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  1. #11
    Quote Originally Posted by dsc View Post
    In between the bearings there's a pulley, so the tube idea is not possible.
    A tube each side of the pulley would also fasten the pulley to the shaft

  2. #12
    dsc's Avatar
    Lives in Lincoln, United Kingdom. Last Activity: 6 Hours Ago Has been a member for 5-6 years. Has a total post count of 248. Received thanks 1 times, giving thanks to others 9 times.
    John, wouldn't a tube cause more problems, if it's length is not super precise?

    I was asking about tolerances on the bearing fits, as I'm not quite sure how ACs are normally fitted. I've seen interference fits mentioned a few times in technical literature and I can understand that on the bottom bearing, but should the top bearing be an interference fit as well? the bottom can be easily pressed against the shoulder, so that's not an issue, but I guess the top should simply slide over the shaft? if so, isn't there a risk of the shaft rotating within the top bearing inner ring? I guess preload would create friction between the top of the inner ring and locknut / cap, but is that enough?

    Regards,
    dsc.

  3. #13
    Quote Originally Posted by dsc View Post
    John, wouldn't a tube cause more problems, if it's length is not super precise?
    I have been talking about collapsible tubes as used extensively in some applications.

    Because your tubes would be relatively long a pair of thin wall aluminum tubes would compress the amount needed, a bit of trialing to get the right combination of force/distance needed, perhaps a bit OTT for you.

  4. #14
    Last edited by johnsattuk; 05-01-2014 at 08:08 PM. Reason: Added pics

  5. #15
    dsc's Avatar
    Lives in Lincoln, United Kingdom. Last Activity: 6 Hours Ago Has been a member for 5-6 years. Has a total post count of 248. Received thanks 1 times, giving thanks to others 9 times.
    I guess the tube acts as an additional way of protecting from too much preload, right? without the tube, there's no way to stop the bearings from being practically destroyed by over tightening the locknut / cap-bolt?

    I'll probably be less scientific with my approach and tighten the top until there's no play and maybe go 1/8 turn further.

    Regards,
    dsc.

  6. #16
    Quote Originally Posted by dsc View Post
    I guess the tube acts as an additional way of protecting from too much preload, right? without the tube, there's no way to stop the bearings from being practically destroyed by over tightening the locknut / cap-bolt?
    Well not quite, if you get too enthusiastic with the wrench and collapse the tube too much, you can still destroy the bearings. If you exceed the preload on assembly the recommendations are that you use a new sleeve, which of course they always do

    What it gives you is a high torque retaining nut/bolt with the ability to set a small preload and a very rigid assembly. In practice it is quite easy to feel the spindle start to take a preload and is also possible to adjust later if required, not so easy with fixed length spacers.

    Differential pinions do have stringent requirements, high loads from the hypoid gear at perhaps 200hp 6000+ rpm and must run quietly.

  7. #17
    dsc's Avatar
    Lives in Lincoln, United Kingdom. Last Activity: 6 Hours Ago Has been a member for 5-6 years. Has a total post count of 248. Received thanks 1 times, giving thanks to others 9 times.
    As this is for a 240RPM spindle with rather low load requirements, I think a sleeve will be a bit OTT. All that is required is for the whole assembly to be as stiff as possible and to be assembled with the least amount of effort. So far two single row AC bearings win on all levels, with taper rollers in second place.

    I've found some additional info on CNCzone regarding the fittings of the single row AC bearings, the bottom one against the shoulder should be an interference fit, the top will be a slide fit. Hopefully that's the right way to do it.

    Regards,
    dsc.

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