A surgical instrument system that includes a housing and a rotatable drive shaft, a motor operably coupled to the drive shaft, and a plurality of replaceable end effectors that can be connected to the housing. Each replaceable end effector includes a drive screw that is turned a fixed number of revolutions by the motor-driven rotatable drive shaft when the end effector is connected to the housing. Each end effector further comprises a firing member operably coupled with the drive screw of the end effector. The drive screw is configured to displace the firing member over a firing length as a result of the fixed number of revolutions. In certain embodiments, each replaceable end effector can include a drive screw with a thread pitch set to the firing length divided by the fixed number of revolutions.L'invention concerne un ensemble joints de support rotatif accouplant une première partie et une seconde partie d'un instrument chirurgical. Dans diverses formes, cet ensemble joints comprend un premier chemin de roulement annulaire ménagé dans la première partie et un second chemin de roulement annulaire ménagé dans la seconde partie. Le second chemin de roulement est configuré pour s'aligner sensiblement sur le premier chemin de roulement annulaire lorsque la seconde partie est reliée à la première partie. Un palier annulaire est porté à l'intérieur du premier et du second chemin de roulement annulaires alignés.
