In a screw-coupling structure between an internally-threaded body and an externally-threaded body, for connecting reinforcing bars: the internally-threaded body includes, on the inner diameter thereof, a parallel-tapered-integrated internal thread section formed by integrating a parallel internal thread section formed as a parallel screw thread, with a tapered internal thread section formed on one end of the parallel internal thread section so that the minor diameter thereof gradually narrows; and the externally-threaded body comprises, on the outer diameter thereof, a parallel-tapered-integrated external thread section formed by integrating a parallel external thread section formed as a parallel screw thread, with a tapered external thread section formed on one end of the parallel external thread section so that the major diameter thereof gradually narrows.

A screw including a shank having a tip, a rear end, which is located opposite the tip, and a longitudinal axis, which extends through the tip and through the rear end, and a screw thread helix, which is arranged on the shank, wherein the screw thread helix has a screw thread ridge for engaging into an internal screw thread groove, wherein the shank has a rearwardly facing abutment structure, which extends alongside the screw thread helix, for axial abutment of the screw thread helix. The pitch of the screw thread ridge increases as the axial distance of the screw thread ridge from the tip increases, and the screw thread helix has axial tipward play with respect to the rearwardly facing abutment structure, so as to permit axial compression of the screw thread helix.

According to one aspect, a hammer union includes a female sub; a male sub; and a wing nut that is concentrically disposed about the female and male subs. The wing nut includes a body having first and second end surfaces, and an exterior surface extending therebetween; a passage extending through the body from the first to second end surface that defines an interior surface of the body; an internal shoulder formed by the interior surface; an internal threaded connection that extends from the first end surface and towards the internal shoulder; and lugs extending radially from the exterior surface. In one aspect, the body has a wall thickness defined between the interior and exterior surfaces, with a greater wall thickness at the internal shoulder than at the first end surface; the internal threaded connection has a full-root radius; and a lug that extends along the axial length of the body.

According to one aspect, a hammer union includes a female sub; a male sub; and a wing nut that is concentrically disposed about the female and male subs. The wing nut includes a body having first and second end surfaces, and an exterior surface extending therebetween; a passage extending through the body from the first to second end surface that defines an interior surface of the body; an internal shoulder formed by the interior surface; an internal threaded connection that extends from the first end surface and towards the internal shoulder; and lugs extending radially from the exterior surface. In one aspect, the body has a wall thickness defined between the interior and exterior surfaces, with a greater wall thickness at the internal shoulder than at the first end surface; the internal threaded connection has a full-root radius; and a lug that extends along the axial length of the body.

The invention relates to a locking device (300) comprising: a shaft (24) comprising a first thread (22); and a nut (12) and a ring (13) to be assembled on the shaft; the nut comprising a first inner thread (18) defining a first radial clearance with the first thread of the shaft; the nut further comprising a second inner thread (20) in the opposite direction to the first inner thread, the ring (13) comprising a second thread (40) defining a second radial clearance with the second inner thread of the nut; the ring comprising a third inner thread (38) defining a third radial clearance with the first thread of the shaft. The inner threads and the first and second threads have an identical and constant thread pitch; and each of the second and third radial clearances is greater than the first radial clearance.

A threaded fastener assembly for use with a nut includes a shaft head and a separate shaft. The shaft head includes a head, and an internally-threaded portion. The shaft has a first externally-threaded portion for cooperation with the internally-threaded portion of the shaft head to selectively secure the shaft to the shaft head, a second externally-threaded portion for cooperation with the nut, and an integrated nut or wrenching portion for tightening the shaft to the shaft head.

A threaded fastener assembly for use with a nut includes a shaft head and a separate shaft. The shaft head includes a head, and an internally-threaded portion. The shaft has a first externally-threaded portion for cooperation with the internally-threaded portion of the shaft head to selectively secure the shaft to the shaft head, a second externally-threaded portion for cooperation with the nut, and an integrated nut or wrenching portion for tightening the shaft to the shaft head.

A screw including a shank having a tip, a rear end, which is located opposite the tip, and a longitudinal axis, which extends through the tip and through the rear end, and a screw thread helix, which is arranged on the shank, wherein the screw thread helix has a screw thread ridge for engaging into an internal screw thread groove. The screw thread helix has axial tipward play with respect to the shank, wherein the tipward play increases as the axial distance of the screw thread helix from the tip increases.

A screw including a shank having a tip, a rear end, which is located opposite the tip, and a longitudinal axis, which extends through the tip and through the rear end, and a screw thread helix, which is arranged on the shank, wherein the screw thread helix has a screw thread ridge for engaging into an internal screw thread groove. The screw thread helix has axial tipward play with respect to the shank, wherein the tipward play increases as the axial distance of the screw thread helix from the tip increases.

An indicator assembly includes a fastener defining a first end, a second end opposite the first end, and an axis extending from the first end to the second end; a first indicator positioned radially outwardly of the fastener relative to the axis of the fastener; and a second indicator positioned radially outwardly of the fastener relative to the axis of the fastener, wherein the second indicator is axially in between the first indicator and the second end of the fastener upon the fastener being oriented in a first position, and wherein the second indicator is radially inwardly or radially outwardly of the first indicator upon the fastener being oriented in a second position.