Abstract: In an electric cable or other elongate body, a tubular textile braid comprises two sets of yarns each made up of a plurality of synthetic monofilaments, the yarns of the two sets extending in opposite directions around the axis of the braid corresponding to upper and lower yarns in the braiding machine differing in twist to an extent such that the more twisted yarns have their tensile strength increased by at least 10% but do not have their cover in the braid decreased by more then 25%, both by comparison with an otherwise identical yarn having the same twist of those of the ess twisted set. Preferably the twist in the upper yarns is zero. The invention allows higher production speed and reduced down-time without significant loss of cover, because the small extra twist in the lower yarns gives them better abrasion resistance to withstand passage through their greater exposure in the braiding machine.

Abstract: An electric wire or cable having at least one aluminum conductor with extruded insulation with or without a semiconducting extruded screen or screens has the surface of the metallic conductor textured to provide a mechanical interlock with extruded material applied closely to it. This reduces the effect of shrink-back when the wire or cable is cut back for termination or jointing, and may thus allow faster extrusion in manufacture.

Abstract: In a method of manufacturing a stranded conductor for use in an electric power cable, the cross-sectional shapes of wires being drawn towards or through a rotatably driven lay plate by which the wires are laid helically in a layer around the axis of the conductor are so modified that, on emerging from the lay plate and passing into at least one die downstream of the lay plate, the wires of modified cross-sectional shape fit tightly together and, if present, around a central wire or a preceding layer of helically applied wires. The wires of each layer preferably are initially of the same cross-sectional shape and size as one another, e.g. approximately circular, and, preferably, the modified cross-sectional shapes imparted to the wires of each layer are the same as one another, e.g. approximating to a sector of an annulus. No compacting of the wires is required in the die or dies and, as a consequence, a capstan drawing the wires through the die or dies is not subjected to a undesirable load.

Abstract: An insulating coating of extruded polymer material is formed around a moving conductor wire; the extruder includes a decompression zone effective to arrest shear degradation of the polymer such that the melt index of the insulating polymer on the insulated wire is not more than 50% of the melt index of the solid, particulate polymer material before extrusion; the extruder includes valve means and intense mixing means which ensure that the polymer melts in a controlled manner whereby a uniform extrudate is formed.

Abstract: A composition useful for filling communication cables is described which comprises petroleum jelly and a small amount of siliceous material which renders the petroleum jelly viscous at elevated temperatures, and prevents leakage of the petroleum jelly from a cable having a flaw, which is subjected to elevated temperatures; the composition is particularly useful in communication cables having cellularly insulated conductors where migration of the flowable filler composition into the cellular insulation is diminished.

Abstract: Molten plastic material is extruded uniformly about an advancing core by dividing a single stream of the plastic flowing to a die assembly transversely to the direction of advance of the core, into a plurality of streams, in which one half of the plastic flows along a first path spaced around the core and then towards the core; the other half of the plastic flows in a second path which is, in essence, a mirror image of the first path; the divided streams are reunited as a tubular sleeve of flowing plastic flowing in the direction of the advancing core, spaced around the core and flowing towards the advancing core.

Abstract: A particulate concentrate, for example pellets, is provided comprising predetermined amounts of a pigment and a blowing or foaming agent in a polymer matrix. The concentrate can be added to an extruder together with a polymer insulating material for the formation of color-coded cellular insulation on a conductor wire of a cable, for example a communication cable. The composition of the concentrate is so determined that different color-coded, cellular, insulating coatings can be produced which are dielectrically matched, as required.

Abstract: A method and apparatus are provided for the extrusion of a thermoplastic material in modified form in which the thermoplastic material is introduced into the barrel of a screw extruder, and is heated and forced through the barrel: the material is passed through valve means which together with the temperature of the material is effective to produce a melt transition in the material at a predetermined point and to thoroughly mix the material; subsequently, the material is forced into a low pressure zone in the barrel where a modifying agent is introduced into the material; the resultant mass is forced out of the low pressure zone, and is passed through a mixing means effective to intensify the dispersion of the modifying agent in the mass, the mass is extruded and the extruded material collected.

Abstract: A method and apparatus are provided for the extrusion of a thermoplastic material in modified form in which the thermoplastic material is introduced into the barrel of a screw extruder, and is heated and forced through the barrel: the material is passed through valve means which together with the temperature of the material is effective to produce a melt transition in the material at a predetermined point and to thoroughly mix the material; subsequently, the material is forced into a low pressure zone in the barrel where a modifying agent is introduced into the material; the resultant mass is forced out of the low pressure zone, and is passed through a mixing means effective to intensify the dispersion of the modifying agent in the mass, the mass is extruded and the extruded material collected.

Abstract: The rim of the upper sheave in a wire induction heating apparatus contains a peripheral groove. The wire passes over a portion of the groove twice, and overlaps for a certain portion. The width of the groove at a height one half the wire width from the bottom supporting surface of the groove is from one and one half to less than two times the width of the wire.

Abstract: A composition useful for filling communication cables is described which comprises petroleum jelly and a small amount of siliceous material which renders the petroleum jelly viscous at elevated temperatures, and prevents leakage of the petroleum jelly from a cable having a flaw, which is subjected to elevated temperatures; the composition is particularly useful in communication cables having cellularly insulated conductors where migration of the flowable filler composition into the cellular insulation is diminished.

Abstract: A composition useful for filling communication cables is described which comprises petroleum jelly and a small amount of siliceous material which renders the petroleum jelly viscous at elevated temperatures, and prevents leakage of the petroleum jelly from a cable having a flaw, which is subjected to elevated temperatures.