The lengths of the links comply with the conditions: A͞D=2A͞B, B͞C=D͞C=C͞E=2.5A͞B, B͞E=G͞F, B͞G=E͞F=A͞H and H͞G=A͞B. The mechanism is based on four-bar linkage ABCD. When link 1 turns about fixed axis A, point E of connecting rod 2 describes a path of which a certain portion approximates straight line q-q, belonging to the fixed link and parallel to line AD. For the specified dimensions, figures ABGH and BEFG form parallel-crank linkages and link 4 has translational motion. During the period of time that point E travels along the approximately rectilinear portion of its path, all points of link 4 also travel approximately rectilinearly and its axis EF is perpendicular to straight line q-q. Links 3 and 7 turn about fixed axes D and H.
$720$LW,GI$