Patent ID: 7794355

Claim:
A planetary gear train for a power tool having an output shaft, the planetary gear train comprising: a ring gear having an inner diameter and gear teeth disposed on an inside surface of the ring gear; a planetary centering ring positioned within the ring gear, the planetary 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, the planetary gears engage the gear teeth of the ring gear; a planetary gear carrier is positioned within the planetary 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 moves within the centering ring when the planetary gears are driven to rotate the planetary gear carrier and is limited from shifting perpendicularly to the axis of rotation when a reverse torque load is applied to the output shaft of the power tool.