Tooth number of pink crank gear: 20
Tooth number of yellow gear: 40
The crank gear, green connrod and orange slider create a slider crank mechanism. Input is the crank gear rotating regularly.
The green conrod length = Center distance of the gear drive.
The blue slider has linear motion of complicated velocity rule.
Beside geometric dimensions of the links, its motion also depends on the position between the pin of the yellow gear and the crank gear when assembling.