26 Fundamental concepts
space to make them share a common axis, and, after this common joint
was removed, the resulting linkage would certainly remain mobile. The
condition for the resultant linkage to have mobility one is that the equivalent screw systems of the original linkages shall intersect only in the screw
axis of the common joint when they are placed. Waldron listed all six- bar
linkages, which can be formed from two four- bar linkages with lower
joints. It is obvious that the double- Hooke’s-joint linkage and the Bennett
6R linkages that we discussed above belong to this linkage family.
(c)
Figure 2.16 continued.
space to make them share a common axis, and, after this common joint
was removed, the resulting linkage would certainly remain mobile. The
condition for the resultant linkage to have mobility one is that the equivalent screw systems of the original linkages shall intersect only in the screw
axis of the common joint when they are placed. Waldron listed all six- bar
linkages, which can be formed from two four- bar linkages with lower
joints. It is obvious that the double- Hooke’s-joint linkage and the Bennett
6R linkages that we discussed above belong to this linkage family.
(c)
Figure 2.16 continued.