Slider Crank Mechanism of Equal Crank and Conrod Length
The mechanism gives long stroke length of blue slider L = 4R.
R is crank radius (in yellow) and length of conrod (in green).
If the crank is driving, the mechanism faces unstable positions when the crank rotary axis and the slider pivot are in line.
To fix this problem here the green conrod is driving thanks a motor (in blue) fixed to the slider.
If L differs from R, the mechanism does not work.