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  1. #14
    Join Date
    Jun 2012
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    Northern NV
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    I honestly never knew that sleeve bearing were ever installed on a condensing unit for a/c... Always was ball bearings as they last longer and handle the thrust load better. Only real shortcoming is they are nosier which is why sleeve bearings are used in the indoor a/h.

    Fractional hp refrigeration condensers? They tend to go with unit (sleeve) bearing motors. Probably because they are located in the same equipment indoors.

    Some of the new R290 coolers I'v had are using box fans. Much nosier than the unit bearing ones..

    Sleeve bearing probably fails sooner with propeller type air mover as they have a high thrust load.

  2. #15
    Join Date
    Nov 2011
    Location
    USA
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    Quote Originally Posted by hvacker View Post
    You haven't told why they failed.
    Because so many sleeve bearings motors are successful there seems to need another explanation why you have failures.
    How the hell would I know? The bearings either seized or got sloppy (clearance). I remove a 20 year old, totally enclosed shaft down motor and replace with a similar design shaft down motor...the info on the box said "Condenser Motor". Motor guru's tell us to match the HP, FLA, voltage, frame etc when replacing motors. That's what I do.

    I don't remember the particular brand or motor specs, but I have always pretty much stuck with AO Smith or Emerson and kept up with the name changes...and learned (the hard way) to stay away from the cheap "store brand" motors.

    Maybe the faulty motors were spec'd in some way that didn't meet the 20 year old motor spec's...I don't know. The box said "Condenser Motor"...I installed it on a condenser and the bearings failed. If it ain't due to cheap s**t...you tell me.

  3. #16
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    7,004
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    How can i figure out how to know if an existing motors is ball or sleeve?

    Like if you walked up to an old unit, or couldn’t find a spec sheet

  4. #17
    Join Date
    Dec 2011
    Location
    Maryland
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    567
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    Quote Originally Posted by hvacvegas View Post
    How can i figure out how to know if an existing motors is ball or sleeve?

    Like if you walked up to an old unit, or couldn’t find a spec sheet
    Give the shaft a tug ...no, seriously...a sleeve bearing motor generally has some endplay and a ball bearing motor will not. I actually picked that up from someone here, might have been hvacker.

  5. #18
    Join Date
    Jun 2012
    Location
    Northern NV
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    Have replaced an Aaon 480V single phase condenser fan motor with a GE and had it fail in short order. Got an OEM from a rep and it continues to work years later. Not sure why as the specs looked to be the same...

  6. #19
    Join Date
    Sep 2002
    Posts
    25,218
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    Balls are better. Sleeves are quieter.

    Sleeves require some kind of axial / thrust 'bearing' arrangement as a sleeve bearing does not inherently provide it.

    PHM
    --------



    Quote Originally Posted by Snapperhead View Post
    Im always torn on which to buy

    Do you really think there is a difference in quality ?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  7. #20
    Join Date
    Jan 2015
    Location
    Iowa
    Posts
    1,366
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    The sticker/name plate on the motor should tell what bearing are in the motor

    Ball bearings are better than sleeve for almost every situation

    Some need to be re-lubricated some do not

    Here I go thinking again, but I thought most of the multiple position fans had one ball bearing (fan side) and one sleeve bearing just because of the lateral movement. I know I have fought with several motors over the year with shaft up or shaft down position and wether the motor would start and run correctly or not. The fix was to make sure the motor had ball bearings

  8. #21
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
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    The deciding factor for a manufacturer is probably cost. Sleeve bearings seem to be OK for fractional motors. I just haven't had problems with them except with speed controls. Actually I never had the problem as it was solved many years ago when the failure mode was found.
    I know ball's load better if loading is a problem. Serious side thrust loading would require a roller or even a tapered roller. As these aren't offered I would conclude they aren't necessary. If price wasn't considered I'd use a ball motor because they are a better choice for longevity. My understanding is a sleeve bearing has an expected life of 10 years. The factory lube has a 5 years and should be oiled. Normal conditions.
    I haven;t seen any life expectancy for ball.
    Give me a relay with big enough contacts, and I'll run the world!

    You can be anything you want......As long as you don't suck at it.

    If a person wants to create a machine that will be more likely to fail...Make it complicated.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

  9. #22
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    8,894
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    Quote Originally Posted by GorillaTight View Post
    Give the shaft a tug ...no, seriously...a sleeve bearing motor generally has some endplay and a ball bearing motor will not. I actually picked that up from someone here, might have been hvacker.
    Wasn't me but that's is a good way to tell. Some ball are fixed on the shaft and won't move. My circle saw is that way.
    Give me a relay with big enough contacts, and I'll run the world!

    You can be anything you want......As long as you don't suck at it.

    If a person wants to create a machine that will be more likely to fail...Make it complicated.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

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