[Vwdiesel] TDI alternator pulley

[dieseltdi at verizon.net]

As I understand this thing (I had to replace both alt pulley and belt tensioner on my car) the clutch prevents overrevving of the alt on slow down to idle.  It also helps to cushion some of the pulses that travel along the serpentine belt from the engine.  With the tensioner these pulses are absorbed rather than passed to the various other components.  This was not a problem when you ran everything off of multiple belts but the serpentine belt presents special problems that must be addressed differently.  Hayden

Sep 16, 2010 03:27:01 PM, LBaird119 at aol.com wrote:

In a message dated 9/16/2010 6:41:14 AM Pacific Daylight Time, 
brian at gochnauer.net writes:

> It's is a 'sprag clutch' (couldn't find a good example pic) and the 
> reverse
> direction resistence isn't really of much value as long as it locks in the
> 'forward' direction.
> It's there to reduce the spinning forces internal to the alternator when 
> the
> engine is shut off.

That just sounds silly. There's not that much rotating mass to 
an alt, especially compared to a crank assy, to seem like it'd have 
much of any affect on shut down shudder, after spin or even stress 
on the belt.
Not that you sound silly, VW, for putting one on there.
Auto trannies use sprag clutches, older Honda motorcycle starters.
Doesn't help with a visual though unless you've had one in your hand...
Loren
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