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Unread 08-11-2011, 03:17
Trent B Trent B is offline
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Re: High Tensile Sprocket Bolts

Quote:
Originally Posted by DonRotolo View Post
I think you mean a spacer that actually enters the holes in the wheel or sprocket? In that case, the larger surface contacting the spacer ends would help by distributing forces over a larger area. My previous comments assumed the spacer was on the surface of the wheel & sprocket. But a larger diameter spacer would help even more.
Yeah a spacer actually entering the holes on the wheel (like plaction wheels for example have those holes that nuts can slide into), what if you mounted the sprocket on that side for instance. I am guessing in this case there would be a certain point where larger radius would help more than the spacer in the holes on the wheel but not the radius immediately larger?

And I was trying to get at what Don was saying, cyclic loading will cause failures, this can be impacts, if the load on the bolts changes significantly in normal rotation etc.

Here is an S-N curve


If you notice based on the load the number of cycles til failure varies, this is the amplitude of the stress in the cyclic cycles, if steel is kept below a given stress it should never fail, otherwise it should fail fairly regularly after a predictable number of cycles (as it appears to be for you guys) so you need to find a way to make the stress on the bolt less be it spacers, less threads, thicker bolts, etc.
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