Abstract: A threaded fastening member includes an actuating end having a head. The head has a diameter projecting beyond a diameter of the thread of the fastening member and is coaxial with a thread axis. A centrally located recess is provided within the head for the application of interior forces. The recess includes radial outwardly projecting slots, each having two flanks lying in respective planes. Each flank plane is essentially tangential to an imaginary cone that is co-axial with the thread axis. The recess further includes a pair of segmented circumferential faces separating each slot from an adjacent slot, and a transitional linear inner edge formed between each pair of segmented circumferential faces and each flank of a respective slot.

Abstract: A mechanical automatic clearance adjuster (10) of the type comprising a screw (24) of generally buttress thread form running within an internally threaded housing (22) on running flanks (38,40) under the action of axially directed spring means (26) has the screw (24) provided with grooved locking flanks (42) incapable of establishing contiguous engagement with the co-operating locking flanks (44) of the housing. The adjuster (10) is described for use in a valve train application in an internal combustion engine.

Abstract: A mechanical automatic clearance adjuster, such as may be used as a valve clearance adjuster in an internal combustion engine, comprises a self-contained mechanism having an internally screw threaded housing (26) within which there is a complementarily threaded screw member (28). The screw threads exhibit a relatively high friction in one direction of axial loading thereof compared with a relatively low friction in the opposite direction of axial loading whereby the screw member (28) may rotate and advance axially of the housing (26) solely under the action of a compression spring (34) acting between the screw member (28) and an end cap (30).

Abstract: An automatic tappet adjuster for a valve operating mechanism has two components 12, 14 with co-operating buttress thread form screw threads 32. The axial free play in the threads 32 sets the valve clearance. Excess clearance 56 is taken up by movement of one component, 14 acted on by a spring 40, relative to the other component 12. The buttress thread form 32 exhibits higher friction against rotation in one direction than in the other.

Abstract: A combination of a cruciform recess in a fastener and cruciform driver has driver wings 13 which are narrower than corresponding recess radial grooves 21 and has downwardly tapered grooves and wings such that driving engagement between driver and fastener takes place at the outer upper edges of the recess. There is a relative downward taper between the wing width and groove width and these widths are so selected that the lower ends of the wings are confined by and preferably wedge in the recesses.

Abstract: Described herein is a process for preparing polyarylates which comprises reacting a diester derivative of a dihydric phenol with an aromatic dicarboxylic acid in the presence of from about 10 to about 60 weight percent of a diphenyl ether compound at a temperature of from about 260.degree. to about 350.degree. C. and in the presence of a magnesium catalyst.

Abstract: Described herein is a process for preparing polyarylates which comprises reacting a diester derivative of a dihydric phenol with an aromatic dicarboxylic acid in the presence of from about 10 to about 60 weight percent of a diphenyl ether compound at a temperature of from about 260.degree. to about 350.degree. C.

Abstract: Method and apparatus for tightening a nut and bolt assembly to ensure that the bolt shank is tensioned correctly using a wrench having two relatively movable detector parts carried by the body of the wrench, one part being a cylindrical outer casing which engages the abutment surface non-rotatably, the other part being a stem extending axially from the body and having its outer end engaging the body of the nut and its inner end connected to a holder for a microswitch arranged to cooperate with an actuating member fixed to said outer casing, said microswitch being in an electrical circuit which controls power to the wrench and/or a visible or audible signal.

Abstract: A screw having a head and a threaded shank and, in the head, a cruciform shaped recess comprising a central cavity and four grooves radiating from the central cavity at 90.degree. angular spacings, the bases of the grooves lying on a conical (or pyramidal) surface and wherein the included angle at the vertex of such cone (or pyramid) has a value within the range 40.degree. - 45.degree., the preferred value being 40.degree..