Green cover is a connecting rod of an ellipse mechanism of two pink sliders. Driving force from fixed cylinder is applied to the connecting rod via a pinion rack drive (instead of to pink lower slider) ensures smooth motion of the mechanism even at death position when the connection rod is vertical.
Gap between the floor and the cover is rather small.
The cover occupies rather small space during motion.
The mechanism can be used for a door with ceiling arrangement of the runways.