Patent ID: 8220561

Claim:
A power tool comprising: a housing; a motor received in the housing and having an output shaft; a transmission having a plurality of planetary transmission stages comprising a first planetary transmission stage and a second planetary transmission stage, each of the plurality of planetary transmission stages comprising a sun gear, a plurality of planet gears meshingly engaged to the sun gear, and a ring gear having internal teeth that are engaged by the plurality of planet gears, the sun gear of the first planetary transmission stage being directly driven by the output shaft of the motor, the ring gear of the first planetary transmission stage not being shared by another of the plurality of planetary transmission stages, the ring gear of the first planetary transmission stage having a first side and a second side, the first side facing toward the motor, the second side being disposed opposite the first side so as to face away from the motor, the first planetary transmission stage receiving an input torque from the motor and producing an intermediate output torque in response thereto that is transmitted to the second planetary transmission stage; an output member drivingly coupled to the transmission on a side of the transmission opposite the motor; and a clutch assembly that comprises a clutch profile and an engagement assembly, the clutch profile being coupled to the second side of the ring gear of the first planetary transmission stage, the engagement assembly being disposed axially between the ring gear of the first planetary transmission stage and a distal end of the output member, the engagement assembly including a follower and an adjustment collar, the adjustment collar being movable to change a magnitude of a biasing force exerted by the follower member onto the clutch profile, the follower assembly cooperating with the clutch profile to permit continuous rotation of the ring gear of the first planetary transmission stage relative to the housing when the magnitude of the intermediate output torque exceeds a selected maximum torque to thereby limit rotary power that is output through the output member to a selected maximum tool torque, the follower assembly also cooperating with the clutch profile to inhibit rotation of the first ring gear relative to the housing when the magnitude of the intermediate torque does not exceed the selected clutch torque.