Cam 1 rotates about fixed axis A and, through roller 5, turns link 6 about fixed axis B. Pawl 2 turns about axis C of link 6 and engages teeth b of ratchet wheel 3 which rotates about fixed axis D. When roller 5 is raised by the lobe of cam 1, pawl 2 turns wheel 3 counterclockwise. As roller 5 rolls around lobe surface a-a of cam 1, tooth 4 of link 6 locks wheel 3 against further counterclockwise rotation and pawl 2 locks it against clockwise rotation.
$2722$RG,ML$