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  • How would you fix it?

    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...





    There is room for brush cage to lower, and the bearing with wavy washer has room to better seat in cage.


    Turn fingers on cage and deepen register slot?
    John M...your (un)usual basement dweller

  • #2
    Here's some extra pictures.....




    Maybe turn down the "fingers' and registration slot to move cage down the commutator?
    Last edited by Deja Vu; 04-09-2010, 07:52 PM.
    John M...your (un)usual basement dweller

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    • #3
      Make deeper brush cages, with insulating spacer on the outside to maintain full brush contact with the commutator

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      • #4
        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.
        Any products mentioned in my posts have been endorsed by their manufacturer.

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        • #5
          Originally posted by bob_s
          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.
          John M...your (un)usual basement dweller

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          • #6
            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.

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            • #7
              Originally posted by Deja Vu
              Here's some extra pictures.....




              Maybe turn down the "fingers' and registration slot to move cage down the commutator?
              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

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              • #8
                Originally posted by winchman
                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).
                John M...your (un)usual basement dweller

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                • #9
                  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

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                  • #10
                    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...
                    Last edited by Deja Vu; 04-09-2010, 08:32 PM.
                    John M...your (un)usual basement dweller

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                    • #11
                      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.
                      Location: Saskatoon, Saskatchewan, Canada

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                      • #12
                        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?

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                        • #13
                          Originally posted by Glenn Wegman
                          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.
                          John M...your (un)usual basement dweller

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                          • #14
                            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.
                            Any products mentioned in my posts have been endorsed by their manufacturer.

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                            • #15
                              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.
                              John M...your (un)usual basement dweller

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