Shaft drive tools, generally, have insufficient torque carrying capability and can fail under torsion loading. Specifically, shaft drive tools incorporate a drive feature that transitions rapidly to a base geometry (usually a cylinder), and this rapid transition in geometry creates a failure location at which stress risers accumulate and cause catastrophic failure under load. Occurrences of this type of failure are increasingly likely as drive tools are narrowed for the delivery of increasingly smaller diameter fasteners. A need therefore exists for an improved shaft drive.
USPTO Backgrounds
USPTO Backgrounds