Constant-breadth cam 1 rotates about fixed axis A and is enclosed by square opening b of link 2 which has pawls a at its ends. Link 3 rotates about axis A and has teeth d. When cam 1 rotates, pawls a engage teeth d and rotate link 3 intermittently with dwells. When one pawl a engages a tooth d, the opposite pawl a runs up against the top of a tooth.
$3321$GrC,D$