Rocker arm 5 of four-bar linkage ABCD is connected by turning pairs E and F to pawls a and b. Ratchet wheel 2 rotates about fixed axis D. When crank 1 rotates about fixed axis A, pawl a turns ratchet wheel 2 intermittently counterclockwise. During this time, pawl b is kept out of engagement by shield d on lever 3. Lever 3 can be turned to bring pawl b into engagement and take pawl a out of engagement with wheel 2. Then wheel 2 will be turned intermittently clockwise. Spring 4 serves to brake the motion of wheel 2.
$1808$LR,6L$