Crank 1 rotates about fixed axis B and is connected by turning pair E to slider 3 which moves along slot b of slotted link 2. Link 2 turns about fixed axis A. Link 4 is connected by turning pairs K, F and G to slider 8 and links 9 and 5. Slider 8 moves along circular slot a of link 2. Link 5 turns about fixed axis D and carries pivoted pawl 6 which engages ratchet wheel 7. When crank 1 rotates clockwise, slotted link 2 oscillates. This motion is transmitted to pawl 6 which turns ratchet wheel 7 intermittently counterclockwise about axis D. The angle of rotation of wheel 7 depends upon the position of point H which is changed by turning lever 10. Lever 10 is set in the required position by turning it with handle d about fixed axis C and locking it in this position by having the pin on handle d enter the corresponding slot of fixed quadrant 11.
$1843$LR,SF$