| 摘要 |
A control device for trimming knives on flat-bed sewing machines comprises a rocking lever 19 fulcrumed on a fixed pivot 20 and receiving an oscillatory motion from a connecting rod 18. The rocking lever operates a movable knife 14 through a drive group 21 provided with a movable pivot 29 slidably engaged in an elongate shaped opening 30 associated with the the rocking lever. A disengagement group 40 enables the movable pivot 29 to be brought from an engagement position in which it is in engagement with an engagement portion 30b of the elongate shaped opening 30 to operate the movable knife 14, to a disengagement position in which the movable pivot slides within a curvilinear portion 30a of the elongate opening in order to deactivate the movable knife 14. The displacements of the movable pivot 29 take place upon command of a disengagement lever 32 slidably engaging said pivot in the region of an elongate guide opening 32a. The movable pivot is axially locked by a plate 38 fastened to the disengagement lever 32 by means of a screw 39 and provided with an elongate slide opening 38a engaging the pivot in the region of a circumferential groove 41 formed thereon.
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