Abstract: An overlock sewing machine includes a first switching part for switching an interlocked state where an upper knife drive part and an upper knife are interlocked and a released state where the upper knife drive part and the upper knife are not interlocked; a second switching part for switching the upper knife between a projection position and a retreat position; and an operation part for switching the first switching part and the second switching part between a first mode, a second mode, and a third mode.

Abstract: A cloth cutting knife driving device is capable of being released, through an interlocking connection between an upper knife rocking arm and a sewing machine main shaft. The device includes a drive shaft, which is able to swing rotatably, by interlocking with a main shaft, a rocking arm rotatably supported on the drive shaft at one end providing a rocking motion, and a cloth cutting knife supported at the one end of the rocking arm that is rigidly held in a cloth cutting position or an inactive position, which is vertically displaced through the motion of the arm. The device has a coupled and released state between the drive shaft and rocking arm, which are brought about by an engaging part on the drive shaft and a movable member, movable relative to the rocking arm in a direction perpendicular to an axis of the drive shaft.

Abstract: In an overlock sewing machine for an overedge stitch and at least one kind of chain stitch other than the overedge stitch, an upper knife releasing device according to the invention comprises: an upper knife rocking arm 26 to which an cloth cutting upper knife 30 is secured; an upper knife rocking shaft 28 which is fixedly secured to the upper knife rocking arm and is rotatably supported relative to a frame; a controller shaft 50; and a controller 52 having a guide groove 52a, the controller being rotatable about the controller shaft, a link mechanism (38 and 34) having one end which is linearly reciprocated along the guide groove, and the other end which is fixedly secured to the upper knife rocking shaft.

Abstract: Work trimmer mechanism is provided for a sewing machine in a module including a frame securable on the machine, a split eccentric securable on the arm shaft, a split bearing securable about the eccentric, a link reciprocable by the bearing during rotation of the arm shaft, linkage means mounted on the frame and actuable by the linkage means, and a trimmer knife carrier operable by the linkage means.

Abstract: An overedge sewing machine having a reciprocating trimmer knife is used to sew elastic tape to a fabric. The elastic tape is fed through a tape guide which is movable from a rest position in which it guides the tape toward the stitch-forming mechanism of the sewing machine in the direction of material movement, to a second position in which it guides the tape to a position to be cut off by the trimmer knife. The tape guide includes a controllable tension which is located close to the stitch-forming mechanism when the tape guide is in its rest position to effect instant control of gathering. The tape guide is controlled by a knee shift which is movable from a rest position, through a "gathering" position, to a "cut-off" position. A stop mechanism requires the application of significant additional pressure on the knee shift to move it from the "gathering" position to the "cut-off" position.

Abstract: A trimming mechanism for a sewing machine for cutting the edges of a workpiece in the feeding direction by means of a reciprocating trimmer blade cooperating with a stationary counterknife. While sewing at high speed the trimmer blade is driven by the arm shaft of the sewing machine normally in synchronism with the needle. Drive- and control means are provided for imparting additional up and down movements to the blade when sewing at a low speed and continuation of trimming when the machine is stopped, in order to turn the workpiece about the needle, which is required when changing the sewing direction.