Work indexing mechanism for sewing machines

Claim 1

IN A SEWING UNIT HAVING A SEWING MACHINE, A WORK INDEXING MEANS FOR SHIFTING A FABRIC RELATIVELY TO THE STITCHING POINT OF SAID SEWING MACHINE COMPRISING AN ENDLESS CONVEYOR SUPPORTED FOR MOVEMENT IN ONE DIRECTION RELATIVELY TO THE STITCHING POINT OF SAID SEWING MACHINE, MEANS CONSTRAINING SAID ENDLESS CONVEYOR IN AN ELONGATE LOOP HAVING SUBSTANTIALLY STRAIGHT AND PARALLEL ELONGATE LIMBS, A PLURALITY OF PAIRS OF WORK GRIPPING CLAMPS CARRIED BY SAID ENDLESS CONVEYOR, THE WORK GRIPPING CLAMPS OF EACH OF SAID PAIRS BEING CARRIED IN SPACED RELATION ALONG SAID ENDLESS CONVEYOR FOR ENGAGEMENT WITH OPPOSITE EXTREMITIES OF A WORK FABRIC PANEL, EACH OF SAID WORK GRIPPING CLAMPS COMPRISING A PAIR OF JAWS, MEANS SUPPORTING SAID JAWS FOR MOVEMENT RELATIVELY TO EACH OTHER INTO AND OUT OF WORK GRIPPING RELATION, MEANS DEFINING A STARTING POSITION OF ANY OF SAID PLURALITY OF PAIRS OF WORK GRIPPING CLAMPS RELATIVELY TO SAID SEWING MACHINE STITCHING POINT, SAID PLURALITY OF PAIRS OF WORK GRIPPING CLAMPS BEING SPACED ALONG SAID CONVEYOR SUCH THAT IN THE STARTING POSITION THE LEADING WORK GRIPPING CLAMP OF A PAIR OF CLAMPS ON ONE OF SAID CONVEYOR LINKS IS DISPOSED DIRECTLY OPPOSITE THE TRAILING WORK GRIPPING CLAMP OF ANOTHER PAIR OF CLAMPS ON THE OPPOSITE CONVEYOR LIMB, AND A PAIR OF WORK CLAMP OPENING SOLENOIDS CARRIED ON SAID SEWING UNIT, SAID SOLENOIDS BEING DISPOSED FOR OPERATIVE ENGAGEMENT IN THE STARTING POSITION OF SAID WORK GRIPPING CLAMPS TO OPEN SIMULTANEOUSLY BOTH OF A DIRECTLY OPPOSITE SET OF LEADING AND TRAILING WORK GRIPPING CLAMPS.