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Deja Vu
04-09-2010, 06:23 PM
I have this 12VDC hydraulic pump motor that has an alignment problem.....the brushes are not fully contacting the commutator's surface. (see pic of brushes). They are held by the brush cage so that they wear off the end of the commutator.
Now, I have thought of mounting the cage in a four-jaw chuck and turning down the "fingers" so that the brushes would track fully on their intended surfaces.
Another option would be to remake the coupler to the pump (see pic of coupler) and extending it so the commutator tracks properly under the brushes. This would also require adding extra thrust washers inside the end plate of the motor. (see pic of "fiber" thrust washer).
I suppose I could go with a third "sir John" option by welding up the shaft end of the motor and recutting the slot for the coupler.

I cannot detect any wear that might have caused the brushes to run off the end of the commutator. This pump/motor is off of an older forklift type stacker. It just seems to have originally been designed improperly.
I've already cleaned up the commutator which had a sizable ridge where the brushes made contact, so now they can be moved to their proper location.

What would you guys(gals) do to remedy this...

http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/Motor%20assembly2.JPG

http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/Motor%20Brushes.JPG

There is room for brush cage to lower, and the bearing with wavy washer has room to better seat in cage.
http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/Brush%20Holder.JPG

Turn fingers on cage and deepen register slot?

Deja Vu
04-09-2010, 06:36 PM
Here's some extra pictures.....

http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/Over-all%20pump.JPG


Maybe turn down the "fingers' and registration slot to move cage down the commutator?
http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/Brush%20Cage-1.JPG

bob_s
04-09-2010, 06:51 PM
Make deeper brush cages, with insulating spacer on the outside to maintain full brush contact with the commutator

winchman
04-09-2010, 06:52 PM
I'd just trim the corner off the brushes so they won't hang over the end of the commutator as they wear.

It's just pathetic that the manufacturer never checked to see how the parts are fitting together, and even more so if he did check and didn't care.

Deja Vu
04-09-2010, 06:56 PM
Make deeper brush cages, with insulating spacer on the outside to maintain full brush contact with the commutator

That's an idea! But the whole unit is stamped together with quite a few(8)
hefty rivets...although I could drill them out and replace after adding spacers.

rolland
04-09-2010, 06:56 PM
Add or subtract spacers until you get the brushes lined up correctly. that is where you get the power, if part of the brush is off the edge or incorrectly alined you will loose power. Once you get the brush rack and brushes correctly alined then adjust the front plate with the correct spacers.
You should not have any endplay on the armature.

jack3140
04-09-2010, 06:57 PM
Here's some extra pictures.....

http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/Over-all%20pump.JPG


Maybe turn down the "fingers' and registration slot to move cage down the commutator?
http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/Brush%20Cage-1.JPG
i would shim the brushholders to realign them with the commutator with insulating material such as glastic i would not attempt to change the position of the armature in the field housing good luck

Deja Vu
04-09-2010, 07:01 PM
I'd just trim the corner off the brushes so they won't hang over the end of the commutator as they wear.

It's just pathetic that the manufacturer never checked to see how the parts are fitting together, and even more so if he did check and didn't care.

The brushes will be replaced ( of course). There are no parts available for this model anymore, so I will try to match at the automotive shop. They seem to be the same found in general earlier starter motors.

for what I'll be using this for, I think I could do that. (shave off the brushes).

MrSleepy
04-09-2010, 07:03 PM
The wavy crinkle washer is important as it allows the armature shaft to expand and contract under pre load..so you shouldnt do anything that calls for its removal.


Rob

Deja Vu
04-09-2010, 07:21 PM
I should mention that the end bearing and wavy washer have room to go further into the seat. The brush holding cap where the bearing seats seems to be too far away from the bearing as the wavy crinkle washer doesn't appear to have any compression when assembled. It remains loose.

Would there be any problem by turning down the fingers of the brush holder in a four jaw to add the missing compression to the crinkle washer?

I'm thinking that the intermitant contact with the tool would tend to possibly cause a problem. This whole procedure would also move the brushes completely over the commutator.

If I shim the other end to remove endplay, the slotted coupler will have less bearing and would be prone to wear.

P.S. as you can see, I'm trying to avoid taking all those rivets out...:(

Arcane
04-09-2010, 07:35 PM
It's hard to tell from the pics if there is room or not, but could you space the armature back farther with a washer on the end opposite the brush holders? You might have to make a slightly longer adapter but that's a small operation.

Glenn Wegman
04-09-2010, 07:39 PM
Are you sure the wavy washer does not belong in the other end so it preloads the armature into the brush end of the motor?

Deja Vu
04-09-2010, 07:48 PM
Are you sure the wavy washer does not belong in the other end so it preloads the armature into the brush end of the motor?

Not the one that is pictured. It fits perfectly into the bearing pocket on the brush holder. The other end would require a new size for the washer as it is a bronze bushing straight through. The inside DI of the "fiber" thrust washer on that end is the motor shaft diameter.

This whole setup seems "unfinished" to me. I mean...the fiber thrust washer takes all the load from the armature and maintains clearance for the slotted coupler. I was surprised it wasn't worn out.

winchman
04-09-2010, 08:02 PM
If you can find shorter brushes, you could make H-shaped spacers to fit in the gap between the brushes and the riveted ends of the brushholders. That would position all of the shorter brushes on the commutator.

Not having full contact on the brushes may be a cheap way to "derate" the motor so it won't overheat. Doesn't do the brushes any favors, though.

That's an interesting little shaft extension in the lower left of the first picture.

Deja Vu
04-09-2010, 08:05 PM
Here's a pic of the pump with the coupler. The aluminum motor end plate sits on this. The coupler does not bind, nor is it too loose.
http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/Pump-1.JPG

914Wilhelm
04-09-2010, 08:48 PM
Have you measured to see how far the armature slops back and forth? Probably easier to shim the armature to place it fully under the brushes. Bet a thrust washer is gone or worn out.

darryl
04-09-2010, 08:59 PM
I'd start by figuring out how much the rear housing could come in to remove all the play from the wave washer area, then see how well that matches with the amount the brush holder needs to move. It looks like you could machine some off the endbell to bring the rear bearing in somewhat, and if you removed that same amount from the fingers- would that be enough to move the brushes?

I can't tell if the endbell comes into contact with the brush holder, but if it does then the endbell is acting as a heatsink for the brush holder. If you have to remove more off the fingers than you take off the endbell to bring the bearing in closer, then take an amount off the fingers to allow an aluminum disc to be sandwiched between the brush holder and the endbell.

Of course if the brush holder is secured to the motor, and the endbell just goes on far enough to contact the brush holder and stops there, then you won't have to machine the endbell at all. You will have to consider the difference between what is required to move the bearing and what is required to move the brush holder.

Personally, I wouldn't muck with the individual brush holders, just the entire assembly. I'd also be quite inclined to sand off the protruding part of each brush, then re-use them. It looks like you could get at least as many more hours out of those as they have run already, providing they aren't so short that they rack sideways in their holders. I'd also want to seat them against the comm and run the motor unloaded for a bit before putting it back into use.

Deja Vu
04-09-2010, 09:20 PM
The end bell does nothing other than keep in the worn copper..:D
Two scews lightly secure it to the brush holder with a space between the two parts. It fits to the lip of the motor housing.

That motor was packed with grime. So much so, that I suspect the brushes are worn at least a 1/4 inch. Now that you mention the brush wear, I'm starting to think that maybe they had a "wedge" edge and tapered in a little at the edge of the commutator. They do rack a bit.

I think from the "looks" of it that by modifying the brush holder and tool grinding the chucked brush assembly's seating fingers, enough could be taken down to both proprly seat the brushes AND bring the bearing with spring washer to correct tension depth into the brush assembly's bearing pocket.

As far as anything having been broken or disintegrated inside, I found no evidence of particles other than copper mixed with oil creating a dry "sludge".

P.S. I sure wish I was up on the correct terminology for all the individual parts...I could communicate so much better...;)

Deja Vu
04-09-2010, 09:38 PM
This is the bearing in the brush cap as it looked when assembled.
Lots of space for further seating with the spring washer.
Notice all those lovely rivets for holding the brush guides? I'd hate to have to remove those.
http://memberfiles.freewebs.com/78/43/42124378/photos/Bearing%20in%20Brush%20assembly.JPG

Don Young
04-09-2010, 09:38 PM
I see nothing whatsoever wrong with the design of the brushes or their holders. That is a common design that has been used in auto starters since the 1920's. There definitely is a problem with the armature location with respect to the brush holders. There are several ways to correct it, depending on other relationships. The armature must go into the end housing far enough to locate the brushes properly and must not have excessive end float. From what I understand about the situation it seems that a proper spacer at the opposite end is all you need. If this does not provide proper engagement of the drive, then work on that problem, probably by just making a longer coupling. In the worst case, the housing could be trimmed on one or both ends to get things right. I would make no attempt to modify the brushes or their holders. A good auto starter rebuild shop should be able to sort it out for you.

Deja Vu
04-09-2010, 10:14 PM
Okay, here's the plan. I will chuck the brush housing up as shown but mounted to the machine, turn it by hand to the four indexes created by the fingers, and gently rotate each finger across a grinding tool mounted on the crossslide. The amount to be taken off will be determined prior to setup by assembling the motor and making the required measurements. Hope it works out!

If I had a rotary table I could mill the fingers to depth. Gotta get one of those...

I'll post later as a progress report....and of course, lots of pictures.;)

http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/chucked%20brush%20housing.JPG

bruto
04-09-2010, 10:21 PM
I would have to agree with Don Young above that you'd do better to try to move the armature back a little by shimming it at the output end. If that doesn't work, you haven't done anything irreversible.

gunbuilder
04-09-2010, 10:26 PM
I would have to agree with Don Young above that you'd do better to try to move the armature back a little by shimming it at the output end. If that doesn't work, you haven't done anything irreversible.
I guess I will go along with brto, in my work you always modify the cheapest part.

So that is why I go with his words of wisdom. I would remake the shaft coupler to push the armature in fully, if I am understanding this correctly.

Thanks,
Paul

Deja Vu
04-09-2010, 10:34 PM
Okay Okay...I promised you a progress report...

Change of plans.... will now leave the three-jaw chuck on the lathe.
Moving to the mill, I will attempt to make an "extended" coupler by clamping the appropriate diameter stud in the vise and shaving a tab on its end, then reversing and clamping the tab in the vise to cut a slot. Intermediate actions may/will be required.

Whew! Above procedures are subject to change....

Arcane
04-09-2010, 11:25 PM
I think that's going to work best for you. You have to consider, the factory has made several hundred at least and probably thousands of these motors. There's always the chance they buggered up the measurement on the brush holder, but I think it's unlikely. A spacer on the other end that has gone missing at sometime or other is highly possible and very probable. Besides, it's always nice to not make a permanent alteration to something unless you absolutely have to. :)

Deja Vu
04-09-2010, 11:45 PM
I also flirted with the idea of turning down the motor baseplate (after removing the roll-pin indexer).
The thing is, as is, the coupler now has just the right clearance when meshed. The fiber washer on the picture below supports the armature just right for proper mating of the coupler. So when I entertained the idea of trimming the plate, the entire motor housing would be lowered, bringing with it the brushes, while the armature stayed as is.

But you all are right....best to do what is reversible first rather than possibly muck something up permanantly. Although, if I took too much off the aluminum base plate I could add a shim/spacer back on to it.

http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/motor%20base%20plate.JPG

J Tiers
04-10-2010, 12:00 AM
I think I'd file the corners, figure it for maintenance periodically, and get on with existence..........

Deja Vu
04-10-2010, 12:08 AM
:D Heck, JT, I was having fun posting pictures. In fact I'm getting primed for adding to the "projects-past and future" threads. :)
....just getting into how to efficiently take and post pics.

This hydraulic pump along with the nice 6' ram and lifting rig will go alongside the house into an access hole(that I still have to dig) to raise things up and down to the basement. ...Can you imagine lifting up the wood table saw and letting the sawdust fly(outside) and then lowering it quickly especially if it decides to rain?

Oh yeah J Tiers, any place you might prefer me to do my existing?:confused:

winchman
04-10-2010, 02:53 AM
It wasn't obvious in the first pictures that there was so much room for the ball bearing to move in its bore.

It's been my experience with similar motors (for my winches) that the armature thrusts toward the output end when running. That's the reason for the thrust washer there.

It looks like you could put everything in the correct place by adding a spacer behind the thrust washer on the output end and making a longer shaft extension.

None of that would be irreversible. Make the spacer first to get the armature in the right place, then make the extension to fit.

Deja Vu
06-28-2010, 11:16 PM
Update!
http://memberfiles.freewebs.com/78/43/42124378/photos/pump4.JPG

wierdscience
06-28-2010, 11:54 PM
Okay,looks like museum quality now.:)

Did you under cut the comm?

oldtiffie
06-29-2010, 01:19 AM
I think I'd file the corners, figure it for maintenance periodically, and get on with existence..........

+1 JT.

Or is it just too easy and was just asking to be "worked up" into a problem?

Deja Vu
06-29-2010, 10:13 AM
Okay,looks like museum quality now.:)

Did you under cut the comm?

I've grooved or undercut other commutators, but this one appeared to be originally smooth as evidenced by the untouched portion of the comm by the brushes.....That is, if you are talking of the gap between comm surfaces.
I could be wrong, but some types of motors/starters if grooved would capture conducting bits of material causing shorting.

Tell me I'm not negligent/lazy for not setting up a grooving/slitting apparatus on the crosslide when I have to do other things.;)

wierdscience
06-29-2010, 02:38 PM
I've grooved or undercut other commutators, but this one appeared to be originally smooth as evidenced by the untouched portion of the comm by the brushes.....That is, if you are talking of the gap between comm surfaces.
I could be wrong, but some types of motors/starters if grooved would capture conducting bits of material causing shorting.

Tell me I'm not negligent/lazy for not setting up a grooving/slitting apparatus on the crosslide when I have to do other things.;)

That Mica does a great job of not wearing down and making brushes jump/arc and burn comm bars,but it's up to you;)

Deja Vu
06-29-2010, 03:17 PM
That Mica does a great job of not wearing down and making brushes jump/arc and burn comm bars,but it's up to you;)

You're right....I'll find time to do that before I completely assemble and put this pump into use.:o
I can't be certain that the composition of the insulating material isn't Mica, nor that it wears at a rate more than that of the copper/alloy.

The Fixer
06-29-2010, 04:04 PM
over complicated because the K.I.S.S principle was not applied!

Deja Vu
06-29-2010, 07:02 PM
Before the "fix":
http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/motor%20base%20plate.JPG

After the fix:
http://memberfiles.freewebs.com/78/43/42124378/photos/motor-and-pump/motor-pump%20adapter%20plate.JPG


So simple....chuck it, turn it.....The hardest part was making a path to the lathe.:rolleyes: Now the wavy washer has about 75% compression. Before it was loose and then some. The brushes track fully on the commutator. No fooling with making a coupler. And it is reversable by making shims to replace any overly removed material.

Don Young
06-29-2010, 10:15 PM
A high current motor of that type is similar to an auto starter and generally uses rather hard low resistance brushes that are usually copper in color. The commutator should not be undercut for that type of brushes. Undercutting can result in the brush material shorting the commutator bars and will also cause short brush life. The old auto generators (as well as other DC motors and generators) use the soft high resistance black brushes and for those the commutator does need to be undercut.

Glad you got the alignment problem solved.