Cam 1 turns about fixed axis A and has groove a-a along a logarithmic spiral. Follower 2 reciprocates in fixed guide b and carries roller 3 which rotates freely about axis B and slides and rolls along groove a-a. Positive motion is achieved because roller 3 is confined between side surfaces d and e of groove a-a. Cam 1 oscillates through an angle of 720° about axis A. Within these limits, equal angles of rotation of cam 1 correspond to equal displacements of follower 2.
$2991$SmC,3L$