Abstract: An expandable shaft includes an outer shaft and an inner shaft. Plural rolling elements are pinched elastically in a space between raceway grooves of the outer shaft and the inner shaft. An outer peripheral surface of the inner shaft includes flat portions parallel to each other. An inner peripheral surface of the outer shaft includes flat limiting portions parallel to each other. The respective limiting portions limit relative rotation of the outer shaft and the inner shaft by engaging with corresponding flat portions. A deformation promoting portion is placed in a specific region of the outer shaft between a plane including a center of curvature of the raceway groove of the outer shaft as well as a central axis line of the outer shaft and each limiting portion.

Abstract: A yoke for universal joint includes a cylindrical base, and a pair of arms extending from an end of the base in parallel to a center axis of the base. Each of the arms is formed with a support hole for supporting a corresponding trunnion of a cross shaft via a bearing. The support hole of each arm has a center axis extending in a direction orthogonal to the center axis of the base. A relief portion including a concave curved surface is formed at the end of the base. The concave curved surface of the relief portion has a center of curvature located at place offset from a center of a joint 1 toward a distal end of the arm.

Abstract: A yoke for universal joint includes a cylindrical base, and a pair of arms extending from an end of the base in parallel to a center axis of the base. Each of the arms is formed with a support hole for supporting a corresponding trunnion of a cross shaft via a bearing. The support hole of each arm has a center axis extending in a direction orthogonal to the center axis of the base. A relief portion including a concave curved surface is formed at the end of the base. The concave curved surface of the relief portion has a center of curvature located at place offset from a center of a joint 1 toward a distal end of the arm.

Abstract: An expandable shaft (5) includes an outer shaft (13;13A;13B;13C;13D) and an inner shaft (14;14A;14B;14C;14D;14E;14F). Plural rolling elements (15) are pinched elastically in a space between raceway groves (16;17) of the outer shaft (13;13A;13B;13C;13D) and the inner shaft (14;14A;14B;14C;14D;14E;14F) by an elastic restoring force of the outer shaft (13;13A;13B;13C;13D). An outer peripheral surface (141) of the inner shaft (14;14A;14B;14C;14D;14E;14F) includes at least a pair of flat portions (21;22;41;42;43;44;45;46) that are parallel to each other. An inner peripheral surface (131) of the outer shaft (13;13A;13B;13C;13D) includes at least a pair of flat limiting portions (31;32;71;72;73;74) that are parallel to each other. The respective limiting portions (31;32;71;72;73;74) limit a quantity of relative rotation of the outer shaft (13;13A;13B;13C;13D) and the inner shaft (14;14A;14B;14C;14D;14E;14F) by engaging with the corresponding flat portions (21;22;41;42;43;44;45;46).

Abstract: In a hydraulic power steering apparatus, when the relative rotation between input and output shafts which are connected by a torsion bar is converted into the relative rotation between an outer valve element and an inner valve element, the ratio of the relative rotation angle of the latter to the relative rotation angle of the former is varied in accordance with an operating condition of a vehicle. The hydraulic pressure to generate steering assist force is controlled in accordance with the relative rotation angles between both valve elements. The outer valve element is capable of relative coaxial rotation to the input and output shafts, and the inner valve element is formed integrally with the input shaft. A swinging member is supported by first, second and third supporting parts which respectively rotate together with the input shaft, the output shaft or the outer valve element.

Abstract: An extendable shaft includes a first and a second shaft sections aligned on the same axis. External splines on an outer periphery of the first shaft section engage external splines on an inner periphery of the second shaft section. The first shaft section includes a slit extended from an opening end thereof for a predetermined length along an axial direction. A diametrically contractible portion adapted for elastic reduction in diameter is provided in a region ranging from the opening end of the first shaft section to place away therefrom by the predetermined length along the axial direction. A thin-wall portion is formed in a part of the diametrically contractible portion. A clamping member elastically clamps the diametrically contractible portion.

Abstract: In a hydraulic power steering apparatus, when the relative rotation between input and output shafts which are connected by a torsion bar is converted into the relative rotation between an outer valve element and an inner valve element, the ratio of the relative rotation angle of the latter to the relative rotation angle of the former is varied in accordance with an operating condition of a vehicle. The hydraulic pressure to generate steering assist force is controlled in accordance with the relative rotation angles between both valve elements. The outer valve element is capable of relative coaxial rotation to the input and output shafts, and the inner valve element is formed integrally with the input shaft. A swinging member is supported by first, second and third supporting parts which respectively rotate together with the input shaft, the output shaft or the outer valve element.

Abstract: An extendable shaft includes a first and a second shaft sections aligned on the same axis. External splines on an outer periphery of the first shaft section engage external splines on an inner periphery of the second shaft section. The first shaft section includes a slit extended from an opening end thereof for a predetermined length along an axial direction. A diametrically contractible portion adapted for elastic reduction in diameter is provided in a region ranging from the opening end of the first shaft section to place away therefrom by the predetermined length along the axial direction. A thin-wall portion is formed in a part of the diametrically contractible portion. A clamping member elastically clamps the diametrically contractible portion.