How to remove pinion gear and seized bearing from vacuum motor
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  1. #1
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    Default How to remove pinion gear and seized bearing from vacuum motor

    Hello Machinists,

    I'm trying to replace a seized up bearing on an electric motor from the power nozzle of an old central vacuum. I'm a guy that likes to fix things instead of buy new, but I want to make sure I'm actually able to remove the gear and bearing before purchasing a replacement. The original bearing was an NMB 608S.


    I've attached some pictures of the armature of the vacuum motor. I need to remove and replace the bearing on the gear end of the shaft. I'm at a loss of how to remove the gear (and subsequently the bearing) from the armature. My guess is that the gear is press fit on the shaft, but I'm at a loss as to how to remove it. Do I need to do something with the pin thru the gear at the end of the shaft?

    img-0062.jpgimg-0065.jpgimg-0064.jpgimg-0063.jpg

    Thank you in advance for any advice that you can provide. I'm always interested in learning something new.

    Thanks,

    Kyle

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    looks to me like the shaft probably has a groove near the gear end. The gear was pressed on then staked in three spots forcing metal into that groove or maybe three little holes? You will have to shear that metal off as you push the gear off. It may damage the gear. If you get it off use locktite to install the new one.

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    That last picture looks like the end of the shaft is mushroomed or swadged into the 3 groove. If so that complicates things.
    Assuming that is NOT true.
    Make a keyhole shaped hole through a plate that is thinner than the length of the gear
    Big hole clear the flange on the gear, small hole close fit to teeth od.
    Drop plate over flange and slide sideways to support the gear 1/2 way around the underside of the flange.
    Put in a press and push on the end of the shaft with a pin to remove gear from shaft.

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    Bill, Erich,

    Thank you very much for the advice. The shaft does appear to have 3 or 4 grooves in it, but they are not apparent until you are past the bearing and motor fan. The shaft just past the gear is smooth.

    My guess after reading your comments is that the main shaft was reduced to a smaller diameter to allow the pinion gear to be mounted. I'm not familiar with the term mushroomed, but if the small "pin" I see on the end of the pinion gear is actually the shaft at a reduced diameter, then I can confirm that it is wider than the hole in the pinion gear, with a mushroom like cross section that would help to hold it on.

    Erich,
    Thanks for the explanation of building something like a DIY bearing puller. I should be able to give that a shot. Given that the smaller shaft has a slightly "mushroomed" top should I still go about it the same way?

    Thanks for any additional thoughts you have.

    Kyle

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    My guess is the motor shaft is 4mm diameter and it is only mushroomed to hold the washer on, which keeps the belt on the cog pulley, which is press fit.

    You can pry the washer off. Clean up the shaft protruding out of the pinion with a file.

    Get or build a two piece bolt together bearing puller for that 608 bearing, support it ridgedly on something heavy, like steel or concrete blocks, not wood. (if you don't have an arbor press). Find a short 1/8 diameter pin punch and hammer the shaft, taking the bearing and pinion off at the same time.

    You will want to be very careful as one off axis strike will mushroom the shaft.

    An alternative is to file the pinion down so its 8mm outside diameter and leave it on. The belt wont last as long but my guess is it will survive

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    Before trying to remove the bearing, see if you can free it. Most likely has dirt in it from the vacuum.

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    What does the gear turn? And most universal motors have the impeller directing the air flow right through the motor/winding's to cool them down. May be clean air, or almost clean air. Check the wire and commutator before repairing it. Wire could be sandblasted and ready to short, comm maybe sim situation.
    Sometimes the best tool is the dumpster. Scrap bin does not work because you will see it and not be able to stop yourself from taking it out. Reach out to us before taking it out, we are here to help.

  10. #8
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    A small bearing splitter may be able to get under the bearing and pull it off.
    Bill D


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