Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Mounting a Needle bearing

  1. Apr 1, 2017 #1
    Hi,

    I am have been trying to figure out the correct way to mount a needle bearing.
    I have previously worked with ball bearings.

    Here is the application:

    The needle bearing will be pivot point of a swing arm of a trike. Another will form the central pivot point that breaks the vehicle from front to rear. See image for reference. The red arrows mark moving points.

    The pivot points should ideally be hollow so that I can pass wirings and brake hoses through them. The rear wheels are hub motors (hence wires have to pass through them).
    By using needle bearings, I think I can reduce the outer diameter of the bearings, yet get sufficient inner diameter for all the wires to pass through. What I can't figure out is how to mount them.

    Also what is the difference between this bearing
    and this bearing
    Besides their width/length, both bearings should be mounted the same. Why is the mounting assembly image different?

    The second link: NKI bearing, it seems both the other housing and inner shaft have a flange on one side and retainer rings on the other side to lock the bearing in position. My problem is difference in ID and OD of bearing is so low that they interfere with each other. Besides the OD of the bearing is 68, for which I can't find a suitable retainer ring (sizes of 65 or 70 are available). Also , if I have a flange to lock the bearing from one side, it feels that the flange will be too thin (ID vs OD).
    Is there is any other way of mounting a needle bearing (press fitting is one option, at least for the other end).
    I have been trying to find material on the same but nothing on needle bearing with hollow shafts.

    And yes I am open to alternative bearing/bush options as well.

    Thanks in advance
     

    Attached Files:

  2. jcsd
  3. Apr 1, 2017 #2

    Nidum

    User Avatar
    Science Advisor
    Gold Member

  4. Apr 1, 2017 #3
    So what I understand is that the inner ring of the bearing can slide in or out in the bearings I had selected.
    On other hand drawn cup bearing doesn't have inner ring. Assuming I press fit the bearing in housing, the bearing and housing are locked with each other.
    Now the shaft can still slide in and out of the bearing? Assuming I use a shoulder on one end of the shaft and retainer ring on other end, the shaft can be locked as well with the bearing.

    Thanks
     
  5. Apr 1, 2017 #4

    Nidum

    User Avatar
    Science Advisor
    Gold Member

    When using needle bearings it is generally better to have separate bearings for the radial and axial loads .

    Thrust needle bearings .
     
  6. Apr 1, 2017 #5

    Nidum

    User Avatar
    Science Advisor
    Gold Member

    If I understand what you are doing correctly though there is no continuous or rapid motion in these bearings . It may be that sleeve bearings will do all that you want at lower cost and with less complexity than for rolling contact bearings .

    Can you post a dimensioned sketch of the actual shafts and housings that you are asking about bearings for ?
     
  7. Apr 1, 2017 #6
    I don't think there is any axial load on the needle bearing.

    On the sleeves, I want to use the same but have absolutely no knowledge on the same. Any references or books or pointing in the right direction will help. Googling sleeves already though.

    Sizes are not fixed yet but I'll post rough dimensions, forces etc.
    Thanks
     
  8. Apr 1, 2017 #7

    Nidum

    User Avatar
    Science Advisor
    Gold Member

    Also called plain bearings and journal bearings .

    Have a look here . The technical data downloads are full of useful information .

    Note though that plain bearings for less demanding purposes are quite easy to make in a home workshop . Can be metal but can also be Nylon , Teflon , Tufnol and other modern non metallic bearing materials .
     
  9. Apr 1, 2017 #8

    JBA

    User Avatar

    Every location you indicate on your illustration is going to have thrust loads. Axial needle bearings are not designed for thrust loading. There are radial thrust needle bearing assemblies that can be used in concert with axial needle bearing but these are radial in design and would defeat you intended purpose to reduce the O.D. to I.D. of your assembly design.
     
  10. Apr 4, 2017 #9

    Baluncore

    User Avatar
    Science Advisor

    A single needle roller bearing is not good at controlling alignment. Any misalignment will put very high loads at the ends of the small radius rollers, that will quickly Brinell the bearing surface. https://en.wikipedia.org/wiki/Brinelling
    To overcome that, where needles or rollers are used you must control the alignment with another bearing some axial distance away.

    A better way, which will handle all loads, would be to use two opposed tapered roller bearings, as in a vehicle stub-axle/hub. But rolling bearings need lubrication, and then seals to keep the dirt out.

    If rollers or balls do not rotate sufficiently they do not spread lubrication.
    The attractive alternative is to use a hard polymer sleeve bearing to carry the load.
     
  11. Apr 4, 2017 #10

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    Some ordinary ball bearings (eg Conrad) have thrust capability. Wouldn't a pair of those in bearing blocks work?

    I hesitate to suggest it but it is possible to run electricity through the ball races themselves. OK for a one off project but perhaps not reliable for mass production.


    RTPsetup800.png
     
  12. Apr 5, 2017 #11

    Baluncore

    User Avatar
    Science Advisor

    You hesitate I presume, because 'spark erosion' is a recognised cause of bearing failure.

    Electrical Discharge Machining is a non-traditional machining technique that includes Wire EDM and Plunge or Ram EDM.

    In the presence of efficient lubrication, spark erosion can continue for as long as electrical energy is available. Without lubrication, air is present so oxidation of the bearing material following spark erosion quickly generates a layer of oxide powder that insulates the contact and so reduces current flow. Both destroy the bearing surfaces if current is permitted to flow.
     
  13. Apr 7, 2017 #12
    That drawing is not complete. show bearing placement.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Mounting a Needle bearing
  1. Making a mount (Replies: 8)

  2. Motor mounting (Replies: 3)

  3. Needle inside the Die (Replies: 0)

  4. Sizing Needle Valves (Replies: 5)

Loading...