Orange conrod, green and upper yellow cranks create a parallelogram mechanism.
R1: pitch radius of green gear
R2: pitch radius of blue gear
i = R1 / R2 = 40 / 19. This ratio is needed to meet requirement when green gate rotates α = 58 deg., blue gate rotates 90 deg. in relation with the green gate.
i changes when α has different values. i = 1 if α = 90 deg.
If necessary a supporting swivel wheel for the blue gate is mounted at its lower right corner.
This video was made on request of Mr. JC Lo from Malaysia.