An end effector includes first and second jaws, a drive screw, a lead screwnut, and a drivebeam. The drive screw is disposed within the first jaw. The lead screw nutdefines athreaded bore that receives the drive screw. The lead screw nut is advancedalong the drivescrew as the drive screw is rotated in a first direction and is retractedalong the drive screw asthe drive screw rotates in a second direction. The drive beam is releasablycoupled to thelead screw nut when the lead screw nut is in a retracted position. As the leadscrew nut isadvanced the drive beam is pulled by the lead screw nut. The drive beam isdecoupled fromthe lead screw nut as the lead screw nut is advanced such that the lead screwnut is advancedrelative to the drive beam.
