| 摘要 |
PROBLEM TO BE SOLVED: To provide a driving force transmission device for a twin-needle sewing machine by which a needle bar falling-off accident upon switching operation to discontinue vertical motion of the needle bar can be surely prevented as well as fracture of a needle bar and a throat plate. SOLUTION: When vertical motion of a needle bar 7L is discontinued halfway through sewing, and when a main shaft is rotatively driven in high speed upon switching operation, even if projecting timing of a second engaging piece 41L to engage the second engaging piece 41L with an upper engaging recess part 7a by spring force is delayed and the upper engaging recess part 7a passes under the second engaging piece 41L to fall off the needle bar 7L from a needle bar support frame 5, the needle bar 7L is prevented from falling off the needle bar support frame 5 because a washer 22L fixed to the upper end of the needle bar 7L abuts on an upper frame 5a of the needle bar support frame 5. Furthermore, a distance L between upper and lower engaging recess parts 7a, 7b is set larger than an operation stroke SS of the needle bar 7L to surely prevent fracture of the needle bar 7L and the throat plate 10. COPYRIGHT: (C)2006,JPO&NCIPI
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