Turbine wheel

Claim 1

IN A TURBINE WHEEL HAVING A DISC-LIKE BODY AND A PLURALITY OF CIRCUMFERENTIALLY SPACED RADIALLY DIRECTED TURBINE BLADES, A CIRCUMFERENTIALLY CONTINUOUS ANNULAR PEDESTAL PORTION CARRIED BY SAID BODY AND IN TURN PERIPHERALLY CARRYING SAID TURBINE BLADES, SAID ANNULAR PEDESTAL PORTION COMPRISING A PLURALITY OF RADIALLY DIRECTED RIBS EXTENDING GENERALLY AXIALLY OF SAID WHEEL, AN ANNULAR AXIALLY EXTENDING RIM, SAID RIBS BEING FORMED SO AS TO BE JOINED TO SAID DISC BODY AT THEIR RESPECTIVE RADIALLY INNERMOST ENDS AND TO BE JOINED TO SAID ANNULAR AXIALLY EXTENDING RIM AT THEIR RESPECTIVE RADIALLY OUTERMOST ENDS, A RADIALLY DIRECTED WALL FORMED BETWEEN AND JOINING SUCCESSIVE SPACED RIBS, EACH OF SAID WALLS HAVING FORMED THEREIN A GENERALLY RADIALLY DIRECTED STRUCTURALLY WEAKENED AREA SO AS TO DEFINE A GENERALLY RADIALLY DIRECTED AREA FOR LOCALIZING THERMALLY INDUCED STRESS THEREBY ENHANCING THE OPPORTUNITY FOR RADIAL LY DIRECTED CONTROLLED THERMAL STRESS DISSIPATING CRACKS TO BE FORMED THROUGH SAID AREAS OF LOCALIZED STRESS WHENEVER SAID TURBINE WHEEL IS FIRST CAUSED TO EXPERIENCE A RADIAL TEMPERATURE GRADIENT AND SUBSEQUENTLY PERMITTED TO EXPERIENCE A REDUCTION IN SAID TEMPERATURE GRADIENT, AND MEANS GENERALLY BETWEEN THE RADIALLY INNERMOST ENDS OF SAID RIBS FOR LIMITING THE RADIALLY INWARD PROPAGATION OF SAID CRACKS, SAID LAST MENTIONED MEANS COMPRISING A GENERALLY CIRCULAR APERTURE FORMED THROUGH EACH OF SAID WALLS SO AS TO INTERSECT SAID STRUCTURALLY WEAKENED AREA, AND MEANS INSERTED THROUGH EACH OF SAID CIRCULAR APERTURES AND MECHANICALLY RETAINED THEREIN FOR FORMING A SUBSTANTIAL BARRIER TO THE FREE PASSAGE OF FLUID THROUGH SAID CIRCULAR APERTURES.