For a morning diversion from my other projects, I made a Marinov motor. This is a motor that is simply two ball races and an axle.
“Continue reading” for details and photos.
It runs on 100+ amps AC or DC and will run in whichever direction it is started. My understanding is that it is powered by thermal expansion. The contact point of the ball with the ring forms a hump of hot expanded metal on the flat surface and it is effectively propelled on by this wave behind it once it starts moving in whichever direction. It is a bit like a surfer being carried forward on the crest of a wave. As you would expect from 160 A at 12 V (dropping to 2 or 3 from my rather old battery) it rapidly heats up.
I used new ball races (AUD$ 35) with a 1 inch internal diameter and an axle from a Fisher and Paykel washing machine (I originally got this as they make great wind powered generators). I removed the plastic covers from the bearings and degreased them, replacing this with a little light machine oil so they spin well. Interestingly there is about 0.5 mm free play between the ball races and the axle but by the very manner of operation this may also add to rotation and indeed the performance is better if I don’t remove this with shims and peak rotation is up to 1600 RPM.
Mike’s Electric Stuff has the best background on this.
The upper photo shows it running at 1223 RPM at 165 A but the flash has stopped the motion. The lower photo shows it running at higher power on AC this time from my 6 V 90 A transformer ($20 junkyard find) which I have added to my spotwelder setup which happens to work fine as a high current switch. With the AC the current is 365 A and peak RPM 2016 before thing start sparking, overheating and slowing after only 5 or 10 seconds. Even the heavy black cables 6 and 8 mm get warm.
Video here
This is a video showing the motor running underwater (1Meg). It runs slower as expected but still runs. You can see the tungsten switch electrodes glowing red as well.
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Photo Date: 2005