Crank 1 rotates about fixed axis A and is connected by turning pair C to slider 5 which moves along link 6. Link 6 turns about fixed axis B. Slider 7 moves along slot a of link 6 and is connected by turning pair D to gear 8 which meshes with fixed rack 3 and with moving rack 4. Rack 4 belongs to slide 2 which moves along fixed guides b-b. When crank 1 rotates, slide 2 reciprocates at a velocity twice that of point D. Thus the stroke of slide 2 is twice that of point D.
$2451$LrG,ML$