(A) one smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
(B) a slot is cut partly in middle of nut and then slot reduced by tightening screw
(C) a hard fiber or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip
(D) through slots are made at top and a cotter-pin is passed through these and a hole in the bolt, and cotter pin splitted and bent in reverse direction at the other end
(E) none of the above
