And now on to what I found...
Before I did any tear downs, I wanted to just try them "as is" so to speak. To that end, I did a wet break in on the first motor, figuring that if it had small brushes in there, they needed all the help they could get. I started at 2 volts for 5 minutes, everything looked/sounded good, went to 4 volts for five minutes - at the start you could see light arcing in the solution, but it minimized by the end to the point of not being visible in normal lighting. Again, thought it looked pretty promising. Then went to 6 volts. Notable arcing at the start. At the end of the 5 minutes it had reduced, but not to a level I was happy with. So I ran an additional four, five minute cycles... At the end of these the arcing was reduced notably, but still present... From there, decided to go for broke and went to 12 volts.
This generated PRONOUNCED arching similar to a set of fresh, non-seated brushes... Decided that I was going to see the end of the arching one way or another. Ran the motor in 15 minute segments submerged... First for one more run at 6 volts (no notable change by it's end) and then at 12 volts for the balance of the runs. At 12 minutes into the 8th segment 12volts, the motor stopped running.
Thinking that maybe this one was a fluke (not being able to get away from the arcing), I started a second motor on the same wet break in regime. Same general arcing performance was seen, so after one stint for 5 min at 12 volt, and seeing the same arcing level I did before, I decided that it was time to see what it would do on the track. I dropped one into a Womp chassis with a bunch of lead in it (circle track set up) and started to "abuse" it. The heavy weight and short straights of the banked oval made short work of motor #2 - with it getting VERY hot and doggy after about 6 minutes of run time. (stopped there)
Overall impression in it, was that it seemed to have some decent rpm, but was sorely lacking low end torque. Similarly, braking performance was notably less than the Plafit Fox motor that normally resides in that chassis.
After the return from the track it was teardown time.
Not sure if there is more than one version of these critters - but I have dissected three out of the five I bought, and all three were set up the same, and are all designed with finger type contacts verses brush material. The set up looks to be somewhat similar to the system used on the M/T SL-1 motor I tore down, except, instead of three flat fingers on each arm, these use two "V" shaped fingers. I am not sure if that is to insure solid contact (high point loading) and low friction with the low voltage that they normally run at or?
The effect looked like this if you looked at the profile of the toothbrush fingers verses the M/T SL-1 fingers:
\/ \/ verses __ __ __
The "V" set up is good for insuring solid contact/low friction, etc, but is not so hot for current flow due to the small contact point (which explains the arcing at higher power levels)
I took pictures of both a "fresh" endbell and a the one killed in wet break in. If you zoom in on the pictures, you can kind of see the "V" shape of each of the fingers and can also see the "stumpy" ones from the one that "stopped running". :oops:
This shot shows just how much damage the "little fingers" did on the road to failure to the commutator. Pretty impressive trenches for a total of less than three hours of unloaded run time!
So as it was mentioned above - it doesn't look like, in stock form, these are going to be a good application, but I applaud ShotgunDave for finding them and giving us something to tinker with!
:clap:
Enjoy!
