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Can someone say me what is the advantage of

  1. Aug 11, 2011 #1
    Can someone say me what is the advantage of "X" and "O" arrangement of bearings?

    Regards.
     
  2. jcsd
  3. Aug 11, 2011 #2

    Mech_Engineer

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    Re: Bearings

    You're going to have to be more specific in which orientations you're referring to. Perhaps a couple of drawings of the two orientations you're referring to?
     
  4. Aug 11, 2011 #3
    Re: Bearings

    Are you talking about the preload or contact angle with angular contact bearings? What is the application?
     
  5. Aug 11, 2011 #4
    Re: Bearings

    I hope the pic makes my query clear!

    The purpose is to support a vertical shaft with a considerable load at the top.

    Also want to know if the two angular contact bearing also supports radial loads (incase the shaft rotates at higher rpm).

    I am able to understand that the O is more supportive towards stability. But I want to get clarified more in technical terms. Also, if O arrangement is more supportive, what is the necessity for X or the tandem arrangement

    Regards.
     

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  6. Aug 11, 2011 #5

    Mech_Engineer

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    Re: Bearings

    There are basically three tradeoffs in each of the orientations: angular compliance, axial load capacity, and speed.

    a) Is stiffest in angular compliance, axial load capacity is the same as (b) but lower than (c), and will allow the highest high speed operation with proper preload.

    b) Allows more angular misalignment, axial load capacity is same as (a) but less than (c), and would be for use on lower speeds than (a) (because angular stiffness is lower).

    c) Allows the most angular misalignment, axial load capacity is double that of (a) and (b) (but would require a constant load in one direction), and would be for the lowest speed use.

    The distance between the intersection points for the ball/race interfaces is a good guage of how stiff the bearing combination will be against axial misalignment (larger distance means higher moment stiffness). The stiffer the bearing combination, the higher thespeed capacity (keep in mind though speed will still be limited by the bearing's internal tolerances). Note that the pictures show "ideal" bearings or matched bearings. For two bearing that aren't bought as a matched set, spacers would be required to achieve the proper race preloads.
     
  7. Aug 12, 2011 #6
    Re: Bearings

    Thnx.

    Btw, what is meant by reversing of axial loads in bearings.

    Also, how the above arrangement is better or not when compared to "Double-Row Angular Contact Ball Bearings"
     

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  8. Aug 12, 2011 #7
    Re: Bearings

    What exactly is the application? The main reason you would choose to go with an angular contact is if significant thrust loads are involved. The back to back <> would accomidate thrust loads moving in both directions where the >> is normal for just one. Double row bearings do have similar properties (thrust load accomidation) to the angular contacts but have to be run slower because more balls prevent the higher speeds. Double rows can take larger radial loads than angular contacts because of this as well. At a minimum you need to know what your radial load is static and dynamic, and the RPMs you plan on running at. Double rows and angulars are typically not interchangeable so specifics are needed. Also, the double rows tend to be cheaper than a set of matched angular contacts.
     
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