A method for manufacturing a hollow spring member having a hollow steel spring rod having terminal sealed portions at both ends thereof. Each terminal sealed portion has a rotationally symmetric shape in which an axis passing through a center of the spring rod is an axis of symmetry. Each terminal sealed portion has an end wall portion including an end face; an arc-shaped smoothly curved surface between an outer peripheral surface of the spring rod and the end face, and a hermetically closed distal-end-center closure portion on the axis passing through the center of the spring rod. The method includes forming each of the end portions of the spring rod by forming a chamfered portion on an inner or outer peripheral side of the end portion of a hollow wire, the end portion having an opening portion at a distal end, heating the end portion of the hollow wire having the chamfered portion, and spinning the heated end portion to be gathered toward the axis from the outer peripheral side by a jig. The end wall portion, which includes the distal-end-center closure portion, is formed by the distal end of the end portion being joined together on the axis.

A method for manufacturing a hollow spring member having a hollow steel spring rod having terminal sealed portions at both ends thereof. Each terminal sealed portion has a rotationally symmetric shape in which an axis passing through a center of the spring rod is an axis of symmetry. Each terminal sealed portion has an end wall portion including an end face; an arc-shaped smoothly curved surface between an outer peripheral surface of the spring rod and the end face, and a hermetically closed distal-end-center closure portion on the axis passing through the center of the spring rod. The method includes forming each of the end portions of the spring rod by forming a chamfered portion on an inner or outer peripheral side of the end portion of a hollow wire, the end portion having an opening portion at a distal end, heating the end portion of the hollow wire having the chamfered portion, and spinning the heated end portion to be gathered toward the axis from the outer peripheral side by a jig. The end wall portion, which includes the distal-end-center closure portion, is formed by the distal end of the end portion being joined together on the axis.

A body weight adjustment mechanism for automatic adjustment to a balanced point is provided to improve vibration absorption characteristics and impact absorption characteristics. A torsion angle of a lower frame-side torsion bar when an upper frame is at a balanced point is found in advance, a torsion angle of the lower frame-side torsion bar in a state in which a person is seated is detected, the detected torsion angle is compared with the aforesaid balanced point torsion angle, a control signal is sent to an elastic force adjusting unit, and torsion angles of upper frame-side torsion bars are adjusted so that the torsion angle of the lower frame-side torsion bar becomes equal to the balanced point torsion angle. The upper frame can be set to an appropriate position in an initial state and a static state in which a person is seated and vibration and impact absorption characteristics are improved.

Provided is a vehicular holding device that, in an ON state, holds a vehicle component in a state where displacement of the vehicle component in an axial direction is restrained, and that, in an OFF state, holds the vehicle component in a state where displacement of the vehicle component in the axial direction is possible. The vehicular holding device includes at least one engagement part, a cam mechanism, and an axial direction restraining part. The at least one engagement part is at a position where the engagement part engages with an engaged part in the ON state, and is at a position where the engagement part is separated from the engaged part in the OFF state. The cam mechanism displaces the at least one engagement part from the OFF-state position to the ON-state position. The axial direction restraining part receives axial-direction force acting on the at least one engagement part.

A hollow stabilizer includes a curved part having eight regions defined in a cross section. A first region includes a 90° first part when the center of the inside of the curve is taken to be at 0° and the center of the outside of the curve is taken to be at 180°. A third region includes a 0° third part. A fifth region includes a 270° fifth part. A seventh region includes a 180° seventh part. The radii of curvature of the respective outer surfaces of the third part and the seventh part are larger and the radii of curvature of the respective outer surfaces of the second part and the sixth part are smaller than the radii of curvature of the respective outer surfaces of the fourth part and the fifth part.

A hollow stabilizer includes a curved part having eight regions defined in a cross section. A first region includes a 90° first part when the center of the inside of the curve is taken to be at 0° and the center of the outside of the curve is taken to be at 180°. A third region includes a 0° third part. A fifth region includes a 270° fifth part. A seventh region includes a 180° seventh part. The radii of curvature of the respective outer surfaces of the third part and the seventh part are larger and the radii of curvature of the respective outer surfaces of the second part and the sixth part are smaller than the radii of curvature of the respective outer surfaces of the fourth part and the fifth part.

A shaft coupling includes a drive hub that is coupled to a drive shaft to rotate integrally with the drive shaft, a driven hub that is coupled to a driven shaft to rotate integrally with the driven shaft, and a rotation transmission portion that transmits rotation between the drive hub and the driven hub. A dynamic vibration absorber is integrally coupled to a section of at least one of the drive hub and the driven hub. The section is an uninvolved section that is not involved in a torsional stiffness of the whole shaft coupling.

The invention relates to a composite shock absorber for a polycrystalline diamond compact bit, comprising a drilling tool body having a water inlet, an impact body having a water outlet and forming a shock absorption cavity, a disc spring group having an annular pressing sleeve, a cylindrical torsion bar spring which has an external thread and a spline, is connected to the drilling tool body through threads and extended into an impactor and connected thereto through the spline, and the annular pressing sleeve, wherein bit vibration impact force is transmitted therebetween through a torsion transmission joint, and a bearing group is arranged between the lower end surface of the annular pressing sleeve and an annular step of the impact body. The composite shock absorber can weaken damage of the slippage effect to polycrystalline diamond compact cutting teeth, absorb axial vibration from a drill stem and prolong the service life of the bit.

A transmissive joint has an elastic response for transmitting a torsional load capable of ensuring the transmission in the absence of coaxiality between two actuating and actuated devices, and allowing the internal passage of cabling or possible accessory components along the axis of transmission/torsion.

A stabilizer formed by using a metal bar having a solid structure and configured to reduce a displacement between right and left wheels, including a torsion part extending in a vehicle width direction, being capable of a torsional deformation, and having a diameter of 10 to 32 mm, is provided. The stabilizer has a chemical composition containing at least C: 0.15% by mass or more to 0.39% by mass or less, Mn, B, and Fe, and also has a metal structure 90% or more of which is a martensite structure.