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Date: Mon, 12 May 2014 07:39:18 -0400
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From: John Cooper <snopercod@comporium.net>
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Subject: Re: [LML] [LNC2] Fast taxi testing - found the problem
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Thanks for the link to the Timpken Engineering Manual. It was very 
informative. All these years I had thought that bearings should have a 
tiny bit of end-play to allow for thermal expansion, but Timken says 
that's not true. On Pg. 82 they state:

    "Generally, the ideal operating bearing setting is near zero to
    maximize bearing life (fig. 83). Most bearings are set with endplay
    at assembly to reach the desired near-zero setting at operating
    temperature.

    There is an ideal bearing setting value for every application. To
    achieve this condition, the bearing setting must take into account
    deflection under load (radial + axial) as well as thermal expansions
    and material used.

Figure 83 indicates that bearings have a longer life with a small 
pre-load. Live and learn. I guess the only way to set the end play 
accurately would be with a dial indicator so I just ordered one from 
Amazon for $25. One would have to test the end play cold and then hot.

So maybe my problem all along was the right brake locking up and not the 
tightness of the bearings (or both)????


> John,
> A little pre-load is actually beneficial in roller bearings. You 
> apparently had a too much on one wheel.
> I re-grease my bearings every year and during installation tighten the 
> nut until I get just under one revolution of spin. It is a good idea 
> to re-check this after a few hours of use.
> http://www.timken.com/en-us/products/Documents/Timken-Engineering-Manual.pdf
>
> Chris Zavatson
> N91CZ
> 360std
> www.N91CZ.net
>


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    Thanks for the link to the Timpken Engineering Manual. It was very
    informative. All these years I had thought that bearings should have
    a tiny bit of end-play to allow for thermal expansion, but Timken
    says that's not true. On Pg. 82 they state:<br>
    <blockquote>"Generally, the ideal operating bearing setting is near
      zero to<br>
      maximize bearing life (fig. 83). Most bearings are set with
      endplay<br>
      at assembly to reach the desired near-zero setting at operating<br>
      temperature.<br>
      <br>
      There is an ideal bearing setting value for every application. To<br>
      achieve this condition, the bearing setting must take into account<br>
      deflection under load (radial + axial) as well as thermal
      expansions<br>
      and material used. <br>
    </blockquote>
    Figure 83 indicates that bearings have a longer life with a small
    pre-load. Live and learn. I guess the only way to set the end play
    accurately would be with a dial indicator so I just ordered one from
    Amazon for $25. One would have to test the end play cold and then
    hot.<br>
    <br>
    So maybe my problem all along was the right brake locking up and not
    the tightness of the bearings (or both)????<br>
    <br>
    <br>
    <blockquote type="cite">
      <div>John,</div>
      <div>A little pre-load is actually beneficial in roller bearings.&nbsp;
        You apparently had a too much on one wheel.</div>
      <div>I re-grease my bearings every year and during installation
        tighten the nut until I get just under one revolution of spin.&nbsp;
        It is a good idea to re-check this after a few hours of use.</div>
      <div><a
href="http://www.timken.com/en-us/products/Documents/Timken-Engineering-Manual.pdf"
          target="_blank">http://www.timken.com/en-us/products/Documents/Timken-Engineering-Manual.pdf</a></div>
      <div><br>
      </div>
      <div>Chris Zavatson</div>
      <div>N91CZ</div>
      <div>360std</div>
      <div><a class="moz-txt-link-abbreviated" href="http://www.N91CZ.net">www.N91CZ.net</a></div>
      <div><br>
      </div>
    </blockquote>
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