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  1. #1
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    Default Re-greasing An Old (ex-Sealed) Bearing.

    I've just opened up a 2hp 3ph motor which I'm hoping to use to power a 9" buzzer. Although it's fitted with grease nipples, when I got inside I find it's got sealed bearings (why do people do that - replace open bearings with sealed bearings but leave the nipples in place?).

    The bearings seem okay, but are possibly quite old (the motor dates to 1946) so I'd like to re-grease (I'm not prepared to replace them at this time). I've hooked the seal out of one side in order to clean out the old grease.

    Originally, if I understand this correctly, an application of grease through the nipple would force a little grease into the ball race, pushing a little old grease out the other side (into the motor) - and over-greased motors would be full of grease! I'd like to leave one side of the bearing open (like the original system) but leave the seal in the other side to prevent excess grease from entering the windings.

    Will this cause problems with old grease not being able to exit the bearing after a grease application through the nipple?

    Cheers, Vann.
    Gatherer of rusty planes tools...

  2. #2
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    As the bearing fills with grease it will pop the seal that is left and it will rotate on the armature shaft. This could damage the wires in the motor if it hits them.

  3. #3
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    brisbane
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    I’d just repack with grease and refit seal if it’s not damaged and plug the grease nipple hole

  4. #4
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    If you can remove the old ones, just replace them with fully sealed ones, they should only be a few dollars each.

  5. #5
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    Default Change Ďem.

    Motors bearings designed to be regularly greased need to have an overflow or relief port so they can get rid of the excess. Totally filling a ball bearing with grease is just as bad as running it nearly dry; the grease needs to melt and flow around the races. If the bearing is over full only a thin film around the moving parts gets to melt and simply gets worked to death.

    Have a real good look round the motor casing ends for a relief port or similar; if there is nothing then I really recommend you replace them for a pair of new sealed-for-life bearings. I know you stated that you werenít prepared to replace them at this stage but didnít indicate why.

    What size are they? I have a small number of NOS NSKís kicking around not being needed, if the stars align I might have the ones you want.
    A thief stole my anti-depressants. I hope heís happy now.

  6. #6
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    Nov 2009
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    australia
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    Dont be so bloody cheap, you got it apart then replace and they are good to go for many years down the track.

  7. #7
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    Quote Originally Posted by mardtrp View Post
    Dont be so bloody cheap...
    Cheap is my middle name

    I've kind of painted myself into a corner. I pulled the motor out of storage and pulled it apart without even testing it to see if it runs. So I'm loathe to spend money on new bearings if it might be wasted (I've enough calls on my limited discretionary spending).

    Quote Originally Posted by Chief Tiff
    ...What size are they? I have a small number of NOS NSKís kicking around not being needed, if the stars align I might have the ones you want.
    One end is RMS-9. The other has no marking I can see on the races, but says RMS-7RS on the rubber of the seal. I'm even loathe to fit good free NOS bearings into an unknown motor. Best I re-grease the originals and then test the motor - and take it from there.

    Thanks for all your advice folks. Good to know that leaving one side open will eventually pop the seal on the other side, so I won't do that.

    Cheers, Vann.
    Gatherer of rusty planes tools...

  8. #8
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    RMS 7 & 9 are some big-arsed bearings for only 2 ponies! I donít have any in those sizes so youíll have to repack them. First though, if there is only one seal on them you can give them a damn good clean. Put them in a clean petrol bath with the remaining seal upwards and give them a good shaking from side to side and a spin until all the old grease is out. Iíll make an assumption you know how to pack a bearing race by hand, let me know if you are unsure.
    A thief stole my anti-depressants. I hope heís happy now.

  9. #9
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    Sydney
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    If my old data sheets are correct, RMS 7 & 9 are the SKF sizes 7/8 x 2 1/4 x 11/16 and 1 1/8 x 2 13/16 x 13/16 inches respectively for medium duty single row ball bearings. Good luck in finding replacements. I suggest you regrease with a quality bearing grease; my choice would be a calcium sulphonate complex based grease provided you can completely clean out the old stuff. If not, a lithium based grease should be compatable with any grease remaining.

    Chas.

  10. #10
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    Quote Originally Posted by Chief Tiff View Post
    RMS 7 & 9 are some big-arsed bearings for only 2 ponies! I donít have any in those sizes so youíll have to repack them. First though, if there is only one seal on them you can give them a damn good clean. Put them in a clean petrol bath with the remaining seal upwards and give them a good shaking from side to side and a spin until all the old grease is out. Iíll make an assumption you know how to pack a bearing race by hand, let me know if you are unsure.
    The easiest and least messy way is to put some grease and the bearing in a plastic bag, twist the neck of the bag tight against the bearing and then push the grease into the bearing. make sure you use a strong plastic bag or you may as well not bothered. you could remove all the seals and use the grease nipple also which may be the easiest way.
    CHRIS

  11. #11
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    Quote Originally Posted by Chief Tiff View Post
    ...Iíll make an assumption you know how to pack a bearing race by hand, let me know if you are unsure.
    I'm unsure. I have heard of the plastic bag method that Chris Parks mentions below.

    Quote Originally Posted by Chas
    ...my choice would be a calcium sulphonate complex based grease provided you can completely clean out the old stuff. If not, a lithium based grease should be compatable with any grease remaining.
    I have a tube of electric motor bearing grease (that the boss told me I could have, if I put it in my car immediately - he was expecting a safety compliance audit and couldn't track down the SDS sheets for it. He needed it binned or removed without delay). Happy to help boss..

    It's UNIWRL EMB Electric Motor Bearing Grease, a Fuchs product (hah, good thing there weren't two tubes ) by Century Lubricants Co., Kansas City, USA. Suitable?

    Cheers, Vann.
    Gatherer of rusty planes tools...

  12. #12
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    Quote Originally Posted by Vann View Post
    I'm unsure. I have heard of the plastic bag method that Chris Parks mentions below.

    I have a tube of electric motor bearing grease (that the boss told me I could have, if I put it in my car immediately - he was expecting a safety compliance audit and couldn't track down the SDS sheets for it. He needed it binned or removed without delay). Happy to help boss..

    It's UNIWRL EMB Electric Motor Bearing Grease, a Fuchs product (hah, good thing there weren't two tubes ) by Century Lubricants Co., Kansas City, USA. Suitable?

    Cheers, Vann.

    The SDS info on the 'net has proved elusive for that particular EMB grease; its' components are listed on the specificr SDS as 'trade secret'.

    http://sds.chemtel.net/docs/Fuchs%20...15_English.pdf

    However, the Fuchs series of UNIWRL greases from Century Lubicants are identified as being a lithium complex grease of high quality, and the Timken equivalent table indicates it would be most suitable for your application.

    Chas.

  13. #13
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    Sorry Vann; I completely missed your comment earlier.

    Ok; to re-pack a bearing you hold a small amount of grease in the palm of one hand; then holding the bearing by one edge in your other hand you "scrape" the bearing into the grease so your palm forces the grease between the races. You only need to put a small amount in your palm and just keep scraping it into the races until it's all gone.

    Normally you'd keep on going until the grease is forced all the way through to the top of the bearing; however if you are keeping a grease seal on one side obviously that's not going to work very well. Just scrape in as much as you can WITHOUT ROTATING THE BEARING just yet, turning the whole bearing until every visible gap in the races is filled. Then you can spin the bearing a few revolutions, and repeat the packing process until you can't get any more in.

    Last thing is to use a finger to scrape out all the grease running along the sides of balls; the grease that you've spent all this time putting in. What remains between the balls and the remaining seal is enough to adequately lubricate the bearing; they really don't need that much and what is there will quickly get hot and melt into a liquid, providing better lubrication than a semi-solid grease.

    This is a messy job; you can wear gloves but I've never bothered. Chris' bag idea may have merit; I've never tried it but I can see how it would work. The only issue I can see with it is that you may need to have a lot more grease in the bag than you actually need to do the job so there may be a potential waste issue. Many bearings being packed obviously would reduce that down as it would be a finite amount left over, whether it be one or one hundred bearings.
    A thief stole my anti-depressants. I hope heís happy now.

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