My grandfather made one of these many years ago, I last saw it when I was 5 and not allowed to play with it :D His was octagonal, not round, but the same idea as this. Expanding circular table
My sister's current dining room table has some fancy mechanism to move the leaves up into position and back into storage... or at least did until the movers managed to damage the mechanism.
Her original dining room table, has an extremely simple, all wood, sliding mechanism that's pretty much bullet proof.
Just because you can be fancy and impressive, doesn't mean there isn't simple, bulletproof wonderful techniques out there for the finding.