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Date: Sat, 26 Feb 2005 09:40:25 -0600
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Racemate alt/water pump
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I wonder if the high failure rate on the trucks is related to a much 
higher use rate? Kind of like the number of car engine failures is 
higher than the number of a/c engine failures, but if you look at 
failures per mile or failures per thousand engines in use, I'd bet that 
car engines are much more reliable.

 The only belt failures I've had on cars in the last 25 years were cam 
drive (timing) belts on two occasions & both cars leaked oil everywhere. 
The belts were saturated with oil. (And they had both run loooong past 
the recommended 60,000 change interval.) I replace the serpentine belts 
on my cars when they start to look really bad but I don't pay much 
attention to them. Over the same period, I've probably replaced at least 
half a dozen alternators because they quit. It's usually easy to see a 
belt failure coming if you just look, but there's no warning with an alt.

I'm excited about the shaft mounted alt. because it has the potential to 
make installation simpler & it should be more reliable, with no bearings 
& belt side load. It also has the potential (if you have 2 alts.) to 
make the engine self sufficient & allow you to shut down the rest of the 
a/c electrical system in an emergency like a 'traditional' a/c design. I 
can't decide if that's really significant, but it does help when 
contemplating an electrical fire type problem in flight.

Charlie

Paul wrote:

> Hi, Todd....I have had to replace the serpentine belt on my Ford motor 
> home. (Broke on the highway on the way to a canard fly-in of course). 
> All of our tractor-trailer units have serpentine belts. Fairly high 
> failure rate. I always keep at least 12 different serpentine belts (2 
> of each size) in my repair truck so that I can fix them on the 
> roadside. We use Gates and/or Goodyear.  In fairness, however, a few 
> of the older units have a V belt for the alternator.  They fail as 
> well.  Don't know which type of belt fails more frequently, but they 
> both fail with regularity.  Now if we changed them at every annual 
> condition inspection, however.....   Paul Conner
>
>     ----- Original Message -----
>     From: Todd Bartrim <mailto:haywire@telus.net>
>     To: Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
>     Sent: Saturday, February 26, 2005 4:51 AM
>     Subject: [FlyRotary] Re: Racemate alt/water pump
>
>
>     V-belt is cheaper and lasts longer,
>     Are you sure? I've never had to replace a serpentine yet. But I've
>     seen allot of V-belts come & go.
>
>     serpentine belts bend both ways,
>     multi-rib belts I haven't seen much of, but I think they're a lot like
>     serpentine.
>     Multi-rib & serpentine are the same animal, I believe. Multi-rib
>     refers to the belt design, but the belts can vary in length. I'm
>     using a short multi-rib belt for my alternator only, but if it was
>     longer and was used to go around my alternator, water pump, idler
>     pulley, power steering pump, A/C compressor, etc, then it would be
>     called a serpentine belt. But the term is often used interchangeably.
>
>         At least that's my take on it. I could be wrong.
>
>     Todd
>