A measure to ensure proper engagement (jam avoiding).
Input: the pink gear.
Its number of remained teeth Z1c = 30
Its original number of teeth Z1 = 40
Its number of cut-off teeth Z1f = Z1 – Z1c = 10
The blue gear sector has 4 teeth (Zs)
Output: the yellow gear of Z2 = 20 teeth.
When the pink makes 1 revolution, the yellow makes (Z1c + Zs + A)/Z2 = (30 + 4 + 2)/20 = 36/20 = 1.8 revolution and pause during (40 – 36)/40 = 1/10 revolution of the pink.
Why A = 2?: If the pink gear has only 1 tooth and the blue gear sector is absent so when the pink makes 1 revolution, the yellow makes 3/20 revolution.
Measure to keep the output gear immobile during its pause is not shown.
Disadvantage: Pause time can not be long.