Elliptical gear 1 rotates about fixed axis A which passes through one focus of the ellipse. Gear 1 meshes with identical gear 2 which rotates about fixed axis B, also passing through a focus of the ellipse. Crank 5 is rigidly attached to gear 2. Connecting rod 3 is connected by turning pairs C and D to crank 5 and slider 4. Slider 4 reciprocates in fixed guides a-a. When gear 1 rotates at uniform velocity, slider 4 travels at the ends of its stroke at almost constant velocity.
$2428$LrG,5L$