On Thu, 19 Jan 2012 15:49:47 -0000, "Ian Field"
wrote:


"Jim Thompson" wrote in
message ...
On Wed, 18 Jan 2012 18:46:14 -0500, Jamie
t wrote:

[snip]

And let us not forget that these non-pm alternators have not used
brushes for the field for years now. Nothing but bearings and the
unexpected mishap to take place now.

[snip]

Huh? How does that work?

The type used on motorcycles has a "claw" type poles arrangement, but
instead of them being fixed to a core in the middle with the field winding
on - the claw fingers are brazed together with non-magnetic spacers.

The field winding is static and magnetically coupled to the claw poles
coaxially. The inner claw is integral with the taper that fits on the end of
the crankshaft and also extends to form the center pole.

The outer claw poles are simply a brazed on ring of poles that form the
outer of the coaxial poles.


Hey, I suggested that, but didn't think it would work! I figured there
would be too much reluctance in the field path, but that geometry
seems to fix that.

John