On Jun 24, 2009, at 12:28 PM, William Beaty wrote:
Here's something I've been meaning to test. I expect that it's
real, and
would get the experimenter some fame: Marinov's ball-bearing motor.
http://www.electricstuff.co.uk/bbmotor.html. The othodox concensus is
that it's driven by thermal humps in the steel. But this is
debunkery, not experiment. Nobody bothered to test whether the
phenomenon
requires thermal humps! A fair test would be to use some loose
bearings,
and to immerse them in liquid mercury. No hot contact points, no
thermal
humps. Does the device still run? If so, then it's proved to be a
Homopolar Motor, or perhaps some other unknown effect, and all the
people
who distainfully rejected Marinov's motor are shown to be dishonest
idiots. (But man, it's mercury. Do you want that stuff all over your
kitchen or garage? It's guaranteed to get spilled one or two times.
Finally we can buy GALINSTAN gallium-based liquid metal from
scitoys.com)
PS
It would be nifty to find bearings made of a non-magnetic yet
conductive material, especially if there were an identical steel
bearing available as control.
The above web site states: "This interesting but unfortunately not
very useful device produces motion from electricity without magnetism
being involved. It operates purely by thermal means, so it works on
AC or DC, and the motor can rotate in either direction, determined by
the initial spin which is usually required to get it going."
A good test of this statement I think would be to use fully non-
magnetic (both balls and races) steel bearings. It would also to
some degree test my hypothesis, that the torque is due to hysteresis
in the races interacting with fields in the balls. See:
http://www.mtaonline.net/~hheffner/HullMotor.pdf
My hypothesis is possibly more easily checked. "The motor will work
well with low permeability ball bearings like stainless steel or even
copper or aluminum. The motor will not work without at least one
magnetic material race exhibiting hysteresis. The more hysteresis in
the races the better the motor works. Two high permeability ball
races should give about twice the torque as one highly permeable
race. Thinner races (in the axial direction) should work better than
thick ones. In other words ball bearings should work better than
roller races where the rollers are longer than their diameters, due
to the need for the external field to be projected out of the race
and into the bearing. (Note, however, that roller bearings that are
thinner than their diameters should work better than ball bearings,
because more roller material is located where the effective fields M
are.) Ordinary brushes or slip ring
brushes should not work at all."
Another way to look at this is two (a total of 4) axially thin roller
bearings separated a bit should work better than one long roller
bearing at the same current.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
