MACHINERY USED IN CONJUNCTION WITH WELDING - NAMELY, SHEET STACKERS, SHEET DESTACKERS, CONVEYORS, WORKPIECE OR PARTS LOCATING AND SENSING UNITS, WORKPIECE OR PART RACKING UNITS, WORKPIECE NOTCHING AND PIERCING UNITS, AND WORK TRANSFER AND HANDLING MACHINERY- NAMELY, WORKPIECE OR PART ROTATING ANDTURNOVER DEVICES, WORKPIECE OR PART UNLOADERS, WORKPIECE OR PART LOADERS, AND TABLES FOR FEEDING SHEET TO ROLL FORMING EQUIPMENT, AND TOOLING - NAMELY,PART OR WORKPIECE HOLDING AND LOCATING FIXTURES, PART OR WORKPIECE SELECTION AND PLACEMENT DEVICES, NAMELY - FEED HOPPERS AND ORIENTATION, ESCAPEMENT AND PLACEMENT DEVICES; PART OR WORKPIECE SHIFTING DEVICES, PART OR WORKPIECE CLAMPING FIXTURES, AND PART OR WORKPIECEEJECTING UNITS; FOR: ASSEMBLY SYSTEMS - NAMELY MACHINES FOR AUTOMATICALLY POSITIONING AND ASSEMBLING COMPONENT PARTS AND MONITORING PROGRESSIVE STEPS IN THE ASSEMBLY PROCESS SOLD AS A UNIT, AND PARTS THEREOF AND, FOR: WELDING MACHINES AND ALLIED EQUIPMENT - NAMELY, PRESS TYPE AC AND DC WELDING MACHINES, ARC WELDING MACHINES, STRIP MILL WELDERS, PROJECTION WELDING MACHINES, SPOT WELDING MACHINES, FLASH-BUTT WELDERS, AUTOMATIC STRIP SPLICER WELDINGMACHINES, SEAM WELDERS, WELDING AND METAL FORMING MACHINES CONSTITUTING MULTIPLE STATION FABRICATING LINES WHEN ARRANGED IN LINE WITH TRANSFER AND HANDLING MACHINERY; AND WELDING MACHINE TOOLING - NAMELY WELDING GUNS AND WELDING ELECTRODES; AND PARTS THEREOF