# Re: [EVDL] Where do I find Belleville washers? ( force vs torque)



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Where do I find Belleville washers? ( force vs torque)*

The belleville washer will be rated ( if you can find one) in pounds of force, not torque. 

The force applied by a torqued bolt is approximately F = 5 x T / D, where F is the force ( in lbs); T is the torque (in-lbs), and D is the major diameter of the bolt or screw ( inches). This is for an un-lubricated bolt. If your bolt is well lubricated, the force will be somewhat higher for the same torque. It also depends a little on the thread pitch, but this is a pretty good general approximation.

So, for example, it you had a 3/8 bolt, the force on your washer would be about : F = 5 X 70 / 0.375 = about 900 lbs. If you look at the McMaster Carr bellevilles, they have some in that range. 

You say they are "permanently" deflected. Do they spring back to their original condition (overall thickness) when you loosen the nut? They should; if they don't they're defective ( or, poorly/cheaply made), and, they're not doing you much good. 

Phil

> From: [email protected]
> To: [email protected]
> Date: Mon, 18 Aug 2008 13:45:05 -0500
> Subject: Re: [EVDL] Where do I find Belleville washers?
> 
> I'm curious what load rating most folks choose. The ones I have permanently
> deflected (went "flat") at a 70 in/lb torque
> 
> 
> 
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf
> Of SteveS
> Sent: Monday, August 18, 2008 12:01 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Where do I find Belleville washers?
> 
> http://www.mcmaster.com/
> 


> > David Nelson wrote:
> > > Where can I find good Belleville washers. The ones that came on my
> > > Gizmo are rusted and I was wanting to get something better, possibly
> > > stainless steel. I have T-875s with the low profile bolt posts.
> ...


----------

