Plate cam 1 rotates about fixed axis A and its contour slides along profiled surface d-d of follower 3 which turns about fixed axis B. Pawls a and b of follower 3 alternately engage the teeth of ratchet wheel 4 which rotates about fixed axis C. When cam 1 rotates, pawl a turns ratchet wheel 4 which is rigidly attached to the type wheel (not shown). As follower 3 swings back by the action of spring 2, pawl b turns ratchet wheel 4 further in the same direction.
$3355$CR,FD$