Vacuum cleaning system

Claim 1

A VACUUM CLEANER COMPRISING: A FRIST CASING HAVING AN INTAKE OPENING IN ONE END THEREOF AND DISCHARGE VENT THEREIN; MEANS IN SAID CASING FOR PRODUCING A VACUUM; A FILTER ELEMENT SECURED OVER SAID INTAKE OPENING FOR FILTERING AIR DRAWN INTO SAID FIRST CASING THROUGH SAID INTAKE OPENING, THE FILTER ELEMENT COMPRISING A HOLLOW CYLINDER HAVING A CYLINDRICAL INNER SURFACE AND A CYLINDRICAL OUTER SURFACE WITH FILTER MATERIAL THEREBETWEEN, A PLATE FOR BLOCKING THE FLOW OF AIR TO ONE OF THE FILTER ELEMENT, THE INLET TO THE FILTER ELEMENT COMPRISING ITS OUTER CYLINDRICAL SURFACE, THE OUTLET COMPRISING THE END OF THE CYLINDRICAL SURFACE OPPOSITE THE PLATE; A CASING OF GENERALLY CYLINDRICAL CONFIGURATION ON A VERTICAL AXIS CONNECTED TO SAID ONE END OF SAID FIRST CASING AND ENCLOSING SAID FILTER ELEMENT, SAID CYLINDRICAL CASING HAVING AN AIR INTAKE OPENING IN THE SIDE WALL THEREOF; AN ANNULAR FLANGE OF GENERALLY L-SHAPED TRANSVERSE CROSS-SECTION COAXIALLY SECURED IN SAID CYLINDRICAL CASING AND SPACED FROM SAID FILTER ELEMENT, SAID FLANGE DEFINING WITH THE CYLINDRICAL WALLS OF SAID CYLINDRICAL CASING AN ANNULAR CHANNEL INCLUDING A PLATE EXTENDING RADIALLY INWARDLY FROM THE CYLINDRICAL CASING, AN OPENING IN THE CENTER OF THE PLATE,