Link 1, rotating about fixed axis A, is connected by spherical pair C to link 2 which, in turn, is connected by spherical pair D to link 3. Link 3 rotates about fixed axis B. Link 2 has two spherical sockets a that fit over spherical heads b of links 1 and 3. The mechanism transmits rotation between any two arbitrarily located axes A and B.
$565$LW,4L$