I've been puzzling over this for some time. In this picture, there are two steel frames, with four height-adjust screws controlling the height between them. The roller shown is applying a good amount of pressure (maybe analogous to someone rolling dough with a rolling pin). It appears that there is one screw going into a green "nut" fixed to the top frame and passing through to a sort of collar fixed (but allowed to rotate?) to the bottom frame.
My thinking is that the screw functions as a sort of lead-screw, rotating to bring the top frame up and down, while remaining fixed on the bottom frame. Of course, it also has to rotate.
The thing is, with the upward pressure, the green collar in the bottom frame would be pulled out, unless it snaps in on both sides. As well, there isn't anything visibly stopping the top frame's green collar/nut when upward pressure is applied on the roller (and thus the frame).
Unfortunately, no other information than this image of the fixture is given, and the images are evidently not great quality.
What mechanism could be used here to adjust the height? What methods are commonly used for precise height adjustment of platforms like this?
