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  1. #1
    Join Date
    Apr 2007
    Location
    houston
    Posts
    32

    Confused evapco cooling tower 500ton

    i have a 500ton cooling tower with belt drive and vfd on it keep losing bearings on this tower what do you think maybe blade out of bal lose couple bearing a year top and bottom bearings

  2. #2
    Join Date
    Feb 2007
    Location
    Sugar Land, Texas
    Posts
    80

    Talking

    No "YOU" have 3 - 500 ton cooling towers that keep losing bearings.

  3. #3
    Join Date
    Jan 2003
    Location
    San Jose, Ca
    Posts
    2,089
    Quote Originally Posted by chillermafi View Post
    i have a 500ton cooling tower with belt drive and vfd on it keep losing bearings on this tower what do you think maybe blade out of bal lose couple bearing a year top and bottom bearings
    Fan or Motor bearings.

    If fan are beearings shielded from water, are they proper bearings for tower enviorment. belt tension?

    If motor is it outdoor motor. does the motor sit vertical or horizontal? If vertical is it designned to take the weight load of the rotor. are the shives aligned.

    I know these are simple things but without seeing It takes a wild guess,
    Old snipes don't die they just loose their steam

  4. #4
    Join Date
    Aug 2006
    Posts
    2,607
    What grease are you using? The only ones I trust for Tower service is the Red Never-Seiz , and the grease BAC sells, which looks the same. Also check out BAC auto lubes.

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,370
    Quote Originally Posted by chillermafi View Post
    i have a 500ton cooling tower with belt drive and vfd on it keep losing bearings on this tower what do you think maybe blade out of bal lose couple bearing a year top and bottom bearings
    Evapco forced draft tower? Check your belt/sheave alignment. I had a motor burn up due to this. Shaft bearings for blower wheels? Keep them greased, but don't over-grease them.

    If you keep losing motor bearings, since you mention VFD, you could be experiencing arcing between the bearing balls and the race, causing pitting within the race. This eventually kills the bearings. The solution involves grounding the motor shaft and/or adjusting the carrier frequency of the VFD. Generally, a higher carrier frequency will give a quieter running motor, but it won't live as long.

    Here's a link to an article that goes into more detail concerning the subject of VFD's and motor bearing damage:

    http://www.greenheck.com/technical/t...guide/fa117_03
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    • Refrigeration makes the HVAC psychrometric process happen.
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  6. #6
    Join Date
    Feb 2004
    Location
    SW Florida
    Posts
    1,264
    Are there shims under the bearings? If there are, make sure they are a solid block and not multiple shims. When you get it repaired have a vibration analysis done and he will be able to tell you what the problem is.

  7. #7
    Join Date
    Nov 2003
    Location
    Boston
    Posts
    600
    You may know this, but in case you don't:

    After installing the bearings you should loosen up the bottom bearing.
    Adjust it so the top bearing carries the weight of the fan.
    Finally, tighten up the bottom bearing.

    The top bearing is designed to carry the thrust load.
    Edited by powerhead on more than one occasion

  8. #8
    Join Date
    Feb 2007
    Location
    Sugar Land, Texas
    Posts
    80

    Confused

    The bearings that keep failing are the drive line bearings, not the ones on the motor. The grease used in them is a high heat moisture resistant lithium based grease I believe. It is what was recommended by an engineer at another facility. The loosening of the bottom bearing is something we will surely try.

  9. #9
    Join Date
    Apr 2007
    Location
    houston
    Posts
    32
    Hey 19d Guy how about i give u the shaft and bearings and u put them in

  10. #10
    Join Date
    Jul 2007
    Location
    Georgia
    Posts
    2
    I too am wearing out bearings on the fan shaft, the lower bearing. I grease regularly with synthetic grease. I get water in my sealed bearings because they sit like a dish and condensation just sits on the bearing. Any solutions will be greatly appreciated.
    Thanks in advanmce, Walt

  11. #11
    Join Date
    Jul 2007
    Location
    Georgia
    Posts
    2

    Cool

    Just had another lower fan shaft bearing fail. It too shows signs of water in it and these bearings are greased regularly with the proper grease.

  12. #12
    Join Date
    Apr 2001
    Location
    Riverside CA
    Posts
    64
    What is the min. speed of the fan?

  13. #13
    Join Date
    Aug 2006
    Posts
    2,607
    Evapco Bearings call for a high synthetic grease, not Lithium based. Try Mobil SHC 32. Also do your bearings have cap bolts? They have to be torqued down with an inch/pound torque wrench while spinning the shaft by hand. If you are buying preloaded bearing housings from Evapco don't touch the caps, also resist the temptation to "check" the torque. If they have been over torqued in the past you need to replace them with preloaded bearing housings from Evapco. Do you have an engineer that slams the grease into the bearings? Bearings need to have grease s-l-o-w-l-y pumped into them preferably at low spin rpms.

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