Abstract: A housing forming the free bed base in a sewing machine which is detachable from the remainder of the machine and which is comprised of a tray-shaped base module on which are mounted all lower sewing members that cooperate with the needle in the formation of stitches. These members include a needle plate, closing flat plates located alongside the opposite edges of the needle plate and closing interchangeable elements defining both the front and rear walls of the housing and the remaining portion of the upper flat surface of the latter which is not covered by the closing flat plates and the needle plate.

Abstract: A sewing machine which has two substantially independent sets of feed dog teeth comprising a set of main fabric feed dog teeth and secondary or differential feed dog teeth and includes a drive therefore defined by a main drive shaft and a two piece interconnected secondary shaft. Feed dog teeth supporting brackets are mounted between the shafts. A stirrup interconnects the support brackets so that both sets of dog teeth are moved cyclically and in a synchronized manner with one another.

Abstract: An upper feed dog for sewing machines carried by an actuating arm pivotably mounted on a support fixed to the upper surface of the main feed bar that carries the main lower feed dog. A control arm has one end pivotably connected to the same pivot as the actuating arm and its opposite end is pivotably connected to a guide block carried in one end of a double-forked lever. The opposite end of this lever is operatively associated with an oscillatably driven shaft, the motion of which is transmitted to the actuating arm by a coil spring interposed between the latter arm and the control arm and is effective so as to cause pressure of the upper feed dog on a workpiece to be progressive and prevent direct impact between the control arm and the actuating arm, whereby the operating noise level of the machine operating at high speed is greatly reduced.