Abstract: A tape feed device for an elastic tape from a supply at a sewing machine having a biased actuating lever, whose angular position varies in dependence upon the size of a loop and which controls the motor of a take-off roller. An adjuster, which is electrically actuable in a controlled manner, acts on the actuating lever in such a way that the tape tension can be altered in accordance with an electrical variable. The adjuster has a coil whose electromagnetic field lines cut an armature which is connected to the actuating lever.

Abstract: A sewing machine having differential material feed, with a main feed dog and differential feed dog being mechanically connected to one another in such a manner that if the feed stroke length of the first feed dog is changed, the feed stroke length of the second feed dog is changed inversely in a predetermined ratio.

Abstract: A looper drive for a chain stitch sewing machine, in which the joint between a connecting rod driven by a main shaft and a lever seated on a swivel shaft is a sliding and swiveling joint. Upon rotation of a ball eccentric, the transverse component of the rotary motion of a spherical shell is enabled by a rod sliding in bearing eyes on a bifurcated lever and the swinging motion of the lever, caused by the longitudinal component of the rotary motion of the spherical shell is enabled by the rod turning in the bearing eyes.

Abstract: A needle thread control mechanism for sewing machines which permits a machine operator to adjust the stitch tightness includes a thread take-up mechanism arranged wholly outside of the machine frame and a thread controlling mechanism arranged directly between the needle thread take-up mechanism and a thread supply source. A thread controller, adapted to cooperate with the thread take-up mechanism, is also provided.

Abstract: A thread chain cutting mechanism for a sewing machine which includes a swingable blade which is actuated by means independent from the mechanical workings of the machine. The actuating mechanism includes a cantilevered resiliently urged member which carries at its free end the swingable cutter blade. A pneumatically operated plunger oscillates said resilient member and thus the blade carried thereby between a cutting position and a non-cutting position at a frequency which is adjustable. Means for providing a section in the cutting area so as to draw the thread chain into the path of the blades.