Efficiency of u-joints

[frankiee]

Sorry for such a base question.
But could someone tell me a ball park figure for the mechanical efficiency of a U-joint?

 

[GregLocock]

Depends. Used as in a prop shaft it is probably better than 99%. Used in a PTO drive as in agricultural products, better thna 95% but I don't know.

I think the way to work it out is to figure out the load in the bearings, and then for your joint articulation angle and speed you can work out a surface speed for each bearing, and then using a coefficient of friction of 0.1-0.3, you can work out the power lost. I've never done that.

Cheers

Greg Locock

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