US Patent 8348124 Knife bar with geared overdrive

A surgical instrument is disclosed. The surgical instrument includes a handle assembly, an elongated portion, an end effector and a drive assembly. The elongated portion extends distally from the handle assembly and defines a longitudinal axis. The end effector is disposed adjacent a distal portion of the elongated portion and includes a first jaw member and a second jaw member. At least one jaw member is movable with respect to the other jaw member between spaced and approximated positions. The drive assembly is disposed in mechanical cooperation with the end effector and includes an input portion, an output portion and a gear system disposed therebetween.