GB2144779A - Cables - Google Patents

Abstract

The cable has a passage a accommodating a core 1 comprising a transmission element 2 (e.g. an optical fibre). The structure of the cable is radially and longitudinally self-supporting and sufficiently strong to resist reduction of the cross-section of the passage a in normal use. One or more elongate elements 4,6,7 of soft material extend along the exterior of the core 1, are in contact with the wall of the passage a, and space the core from the wall, thereby providing longitudinal frictional support of the core. <IMAGE>

Description

SPECIFICATION Cables This invention provides a cable having a passage accommodating a core comprising at least one transmission element, the structure of the cable being radially and longitudinally self-supporting and being sufficiently strong to resist reduction of the cross-section of the passage when tension is applied to the cable in normal use and to protect the core against transverse stresses, and at least one elongate element extending along the exterior of the core and spacing the core from the wall of the passage, the or each elongate element being of soft material and being in contact with the wall of the passage.

One advantageous effect of the elongate element or elements is to provide longitudinal frictional support of the core in the passage, so that the core does not have to support its own weight when the cable is vertical.

Figures 1 to 3 of the accompanying drawings show cross-sections through three types of strain cable as described in GB 2096 656A and EP 60061 A1, each having a central passage a which accommodates a core 1 in the manner shown in any of Figures 4 to 6. The core 1 comprises a transmission element 2 comprising an optical fibre of a bundle of optical fibres, surrounded by a sheath 3 of resiliently deformable plastics material.

In Figure 4, three fins 4 integral with the sheath 3 are in contact with the wall of the passage a; the fins may extend longitudinally or helically.

In Figure 5, four elongate elastomeric elements 6 are arranged between the sheath 3 and the wall of the passage a; the elements 6 may extend generally longitudinally or be wound around the sheath.

In Figure 6, a single tape 7 of cellular plastics material is wound helically around the sheath 3 and is slightly compressed between the sheath 3 and the wall of the passage a.

In each case, the cross-sections of the elements 4, 6, 7 can differ from that illustrated.

The core 1 may comprise one or more copper conductors instead of or in addition to the optical fibre(s).

1. A cable having a passage accommodating a core comprising at least one transmission element, the structure of the cable radially and longitudinally self-supporting and being sufficiently strong to resist reduction of the cross-section of the passage when tension is applied to the cable in normal use and to protect the core against transverse stresses, and at least one elongate element extending along the exterior of the core and spacing the core from the wall of the passage, the or each elongate element being of soft material and being in contact with the wall of the passage.

2. A cable as claimed in claim 1, in which the core has a sheath of resiliently deformable plastics material, the or each elongate element being integral with the sheath.

3. A cable as claimed in claim 1, in which the core has a plastics sheath, the or each elongate element being separate from the sheath and in contact with it.

4. A cable as claimed in any preceding claim, in which the transmission element comprises an optical fibre or a bundle of optical fibres.

5. A cable substantially as described herein with reference to, and as shown in, any of Figures 1 to 3 and any of Figures 4 to 6.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Cables This invention provides a cable having a passage accommodating a core comprising at least one transmission element, the structure of the cable being radially and longitudinally self-supporting and being sufficiently strong to resist reduction of the cross-section of the passage when tension is applied to the cable in normal use and to protect the core against transverse stresses, and at least one elongate element extending along the exterior of the core and spacing the core from the wall of the passage, the or each elongate element being of soft material and being in contact with the wall of the passage. One advantageous effect of the elongate element or elements is to provide longitudinal frictional support of the core in the passage, so that the core does not have to support its own weight when the cable is vertical. Figures 1 to 3 of the accompanying drawings show cross-sections through three types of strain cable as described in GB 2096 656A and EP 60061 A1, each having a central passage a which accommodates a core 1 in the manner shown in any of Figures 4 to 6. The core 1 comprises a transmission element 2 comprising an optical fibre of a bundle of optical fibres, surrounded by a sheath 3 of resiliently deformable plastics material. In Figure 4, three fins 4 integral with the sheath 3 are in contact with the wall of the passage a; the fins may extend longitudinally or helically. In Figure 5, four elongate elastomeric elements 6 are arranged between the sheath 3 and the wall of the passage a; the elements 6 may extend generally longitudinally or be wound around the sheath. In Figure 6, a single tape 7 of cellular plastics material is wound helically around the sheath 3 and is slightly compressed between the sheath 3 and the wall of the passage a. In each case, the cross-sections of the elements 4, 6, 7 can differ from that illustrated. The core 1 may comprise one or more copper conductors instead of or in addition to the optical fibre(s). CLAIMS

1. A cable having a passage accommodating a core comprising at least one transmission element, the structure of the cable radially and longitudinally self-supporting and being sufficiently strong to resist reduction of the cross-section of the passage when tension is applied to the cable in normal use and to protect the core against transverse stresses, and at least one elongate element extending along the exterior of the core and spacing the core from the wall of the passage, the or each elongate element being of soft material and being in contact with the wall of the passage.

2. A cable as claimed in claim 1, in which the core has a sheath of resiliently deformable plastics material, the or each elongate element being integral with the sheath.

3. A cable as claimed in claim 1, in which the core has a plastics sheath, the or each elongate element being separate from the sheath and in contact with it.

4. A cable as claimed in any preceding claim, in which the transmission element comprises an optical fibre or a bundle of optical fibres.

5. A cable substantially as described herein with reference to, and as shown in, any of Figures 1 to 3 and any of Figures 4 to

6.