The lengths of the links comply with the conditions: A͞D=D͞C, A͞B=B͞C, A͞E=E͞F and C͞G=G͞F=G͞H. Figure CDAB is a rhomboid linkage. Link 2 turns about fixed axis B and is connected by turning pairs A and E to links 1 and 5. Link 4 turns about fixed axis C and is connected by turning pairs D and G to links 1 and 6. Links 5 and 6 are connected by turning pair F. When link 2 turns about axis B, point F describes straight line Ca which is perpendicular to BC, and point H describes straight line Bb which coincides with BC. The points of link 6 describe ellipses. Angle ∠ AEF is always equal to angle ∠ FGC.
$709$LW,GI$