Pinions 1 and 2 rotate about fixed axis A. Link 3 reciprocates along axis B-B in fixed guides a-a. Pinions 1 and 2 rotate freely on shaft 7 and ratchet wheel 4 is keyed on shaft 7 between pinions 1 and 2. On their inside faces, pinions 1 and 2 carry freely pivoted pawls 6 and 5 which engage ratchet wheel 4. The pawls are located so that in the reciprocation of link 3 whose rack teeth b rotate pinions 1 and 2 in opposite directions, each pawl engages ratchet wheel 4 only when its pinion is rotating clockwise. Thus, being rotated alternately by pinions 1 and 2 through pawls 6 and 5, ratchet wheel 4 and shaft 7 rotate continuously in one direction (clockwise in this case).
$2327$SG,3L$