The nuts stay on the studs in the back of the chuck and pass through large clearance holes in the spindle flange.
The ring with the knurled edge has three "keyhole" shaped slots in it.
Chuck nuts pass through the large part of the keyhole, you then turn it slightly so the nuts are over the narrow part and then just tighten up the three nuts
saves having to faff about with loose nuts and washers.
EDIT
Jo beat me to it