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.

Assembling method of a pinion on a turbine axis of an internal combustion engine, wherein said pinion is made in a single piece having axial symmetry and equipped with an annular toothed part and with an axial part coaxial with said annular part and provided with a coaxial hole with a thread to screw the pinion on said axis of the turbine, wherein said thread has localized pitch variations.

A self-locking insert includes an insert body having an outer surface. Also included is a bore extending through the insert body, the bore defining an inner surface and configured to receive a lead screw. Further included is a self-locking feature configured to engage a holder to retain the self-locking insert in a predetermined position, the self-locking feature comprising at least one lug configured to be compressed by the holder during installation of the self-locking insert in the holder, the self-locking insert configured to be pressed into position in the holder. Yet further included is a de-lashing feature configured to interference fittingly engage the holder.

A self-locking insert includes an insert body having an outer surface. Also included is a bore extending through the insert body, the bore defining an inner surface and configured to receive a lead screw. Further included is a self-locking feature configured to engage a holder to retain the self-locking insert in a predetermined position, the self-locking feature comprising at least one lug configured to be compressed by the holder during installation of the self-locking insert in the holder, the self-locking insert configured to be pressed into position in the holder. Yet further included is a de-lashing feature configured to interference fittingly engage the holder.

A mounting assembly has a machine element with a threaded coaxial bore on a shaft, for rotation with the shaft. A split sleeve having external threads is provided and adapted to be fit into the element's threaded bore and mounted around the shaft at any desired position longitudinally and circumferentially. The threads of the split sleeve have apexes at a uniform diameter when unstressed. The threads of the split sleeve are shaped to cause contraction of the sleeve, when threaded into the element's bore, to secure gripping engagement with the shaft so that it frictionally clamps onto the machine element.