Servo device for a multineedle sewing machine with engageable and disengageable needle bars

摘要

A servo device for a multineedle sewing machine which includes two needle bars; driving and steop devices for said needle bars; devices for engaging and disengaging the two needle bars relative to the driving and stop devices; a feed-length adjustment device associated with at least one feed dog for the transport of the material being sewn; an adjustable thread tensioning device for the needle threads; devices for locking each needle bar selectively in its highest position; a positioning drive for the multineedle sewing machine; and a device including a position indicator attached to an arm shaft of the multineedle sewing machine, for adjusting the speed of rotation and positioning of the needle bars in predetermined positions. The servo device comprises a control system including a pair of electrical switches which respectively correspond to the needle bars, for controlling the engagement and disengagement of the needle bars relative to the driving and stop devices; a first setting device associated with the control system, for selectively interrupting the transport by the feed dog of the material being sewn; and a second setting device associated with the control system, for temporarily increasing a thread tensioning force exerted on the needle thread by the thread tensioning device.