Gear 1 rotates about fixed axis A and meshes with gear 3 which rotates about fixed axis B. Pin 4 of gear 1 rotates about axis C and slides along curvilinear slot d-d of slotted lever 2 which is connected by turning pair D to gear 3. The shape of slot d-d is designed so that point E of lever 2 describes curve q of which portion ab is approximately a straight line.
$2524$LrG,GI$