Patent ID: 7370684

Claim:
A nut stacking mechanism comprising: a rotatable screw with external thread of length L and pitch P 1 ; at least one traveling nut mounted on said screw, said traveling nut having internal thread of pitch P 1 and external thread of pitch P 2 coaxial with said internal thread, P 1 >P 2 ; an arrester adapted to engage said traveling nut so as to prevent rotation thereof within an axial length L 1 of said screw, while allowing said traveling nut to slide along said screw; a threaded member with internal thread of pitch P 2 adapted to engage the external thread of said traveling nut within an axial length L 2 of said screw, said length L 2 being adjacent to said length L 1 , so that, by means of continuous rotation of said screw in one direction, said traveling nut can slide along said screw within said length L 1 at rate P 1 per 1 turn of the screw under the action of said arrester and said thread with pitch P 1 , can transit smoothly and reversibly from L 1 to L 2 , and can slide with rotation along said screw within said length L 2 at a rate P 2 per 1 turn of the traveling nut under the action of said thread with pitch P 1 and said thread with pitch P 2 .