The lengths of the links comply with the conditions: A͞D=B͞C=A͞E=B͞F=A͞G=B͞H and D͞C=E͞F=G͞H=A͞B. When triple crank 1 rotates, the axes of links 2 remain parallel to the line of centres AB and are therefore horizontal during travel. The mechanism is based on parallelogram linkage ABCD in which turning pair B is designed as a fixed disk encircled by collar 3. Paddles a are mounted on links 2.
$911$LW,FD$