Sewing machines attachment for the sewing of resilient workpieces

Claim 1

A SEWING-MACHINE ATTACHMENT COMPRISING A LOOPER BAR SPACEDLY POSITIONED ABOVE A WORK SURFACE, A STATIONARY SUPPORT HOLDING MEANS FOR SAID BAR INCLUDING AN ELONGATED MEMBER EXTENDING FROM SAID SUPPORT SUBSTANTIALLY PERPENDICULARLY TO SAID SURFACE AND A MOUNTING LONGITUDINALLY SLIDABLE AND ANGULARLY SWINGABLE ON SAID MEMBER, SAID BAR BEING SECURED TO SAID MOUNTING, ACTUATING MEANS FOR PERIODICALLY SWINGING SAID MOUNTING ON SAID MEMBER WHEREBY SAID BAR OSCILLATES ABOVE SAID SURFACES, A FIRST LEVER LINKED WITH SAID MOUNTING AND PIVOTED TO SAID SUPPORT AT A FIRST FULCRUM, A SECOND LEVER PIVOTED TO SAID SUPPORT AT A SECOND FULCRUM SPACED FROM SAID FIRST FULCRUM AND ENGAGEABLE AT A LOCATION ADJACENT SAID BAR WITH A WORKPIECE ADVANCING ON SAID SURFACE IN A DIRECTION TRANSVERSE TO THE OSCILLATIONS OF SAID BAR, A MOTION-TRANSMITTING CONNECTION BETWEEN SAID LEVERS FOR VARYING THE ELEVATION OF SAID BAR ABOVE SAID SURFACE IN ACCORDANCE WITH THE THICKNESS OF SAID WORKPIECE.