Hi Marcin,
Nice drawings! I think the Obsession UC is based on Greg Babcock's 24 inch as described here:
http://synrgistic.com/astro/24inch.htm
I would suggest you look at how Greg has made the base ring larger so that the altitude bearings don't overhang the base. This is a much more stable design, sometimes referred to as a 'flex-rocker'. The idea is to place the azimuth teflon pads directly below the altitude pads so the force is transferred vertically through the ring to the ground. If you google 'flex rocker' you'll see lots of examples.
Rod.