Rack 1 with slots a slides in fixed guide p. Disk 2 with slots b can turn about fixed axis A. Slots a of rack 1 are slightly wider than disk 2 and slots b of disk 2 are slightly wider than rack 1. In its reciprocating motion, rack 1 periodically locks disk 2 against rotation; disk 2 in rotation periodically locks rack 1 against reciprocation so that their simultaneous motion is impossible.
$333$SL,SD$