i = nc/n1 = Z1/(Z1+Z3)
nc: velocity of the blue crank.
n1: velocity of the orange gear, its tooth number: Z1 = 20
Z2 = 20, tooth number of the yellow gear.
Z3 = 60, tooth number of the fixed green internal gear.
Z1 + 2Z2 = Z3
i = 1/4
The crank, the orange gear always rotate the same direction independently of the tooth numbers..