Mailing List flyrotary@lancaironline.net Message #3428
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Re: [FlyRotary] Re: alternator choice and pulleys?
Date: Wed, 1 Oct 2003 15:27:28 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
 
----- Original Message -----
Sent: Wednesday, October 01, 2003 3:25 PM
Subject: [FlyRotary] Re: alternator choice and pulleys?

Russell Duffy wrote:

  I use the GEO alt and an advantage with it is that if you kill power
to the exciter lead it will stop the power output so you can shut it
down in the event of a voltage overrun.

  Ken Welter

 
East Coast confirmed that the UltraMini works like that as well.  After seeing Mark's message, I called around, but the cheapest I could get one was $135 + $35 core, and that was for a rebuilt unit.  I just went ahead and ordered a new alt from East Coast for $219.
 
Now, the problem will be coming up with a double pulley.  They said the shaft was 15mm, and the normal size was 17mm, so finding a double pulley might be tricky.  If I can't make one work, then I'll have to consider using just a single V belt, or trying to convert to a serpentine belt.  On one hand, a dual belt seems like it would be twice as likely to keep the water pump running, but in reality, it's not.  If the outer belt comes off, the inner could remain, but if the inner comes off, the outer belt will go with it.  It's tough to say if it really offers any redundancy, but it does offer more contact area on the water pump pulley, which has a terrible geometry already.
 
Cheers,
Rusty
  

 Rusty, for what is worth - you know - my usual 0.02 worth.

I previously ran two belts to alternator and water pump.  Once I added the smog pump for a vacuum source, the geometry forced me to either give up dual belts on the water pump OR the alternator.  I figure I wanted the water pump working more than the alternator.  So only one belt on the alternator.  I do use top quality Gates belts as I found that some of the off brand automobile belts would shread in a short amount of time.  I came back from one long flight with half of the "cogs" missing from one such, so the belt was clearly on the verge of failure.

Ed

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