On the Finite Screw System of the Third Order Associated With a Revolute-Revolute Chain

The finite displacements of the outermost body of a revolute-revolute chain are investigated. All the possible screws of the finite twists of the outermost body of an R-R chain are shown to form a screw system of the third order. The analytic expression of the screw system is given. The finite screw systems of special configurations of an R-R chain as well as the degenerate forms of the finite 3-system in infinitesimal kinematics and in displacing two points of a body are also discussed.