Shut-off valve for cementitious pressure vessels

Claim 1

IN A MACHINE FOR HANDLING PARTICULATE MATERIAL, THE COMBINATION OF A PRESSURE HOPPER FOR SAID MATERIAL HAVING A MATERIAL INLET PORT AND AN ANNULAR SEAT IN THE HOPPER ADJACENT THE PORT; A VALVE IN THE HOPPER HAVING A CONVEX OUTER FACE SHAPED SUBSTANTIALLY IN CONFORMITY WITH A SECTOR OF A SPHERE, SAID OUTER FACE NORMALLY BEARING AGAINST THE SEAT IN CLOSING RELATIONSHIP TO THE PORT; A SHAFT CARRIED BY THE HOPPER FOR ROTATION RELTIVE THERETO ABOUT AN AXIS SPACED FROM SAID PORT; AN ARM; AND MEANS MOUNTING SAID ARM ON SAID SHAFT FOR MOVEMENT RELATIVE TO THE LATTER, SAID ARM BEING SECURED TO THE VALVE FOR MOVING THE LATTER ALONG A CIRCULAR PATH TO AND FROM A POSITION CLEARING AND THEREBY OPENING THE PORT AS THE SHAFT IS ROTATED SAID ARM BEING SWINGABLE RELATIVE TO THE SHAFT ABOUT AN AXIS DISPOSED ANGULARLY WITH RESPECT TO THE AXIS OF ROTATION OF THE SHAFT AND IN A DIRECTION TO MOVE SAID VALVE TOWARD THE SEAT WHEN THE VALVE IS CLOSED, WHEREBY PRESSURE IN THE HOPPER HOLDS THE VALVE TIGHTLY AGAINST THE SEAT, SAID SEAT BEING RESILIENT WHEREBY MATERIAL BECOMING LODGED BETWEEN THE SEAT AND THE VALVE WHEN THE LATTER IS CLOSED IS PRESSED INTO THE SEAT BY SAID PRESSURE IN THE HOPPER ACTING ON THE VALVE, THEREBY MAINTAINING A SEAL AROUND THE SEAT.