-------------- Original message from "Marvin Kaye" <marv@lancaironline.net>: --------------


> I thought you'd find this interesting.
>
>
>
>
> Posted by "Hamid A. Wasti" to the Lancair Mail List:
>
> I saw this posted on another list. I am passing it along for general
> interest, with no warranty for the accuracy of the information contained in
> it.
>
>
> From Pifer's Airmotive, Inc. Pontiac MI
>
> DIFFERENCES BETWEEN AIRCRAFT & AUTO ALTERNATORS USING A FORD BELT DRIVEN 12v
> OR 24v ALTERNATOR FOR A COMPARISON
>
> 1. Although alternators are bi-rotational, aircraft engines turn opposite of
> automotive. This means cooling fans must be canted in the opposite direction.
> Also, pulley and belt size vary due to coming-in speed.
>
> 2. The thru bolts are of a higher tensile strength utilizing an
> anti-rotation
> device in the form of a lock tab. The rectifier assembly has a heavy duty
> diode with higher voltage and amp. capacity. Also, one excites at 90 PIV (Peak
> Inverse Voltage) and the other at 150 PIV. Radio suppression is designed for
> 108 frequencies and up which is the VHF and 108 and down which is FM band.
>
> 3. The brushes have a higher graphite content and they utilize a tin plate
> on
> the brush leads to prevent corrosion.
>
> 4. The stator is of the Delta wind rather than the “Y" wind and it does not
> utilize the stator terminal. The aircraft unit also carries “H" insulation
> which is capable of 200 degrees centigrade temperatures. It also is rated at
> 60 amp. instead of 55.
>
> 5. The rotor has a shorter shaft and a smaller thread size. Because of the
> opposite rotation it is wound in the opposite direction. It also uses "H”
> insulation and Havel varnish.
>
> 6. The front and rear housings are the same as automotive.
>
> With this brief description, I hope I have enlightened you on the
> differences
> between aircraft and automotive alternators. Using automotive units in an
> aircraft creates a potential safety hazard as well as a short alternator life
> and unreliability.
>
>
>
>
>
>
> >> Homepage: http://www.flyrotary.com/
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