What is the purpose of these locknuts? How tight should they be?
EDIT: I'm asking because even if I remove all the nuts from the axle, leaving just the axle and the bearings, it still won't have any play, and it will turn just the same. The axle won't slide out. How much to tighten the inner nuts (the ones touching the bearings) against each other (when they don't seem to make any difference)?