Lever 3, turning about fixed axis A, is oscillated by link 1 which is connected to a drive (not shown). Link 1 is connected by turning pair B to slider 6 which moves along slot b of link 3. Link 3 is connected by turning pair C to pawl 2. When link 1 reciprocates, pawl 2 turns ratchet wheel 4 intermittently counterclockwise about axis A. Roll 5, mounted on slider 6, moves along cam groove a of ratchet wheel 4. Cam groove a is designed of such shape that the distance between axis A and the centre of roll 5 gradually increases and then decreases again. This varies the angular velocity and angle of rotation of lever 3 and ratchet wheel 4.
$1800$LR,4L$