Ok, the weight of the table acts as a spring, and ok when the bolt attaches to the washer, but I don't understand how the release happens! Is it due to the rounded head of the bolt that manages to move out, or is there something that makes it move/slide?
The top lever has a large washer held loosely with a screw.
The bottom level has a screw which is not screwed all the way in.
To lock, push the top lever down and let the washer go over the head of the bottom screw and then release and the washer locks onto the screw.
To unlock, push down on the top lever until the washer is no longer pressing upwards on the screw, and use the play in the hinge to move the lever out slightly so the washer clears the screw.
