The orange gear (internal teeth number Z5) is the connection rod.
Z4 is teeth number of the red gear.
Z2 is teeth number of the green gear.
Z1 is teeth number of the violet gears.
Velocity relation: ω4 = ω2.(Z2/Z1).(Z5/Z4 - 1)
ω2: velocity of Z2.
ω4: velocity of Z4.