Abstract: In a device for measuring torsional torque applied to a fixed or revolving shaft made of a magnetic material by producing a magnetic circuit in which the flux path includes a section of the shaft and detecting a magnetostrictive change induced by the torque, the surface of said section of the shaft is formed with a series of parallel grooves and/or lands or protuberances inclining at a suitable angle with the longitudinal axis of the shaft to thereby cause magnetic flux in the surface layer of the shaft to extend approximately in the direction of tensile or compressive stress produced by the torque. It is preferred to form a first series of parallel grooves extending sprially and inclining 45.degree. with said axis in one section of the shaft and a second series of parallel and spiral grooves inclining 45.degree. with said axis and reverse to the first series of grooves in another section of the shaft to detect a difference between magnetostrictive changes in the respective sections.

Abstract: In a device for measuring torsional torque applied to a fixed or revolving shaft made of a magnetic material by producing a magnetic circuit in which the flux path includes a section of the shaft and detecting a magnetostrictive change induced by the torque, the surface of said section of the shaft is formed with a series of parallel grooves and/or lands or protuberances inclining at a suitable angle with the longitudinal axis of the shaft to thereby cause magnetic flux in the surface layer of the shaft to extend approximately in the direction of tensile or compressive stress produced by the torque. It is preferred to form a first series of parallel grooves extending spirally and inclining 45.degree. with said axis in one section of the shaft and a second series of parallel and spiral grooves inclining 45.degree. with said axis and reverse to the first series of grooves in another section of the shaft to detect a difference between magnetostrictive changes in the respective sections.