Patent 11525498 was granted and assigned to THK on December, 2022 by the United States Patent and Trademark Office.
A screw device is provided which can detect damage to a groove of a screw shaft, the damage being hidden by a nut, with a high probability. At least two circulation components are mounted on a nut in such a manner as to form at least two circulation circuits that circulate rolling elements. The nut is provided with a sensor that detects a displacement of a groove of a screw shaft between the adjacent circulation circuits.