Green and blue bars create a pantograph.
Input: pink (or violet) crank.
Output: the other crank. It rotates at the same input velocity but in opposite direction.
Line connecting centers of fixed revolute joints of the cranks is perpendicular to sliding direction of orange slider.
When the cranks are parallel to sliding direction of the orange slider, the pantograph three joints with the cranks and the slider are in line.
For this pantograph: length of blue bars: a + a, length of green bars: a.
Length ratio of the pink and violet cranks: 2
White gears do not belong to the mechanism. Their apperance aims to show transmission ratio of -1 between the cranks.The mechanism has unstable positions when the two cranks are in line.