The pivots on the handle ferrules were for folding the handles down over the blade--they're cut out to fit the blade--for transport (tossing in you carpenter's tote). Pivots on the blade tangs were for setting angle and depth of cut.
These were the best drawknives available IMO. A Swan double pivot on top (different mechanism), Wilkinson (the best seller), and 3 Cantelos. The middle Cantelo is double pivot.