Planetary Gear Set Centering Ring

A rotary power tool comprising:

• a housing;
• an output shaft extending from the housing;
• a battery positioned within the housing;
• an electric motor positioned within the housing and electrically coupled to the battery;
• a ring gear having an inner diameter and gear teeth disposed on an inside surface;
• a centering ring positioned within the ring gear, the centering ring having an inner diameter and an outer diameter that is less than the inner diameter of the ring gear;
• a set of planetary gears positioned within the ring gear and driven by the electric motor, the planetary gears adapted to engage the gear teeth of the ring gear;
• a planetary gear carrier positioned within the centering ring and coupled to the planetary gears, the planetary gear carrier having an outer diameter that is less than the inner diameter of the planetary centering ring;
• and
• the planetary gear carrier adapted to move within the centering ring when the planetary gears are driven by the electric motor, the centering ring is adapted to limit the planetary gear carrier from shifting perpendicularly to the axis of rotation when a reverse torque load is applied to the output shaft of the power tool.

A cordless driver gear train comprising:

• a housing having an inner diameter, the housing including a plurality of gear teeth formed on the inside of the housing;
• a metallic centering ring positioned within the housing;
• a planetary gear carrier positioned within the centering ring, the planetary gear carrier adapted to rotate within the centering ring;
• a set of planetary gears coupled to the planetary gear carrier, the planetary gears adapted to engage the gear teeth of the housing and positioned to lie near the centering ring;
• the centering ring adapted to limit the planetary gear carrier from shifting perpendicularly to the axis of rotation of the gear train when torque is applied to the planetary gear carrier by a reverse torque load applied to the cordless screwdriver.