Parallelogram mechanism 2

Input: pink or orange shafts. They are identical. Besides the main connecting rod (in blue) there is an auxiliary connecting rod (in yellow). It is pivoted on the eccentric portions of the shafts. It helps the mechanism overcome the dead positions, when the shaft cranks and the blue connecting rod are in line. So it is possible to state that each shaft has two cranks, one for the blue connecting rod, the other for the yellow one. The angle (A) between them must differ from 0 or 180 deg. In this video A = 120 deg. Without the auxiliary connecting rod the parallelogram mechanism may be converted accidentally to an inverse parallelogram mechanism as shown in the last scene of the video. Inventor files of this video: