The lengths of the links comply with the condition: 0͞B=a. Link 1 turns about fixed axis 0 and is connected by turning pair B to slider 3 which, in turn, moves along axis Ab of link 4. Link 4 turns about fixed axis A. Link 5 is connected by turning pairs C and D to sliders 3 and 2. Slider 2 moves along axis 0d of link 1. When link 1 turns about axis 0, point D of slider 2 describes nephroid p-p with the equation (x²-ax+cd)²+(yx-bc)²=(ab+dy-bx)²
ρD=0͞D=a(1+2sin(ϕ/2)) or (x²+y²)(x²+y²-a²)²=4a²(x²+y²-ax)² where ϕ is the polar angle between ρD and polar axis 0x.
$1227$LG,Ge$