The lengths of the links comply with the conditions: B͞E=C͞F and E͞F=B͞C. Connected to four-bar linkage ABCD are links 1 and 2 which form parallelogram BEFC. Links BC and EF are always parallel. Points G and H, lying on any arbitrary radial line Aa drawn from point A, describe similar paths with a similarity factor k equal to k=G͞B/H͞E.
$626$LW,PC$