These linkages are four-bar Grashof crank-rockers where r3 = r4. They generate coupler curves which have a line of symmetry.
In this example:
r1 = 4 , r2 = 1 , r3 = 3 , r4 = 3 , rp = 2
theta1 = 0 , beta = 30 deg
To see an animation of this linkage select the link below:
