Pick-resistant lock and key therefor

Claim 1

IN A PIN TUMBLER LOCK, A HOUSING OF ELONGATED FORM PROVIDING MEANS DEFINING AT LEAST THREE SERIES OF LONGITUDINALLY ARRANGED DRIVER PIN BORES, EXTENDING TRANSVERSELY OF THE HOUSING IN SPACED ANGULAR RELATION TO ONE ANOTHER A KEY BARREL WITHIN THE HOUSING HAVING MEANS DEFINING A KEYWAY EXTENDING THROUGH THE OUTER END THEREOF AND ROTATABLE IN THE HOUSING BY A KEY, SAID BARREL HAVING MEANS DEFINING TUMBLER PIN BORES THEREIN EXTENDING FROM THE KEYWAY THROUGH THE PERIPHERY OF THE BARREL AND ALIGNABLE AXIALLY WITH SAID BORES FORMED IN THE HOUSING WHEN THE BARREL IS IN ONE ANGULAR POSITION RELATIVELY TO THE HOUSING, AND THREE SERIES OF PIN TUMBLERS IN SAID BARREL BORES EACH OF WHICH PINS IS URGED INWARDLY TOWARD THE KEYWAY, HAVING A TAPERED INNER END, FOR COOPERATION WITH THE KEY WHEN THE BARREL IS IN THE LAST-MENTIONED ANGULAR POSITION THEREOF BY A COMPANION SPRING-BIASED DRIVER PIN IN ITS HOUSING BORE AND PRESENTING A SHEAR LINE BETWEEN THE BARREL AND THE HOUSING WHEN THE KEY IS IN THE BARREL, ONE TUMBLER OF ONE SERIES EXTENDING BEYOND THE POINT TO WHICH A TUMBLER OF A SECOND SERIES EXTENDS INTO THE KEYWAY SO THAT THE LAST-MENTIONED TUMBLERS ARE IN EFFECT IN OVERLAPPING RELATIONSHIP WHEN THE SHEAR LINE IS PRESENTED, ONE TUMBLER PIN OF THE THIRD SERIES EXTENDING INTO THE KEYWAY WHEN THE KEY IS REMOVED FROM THE BARREL AND HAVING ITS AXIS SPACED REARWARDLY FROM THE AXIS OF THE INNERMOST OVERLAPPING PIN A DISTANCE LESS THAN ONE HALF THE DIAMETER OF THE LAST-MENTIONED OVERLAPPING PIN TO INHIBIT PICKING OF THE LOCK.