Restriction indicator for air cleaners

Claim 1

IN A GAUGE FOR REGISTERING INCREASING SUCTION IN AN AIR INTAKE MANIFOLD, (A) A HOUSING DEFINING A GENERALLY CYLINDRICAL PRIMARY CHAMBER HAVING A TRANSPARENT WALL PORTION, (B) A TUBULAR CONDUIT FOR CONNECTING ONE END OF SAID HOUSING TO A MANIFOLD IN A MANNER TO CAUSE COMMUNICATION BETWEEN THE INTERIOR OF SAID MANIFOLD AND SAID PRIMARY CHAMBER, (C) AN AXIALLY EXTENDABLE AND COLLAPSIBLE BELLOWS-TYPE DIAPHRAGM MOUNTED IN SAID HOUSING FOR EXTENDING AND RETRACTING MOVEMENTS OF THE FREE END THEREOF INTO AND OUT OF THAT PORTION OF SAID PRIMARY CHAMBER DEFINED BY SAID TRANSPARENT WALL PORTION, (D) CLOSURE MEANS FOR SAID OTHER END OF SAID HOUSING AND DEFINING WITH SAID DIAPHRAGM A SECONDARY CHAMBER WITHIN SAID PRIMARY CHAMBER, (E) MEANS YIELDABLY BIASING SAID DIAPHRAGM TOWARD A COLLAPSED POSITION AWAY FROM SAID ONE END, (F) CHECK VALVE MEANS PERMITTING PASSAGE OF ATMOSPHERIC PRESSURE TO SAID SECONDARY CHAMBER WHEN SUBATMOSPHERIC PRESSURE OF A PREDETERMINED VALUE EXISTS WITHIN SAID PRIMARY CHAMBER WHEREBY TO EXTEND SAID DIAPHRAGM AGAINST THE BIAS OF SAID YIELDING MEANS, (G) AND MEANS FOR MANUALLY RENDERING SAID CHECK VALVE MEANS INOPERATIVE WHEREBY TO PERMIT COLLAPSING OF SAID DIAPHRAGM UNDER THE BIAS OF SAID YIELDING MEANS, (H) SAID CLOSURE MEANS FOR THE OTHER END OF SAID HOUSING COMPRISING A CAP HAVING AN AXIAL OPENING THEREIN AND A BREATHER PORT RADIALLY SPACED WITH RESPECT TO SAID OPENING, (I) SAID CHECK VALVE MEANS COMPRISING: (1) AN ANNULAR VALVE SEAT THE CENTRAL OPENING OF WHICH IS CONCENTRIC WITH THE OPENING IN SAID CAP, (2) AND A FLEXIBLE VALVE ELEMENT INTERPOSED BETWEEN SAID VALVE SEAT AND SAID DIAPHRAGM, (J) SAID VALVE ELEMENT HAVING AN ANNULAR SEALING RIB NORMALLY BIASED INTO SEALING ENGAGEMENT WITH SAID VALVE SET RADIALLY OUTWARDLY OF THE OPENING THEREIN AND PORT MEANS RADIALLY OUTWARDLY OF SAID SEALING ROD, (K) SAID MEANS FOR MANUALLY RENDERING SAID CHECK VALVE MEANS INOPERATIVE COMPRISING A FLEXIBLE RESILIENT GENERALLY HOLLOW BUTTON PROJECTING AXIALLY OUTWARD THROUGH THE OPENING IN THE CAP AND HAVING SEALING ENGAGEMENT WITH SAID CAP ADJACENT SAID OPENING, (L) SAID BOTTOM BEING PROVIDED WITH AN AXIALLY INWARDLY PROJECTING PLUNGER WHICH IS ADPATED TO PROJECT THROUGH THE OPENING IN SAID VALVE SEAT AND ENGAGE SIAD VALVE ELEMENT SUFFICIENTLY TO CAUSE DISENGAGEMENT OF SAID SEALING RIB FROM SAID SEAT UPON AXIAL MOVEMENT BEING IMPARTED TO SAID BUTTON WHEREBY TO PERMIT PASSAGE OF GAS WITHIN SAID SECONDARY CHAMBER THROUGH THE PORT MEANS IN SAID VALVE TO ATMOSPHERE THROUGH THE CENTRAL OPENING IN SAID VALVE SEAT AND THE BREATHER PORT IN SAID CAP.