You can find assisted opening folders with the detent ball activated but not all are that way. They all have detent balls to make for smoother action that are installed in them just like in any other folder of the same type but in the AO knives with the little lock for the blade, like the Leek, Scallion, Chive and a few others the detent is not falling into a small starter hole in the blade like the ones without the locks. The Blur for example was one I noticed and owned that can manage without the spring because the detent can still prevent the folder from being an illegal gravity knife if the spring was removed or broken.
On the Leek, Scallion, Chive and some others like those if the spring breaks and you don't use the lock installed in the back of the body of the folder there is nothing keeping the blade from opening in the pocket even if it was just the point peeking up out of the body enough to catch a finger or snag into the pocket lining. So in answer to your question yes the spring keeps the blades closed.
STR
