s + l > p + q
s = length of the shortest link
l = length of longest link
p and q are the lengths of the two remaining links.
For linkages of this type continous relative motion between any two of its links is not possible.
Inward/Inward Triple rocker: input inward limited, output inward limited
Outward/Inward Triple rocker: input outward limited, output inward limited
Inward/Outward Triple rocker: input inward limited, output outward limited
Outward/Outward Triple rocker: input outward limited, output outward limited