Two mechanisms are identical.
Lengths of three cranks are equal.
Yellow, green and blue links create a parallelogram.
Input: yellow cranks. Output: orange cranks.
Besides the dead positions (when the cranks and the bars are in line) the mechanisms have unstable positions when the cranks are perpendicular to white and green bars.
When the mechanisms overcome unstable positions output motions may change.
The mechanisms can work stably in the range of less than 90 deg. of the input.
For the left mechanism the input and output turn in opposite directions.
For the right mechanism the input and output turn in the same direction.
This phenomenon depends on initial relative position between input and output cranks.