Abstract: A thread-tensioning device for being mounted on a bobbin housing, the bobbin housing having an upper part and a lower part which define a space for receiving a bobbin, and a jacket for substantially surrounding the bobbin. The thread-tensioning device includes a thread-tensioning member, such as a lever, having a first end swingably supported on the upper part of the housing, and a second end comprising a finger for bearing on the thread package on the bobbin. A central part of the lever is received by a slot in the jacket of the bobbin housing. A leaf spring bears upon the lever to urge the finger toward the interior of the bobbin-receiving space and against the thread package. The arrangement produces a detaining force and a braking force which combine to result in a relatively constant thread-tensioning force.

Abstract: A double-lock-stitch sewing machine in which the needle-thread loop on the underside of the workpiece on a stitching plate is engaged with a gripper thread by the rotating gripper associated with the bobbin housing for the bobbin supplying the gripper thread. According to the invention, in the path of the needle-thread loop in the space between the stitch plate and the gripper, there is provided a spring wire or rod which bears upon the needle-thread loop and prevents the formation of knots or bunching in the needle thread. The spring wire is fastened to the underside of the stitch plate on opposite sides of the needle hole and flanks the latter in its undeflected state.