| 摘要 |
PROBLEM TO BE SOLVED: To prevent the slippage in torque transmission by installing an elastic ring to a major diameter pulley fixed to one end of a main spindle, and laying a toothed transmission belt between the elastic ring and a minor diameter pulley fixed onto the output shaft of a motor. SOLUTION: The rotation of a sewing machine motor 2 is transmitted from a minor diameter pulley 3 to a major diameter pulley 5 through a toothed transmission belt 4 to rotate a main spindle 6. At this time, the transmission belt 4 is frictionally engaged with the outer diameter part of the major diameter pulley 5 through a rubber ring 99, whereby the slippage of the major diameter pulley 5 at the time of torque transmission is prevented. A needle bar 14 is vertically reciprocated through a needle bar crank 9 and a crank rod 12 by the rotation of the main spindle 6. On the other hand, the rotation of a timing pulley 25 mounted on the center of the main spindle 6 is transmitted to a pulley 28 through a timing belt 26 to rotate a lower shaft 29. A shuttle 32 is rotated twice through screw gears 30, 31 by the rotation of the lower shaft 29 while a needle 16 is reciprocated once.
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