The equations of motion of arbitrary moving links and the constraint equations of pairs have been generally derived with consideration of elastic deformations out of ideal moving planes of links and three-dimensional offsets, which makes in possible to construct systematically the equations of motion of planar link mechanisms. Applying the equations to a crack-and-rocker mechanism whose coupler and rocker are elastic links, the influences of the link elasticities, the crank speed and the transmission angle upon the angles of torsions and the deflections of elastic links, the joint forces and moments and the dynamic deviations of rocker angle have been discussed together with experiments.
