I'll try and explain the best I can since no one else has answered you.
The spring keeps the slide release pushed forward, which is connected to a lever that is connected to a cam that goes into a notch in the tang of the blade. When you open the knife, it forces cam into the notch of the blade to lock it open.When you pull back on the slide release, it pulls the cam out of the notch of the blade allowing it to close.
If the spring should collapse, the blade would not be secured, and it will swing freely.
I found all this out when I changed my spring to a lighter compression one, so found out how it functioned.
I'm sure someone else can explain it better, but maybe it gives you some idea.
Hope this helps.
Larry