It is a combination of two sine mechanisms sharing a common yellow slider.
Input: green (or violet) crank.
Output: the other crank. It turns at the same input velocity but in opposite direction.
Input and output are coaxial.
Disadvantages:
- Inertia forces created by reciprocating parts.
- Dead positions when output crank is vertical.
The mechanism becomes a regular coupling (no reversing) when the cranks are set to be always parallel.