Abstract: A cutting device for a sewing machine is provided with a cutting instrument associated to a cutting zone. The cutting instrument is formed with a blade movable towards the cutting zone. Furthermore, a protective guard is provided with a blade cover surrounding the blade, movable from an inoperative position spaced apart from the cutting zone to a position in front of the cutting zone. The blade and the blade cover are drivable in such a manner that the blade is only movable towards the cutting zone after the blade cover has been moved in front of the cutting zone. In order to reliably position the blade cover in front of the cutting zone prior to the movement of the blade to the cutting zone for performing the cutting operation, a mechanical locking mechanism is provided for the blade, which is only released when the blade cover is positioned in front of the cutting zone. The blade cover is non-positively connected to its drive in order to prevent injuries by the blade cover.

Abstract: A thread-chain separating head, in particular for a double chainstitch sewing machine, comprising a heating wire for thermically separating the thread chain and comprising a suction tube for leading the thread chain towards the heating wire. Said heating wire is arranged laterally and outside of the suction tube in order to achieve advantageous conditions during the heating and separating operation.

Abstract: A double chain stitch sewing machine having a feeding device with a feed dog oscillatingly movable in and opposite to the feeding direction for producing a relative movement between a workpiece and the sewing machine. It has a needle reciprocatingly driven by a crank mechanism, at which the feeding mechanism also imparts synchronous jogging movements to the needle in order to generate a needle feed movement. The reciprocatingly and joggingly driven needle cooperates with a looper oscillatingly driven by a looper drive mechanism in parallel with the feeding direction. The looper drive mechanism is formed as a six-bar-linkage-mechanism provided at the input with a stationary pivot and at the output with a stationary pivot and provided with an intermediate pivot.

Abstract: A device for controlling the looper thread of a double chainstitch sewing machine has a looper which can be oscillatingly driven in the sewing direction. A link mechanism is provided to drive the spreader, said link mechanism being designed as a six-bar linkage mechanism with a four-bar linkage and a secondary two-link group. The basic linkage and the two-link group are arranged in such a manner that two links are guided during a movement of the spreader in an extreme position in which it does not spread the looper thread. Thus a spreader movement is produced which is particularly adapted to the sewing process.

Abstract: A fabric feed for a sewing machine has a feed foot and a holddown foot that are vertically oppositely reciprocable between upper positions and lower fabric-engaging positions, and a continuously operating rotary drive with a rotating output whose rotary motion is transformed by an appropriate linkage into alternating reciprocation of the feed foot and the holddown foot. The feet are alternately engaged with and disengaged from fabric in the fabric-engaging position. On moving downwardly from their upper into their lower positions the feet are each first accelerated to a maximum speed reached when approximately midway between the upper and lower positions and thereafter are decelerated to an intermediate speed lying between zero and seven-tenths of the maximum speed reached when they attain the lower fabric-engaging position.