The pictures from your sample are not stereoscopic.
You used the exact same picture for the left and right eye.
You can not recreate a stereoscopic view from a single picture.
Both pictures need a different perspective with preferably lines converging at the focus distance.
Engineering drawings like the illustration uses isometric, so every line curve can be measured at scale regardless of distance from observer.
Isometric 3D is intrinsically incompatible with stereoscopic display because of its fixed perspective whose goal is to represent accurate scales rather than projection at an angle.
To see what change from one eye to the other on stereoscopic images:
- Place your right hand pointing up and perpendicular to your right eye so that you see only your forefinger's edge and the tip of your middle finger's edge.
- Close your left eye, you see only the edge of your fingers.
- Open your left eye and close your right eye: You now see your fingers at a different angle.
Repeat with placing your hand centered to your nose. Now each eye see a different side of your hand.
The closer is your hand to your eyes, the more extreme are the differences between the left and right images.
At a distance, the perspective difference are less extreme because the distance between your eyes is much less than the distance from your eyes to the object.
The gears from your illustration with their isometric proportions, is more like a telephoto shoot. A telephoto shoot renders poorly as stereoscopic because at long distance, both images are nearly the same.
When left and right images are the same, then render a single image, because having two, brings nothing to the perception of 3D but the inconvenience of colored glasses to recover that single image.