Angle of the orange twin equal crank is A = 60 deg.. Angle between sliding directions of the runways is B = A = 60 deg.
The crank pivot center must be on the bisector of sliding directions of two sliders.
Transmission ratio of linear displacement between the blue slider and the yellow one is 1. When the yellow slider moves regularly, so does the blue.
Advantage over rack-pinion drive: high precision of transmission at low manufacture cost.