Two identical mechanisms on the left give two different output motions due to different relative positions of the input and output at starting. Center distance of two grey fixed bearings and the eccentricities of circular slot of green and blue rockers are equal.
Input: pink cranks rotating regularly.
Upper mechanism: green rocker oscillates with large angle.
Lower mechanism: blue rocker is immobile.




The mechanism on the right is an ordinary coulisse one for comparison purpose.




Its yellow rocker oscillates with small angle.