GB428540A - Improvements in or relating to armors for cables - Google Patents

Abstract

428,540. Cables. TELEFONAKTIEBOLAGET L. M. ERICSSON, 33, Kungsgatan, Stockholm, and ELL, B. S. F., Spanga, both in Sweden. Nov. 15, 1933, No. 31871. [Class 36] To enable a lead-sheathed cable, particularly an oil-filled cable, to resist high internal pressures, an armouring is provided, either inside or outside the lead sheath, comprising a large number of bands which are hook-shaped in cross-section and which are wound about the cable at a great pitch so that the bands make an angle of less than 16‹ with the longitudinal direction of the cable. The bands may be wound in a single layer so that the hooks of adjacent bands engage with one another, or they may be wound in two or more layers so that the hooks of the bands in one layer engage with the hooks of the bands in the next layer, the result being that displacement of adjacent bands in a direction transverse to the cable is prevented. Insulation may be provided between the bands, for example, by making the bands of aluminium with oxidized surfaces. An insertion of paper &c. may be provided between the armouring and the lead sheath and an outer armouring, for example, of bands or wires wound at a smaller pitch, may be provided to protect the cable against wear. Fig. 1 shows a cable comprising a conductor 1 having a longitudinal oil channel 2 which communicates with a space 3 filled with insulating material impregnated with oil and which is surrounded by a lead sheath 4. The armouring outside the lead sheath comprises an inner layer of U-shaped bands 5 wound about the cable at a great pitch with their flanges directed outwardly and an outer layer of similar bands 6 wound with their flanges directed inwardly so that the flanges of the bands 5 and 6 engage. The abutting edges 8 and 9 of the bands 5 and 6 respectively may be sharp, as shown, or may be rounded to form shallow helical grooves on the inside and outside of the armouring. The abutting surfaces 7 may be provided with grooves to accommodate key - bands of rectangular or circular crosssection to prevent slipping of the bands in a radial direction. Alternative methods of preventing radial slip are shown in Figs. 3 and 4. In Fig. 3 each band has a wedge-shaped flange 10 intermediate its hook flanges so that when the bands are wound the flanges 10 cause deformation of the hook flanges as shown. In Fig. 4 the bands 5 of the inner layer are formed with the hook surfaces 11 inclined, the flanges of the outer bands 6 being bent round these surfaces when the outer layer is wound. In the form shown in Fig. 8, the outer bands also engage with one another by means of longitudinally extending projections 14 and grooves 15. As shown in Fig. 4, the bands in the outer layer need not abut against one another to form a continuous surface. An armouring comprising a single layer of bands is shown in Fig. 9, the bands 16 being substantially S-shaped in cross-section.