Orange input wave generator of oval shape always contacts with all rollers of a closed chain. A link of the chain has an elongated pin to create a revolution joint with red slider that moves in a slot of a fixed runway. The input and the output gear are coaxial. The chain performs a complicated motion forming “waves”.
Tooth number of the gear Zg = 30
Link number of the chain Zc = 28
Transmission ratio: i = Zg / (Zg – Zc)
If (Zg – Zc) small and Zg large, i can be very large.
The input and output rotate in the same direction.
For this case 15 revolutions of the generator correspond 1 rev. of the output gear.
Velocity of the latter is not constant.
For comparison: if chain, slider and runway of this mechanism are merged into a flexible part, it becomes a familiar harmonic drive of flexible gear.