Now we all know a lot more!

Karl

----- Original Message -----
From: "David Beierl" <dbeierl@IBM.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, May 08, 2000 2:47 PM
Subject: Re: Speedometer problems

> At 15:13 5/8/2000, Karl Wolz wrote:
> >and I was told it was due to a "slipped magnet".  Now you know as much as
I
> >do.
>
> Karl, I believe these things operate by spinning a magnet in close
> proximity to an aluminum disk which carries the pointer.  The rotating
> magnetic field induces a current in the disk, which in turn generates a
> magnetic field that interacts with the one from the magnet, and causes the
> disk to rotate against the tension of a hairspring.  The intensity of
> interaction and hence the rotating force is increased as the magnet is
> moved closer to the disk -- setting this distance is part of the initial
> calibration of the instrument.
>
> david
> David Beierl - Providence, RI
>   http://pws.prserv.net/synergy/Vanagon/
> '84 Westy "Dutiful Passage"
> '85 GL "Poor Relation"