<VV> The Great Fan Belt Toss (Motoring Generator)

[John]

Your generator kept running because you do not have the correct (OEM
factory spec) voltage regulator.  The Corvair generator voltage
regulator is a special low cut out design to prevent exactly what
happened to you.

A DC generator (not alternator) is exactly the same as a DC motor.  Each
has field (stator) windings and armature (rotor) windings.  Used as a
generator, current in the field winding produces a magnetic field. 
Mechanically rotate the armature and you produce current in the armature
windings.  This is rectified by the commutator (the thing the brushes
rub against).  Vola a generator!

Take that same generator, supply current to the field windings from a
battery to produce a magnetic field and you have a motor.  But the
generator, that wants to be a motor, doesn't have a motor starting
winding.  Well it doesn't need one.  It was already spinning when the
belt broke.  It will just keep running until the battery that supplies
the field current dies.  The correct (low drop out) voltage regulator
will break the field current stoping the motor action.  Exactly what you
did when you disconnected the battery.

John Dozsa


> From: GFrenzie@aol.com
> Date: Thu, 10 Jun 2004 04:04:18 EDT
> To: virtualvairs@corvair.org
> Subject: <VV> The Great Fan Belt Toss
> 
> Recently while on my way to attending one of the largest one day car shows on
> the east coast, 1,000/1,200 vehicles (MG car/Victor Lions club, Victor, New
> York) my '61 Rampside 80 hp..decided to throw it's fan belt, not once, but 5
> times over a distance of 12 miles. Every time the fan belt came off, the
> generator light would stay on even after I turned the ignition off. I would then
> disconnect the ground lead on the battery and it would stop turning.
> 
> When the belt came off the first time, I "looked" it over and it looked ok to
> me, it was intact (not broken) so I put it back on. Within a couple of miles,
> poof, off it went. To make a long story short, after reaching our
> destination, a club member gave me another fan belt and I installed it, and drove home
> after the show without any problems.
> 
> My question is....after the belt came off and I turned the ignition off, why
> did the generator keep running until I disconnected the battery lead?
> 
> Thanks for any input....
> George