The lengths of the links comply with the conditions: D͞E=F͞G, D͞F=E͞G, P͞F=E͞Q, D͞P=G͞Q, A͞B=O͞B-O͞A, O͞B=K²/(2O͞Acos(θ)) and O͞E/O͞D=Q͞E/Q͞G=P͞F/P͞D, where θ=α+β and K²=E͞Q×Q͞G-E͞O×O͞D. Figure DEGF is a crossed-crank linkage. When link 2 turns about fixed axis A, point P of triangle PFD, belonging to link 5, describes a circle of radius r=A͞P. Point Q of triangle QEG, belonging to link 4, describes straight line q-q which passes through point B and makes angle θ with straight line n-n perpendicular to OABl. Another feature of the mechanism is that angle ∠ QOP remains constant and equal to θ.
$698$LW,GI$