The lengths of the links comply with the conditions: O͞D=D͞E=K͞F, L͞F=F͞E=K͞D, M͞A=A͞B=K͞C and N͞C=C͞B=K͞A. Figures ABCK and FEDK are parallel-crank linkages. Pins M, K, N and L slide along fixed guide a. When link 1 turns about fixed axis 0, the condition O͞L=O͞M+O͞N is always complied with. Thus, the mechanism adds two lengths: O͞M and O͞N.
$743$LW,MO$