Abstract: An upper decorative stitching device is designed to make it possible to precisely transmit the swing movement of a first lever which is capable of swing movements widthwise in a pendulum manner to horizontal reciprocating motion of a second lever, which is provided with a spreader. The device facilitates the operation of switching between an upper decorative stitching and no upper decorative stitching. A connecting rod (9) is provided at both ends with spherical bearings (10, 11) to provide a connection between the first lever (3) and the second lever (8), thereby converting the rotation of the upper shaft into the reciprocal movement of the spreader.

Abstract: A thread tension regulating apparatus for an over-lock sewing machine is disclosed, wherein there are provided between an adjusting knob and a home position returning lever a first interlock device for displacing a home position returning lever in response to motion of the adjusting knob displacing from a home position in a pressurizing direction, and a second interlock device for displacing the home position returning lever in response to motion of the adjusting knob of the thread tension unit displacing from the home position in a depressurizing direction. These two interlock devices are provided respectively with an interlock obviating device for causing the second interlock device to take a non-operating condition when the first interlock device operates, and an interlock obviating device causing the first interlock device to take a non-operating condition when the second interlock device operates.

Abstract: A spreader driving device is constructed so that the stepping motor (2) driven in synchronism with the elevating motion of a needle bar and the support shaft (3) are provided at a frame mounted to the back side of a presser foot. A lever (4), fitted onto the support shaft, is provided at the rear end with a sector gear (6) and at the fore end with a spreader (5). The sector gear engages with a driving gear (7) driven by an output shaft (8) of the stepping motor, so as to swing the lever (4) and spreader (5) by the drive of stepping motor. Also, the frame is divided into a movable frame having the stepping motor, the support shaft, and the lever mounted thereon, and a fixed frame (17) for mounting the device to the sewing machine. Between the frames is arranged a shifting device (18) for shifting the movable frame a moderate distance parallel to the needle position with respect to the fixed frame, whereby the center of swinging motion of the spreader can be shifted from a point P1 to a point P2.

Abstract: A bed portion, minutely speaking, a portion corresponding to a rise-and-fall position of a needle, of a lock stitching machine or an over-lock stitching machine is formed into a unit and combined with a machine proper in a mounting/detaching free state, and uses plural sewing units that are selectively exchanged for each other. The machine proper 1 is formed by cutting of a top portion of a bed 1" on the right of a needle plate portion, leaving the cut-off portion as a connecting surface 5. A sewing unit 2 or 3 is formed by providing a needle plate 12, feeding teeth 13, a shuttle drive mechanism 15, a cloth feed mechanism 19 or loopers 47 and 49 and their drive mechanism 48 and 58 in one unit body. Its right side is left as a connecting surface 20, and the two elements are combined as one body in a mounting/detaching free state through a shaft coupling 7, a fitting portion 10 and a combining means 11, respectively protruding on the abovementioned two connecting surface.

Abstract: A composite sewing machine has a lock stitch mechanism and an over-lock stitch mechanism. A switching mechanism is connected to the stitching mechanisms for switching the operation of the sewing machine between a lock stitch operation and an over-lock stitch operation. The machine has a single needle carrying element, a needle position converter for changing the position of the needle carrying element laterally of the stitching direction and including a needle bar connecting stud engaging the needle carrying element and a fulcrum shaft on which the stud is rotatably mounted for pivotal movement to change the vertical orientation of the needle carrying element between a lock stitch position and an over-lock stitch position which are adjacent to each other and juxtaposed laterally on the sewing machine.