23 STRIPPING UNITS FOR STRIPPING METAL FROM DIES, HOLE PUNCHING AND NOTCHING EQUIPMENT, FOR MACHINES AND SELF-CONTAINED HOLE-PUNCHING AND NOTCHING UNITS FOR PERFORATING AND NOTCHING METAL SHEETS AND OTHER SHEET MATERIALS; SHEET METAL FABRICATORS-NAMELY, MACHINES FOR PUNCHING, NOTCHING AND NIBBLING SHEET METAL; METAL DRILLING MACHINES, PUNCH PRESSES, LIQUID SPRINGS AND SPRINGS UTILIZING A COMPRESSIBLE SOLID-NAMELY, CUSHIONING DEVICES COMPRISING CYLINDERS FILLED WITH A VARIABLE AMOUNT OF COMPRESSIBLE FLUID OR A COMPRESSIBLE SOLID, USED FOR GENERAL APPLICATION