Pivot friction equation of a ball and socket 1

[chicopee]

Looking for a torque equation for a friction pivot of a ball within a spherical socket. Ball shaft to remain normal to socket horizontal axis and ball shaft assemby is to rotate in the horizontal plane. At most 1/2 (but necessarily) of the ball may seat in the socket. Shaft rotation is slow at at most 1/2 a turn.

 

[chicopee]

One more item and that is the force on the shaft is
in the same direction as the shaft.

 

[BobM3]

Are you making your own? If you buy them then check with the manufacturer. For the ones I've used the initial friction can be much higher than the friction after so many cycles of operation.

 

[israelkk]

Ball friction torque = Resultant force on ball X ball radius X friction coefficient.

 

[chicopee]

No I am not making my own.
isrealkk, I was aware of your equation, howvever,I was under the impression that it was for a cylindrical surface such as a journal. Nonetheless, I'll use it

 

[unclesyd]

There are all types of these joints around an automobile so there should be some information available.

Also you might want to look at a rod end or spherical which could get you in the ball park or maybe in the game.

http://www.rbcbearings.com/aero-pdfs/Plain/018_050/SB_RE_JN_Eng.pdf

 

[unclesyd]

Forgot to add, another name for that joint is a knuckle or ball and knuckle.

 

[BobM3]

SKF has a section on this:

http://www.skf.com/portal/skf/home/products?lang=en&maincatalogue=1&newlink=3_0_32

 

[chicopee]

Unclesyd, your reference bears out israelkk's formula. Thks!