Free-wheeling Alternator Pulley

[NormanC]

A stupid question I know, but what is the rationale behind a free-wheeling alternator pulley?

I'd have thought that the alternator would always be generating power and therefore would never free-wheel so I'm obviously missing something.

Thanks,

 

[grober]

It's engineering name is a sprag clutch. Good explanation here. http://www.ntn.co.jp/english/products/review/pdf/NTN_TR75_en_P124.pdf

Basically its stop shock loadings on the pulley/belt system due to large differences in the rotational speeds/loadings of the various belt driven components. In extreme cases this can lead to premature belt failure or crank pulley keyway wear/failure

 

[NormanC]

Thanks, Graeme.

I hadn't even thought about the cyclic variations of speed and torque.