Round guide (pin) b, secured in prongs a of link 1 , fits into a hole in end c of link 3. Ball-shaped head d, at the other end of link 3, fits into spherical recess e of link 2. With respect to each other, links 1 and 2 accomplish four turning motions about the three perpendicular axes intersecting at point 0 and about axis x' -x' , and one translational motion along axis x' -x' .
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