GB2121080A - Improvements in or relating to hollow poles for cable support - Google Patents

Abstract

A hollow pole for supporting cables typically telecommunications cables comprises a collar 32 which is rotatably mounted towards the upper end of the pole 30. The collar is provided with a plurality of radially extending fins 33 each of which is provided with apertures whereby cable suspension strands and stays for the pole can be attached to the collar. The collar can rotate around the poles so that the stays can assume a correct position and is restrained against axial movement relative to the pole. <IMAGE>

Description

SPECIFICATION Improvements in or relating to hollow poles for cable support This invention relates to hollow poles used to support cables such as telecommunications cables.

Hollow poles are widely used for supporting telecommunications cables because the cables can be run down through the hollow interior of the pole and the required connections made at the bottom of the poles. Access is gained through the wall of the pole at ground level so that the amount of work done at height is reduced. In the past use of hollow poles has been limited to distribution poles. It is an object of this invention to extend the usage of hollow poles to line-of-route situations.

A distribution pole is usually situated near subscribers' premises and light weight connectors radiate from its top. The forces which result are small because the connectors are light and the distances are small and they tend to cancel because they act in different directions. A line-ofroute pole supports two heavy cables which may span a substantial distance before reaching another support pole. Additionally the route is not necessarily a straight line or level and therefore a line-of-route pole may have substantial unbalanced forces with substantial horizontal and vertical components. At the lowest pole in a sequence the vertical force components may be upwards. To be suitable for use as a line-of-route pole, a hollow pole must be capable of meeting all these requirements.

According to one aspect of the present invention there is provided a hollow pole for supporting cables, said pole having a rotatable collar at or near its upper end, said collar being restrained against axial movement relative to the pole and providing means of attachment for cable suspension strands and stays for the pole.

According to another aspect of the present invention there is provided a collar for mounting on a hollow pole for supporting cables, said collar comprising a plurality of part cylindrical segments which can be connected together to form a generally tubular member, each segment having one or more generally radially extending fins or lugs disposed towards axial edges of the segment, the fins or lugs being arranged so that when the segments are connected together the fins or lugs on adjacent segments cooperate to define means of attachment for cable suspension strands or pole stays.

The invention will be described now by way of example only with particular reference to the accompanying drawings. In the drawings: Figure 1 is a cross-sectional view of a telecommunications cable; Figure 2 is a schematic illustration showing part of a typical route taken by telecommunications cables; Figures 3A and 3B are schematic view illustrating telephone poles and their supports; Figure 4 shows schematically another type of telecommunications cable route; Figure 5 is an axial section through a hollow pole in accordance with the present invention; Figure 6 is a diametrical section through a hollow pole in accordance with the present invention; Figure 7 is a scrap section showing part of the collar used with the hollow pole; Figure 8 is a view on the arrow A of Figure 7, and Figure 9 is a view on the arrow B of Figure 8.

As shown in Figure 1 a telecommunications cable 10 consists of a sheath 11 which contains transmission pairs of wires 12 and a suspension strand 13. The suspension strand 13 is not used for telecommunications purposes. It provides mechanical strength. The cable usually contains twenty pairs of wires and each pair normaily provides one channel; if the traffic is multiplexed one pair may simultaneously carry several messages. Each wire has its own insulation usually coloured to aid identification. Individual wires and pairs are not shown in the drawing, the space occupied by the pairs being indicated by numeral 12. At the ends of cable 10 the suspension strand 1 3 is secured to a pole and the pairs 12 connected to the corresponding pairs of the next cable in the sequence on the route.

Figure 2 shows that the route is not always straight. It shows poles 14 and 1 5 supporting a span of cable 1 7 and poles 1 5 and 1 6 supporting a span of cable 18. At the pole 1 5 there is a substantial force tending to tilt pole 1 5 and this is resisted by a stay 1 9. A side view of the stay is illustrated in Figure 3A. In some locations, e.g. at a roadside, it may not be possible to run the stay to ground and a substitute arrangement for this situation is illustrated in Figure 3B. In this arrangement the balancing force is obtained from a gallows stay 1 9A which passes to the top of a secondary pole 15A. This pole is held erect by a stay 19B.

Figure 4 illustrates the situation when the route passes through a dip. It can be seen that the pole 20 is lower than the poles 21 and 22 so that the spans 23 and 24 pull upwardly on the pole 20.

Thus line-of-route poles used to support telecommunications cables must be capable of operating in a wide variety of different conditions.

A hollow pole in accordance with one embodiment of the present invention which has this capability is shown in Figures 5 and 6.

The hollow pole 30 has two blind holes 31 A and 31 B which are located diametrically opposite one another about 1 m below the top of the pole.

The pole is surrounded by a cylindrical collar 32 from which project four radially extending fins 33A, 33B, 33C and 33D. Each fin has upper and lower apertures 34U and 34L. On its internal surface the collar 32 has a circumferentially extending groove 35. Two pegs 36A and 36B which locate in respective holes 31 A and 31 B project into the groove 35 as shown in Figure 5.

This arrangement allows the collar to rotate about the pole 30 but not to move axially relative thereto.

In use of the pole, the stays 1 9 and the suspension strands 1 3 are attached to the collar 1 3 by passing them through the apertures 34U and 34L and securing them in position. The pairs 12 pass down the hollow pole for jointing at the base of the pole. This means that the joint can be made at ground level and, what is even more important, the joint is accessible at ground level throughout the life of the pole so that tests can be carried out at ground level.

The pole is erected as follows. The collar is placed on the pole while the pole is still on the ground and the stay 1 9 (or stays) are attached to the collar. The suspension strands 1 3 are separated from the pairs 1 2 in both cables to be attached to the pole. When this has been done the pole is raised to the vertical position and the stay secured at ground level. The collar is able to rotate so that it can assume a correct position for the stays 1 9 and the cables which extend from the pole.

At this point there is the only work which needs to be done at height. However as heavy equipment is needed on site in order to erect the pole this provides a safe lift to the top of the pole.

The work done at height comprises passing the suspension strand 13 around the collar, through the apertures 34U and 34L, adjusting the cable for height and tension and securing the suspension strand 1 3. The pairs 12 are dropped into the top of the hollow pole so that they reach ground level where jointing takes place. This completes the work done at height.

Preferably, the collar 32 comprises a plurality of segments typically four segments to facilitate attachment to the pole. An arrangement for joining the segments is shown in Figures 7, 8 and 9 which illustrate a joint between segments 40 and 41.

The segments are shown meeting at a radial plane 42. The segment 40 has a fin 33 which projects parallel to the plane 42, the fin extending the full height of the collar as can be seen in Figures 8 and 9. The segment 41 has two lugs 43U and 43L which also extend generally parallel to the plane 42. The fin 33 has an upper portion 44U and a lower portion 44L both of which extend from its outer face and engage respective portions 45U and 45L extending from the outer faces of the lugs 43U and 43L. The portions are bored to receive bolts 46U and 46L which are secured by means of washers 47U and 47L and nuts 48U and 48L. As shown in the Figures the abutting arrangement of portions 44 and 45 define upper and lower cleats to which the stays can be attached. As already described the fin 33 has upper and lower apertures 34U and 34L through which the suspension strands of a cable can pass for attachment.

It will be appreciated that when the pole is horizontal it is easy to bolt together adjacent segments so as to form a complete collar around the upper end of the pole.

The engagement of the pegs 36 with the groove 35 permits the collar to rotate to accommodate the positioning of stays and at the same time restrains the collar from axial movement on the pole. Thus, vertical movement when the pole is erected is restrained so that vertical components in the tensions of stays and suspension strands are resisted. Other arrangements which permit rotation and restrain axial movement include the following: (a) complete circular grooves in both pole and collar with a segmented location ring partially positioned in both grooves.

(b) a ring-projection on the inner cylindrical surface of the sleeve which engages a circular groove on the pole.

(c) a ring-projection on the pole which engages a groove on the inner surface of the sleeve.

Hollow poles are usually molded, e.g. from glass reinforced plastics and a protective surface is formed on the molding. It is traditional to insert screws, nails or staples into wooden poles to secure stays and suspension wires but these traditional fixings would damage the protective surface of a hollow pole. The rotatable collar provides an attachment which meets the mechanical requirements without causing damage to such a protective surface.

Claims (13)

1. A hollow pole for supporting cables, said pole having a rotatable collar at or near its upper end, said collar being restrained against axial movement relative to the pole and providing means of attachment for cable suspension strands and stays for the pole.

2. A hollow pole as claimed in claim 1 wherein said attachment means comprise one or more fins which project radially from the collar and each of which has one or more apertures.

3. A hollow pole as claimed in claim 1 or claim 2 wherein said axial movement is restrained by an arrangement of a member or members which project radially outwardly from the pole into a circumferential groove formed on the interior of the collar.

4. A hollow pole as claimed in claim 1 or claim 2 wherein said axial movement is restrained by an arrangement of a member or members which project radially inwardly from the collar into a circumferential groove formed on the exterior of the pole.

5. A hollow pole as claimed in claim 1 wherein said collar is formed of part cylindrical segments which are connected together to form a tubular collar.

6. A hollow pole as claimed in claim 5 wherein said segments are bolted together.

7. A hollow pole as claimed in claim 5 or claim 6 wherein each segment has one of more generally radially extending lugs or fins disposed towards respective axial edges of the segment and so arranged that when said segments are connected together the fins or lugs on adjacent segments co-operate to define one or more cleats which provide said attachment means.

8. A collar for mounting on a hollow pole for supporting cables, said collar comprising a plurality of part cylindrical segments which can be connected together to form a generally tubular member, each segment having one or more generally radially extending fins or lugs disposed towards axial edges of the segment, the fins or lugs being arranged so that when the segments are connected together the fins or lugs on adjacent segments co-operate to define means of attachment for cable suspension strands or pole stays.

9. A collar as claimed in claim 8 comprising four segments or quadrants.

10. A collar as claimed in claim 8 or claim 9 wherein the segments are connectible together by bolts.

11. A collar as claimed in any one of claims 8 to 10 wherein at least one segment is profiled on its inner surface, said profiled part being arranged to co-operate with a corresponding profile on the pole so that axial movement of the collar relative to the pole is restrained.

12. A hollow pole for supporting cable substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

13. A collar substantially as hereinbefore described with reference to and as shown i the accompanying drawings.