The lengths of the links comply with the conditions: A͞D=B͞C and A͞B=D͞C. The mechanism constitutes parallel-crank linkage ABCD repeated sixfold. Upon rotation of driving crank 1, connecting rods 2 have translational motion. Rotation of ring 3 is provided for by rollers a on which it rests freely. Links 1 and 3 have equal angular velocities.
$636$LW,PC$