| 摘要 |
PROBLEM TO BE SOLVED: To reduce reaction of screw fastening by transmitting rotating power of the air motor via a planetary gear train to a driver bit in a screw driving machine which drives a screw by driving a piston downward in a driving direction while rotating a driver bit by an air motor. SOLUTION: The rotating power is transmitted by engagement between flat surfaces 73b, 73b of a two flat surface hole portion 73a of the planetary gear train, and flat surfaces 23a, 23b of a two flat surface shaft portion 23f of the driver bit 23. Then a cross sectional shape of the two flat surface shaft portion 23f of the driver bit 23 is formed so as to be non-point-symmetrical about a rotation central axis J23, and made engageable with the two flat surface hole portion 73a by abutting at three points on the same in the rotating direction. Thus sliding resistance between the shaft portion and the hole portion in the driving direction is increased, and therefore the reaction occurring at driving is reduced. COPYRIGHT: (C)2009,JPO&INPIT
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