Abstract: A screw threaded method of making fastener particularly intended for use in fastening corrugated sheet material to metal purlins comprises a drilling point (1), a head (2), a first self-tapping screw threaded portion (3) adjacent the drilling point (1), a second screw threaded portion (4) adjacent the head (2), the second screw threaded portion (4) having a larger crest diameter than the first screw threaded portion (3), and an unthreaded portion (5) extending between the first and second screw threaded portions. The diameter of the part of the fastener carrying the second screw threaded portion (4) is generally larger than that carrying the first screw threaded portion 3 and the fastener also includes a transition portion (6) between its portions of smaller and larger diameter, and in particular, interposed between the trailing edge portion of the first screw threaded portion (3) and the leading edge portion of the unthreaded portion (5). The transition portion (6) includes forming portions (8 FIG.

Abstract: A screw threaded fastener particularly intended for use in fastening corrugated sheet material to metal purlins comprises a drilling point (1), a head (2), a first self-tapping screw threaded portion (3) adjacent the drilling point (1), a second screw threaded portion (4) adjacent the head (2), the second screw threaded portion (4) having a larger crest diameter than the first screw threaded portion (3), and an unthreaded portion (5) extending between the first and second screw threaded portions. The diameter of the part of the fastener carrying the second screw threaded portion (4) is generally larger than that carrying the first screw threaded portion (3) and the fastener also includes a transition portion (6) between its portions of smaller and larger diameter and in particular, interposed between the trailing edge portion of the first screw threaded portion (3) and the leading edge portion of the unthreaded portion (5).

Abstract: A re-usable plastic drive rivet is of the type comprising an axially extending shank in association with an axially extending drive pin which is axially drivable into a bore extending axially through the shank. In order to permit release of the entire drive rivet by means of an unscrewing operation, without damaging the workpieces to which the drive rivet is secured, the outer surface of the shank has a thread formation thereon with the outer surface of the drive pin having a non-cylindrical outline complementary to a similar non-cylindrical peripheral outline of the interior wall of the bore. The non-cylindrical outlines can be substantially cylindrical apart from inter-engagable axial ribs and grooves. The shank can be integrally formed with the drive pin through means of frangible connections, but alternatively the shank can be preassembled with the drive pin by inserting the drive pin into the bore through the shank.

Abstract: A closure assembly, such as a filter cap for a vehicle's fuel tank, comprises a first member formed with a circumferentially arranged series of ratchet teeth, and a second member associated with a pair of pawls, the pawls being continuously urged linearly apart from one another by spring means located between their adjacent ends so that their ends remote from the spring means, which remote ends may each be formed with a plurality of ratchet teeth, are continuously urged into gaps defined between the ratchet teeth formed upon the first member, whereby application of torque to the second member in one rotary sense is initially transmitted by means of the pawls so as to rotate the first member in conjunction therewith until the torque exceeds a predetermined level, whereupon the pawls ride over the ratchet teeth formed upon the first member and the second member is rotated relative to the first member, whereas application of torque to the second member in the opposite rotary sense is always transmitted by means