Cam 1 reciprocates in fixed guides a-a and has two profiled cam surfaces b and b'. Follower 3 reciprocates in fixed guide B and carries roller 2 which rolls along cam surface b during the upstroke of cam 1 and along cam surface b' during the downstroke. Cam surfaces b and b' have different profiles. Follower 3 has a long dwell while roller 2 rolls along portion cd of cam surface b. There is sufficient friction in the mechanism to keep roller 2 in contact with surfaces b and b' on the upward and downward motions of cam 1.
$3051$SmC,3L$