Link 1 rotates about fixed axis A. Link 3 and ratchet wheel 4 turn independently of each other about fixed axis B. Link 3 is connected by turning pair E to pawl 2 which engages ratchet wheel 4. When crank 1 of four-bar linkage ACDB rotates about axis A, pawl 2 turns ratchet wheel 4 intermittently counterclockwise. Pawl 5 prevents clockwise rotation of wheel 4. The angular velocity (angle of rotation) of the ratchet wheel can be varied by adjusting slider 6 along slotted link 7 and clamping it in the required position.
$1816$LR,6L$