Author Topic: Axial bearing load for 608 SKF bearing  (Read 3160 times)

Offline picclock

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Axial bearing load for 608 SKF bearing
« on: September 01, 2012, 05:47:26 AM »
I have an application which I need to find the safe axial static and dynamic working load. The radial load values are easily found on the SKF site but I cant seem to get a value for the Axial load - which in this application is the major loading. Google just turns up tons of junk from other bearing manufacturers.

Any help much appreciated

Best regards

picclock
Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

Offline PekkaNF

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Re: Axial bearing load for 608 SKF bearing
« Reply #1 on: September 01, 2012, 06:10:19 AM »
I have the book, but it it still took a little time before I found it on the net.

Would this help:
http://www.skf.com/portal/skf/home/products?maincatalogue=1&lang=en&newlink=1_1_13

If I'm assuming correctly your bearing type this makse interesting rading:
http://www.skf.com/portal/skf/home/products?maincatalogue=1&lang=en&newlink=1_1_1

Pekka

Offline picclock

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Re: Axial bearing load for 608 SKF bearing
« Reply #2 on: September 01, 2012, 06:39:46 AM »
@ PekkaNF

Thank you so much  :thumbup:. I spent ages on their site trying to find that information (- note to self must get book). It does indicate that the design is adequate, as the C0 value is about 300lbs so the reduced 0.25 C0 value is still 75lbs. My worst case value is around 35 lbs so this is a good margin. The really interesting bit is the fact that smaller bearings get a lower % C0 rating.

Really do appreciate the help - I don't think findings things like that on the internet is an easy task for me.

Many Thanks

Best Regards

picclock   
Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

Offline Lew_Merrick_PE

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Re: Axial bearing load for 608 SKF bearing
« Reply #3 on: September 01, 2012, 01:49:21 PM »
Guys,

ABEC, which was the Anti-Friction Bearing Engineering Committee when I was an apprentice and was reformulated into the Annular Bearing Engineering Committee some years back (I must have missed that memo), puts out the standard load requirement equations in a rather expensive set of books.  I have never understood their approach of making such information (gathered by taxpayer funded research) so costly as, it seems to me, more people would use bearings if they had that information more readily available -- but that has been the trend for the past few decades.  One of the things I am looking for is a public domain basis for such information I can use in my ongoing work towards writing a new mechanical design engineer's handbook (the reason I am posting stuff over at http://www.scribd.com/Lew%20Merrick).

In any case, the limiting factor on rolling element bearing design is the Hertzian contact stress concentration that occurs when a round surface impinges on another surface.  The smaller the radius, the larger the Hertzian contact stress concentration factor.  Since a ball bearing has a sphere (one Hertzian contact stress concentration factor) rolling in a radial round groove (a second Hertzian contact stress concentration factor), the effect of the stress concentration is approximately doubled -- making the nomograph curve of overall stress concentrations take the form of concentration factor = 1/roller diameter.

Back in the pre-computer days things requiring more complex calculations were reduced to nomographs[/] to simplify things.  There were whole rafts of mathematical graph people who created them for government agencies and major corporations.  If you look hard enough (older editions of Joe Shigley's Machine Design leap to mind), you will find nomographs for most mechanical design calculations.