| 摘要 |
PROBLEM TO BE SOLVED: To provide a sewing machine in which the rotation speed of an arm shaft 2 for controlling sewing speed of a sewing machine needle 3a can be exchangeable. SOLUTION: The sewing machine includes an arm shaft 2 rotatably supported at a sewing machine body 1, an arm shaft pulley 7 including a large diameter part 4, a small diameter part 5, and a cone part 6, a motor pulley 12 mounted on an output shaft 13 of a motor 11, a timing belt change-over device 9 to stretch a timing belt 8 for transmitting drive force of the motor 11 to the arm shaft 2 on either the large diameter part 4 or the small diameter part 5 of the arm shaft pulley 7, and a tension adjusting device 16 to adjust tension of the timing belt. COPYRIGHT: (C)2008,JPO&INPIT
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