The lengths of the links comply with the conditions: A͞B=D͞C, A͞F=D͞E, A͞G=D͞H and A͞D=B͞C=F͞E=G͞H. Links 1 and 2 rotate about fixed axes D and A. Connected to these disks by turning pairs are links 3, 4 and 5 which form parallelogram linkages together with the disks. Digging members 6 are rigidly secured to links 3, 4 and 5. When link 1 rotates the mechanism holds the digging members in the vertical position.
$912$LW,FD$