It is made possible to give prevailing torque to an adjustment bolt in a simple manner without troublesome adjustment work. An anti-loosening adjustment bolt assembly includes: a cylindrical pipe (6) adapted to be fitted on the screw shaft (2a) of the adjustment bolt (2); and a nut (7) having a threaded hole for allowing the screw shaft (2a) to be threadably mounted thereon; the bottom of the nut (7) includes a recess (7a) adapted to allow the upper end of the cylindrical pipe (6) to be fitted therein; the inner peripheral surface of the recess (7a) is a taper surface decreasing in diameter toward the interior; and the axis of the taper surface is slightly eccentric from the axis of the threaded hole such that, when the nut (7), threadably secured to the screw shaft (2a), is screwed toward the cylindrical pipe (6), a circumferential portion of the eccentric taper surface comes into pressure-contact with the upper end of the cylindrical pipe (6) and the axis (Q) of the threaded hole of the nut (7) is eccentric and/or inclined from the axis (O) of the screw shaft (2a) to generate prevailing torque depending on the amount of tightening of the nut (7) on the adjustment bolt (2).

A bolt includes a shank having a first end, a second end, a first external thread proximate to the first end, and a second external thread proximate to the second end. The first external thread twists in a first direction, the second external thread twists in a second direction, and the first direction is different from the second direction. The first external thread includes a minor diameter, the second external thread includes a major diameter, and the minor diameter of the first external thread is greater than the major diameter of the second external thread.

An object of the present invention is to provide an anti-loosening device that exhibits its anti-loosening effect by means of an eccentric fit between a protrusion 12 of a nut 10 and a recess 22 in a nut 20, wherein the inclination of the nut 20 relative to the nut 10 when they have been tightened is minimized. The outer peripheral surface of the protrusion 12 and the inner peripheral surface of the recess 22 are constructed in such a manner that, with the nuts screwed to a threaded shaft S and an eccentric fit established between the protrusion 12 of the nut 10 and the recess 22 in the nut 20, the tapered outer peripheral surface portion 12a of the protrusion 12 interferes with the tapered inner peripheral surface portion 22a of the recess 22 along part of the circumference while a gap is formed between the distal-end outer peripheral surface portion 12b of the protrusion 12 and the closer-to-bottom inner peripheral surface portion 22b of the recess 22 along the entire circumference.

The present disclosure disclosures a mounting and dismounting nut structure. The mounting and dismounting nut structure comprises a first body, a second body, a plurality of threaded blocks, and a limiting member. Inner walls of the plurality of threaded blocks comprise internal threads, and outer walls of the plurality of threaded blocks comprise second inclined surfaces. When the mounting and dismounting nut structure surrounds the threaded rod and is pushed towards a countertop, the plurality of threaded blocks move toward a center axis of the plurality of threaded blocks, and the second body rotates to drive the plurality of threaded blocks to be locked with the threaded rod. When the plurality of threaded blocks is locked with the threaded rod, the limiting member supports the plurality of threaded blocks in an axial direction of the plurality of threaded blocks.

A lock tight nut and bolt system resistant to loosening due to vibration. The lock tight nut and bolt system includes an upper nut that has a shank part. The upper nut has first threads that are off center from a center of a bolt. The upper nut is configured to receive the bolt. A lower nut has a socket part and second threads that are centered with the center of the bolt. The socket part corresponds with the shank park of the upper nut. The upper nut and the lower nut are concentric with the center of the bolt. The system further may include the bolt.

A fastening device, fixing an exhaust manifold (12) on a cylinder head (14) of an internal combustion engine, has a contact surface (20) supported relative to a cylinder head contact surface (22). A fastening edge area (16) has a wedge fastening flange area (24) with a fastening element support surface (26) inclined in relation to the contact surface (20) that has a wedge angle (W.sub.1). A fastening element (38) is pressed against the fastening element support surface (26) with a fastening flange support surface (40) with a fastening bolt unit (30) supported in relation to the cylinder head (14). The wedge angle (W.sub.1) and a coefficient of static friction (μ) of the frictional interaction of the fastening element (38) in relation to the exhaust manifold (12) is defined by: 0<W.sub.1<2 tan.sup.−1 (μ), in which W.sub.1 is the wedge angle, and μ if the coefficient of static friction.

A nonreversible anti-backlash nut comprises a first nut body and a second nut which are provided with internal threads, and a shrinkage ring which is capable of shrinking inwards in a radial direction and is disposed between the first nut body and the second nut body. Nut body chamfers are separately arranged on sides, connected with the shrinkage ring, of the first nut body and the second nut body. A shrinkage ring chamfer is arranged at a position, corresponding to the nut body chamfers, of the shrinkage ring. After the nut is assembled, the shrinkage ring provides a shrinkage force to push, via the chamfers, the first nut body and the second nut body away from each other, so that an axial clearance of the nut is eliminated. Compared with the prior art, the nut has a better and more uniform clearance elimination effect.

A lock tight nut and bolt system resistant to loosening due to vibration. The lock tight nut and bolt system includes an upper nut that has a shank part. The upper nut has first threads that are off center from a center of a bolt. The upper nut is configured to receive the bolt. A lower nut has a socket part and second threads that are centered with the center of the bolt. The socket part corresponds with the shank park of the upper nut. The upper nut and the lower nut are concentric with the center of the bolt. The system further may include the bolt.

An arrangement is for securing a nut on a threaded bolt comprising a bolt shaft projecting from a bolt head and being provided, in an opposite end portion, with a first threaded portion arranged to engage with an internal threaded portion of the nut. The nut and the bolt head are arranged to abut against adjacent elements. A nut-locking element is provided with a threaded portion arranged to engage with a second threaded portion of the threaded bolt. The second threaded portion is arranged externally on a stepped end portion of the threaded bolt and is concentric with and having a smaller pitch than the first threaded portion. The nut-locking element is provided with a friction portion arranged to rest supportingly against a corresponding friction portion on the nut.

A lock nut includes: a first nut having a tapered cavity; and a second nut including a base portion and a tapered lug boss arranged the base portion. The tapered lug boss can be coupled inside the tapered cavity. The first and second nuts are used in pair by self-locking. A straight slot is formed in the lug boss. Under the locking action of the first nut, the straight slot is deformed to further lock a bolt, or is discontinuously engaged with teeth of the bolt to increase an effective stress surface and locking performance of the second nut for locking the bolt. A convex reinforcing rib extends on a first surface of the first nut. An annular groove is formed in a second surface of the second nut. The convex reinforcing rib is coupled with the annular groove to enhance the strength and reliability of locking.