| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a compact power tool capable of preventing the durability of a spring from being degraded even when the spring is subjected to the total compression. Ž<P>SOLUTION: A clutch torque is adjusted by a ring gear on which a plurality of projections having different angles or heights are arrayed. The torque is adjusted according which part of the projection the ball rides over. During the drill mode, the clutch can be reliably allowed not to be operated by allowing the ball to pass through an outer circumferential part of the ring gear at which the height or the angle of the projection adequately designed so as to allow the ball not to ride over becomes maximum. Further, a spring can be set only by adequately pressing the ball against the ring gear. More extremely, a short spring having a small wire diameter may be used. By applying the spring, the fastening torque can be easily adjusted, and the torque adjusting mechanism can be designed without any limitation of the spring. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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