GB2159206A - Cable cleat - Google Patents

Abstract

A cleat 9, for use in the installation of an electrical cable having at least two spaced conductors, comprises a base plate 10 and an upper plate 12, 13 separated from the base plate by at least one post 15, 16 fixed with respect to the plates. The or each post 15, 16 has between the plates a smoothly curved surface 17, 18 whose axis of curvature is substantially parallel to the longitudinal axis of the post and whose radius of curvature R,R' is large enough to prevent substantial transverse movement of the conductors relative to one another when the cable is positioned between the plates and against the curved surface of the or each post. <IMAGE>

Description

SPECIFICATION Cable cleat This invention relates to cleats for use in the installation of electric cables, pipes or other flexible elongate members, and is especially, though not exclusively, concerned with cleats for use in the installation of pressure sensitive electric cables.

Pressure sensitive cables usually comprise two spaced conductors which, when the cable is subjected to a pressure above a predetermined level (for example by compression, bending or pulling) move towards one another and either electrically connect with one another, or alter the resistance value between one another, either of which is detected by suitable circuitry connected to the conductors.

A coaxial version of this type of cable is described and claimed in the complete specification of U.K. Patent No: 1 509031. Problems can arise when installing this type of cable because if the cable is bent through a curve having too small a radius of curvature movement of the conductors relative to one another may accidentally actuate the circuitry.

According to the present invention we provide, for use in the installation of an electric cable having at least two spaced conductors, an improved cleat comprising a base plate and an upper plate separated from the base plate by at least one post fixed with respect to the plates, the or each post having between the plates a smoothly curved surface whose axis of curvature is substantially parallel to the longitudinal axis of the post and whose radius of curvature is large enough to prevent substantial transverse movement of the conductors relative to one another when the cable is positioned between the plates and against the curved surface of the post.

Preferably, the or each post has a continuous smoothly curved surface between the plates. However, the smoothly curved surface may be discontinuous; for example, it may be parts of the surfaces of a plurality of separate pins arranged in a smooth curve.

Preferably, the upper plate is in two portions, each portion being spaced from the base plate by a post, and the posts have smoothly curved surfaces whose radii of curvature differ from one another. With this arrangement, a cable can be positioned to bend around one or the other post, as desired, thereby allowing the cleat to be used for different requirements. The portions of the upper plate are preferably spaced from one another, the gap between the portions providing an entry for a cable to be positioned in the cleat. Preferably, the cable entry lies in a direction substantially perpendicular to the common diameter passing through the axes of curvature of the posts.

The radius of curvature of the or each post preferably lies in the range 2mm to 40mm.

Preferably, the cleat is made of aluminium alloy or gunmetal. In each of these cases, the cleat is preferably cast in one piece.

The cleat preferably has an aperture extending through the or each post, and the plates.

With this arrangement, a screw or bolt may be passed through the or each aperture for securing the cleat to a surface. Where the cleat comprises two or more separately formed parts, preferably the screw(s) or bolt(s) also act to secure the parts together.

The invention is further illustrated by a description, by way of example, of a preferred form of cleat with reference to the accompanying drawings, in which: Figure 1 is a partially exposed side view of a pressure sensitive electric cable; Figures 2 and 3 respectively are plan and side views of the preferred cleat, and Figure 4 is a cross-sectional view along the line IV-IV in Fig. 2.

Referring to Fig. 1, the pressure sensitve electric cable 1 comprises a core 2, an inner conductor 3, a conductive plastics layer 4 over the inner conductor 3, and separated from a second conductive layer 5 by a spacer thread 6, an outer conductor 7 and a plastics sheath 8. If the cable 1 is pressed or bent through a curve having a radius less than a predetermined value the conductors 3, 7 move relative to one another and are electrically interconnected through the conductive layers 4, 5.

The preferred cleat 9 shown in Figs. 2 to 4 inclusive is cast in one piece from aluminium alloy. The cleat 9 comprises a base plate 10, an upper plate 11 in two portions 12, 13 separated by a cable entry gap 14, and, extending between and fixed to the plates, two posts 15, 16. The cable entry gap 14 lies in a direction substantially perpendicular to the common diameter passing through the axes of curvature A,A' of the posts.Each post 15, 16 has a continuous smoothly curved surface 17, 18 between the plates 10, 11, the axes of curvature A.A' of the curved surfaces being parallel to the longitudinal axes of the posts and the radii of curvature R,R' of the curved surfaces differing from one another and being large enough to prevent substantial transverse movement of the conductors 3, 7 of the cable 1 relative to one another when the cable is positioned between the plates 10.

11 and against one of the curved surfaces. In this example, the radius of curvature R is 1 5mm and the radius of curvature R' is 25mm. The cleat 9 also has two apertures 19, 20 through which screws can pass to secure the cleat to a surface.

In use, a cable 1 can be passed through the gap 14 and positioned against the curved surface 17, 18 of one of the posts 15, 16 to bend the cable through the required angle without causing the conductors 3, 7 to con tact one another.

Cleat 9 has the advantage that it is easy to insert and remove the cable 1, and that by having two posts 15, 16 with radii R,R' differing from one another, it can be used for requirements differing from one another (for example, where temperature conditions differ ing from one another require sensitivities for the cable differing from one another).

Claims (11)

1. A cleat, for use in the installation of an electric cable having at least two space con ductors, comprising a base plate and an upper plate separated from the base plate by at least one post fixed with respect to the plates, the or each post having between the plates a smoothly curved surface whose axis of curva ture is substantially parallel to the longitudinal axis of the post and whose radius of curvature is large enough to prevent substantial transverse movement of the conductors rela tive to one another when the cable is posi tioned between the plates and against the curved surface of the post.

2. A cleat, for use in the installation of an electric cable having at least two spaced con ductors, comprising a base plate and an upper plate separated from the base plate by at least two posts fixed with respect to the plates, each post having between the plates a smoothly curved surface whose axis of curva ture is substantially parallel to the longitudinal axis of the post and whose radius of curvature differs from the radius of curvature of said other post or posts and is large enough to prevent substantial transverse movement of the conductors relative to one another when the cable is positioned between the plates and against the curved surface of one of said post.

3. A cleat as claimed in Claim 1 or Claim 2, wherein the upper plate is in two portions, each portion being spaced from the base plate by a post.

4. A cleat as claimed in Claim 3, wherein the portions of the upper plate are spaced from one another to provide an entry for a cable to be positioned within the cleat.

5. A cleat as claimed in Claim 4, wherein the cable entry lies in a direction substantially perpendicular to the common diameter pass ing through the axes of curvature of the posts.

6. A cleat as claimed in any one of Claims 1 to 5, wherein the radius of curvature of the or each post lies in the range 2mm to 40mm.

7. A cleat as claimed in any one of the preceding Claims, wherein the cleat is made of aluminium alloy or gun metal.

8. A cleat as claimed in Claim 7, wherein the cleat is cast in one piece.

9. A cleat as claimed in any one of the preceding Claims, wherein the cleat has an aperture extending through the or each post and the plates through which a screw or bolt may be passed.

10. A cleat as claimed in any one of the preceding claims, wherein the smoothly curved surface of the or each post is discontinuous.

11. A cleat substantially as hereinbefore described with reference to, and as shown in, Fig. 2 to 4 of the accompanying drawings.