to cock a little wearing a slight angle on the face of the brush. When the motor runs the other way the brush cocks the other way and wears an angle in the other direction.  This can be seen when the brush is removed as a line across the face of the brush, which would sort of be the ridge of the roof shaped brush face.  If the motor is run mostly in one direction this ridge line will favor one direction causing the motor to run with a little less power in the other direction.  Under size new  brushes would cause this same problem.

The ideal location for the commutator bars is to slightly lead the armature coils.  This will improve commutation and add a little power.  But in a dual direction motor this is, of course, not possible.  Lionel does this on some there accessory motors that run only in one direction.  On a locomotive motor the commutator slots need to be centered on the armature coils. The commutator is a press fit on the armature shaft and it is possible for the commutator to move a little from its proper location, limited by the slack in the coil leads.  If this happened it would result in different motor operation depending on the direction.  Checking that the commutator is properly located would be worth while.  I guess the commutator could been mislocated when installed at the factory.  In this case it's mislocation would not be limited by the coil leads. Lionel has been known to have manufacturing errors in the past.

On most post war motors the e-unit reverses the power to the armature coils by reversing the connections to the brush holders.  If there is short to the iron near one end of the coil, it will make little difference in one direction but will be significant in the other direction. Testing for resistance from the commutator segments to the motor shaft should detect this.  However, most meters are using a fairly low voltage to check for resistance. When looking for insulation failures a Meger is usually used to get the voltage high enough to find insulation problems.  I do not know what to suggest here. 

Another potential problem is that between the under side of the commutator and the armature coils there is an 1/8" thick felt pad.  I assume it there so they have something to press the commutator on against without damaging the armature coils.  Over the years this felt pad can get a fair amount of oil and carbon dust on it making it conductive to some degree. It could be causing problems by allowing a conductive path, bar to bar, and bypassing some armature current.  When ever I remove a commutator I put a new felt pad in.  

Please let us know if you solve your mystery. 

That's quite the thesis on electric motors, Dave. Much appreciated interesting information.  In all likely hood, the problem lies with the armature. The easiest solution would be to swap it out. Unfortunately, they are not easy to find for this motor. I can live with this issue as the engine runs smooth and is a very good puller. I'd like to solve this, though. My new bearings will arrive middle of the week, so we'll see what happens when I swap them out. 

And C.W.    .........I have read your posts about using alcohol on motors and your preference for mineral spirits. However, I ran out of my last container of "real" mineral spirits.  The new stuff that I bought a while back lacks the VOCs and looks like skim milk. Is that what you use?  I hesitate to use that stuff for fear it would leave some kind of residue

Roger

Speaking of armatures.......this just popped up on the "Bay...........http://www.ebay.com/itm/Lionel-Modern-Era-Service-Station-Replacement-Part-681-Type-Motor-Armature-/152232712275?hash=item2371c6d853:g:KfMAAOSwvzRXz6TN

It's modern era, but supposedly fits. Worth considering?

Roger

That sounds like the stuff with water in it.  Last mineral spirits I bought I had to get on Amazon as I could not find the water free stuff locally. If anybody knows why they are adding water to mineral spirits please post it as I would like to know. 

With paints, stains and finishes like Polyurethane etc, they contained VOCs and they phased them out (nasty stuff). They went with water base for everything. I just this past week had my wood floors refinished and it was all water base. I have to say.......each coat dried in about an hour and there was almost no odor. The drying and smell was always one of the worst part of the process. That's gone now, but the dust.............

Roger

No you DON'T want to use a modern MPC style 681 armature. It is electrically imbalanced from the original field windings. It is wound to operate at a lower voltage than the original 1950's version, and needs a modern field to match. It will operate hot and run slower than if you used an original 681 armature. 

Thanks, Chuck.  I have nothing in my collection that is MPC.  Another reason why, I guess.

More than likely it is an armature with slow timing. The commutator can be rotated forward in relation to the motor poles, and that will speed it up. When I raced slot cars I always found armatures  with a little slack in the wires so I could advance the timing, even made a gauge for it with a protractor. Over timing will lead to a hot running motor but it sure tunes them up, wanna win a train race, now you know...

The new stuff that I bought a while back lacks the VOCs and looks like skim milk. Is that what you use?

As David wrote, that sounds like the stuff that is cut with water. I won't use it.
The last time I purchased mineral spirits, I found it at our local Ace hardware store. It is a very well stocked place.
I did not see it at the big box store.

David Johnston: What grit garnet paper do you use, and where can it be purchased?

The main reason I've used emery cloth is because I have it in rather fine grits.

I was curious about your comment on using garnet versus aluminum oxide, so I did a little internet hunting.
According to what I read, most "emery cloth" that is available today actually has silicon carbide or aluminum oxide grit (some of my stuff is rather old).

But even if you have real emery paper, other web pages say not to use it on commutators because the grit includes metal particles.
What about silicon carbide cloth, is it ok for commutators?

A couple of sites list garnet "commutator paper", but I did not see ordering information. I suspect they don't sell the small quantities I would probably be interested in purchasing.

Bob,

The springs are new. It had the same issue before I put them in as well as after. And when you push down on the brush springs it doesn't speed up appreciably, so that doesn't appear to be the issue.

Roger

If you can't get it to run right, I have a factory new original 681 armature. Or send me the motor assembly.

Bob,

I may just do that. I am going to try one more thing. As I wrote above, I ordered the two motor bearings from Jeff (should arrive mid week). I'll swap them out. If that doesn't work, I think the only thing left is the armature. Thanks

-Roger

Chuck,

I mistyped "Bob" in the above. Sorry.....it was meant for you

CW, I was always told to use garnet paper on commutators because it was non-conductive and non- embedding, so I really cannot comment on alternatives. I use 220 grit, sometimes known as extra fine or very fine.  You should try eBay. I have seen it there.  Large motors use drum style commutators and the motor maintenance supplers sell garnet paper in long rolls to accommodate these coms. Garnet paper is also used by the fine woodworking people so that is another place to look.  Commutator maintenance is (was) a big business and there are lots of clever tools sold for this field. But the Lionel design does not allow access to the commutator when the motor is running, so most of them can not be used on their motors. 

A rubber track cleaning eraser block works great for cleaning armatures. 

As does a green Scotch Brite. Plus.....it doesn't leave behind any debris or fragments

I don't use abrasive paper to clean armatures. I have a fiberglass brush for that. The abrasive paper comes in when the commutator needs more attention to physically smooth the surface.

This outfit discontinued the particular brush that I use, but they still make similar ones. I think their E111/F is probably the closest to the one I use. Charlie Clark used to sell them.

Well, guess what? I think it's fixed. I know that lightning will strike me, but so far......it's corrected.  Here's what happened. I had a couple of discussions with Bob Hannon, who has written several books on Post War trains. He was especially concerned with the old bearings. The new ones were supposed to arrive yesterday, but the Post Office screwed up and sent them to the next town. I'd never put in motor bearings before and he told me that many times, even with a press (which I don't have), the internal diameter of the bearing gets a bit deformed and the armature won't fit unless you use reamers to reopen it. So, I went down last night to practice on the old ones and mic them for fit. Then I noticed some kind of deposit on the shiny areas of the shaft (where it goes through the bearings). Rubbed it down with some Scotch Brite till it was smooth, pressed in the bearings, reassembled and clipped up to power. Voila! The speeds seemed almost (if not) the same. Did timed tests on the layout and the engine ran around my loop, forwards and back at the same speed. I then compared it to my other 736 and it came out the same. So.....I was very happy and was getting ready to clean up and I noticed that my other 736 was making banging noises and that  was the start of a long night. I think it's got quartering/side rod issues and at one point, I was testing it pulling a load and a side rod rivet sheared off and the engine crashed out. That engine had been problematic with it's wheels/axles when I first got it, but hadn't had issues for a number of years.    This fits the category of "you win some, you lose some".

Roger

 I'd never put in motor bearings before and he told me that many times, even with a press (which I don't have), the internal diameter of the bearing gets a bit deformed and the armature won't fit unless you use reamers to reopen it.

I put the shank of the tightest fitting drill bit that I have in the bearing before pressing it in place. Seems to prevent the issue. I have a full set of fractional, number, and letter bits. They come in handy for things like this.

C.W.

Do you press the bearing in with the shank inside of it?    I was considering doing that with the armature shaft, but ended up just pressing them in because I thought I'd be popping it right back out. 

Do you press the bearing in with the shank inside of it?  

Yes, when it's possible.