Linear translation without runway 3b

It is an embodiment of the mechanism shown at:
https://youtu.be/VnS-V-cnyu4
Input: pink shaft.
Two blue cranks are driven thanks to bevel gear drives.
The yellow platform is translated horizontally along an absolutely straight line (no need of a runway).
Its stroke length L = 4R.
R: length of the cranks (in blue) and bars (in green).
Two chain drives are used to help overcome unstable positions. Refer to:
https://youtu.be/4QBw1wef438
Grey chain wheels of Z2 teeth are stationary.
Green sprockets of Z1 teeth are fixed to the green bars.
Z2 = 2.Z1

STEP files of this video:
http://www.mediafire.com/file/r0f83qudgiv51la/LinearTranslationWORunway3bSTEP.zip/file
Inventor files of this video:
http://www.mediafire.com/file/hd9625o0vxkg76e/LinearTranslationORunway3bInv.zip/file

Видео Linear translation without runway 3b канала thang010146