Patent ID: 7637409

Claim:
A medical instrument having a tool assembly attachable to a distal end of the medical instrument, the tool assembly including a pair of opposing tissue engaging surfaces actuated by advancing a drive beam including a coupling member, the medical instrument comprising: a housing having a fixed handle; a movable handle mounted to the housing and selectively movable relative to the fixed handle from a first position in spaced relation relative to the fixed handle to a second position closer to the fixed handle, wherein the movable handle engages the coupling member such that the drive beam is advanced when the movable handle is moved from the first position to the second position; and a selectively activatable drive assembly including a power source and a motor which is operatively coupled to the coupling member, wherein upon actuation the motor advances the coupling member, the selectively activatable drive assembly also including a controller configured to variably control the rate at which the motor advances the coupling member in response to the force exerted on the movable handle.