Link 1 has spherical half collars a that fit over ball-shaped head b of link 3. Pin d of link 4 fits into a hole at the other end c of link 3. Trunnions e of link 4 fit into holes in prongs f of link 2. With respect to each other, links 1 and 2 accomplish five turning motions about the three perpendicular axes intersecting at point 0 and about parallel axes x' -x' and x"-x".
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