On Aug 8, 2009, at 6:04 PM, Kyle Mcallister wrote:
Or lack thereof.
Tests using various cage-to-race tightnesses showed no motoring
effect whatsoever, even with enough current applied to cause heavy
automotive jumper cables to become uncomfortably hot. Identical
shaft and flywheel setup was used as in the ball bearing motor
which works flawlessly. With this setup, there is no noticeable
change in deceleration speed of the motor, though the 'growling'
noise of the internal arcing is still heard, as with the ball
bearing motor.
This is a bit of a surprise. I would have thought with that much
current it would have had at least some sign of working. I guess
there is probably more inherent friction. Magnetically it is not
nearly as good as ball bearings because the current i is spread out
over the width of the bearing, and that means the B field is reduced
in proportion, which means the i L x mu0 M force due to hysteresis,
being a product, is reduced significantly. The combination of all
three factors must be enough to wipe out visible torque.
Just to be sure the parts were all magnetic it might be worthwhile to
check them with a magnet. If you don't have a magnet small enough,
then a cut off flat head nail stuck to a good magnet can make for a
handy tester.
Bearings used (2): National Bearing S-A-12 automobile wheel
bearings, obtained from Advance Auto Parts.
Shaft: 5/8" all thread, steel. 12" long.
Power supply: 12V 1200 peak Ampere car booster
Horace... I did look for nonmagnetic bearings composed of brass or
something similar. Nothing here. If I have some spare time (not
sure when for a while) I will go down to Buffalo Bearing and ask
what can be had.
--Kyle
I have to call ahead to my bearing shop, because the bearing store
here is in Anchorage, which is a 100 mile round trip drive for me.
They didn't have any such bearings - not even stainless steel, so I
saved myself a trip.
Thanks for doing that experiment. It is further confirmation that
the source of torque for the Marinov Ball Bearing Motor is
hysteresis, and that there really is nothing "Marinov" about it.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
