Double Variomatic has two pairs identical gears with a varying gear ratio. When turning, at first the top square turns 90 degrees together with the bottom square. But then they start to diverge, with one square turning 90 degrees and the other 180 degrees. This local 1:2 gearing ratio is achieved by cascading two 1:sqrt(2) gear sections. Actually, that is not entirely true.The gearing ratio is continuously varying, and the 1:sqrt(2) ratio is only an average. Similarly, overall gearing ratio is 1:1 at average. After one full turn, both squares are back to start.