Model 06: symmetrical mechanism
Kinematic scheme:
Dimensions:

Measured at model [m] 
a 
0.417 
b 
0.417 
c 
0.180 
d 
0.320 
Explanation:
Point C, halfway on the coupler bar, traces a symmetrical curve. The
coupler can make a full rotation.
The model also shows, for the symmetryposition, the instantaneous
centre of rotation of the coupler plane, the inflection circle and the pole
tangent. The latter approximates a straight line. The intention of the
graphical construction is unknown.
Literature:
Remarks:
The drawing is on scale using the measured model dimensions.