Ventilator

Claim 1

IN A VENTILATOR FOR USE ON A ROOF OF A BUILDING, THE COMBINATION COMPRISING A STACK SURROUNDING AN OPENING IN THE SAID ROOF; A FAN MOUNTED IN THE SAID STACK FOR ROTATION ABOUT A VERTICAL AXIS; A FIRST RIM MEMBER SECURED TO THE UPPER EDGE OF THE SAID STACK AND HAVING AN OUTWARDLY EXTENDING FLANGE; A SECOND RIM MEMBER HAVING AN OUTWARDLY EXTENDING FLANGE NORMALLY RESTING ON SAID FIRST RIM MEMBER; HINGE MEANS SECURED TO THE PERIPHERAL EDGES OF SAID OUTWARDLY EXTENDING FLANGES, SAID HINGE MEANS DEFINING A PIVOTAL AXIS; A DOME SHAPED VENT CAP; MOUNTING MEANS FOR MAINTAINING THE SAID DOME SHAPED VENT CAP IN OVERLYING FIXED RELATION WITH THE SAID SECOND RIM MEMBER AND SPACED THEREFROM; A PAIR OF SEMICIRCULAR DAMPERS MOUNTED ON THE SAID SECOND RIM MEMBER FOR PIVOTAL MOVEMENT ABOVE SAID SECOND RIM MEMBER ABOUT PARALLEL AXES ADJACENT THEIR STRAIGHT EDGES, SAID PARALLEL AXES BEING SUBSTANTIALLY PERPENDICULAR TO THE SAID PIVOTAL AXIS; SAID DOME SHAPED VENT CAP AND THE SAID SECOND RIM MEMBER AND THE SAID PAIR OF DAMPERS COMPRISING A UNITARY STRUCTURE WHICH IS PIVOTABLE ABOUT THE SAID PIVOTAL AXIS; DAMPER OPERATING MEANS FOR CONTROLLING THE PIVOTAL POSITION OF THE SAID PAIR OF DAMPERS COMPRISING A CONNECTING CABLE HAVING ENDS SECURED TO THE SAID DAMPERS AND AN OPERATING CABLE SECURED TO THE SAID CONNECTING CABLE; AND GUIDE MEANS FOR DIRECTING THE SAID OPERATING CABLE EXTERNALLY OF THE SAID STACK IN THE REGION ABOVE THE SAID FAN AND SUBSTANTIALLY PERPENDICULAR TO THE SAID PIVOTAL AXIS AND INTERNALLY OF THE SAID STACK IN THE REGION BELOW THE SAID FAN TO A DAMPER CONTROL LOCATION WITHIN THE SAID BUILDING.