A self-locking nut includes a main-nut body and a deformable-nut body. The main-nut body has a recess leading into an interior threaded bore forming x turns of an internal thread therein. The deformable-nut body has an outer flange and an interior threaded bore forming y turns of an internal thread therein. The outer flange of the deformable-nut body is fixed to the main-nut body such that a relief space is formed between the deformable-nut body and the recess. A ratio of x:y is about 2:1.

A self-locking nut includes a main-nut body and a deformable-nut body. The main-nut body has a recess leading into an interior threaded bore forming x turns of an internal thread therein. The deformable-nut body has an outer flange and an interior threaded bore forming y turns of an internal thread therein. The outer flange of the deformable-nut body is fixed to the main-nut body such that a relief space is formed between the deformable-nut body and the recess. A ratio of x:y is about 2:1.

A self-locking nut includes a main-nut body and a deformable-nut body. The main-nut body has a recess leading into an interior threaded bore forming x turns of an internal thread therein. The deformable-nut body has an outer flange and an interior threaded bore forming y turns of an internal thread therein. The outer flange of the deformable-nut body is fixed to the main-nut body such that a relief space is formed between the deformable-nut body and the recess. A ratio of x:y is about 2:1.

A self-locking nut includes a main-nut body and a deformable-nut body. The main-nut body has a recess leading into an interior threaded bore forming x turns of an internal thread therein. The deformable-nut body has an outer flange and an interior threaded bore forming y turns of an internal thread therein. The outer flange of the deformable-nut body is fixed to the main-nut body such that a relief space is formed between the deformable-nut body and the recess. A ratio of x:y is about 2:1.

A self-locking plug assembly includes ratchet ring circumscribing body having centerline and shank having a threaded top portion. Flexible fingers spiral away from periphery of ratchet ring to engage polygonal sides of polygonal sided ring attached to body. Hooks may extend radially outwardly and downwardly from periphery of ratchet ring. Spring around polygonal portion of body rests on ratchet ring. Annular retaining ring snapped into annular groove in body compresses spring. Hooks may engage notches in the upper wall. Alternatively, hooks may include paws extending inwardly from downwardly extending legs of hooks and into the pockets and engaging upper pocket walls to axially secure the ratchet ring. Body may be borescope plug with a lower end of shank conforming to lower port opening in upper wall. Alternatively, flexible fingers extend outwardly from radially outer rim of ratchet ring and engage polygonal sides of inner side of polygonal sided ring circumscribing ratchet ring.

A self-locking plug assembly includes ratchet ring circumscribing body having centerline and shank having a threaded top portion. Flexible fingers spiral away from periphery of ratchet ring to engage polygonal sides of polygonal sided ring attached to body. Hooks may extend radially outwardly and downwardly from periphery of ratchet ring. Spring around polygonal portion of body rests on ratchet ring. Annular retaining ring snapped into annular groove in body compresses spring. Hooks may engage notches in the upper wall. Alternatively, hooks may include paws extending inwardly from downwardly extending legs of hooks and into the pockets and engaging upper pocket walls to axially secure the ratchet ring. Body may be borescope plug with a lower end of shank conforming to lower port opening in upper wall. Alternatively, flexible fingers extend outwardly from radially outer rim of ratchet ring and engage polygonal sides of inner side of polygonal sided ring circumscribing ratchet ring.

Provided is a nut that resists being loosened and is easy to be tightened. A nut 600 includes a nut main body 10 having a tapped hole 30 formed therein; an annular member 41 formed on the side of a top surface of the nut main body 10; and an outer frame member 45 formed on the side of an outer edge of the annular member 41. The annular member 41 includes a second end portion 42b in contact with a top surface 11 of the nut main body 10 and a first end portion 42a located opposite to the second end portion 42b. A top surface of the first end portion 42a is located above a top surface of the second end portion 42b. A first gap 40 is formed between the first end portion 42a and the top surface 11 of the nut main body 10. A second gap 49 is formed between a side surface of the annular member 41 and an inner wall 47 of the outer frame member 45. The top surface of the first end portion 42a of the annular member 41 is located above a top surface 46 of the outer frame member 45. The inner wall 47 of the outer frame member 45 is inclining while tapering in an upward direction.

Provided is a self locking nut and a manufacturing method thereof wherein a body is spiral and has elasticity, and threads are formed in an inner circumferential surface and are engaged to the bolt. The spiral body of the nut is engaged strongly surrounding the bolt. The spiral body expands or contracts depending on the change of temperature, so the threads of the nut and the bolt comes into strong contact with each other for thereby obtaining stable engagement. In case that external force such as vibrations or impacts is applied, the external force may be absorbed elastically, thus preventing the loosening of the nut.

Provided is a self locking nut and a manufacturing method thereof wherein a body is spiral and has elasticity, and threads are formed in an inner circumferential surface and are engaged to the bolt. The spiral body of the nut is engaged strongly surrounding the bolt. The spiral body expands or contracts depending on the change of temperature, so the threads of the nut and the bolt comes into strong contact with each other for thereby obtaining stable engagement. In case that external force such as vibrations or impacts is applied, the external force may be absorbed elastically, thus preventing the loosening of the nut.

A female threaded body (100) is provided with: a female threaded helical structure (114) formed on the inner circumferential surface of a hole (106a) in a cylindrical member (106); a contact surface (110a) formed on an axial direction end face of said cylindrical member (106); and a reverse rotation-preventing member (160), which has a protruding section (168) that is disposed and fixed on said contact surface (110a) and protrudes radially inward toward the rotation axis and in which the tip of said protruding section (168) configures an engaging edge (168a) that forms a continuous or discontinuous helix of a different lead angle and/or lead direction from the lead angle and/or lead direction of the female threaded helical structure (114). The engaging edge (168a) may allow a relative rotation of a male thread body (10) and the female threaded helical structure (114) in one direction.