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Thread: What Bearing do I need for Running Under Water?

  1. #1
    Associate Engineer nippit's Avatar
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    What Bearing do I need for Running Under Water?

    ipt>
    under water bearings

    I am looking for some guidance and directions on what to use under water.

    I am will be putting a belt (more like the treadmill belt) in the water.

    I need 4 bearings to hold the belt down.

    the belt will operate in the water (underwater).

    the water in the tank can be emptied and cleaned etc. saying this dry operation is not required.

    the water is NOT salty or any acids it is just a normal chlorine treated water (like tap / swimming pool water)

    The shaft be 16mm or 18mm (0.62~0.70")

    Sorry for the attached hand drawn drawing.

    Now,

    what type of bearing should I use?
    something without moving parts?
    is there are sealed fully sealed metal bearings?
    PTFE type materials (rulon etc)


    any help is appreciated.

    under.jpg

  2. #2
    Technical Fellow Kelly_Bramble's Avatar
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    There are many bearings rated for operation underwater...

    Search the internt for "Under Water Bearings".

  3. #3
    Technical Fellow jboggs's Avatar
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    I would recommend some kind of plastic non-rolling element bearing rated for under-water applications. I'm assuming the loads will be relatively light. There are several different bearing vendors that could answer your questions. Check McMaster, or Igus.com.

  4. #4
    Associate Engineer nippit's Avatar
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    Thanks @Kelly Bramble @jboggs

    I have searched for ""Under Water Bearings" that is actually how i found this thread.

    yes loads are relatively light, i have never worked with non rolling bearings.

    so basically as long as it is one of those kinds "oil free" "maintenance free" it should be Ok right.

    I do need to avoid any thing that needs oil. I was wondering if there are any that is lubricated but sealed so that it can be submerged.

    I do need to spend more time on this as it comes up with huge selection no matter what i do.

    cheers



  5. #5
    Technical Fellow jboggs's Avatar
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    You should also watch out for water-absorbing materials. That's one reason for the under-water rating. And don't be afraid to actually call the manufacturers and talk to a live applications engineer. That's what they're there for. I don't know if this applies to you but... I am continually amazed at how infrequently the current generation even considers that option.

  6. #6
    Associate Engineer
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    Hello Nippit

    SKF has a lot of different ball bearings used for marine purposes.

    Allthough if the water pressure isn't immense you could use normal, sealed bearings.
    Last edited by Kelly_Bramble; 10-29-2013 at 04:57 PM.

  7. #7
    Project Engineer
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    you might want to have a look at using just nylon blocks. they will work under water and the materials can be worked with hand tools.

  8. #8
    Lead Engineer
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    As an alternative to nylon, which absorbs water, I suggest you consider delrin which will be more dimensionally stable in water; also, there are tfe/delrin composite polymers available as well.

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