Figure OABC is a crossed-crank linkage. Link 1 turns about fixed axis 0 and is connected by turning pairs C to links 3 and 7. Links 3 and 7 are connected by turning pairs B and D to sliders 6 and 2 which move along axis 0n of link 5. Link 5 turns about axis 0. Link 4 turns about fixed axis A and is connected by turning pair B to slider 6. When link 1 turns about axis 0, point D of slider 2 describes elliptic lemniscate q-q with the equation ρD=0͞D= a*sqrt(b²-a²*sin²(ϕ)) or (x²+y²)=d²x²+f²y² where d²=4b², f²=4(b²-a²), ϕ = polar angle between vector ρD and polar axis 0x.
$1180$LG,Ge$