An actuation mechanism for actuating an electromechanical end effector includes a housing, and a shaft assembly extending distally from the housing. The shaft assembly includes a shaft, a longitudinal knife bar, a first hub, and a second hub. The shaft is axially movable relative to the housing and configured to be coupled to the electromechanical end effector. Rotation of a first screw of the housing moves the first hub to effect longitudinal movement of the shaft. The longitudinal knife bar is axially movable relative to the shaft and configured to be coupled to a knife blade of the electromechanical end effector. Rotation of a second screw of the housing moves the second hub to effect axial movement of the longitudinal knife bar.
