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Thread: Anyone see a problem with this One way needle bearing application?

  1. #1
    Project Engineer
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    Oct 2013
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    Anyone see a problem with this One way needle bearing application?

    I have a small system here with a 1/8 HP Motor required to apply a load of about 100lb-in's at 20RPM with a needle type sprague clutch on the driven shaft (where the driven shaft makes the inner race of this bearing type).

    I want to be able to disengage this "one way bearing" by sliding the shaft through to a reduced diameter so as the clutch needles won't engage. the sliding unit will have other support besides this one way bearing. it will only serve to lock the shaft to the load when 2 conditions are met ie. When the shaft is slid through to where the larger diameter can engage the locking needles, and when the shaft turns in the direction to lock the load to it. I'm not familiar with any system where a shaft is allowed (while stopped) to slide through a needle bearing like this. and am wondering if this is an acceptable practice or if anyone knows of a bearing that will survive this kind of operation?

  2. #2
    Lead Engineer
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    From your description it appears that you intend to rely on contact fricton between your shaft ahd the bearing inner race to transfer the rotational loading between these two items. If that is true, it is going to be an very unreliable method of torque transfer. It also will have a very short life due surface wearing or galling and, will potentially damage the bearing due the substantial longitudinal loads during engagement and disengagement.

  3. #3
    Engineer
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    Jan 2015
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    sounds as if you need a coupler of some sort. if i understood your description correctly. If so, tolerancing of the fit will be important for reliability and bearing life.

    John

  4. #4
    Project Engineer
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    Quote Originally Posted by JAlberts View Post
    From your description it appears that you intend to rely on contact fricton between your shaft ahd the bearing inner race to transfer the rotational loading between these two items. If that is true, it is going to be an very unreliable method of torque transfer. It also will have a very short life due surface wearing or galling and, will potentially damage the bearing due the substantial longitudinal loads during engagement and disengagement.
    I understood that these bearings were made to transfer the rotational load to a through the bearing on one direction and free wheel in the other. I have assemblies that do this very thing and have stood up for years of continuous use. They aren't perfect as they engage at diferent times everytime they lock so I never use them alone for indexing but that's not what this is. Isnt this how automatic transmissions coast in cars? With hundreds of hp behind it? If I'm looking at this the wrong way then let me know, I guess I don't understand your concern about reliability

    The only thing i'm doing diferent in this assembly is I want to slide the shaft through the needle bearing longitudinaly to a reduction in the shaft so as to prevent it from locking in either direction. I spoke to the bearing applications people and they said as long as the force to slide the shaft doesn't exceed the spec for installing the bearing on the shaft then there won't be an issue and also it should have a nice ramp to not catch the ends of the rollers when it slides back onto the diameter that can lock. And make sure it's not rotating as the needles engage so as they are nut subjected to forces that would load only the end of the needled. I'm positioning the shaft with a cam.

    I'm about to send a test unit design to manufacturing so it would be good to know if I'm missing a huge error.

    Thanks for your comments. Every comment is helpful.
    Last edited by GlennD; 01-17-2015 at 03:31 PM.

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