Hi Steve,
I'm always with you
. Thx for careing. I was doing some other modelling stuff and was trying to get this internal gear ring.
I'm still thinking about of building a rotary passage for power supply so I decided to use an internal gear rim.
I found it on the TV. It was a report about inventions. Someone was showing a rehab buggy for disabled persons with a connectible electric drive. This gear ring is screwed to the wheels and the pinion is spuring in.
I managed to find the inventor of this system and to purchase one of these internal gears from him.