Patent ID: 8011551

Claim:
A retraction mechanism for use with a hand held surgical apparatus, comprising: a drive mechanism configured to be driven by a motor; a first pulley operatively associated with the drive mechanism, wherein the first pulley is configured to rotate when the drive mechanism is driven; a second pulley disposed in mechanical cooperation with the first pulley, the second pulley being movable relative to the first pulley between at least proximal position and a distal position; a firing drive operatively coupled to the first pulley and the second pulley, the firing drive being movable relative to the first pulley between at least proximal and distal positions, wherein the first pulley rotates in a first direction in response to a distal translation of the firing drive and wherein the firing drive moves proximally upon rotation of the first pulley in a second direction; and a first sensor adapted to detect the second pulley when positioned in the distal position and a second sensor adapted to detect the firing drive when positioned in the proximal position.