Mechanism for reversing rotation direction
i = n1/nc = 1 – Z4/Z1
nc: velocity of the blue crank.
n1: velocity of the orange gear, its tooth number: Z1 = 50.
Z2 = Z3 = 20 (pink gears); Z4 = 100 (fixed green gear)
i = - 1
The blue crank and the orange gear have equal velocity but rotate in opposite directions.