GB2159669A - Installation of communications cables - Google Patents

Abstract

Apparatus for installing a feeder cable 2 (or a duct therefor) and drop cables (or draw lines therefor 28 Fig. 4) in an underground pipe system consisting of a main pipe having side-connecting pipes (Figs. 1 to 3). The apparatus comprises a series of machines for passing successively through the main pipe and arranged to drill holes at intervals, to fix clips 30 into these holes by pushing an interference- fitting projecting pin 33 of each clip into its hole (Figs. 6 to 8), to bend or form successive lengths of the feeder cable to the required path (Figs. 9 & 10), to engage the feeder cable with the successive clips, to catch the ends of drop cables which have been run through the side-connecting pipes to project into the main pipe, to pull these collected drop cables along the main pipe to a required destination, and to install a metal mesh cover strip 40 over the installed feeder cable and the drop cables which run alongside it (Figs. 11 to 14). The cover strip 40 comprises a flattened tube with reinforcing wires 41 made from a knitted mesh of metal wires. <IMAGE>

Description

SPECIFICATION Installation of communications cables This invention relates to the running of communications cables to dwellings or other buildings. These cables may serve for the distribution of information to these buildings, for example in a cable television system, or for collecting information from those buildings, and they may be used for two-way communication. The cables themselves may be coaxial cables or fibre optic cables or a combination of such cables may be used.

We have hitherto proposed to run communications cables to dwellings or other buildings through the pre-existing underground pipes which serve to drain sewage and/or surface and storm water away from those buildings.

In making use in this manner of a preexisting system of underground pipes serving a high percentage of buildings which might require connecting directly with cables, the important advantage is achieved of avoiding unsightly overhead cables, or trench excavation on any large scale.

In practice, a pre-existing sewage-carrying system will typically comprise a variety of pipes of different cross-sectional shapes and sizes and different materials. For example the system may include pipes of relatively small diameter or cross-section which lead from the individual buildings, pipes of larger diameter or cross-section (the smaller pipes connecting into the sides of these larger pipes), and also the much larger tunnels which are common particularly in towns and cities and which are large enough for a man to enter and walk along.

For the latter tunnels, because of the accessibility, it is relatively straightforward to run cables through them and a number of different installation and fixing techniques are available.

For the pipes of intermediate cross-sectional size, not large enough for man-entry, we have proposed that preferably the cable (or duct in which the cable is housed) is secured to the pipe surface generally at the soffit (i.e. top) of the pipe so as to be relatively clear of sewage which passes in use of the pipe. The cable or duct then causes little or no obstruction to the passage of sewage, is itself relatively immune from abrasion or dislodgement by the passing sewage and the risk is minimised of paper or other solid matter becoming attached to the cable or its duct and causing blockage.We have found it necessary for the cable or duct to vary its path, along its length, away from the very top or top-dead-centre) position of the pipe, so as to pass appropriately close to the side-connecting pipes through which cables must also be installed, and to avoid any such pipes joining from above.

In one technique which we have proposed, the cable (or duct in which the cable is loosely housed) is secured to the pipe surface by mechanicai fasteners applied at intervals along the length of the pipe and generally at its soffit. We have now devised improved techniques and equipment for installing a cable in this manner.

In accordance with this invention as seen from one aspect, there is provided a method of installing a cable (or a duct for a cable) in a pre-existing underground sewage and/or water-draining pipe, comprising passing a cable or duct through the pipe, drilling holes into the inside surface of the pipe at intervals along its length, and fixing clips into the respective drilled holes by pushing an interference-fitting projecting pin of each clip into its hole, the clips serving to engage the cable or duct. In the embodiments to be described herein, the cable or duct is (or two cables or ducts are simultaneously) snap-engaged with the clips once these are fixed into the holes drilled in the pipe: successive lengths of the cable(s) or duct(s) are bent or formed to the required path prior to being engaged with the successive clips.

In the embodiments to be described herein, one or two relatively large diameter, highcapacity coaxial cables are installed in a pipe by snap-engagement with such clips fixed at intervals generally at the soffit of the pipe, the path of the cable(s) varying from the top-deadcentre position so as to pass close to the sideconnecting pipes. Each cable is a so-called feeder cable and runs to a local switching substation which serves to switch selected program channels into so-called drop cables which extend to the individual buildings.

These drop cables may comprise optical fibres and, in the completed installation, run alongside the feeder cable(s) (through the same pipe) an then run up the respective sideconnecting pipes to the individual buildings.

Preferably, when installing the feeder cable, draw lines are pulled through the respective side-connecting pipes and into and along the main pipe to the side of the switching substation: then these draw lines can be used to pull the respective drop cables into position, even at some considerably later date should the occupants of certain buildings not desire initially to be connected with the communications system.

Preferably a metal mesh strip is installed to cover the feeder cable and the draw lines (and eventually the corresponding drop cables) which run alongside that feeder cable. The purposes of this metal mesh cover strip are to contain the drop cables and provide a streamlined surface to prevent solids catching on the cables and clips, also to protect the cables against attack by rodents. The strip requires constructing from wire sufficiently fine in diameter that the strip will exhibit considerable flexibility and ability to deform in shear, in order to follow a complex, non-linear path of the feeder cable whilst being transversely curved to enclose the feeder cable and draw lines.Preferably the metal mesh cover strip is provided with reinforcing wires along its opposite edges and the strip is fixed in position by snap-engaging these wires with the opposite ends of the clips which hold the feeder cable.

The wires are not gripped by the mesh or clips and are always free to slide: after installation they are tensioned from their opposite ends. The opposite edges of the cover strip thus lie against or close to the pipe surface along the length of the strip and the strip itself lies more or less freely suspended between its opposite edge wires. Preferably the draw lines (and eventually the drop cables) are simply supported by the thus-suspended cover strip. In a preferred form, the cover strip comprises a tube knitted continuously from wire, which tube has been flattened.

In the embodiments to be described herein, a series of machines are passed successively through the pipe to drill holes at intervals, to fix clips into these holes by pushing an interference-fitting projecting pin of each clip into its hole, bending or forming successive lengths of the cable (or duct for the cable) to the required path, engaging the cable (or duct) with the successive clips, collecting the ends of draw lines (or drop cables) which have been run through side-connecting pipes to project into the main pipe, pulling these collected draw lines (or drop cables) along the main pipe to a required destination, and installing a metal mesh cover strip over the installed feeder cable (or its duct) and the draw lines (or drop cables) which run alongside it.

Thus in accordance with this invention, as seen from a second aspect, there is provided equipment for installing a feeder cable (or a duct therefor) and drop cables (or draw lines therefor) in an underground pipe system consisting of a main pipe having side-connecting pipes, comprising a series of machines for passing successively through the main pipe and arranged to drill holes at intervals, to fix clips into these holes by pushing an interference-fitting projecting pin of each clip into its hole, to bend or form successive lengths of the feeder cable (or its duct) to the required path, to engage the feeder cable (or its duct) with the successive clips, to catch the ends of drop cables (or draw lines therefor) which have been run through the side-connecting pipes to project into the main pipe, to pull these collected drop cables (or draw lines) along the main pipe to a required destination, and to install a metal mesh cover strip over the installed feeder cable (or its duct) and the drop cables (or draw lines) which run alongside it.

In accordance with this invention as seen from a third aspect, there is provided a machine for passing through an underground pipe and securing cable or duct clips to the pipe generally at its soffit, the machine comprising means for drilling holes at intervals in the soffit of the pipe, at selected circumferential points, and means operable for engaging a clip into each drilled hole by pushing a projecting pin portion of the clip upwards into that hole.

Preferably this clip-securing machine comprises a chassis slidable along the bottom of the pipe, a body which is mounted to the chassis for controlled rotation about the lengthwise axis of the chassis and a rotary drill carried by the body. Thus the body can be rotated to an appropriate orientation so that the hole will be drilled at the selected circumferential point of the pipe. Preferably the machine is arranged so that the drill is retracted after drilling a hole, then a clip is stepped into position and the drill is advanced again so as to abut and push the clip to insert its projecting pin portion into the hole. Preferably for this purpose, the rotary drill (including its drive motor and transmission) is mounted to the rotatable body by a linkage arrangement serving to translate the drill generally lengthwise of its drilling bit.Preferably the clips are connected together as a bandolier and drive means are provided for advancing the bandolier, when required to place the leading clip in position, for the drill bit to push the clip into its hole.

In accordance with this invention as seen from a fourth aspect, there is provided a machine for passing through an underground pipe and forming or bending a cable or duct to a predetermined path, the machine comprising an element for engaging the cable or duct and means for turning this element about an axis of the machine which, in use, is substantially parallel to the pipe axis. Preferably this machine also serves for snap-engaging the cable or duct with successive clips already installed at intervals along the pipe and for this purpose means are provided for displacing said cable- (or duct-) engaging element generally radially of the pipe. Preferably the machine engages the cable or duct into the first clip and is then advanced along the pipe to just beyond the next clip: then the cable-(or duct-) engaging element is turned an appropriate amount and in the appropriate direction so as to bend or form the cable or duct (over its length between the first clip and the machine element) such that it becomes aligned with the second clip, whereupon the machine can be actuated to snap-engage the cable or duct into that second clip. The operation is then repeated for the successive clips along the pipe.

In accordance with this invention as seen from a fifth aspect, there is provided a machine for passing through an underground pipe to run along that pipe drop cable (or draw lines therefor) from side-connecting pipes, the machine comprising means serving, upon passage of the machine along the main pipe, to catch the ends of said drop cables (or draw lines therefor) which have been run through the side-connecting pipes to project into the main pipe, and to pull these drop cables (or draw lines therefor) through the respective side-connecting pipes and along the main pipe as the machine advances.

In accordance with this invention as seen from a further- aspect, there is provided a machine for passing through an underground pipe to cover a cable or cable duct which is secured generally along the soffit of the pipe by clips at intervals, the machine comprising means for progressively lifting a metal mesh cover strip into covering relation with the cable or cable duct and its clips and for engaging said metal mesh cover strip with said clips.

In the embodiments to be described herein, the latter two machines are combined into one, the combined machine having a chassis slidable along the pipe with its lengthwise axis substantially parallel to the pipe axis, and a body mounted for controlled rotation about the lengthwise axis of the chassis and carrying the means for catching the projecting ends of the drop cables (or draw lines therefor) and, rearwardly of the catching means, the means for progressively lifting the metal mesh cover strip and engaging it with the cable or duct clips.Thus in operation the body of the machine is turned to follow the path of the installed cable or duct as it varies over the circumference of the main pipe, particularly to pass close to each side connecting pipe: in this manner, it is ensured that the catching means intercepts and catches the end of the drop cable or draw line projecting from each side-connecting pipe and also that the metal mesh cover strip will be appropriately aligned with the cable or duct along its length and particularly with the successive cable or duct clips with which it becomes engaged.Further in the embodiment of combined machine which is to be described herein, the machine body is mounted for movement lengthwise relative to the chassis and arranged so that forward movement of the body causes the corresponding length of metal mesh cover strip to be lifted and guided upwards from the pipe floor to its position in covering relation with the cable or duct and with the drop cables (or draw lines therefor).

In accordance with this invention as seen from a yet further aspect, there is provided a clip for securing a communications cable, or a duct for housing a communications cable, to a pipe generally along the soffit of the latter, said clip having a base portion with a convex arcuate surface for conforming with the inner surface of the pipe, a pin portion projecting from said arcuate surface for interferencefitting within a hole drilled in the soffit of the pipe, and a recess provided on an opposite side of said base portion from said arcuate surface, which recess is arranged to snapengagingly receive and embrace a said cable or duct.

In an embodiment of clip to be described herein, there are two such recesses for positioning two cables side-by-side within the pipe. The opposite ends of the clip are formed with recesses for snap-engagingly receiving the reinforcing wires along the opposite edges of the metal mesh cover strip.

Further in accordance with this invention as seen from another aspect, there is provided a cover strip for applying over a cable or cable duct which is secured along the soffit of an underground pipe, said strip comprising a mesh of metal wires sufficiently fine and spaced to enable the strip to flex and to deform in shear so as to permit deformation to a curved section whilst following a varying circumferential position of the cable or duct on the pipe surface. Preferably, the cover strip comprises a tube knitted continuously from wire, into which tube two reinforcing wires have been introduced and the tube then being flattened with the reinforcing wires becoming positioned along the opposite edges of the strip.

Embodiments of this invention will now be described, by way of examples only, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a switched-star type of cable system for cable television distribution; Figure 2 is a schematic diagram to show cables installed in sewage-draining pipes according to the switched-star system, the pipes and cables shown forming elemental parts of the overall sewer and cable systems; Figure 3 is a schematic diagram for explaining a sequence of procedures for installing the cables shown in Fig. 2; Figure 4 is a cross-section through a main sewer pipe shown in Fig. 2 and on the line IV-IV thereof, showing cable arrangements at the junction of a side-connecting pipe with the main sewer pipe;; Figure 5 is a side view of a plastics clip for securing cables to the soffit of the main sewer pipe, also showing in section a metal mesh cover strip for covering the clips and cables; Figure 6 is a side view, part sectional, of a machine M1 for passing through the main pipe and at intervals drilling holes in the pipe and push-fitting into those holes clips as shown in Fig. 5; Figure 7 is a plan view of the machine M1 of Fig. 6; Figure 8 is a section on the line VIII-VIII of Fig. 6; Figure 9 is a side view, part sectional, of a machine M2 for passing through the main pipe, for bending or forming successive lengths of feeder cable to the required path and for inserting each formed length of cable into an installed cable clip; Figure 10 is a section on the line X-X of Fig. 9;; Figure 11 is a longitudinal section through a machine M3 for passing through the main pipe, catching the projecting ends of drop cables (or draw lines therefor) to pull these through the main pipe, and also for applying a metal mesh cover strip over the feeder cable; Figure 12 is a plan view of the machine M3 of Fig. 11, shown with a catching arrangement removed; Figure 13 is a view on the line XIII-XIII of Fig. 12; and Figure 14 is a plan view of the catching arrangement of the machine M3.

For the purposes of illustrating principles of this invention, description will be given relating to a switched-star type of cable television system. The fundamental lay-out of a switched-star system is shown in Fig. 1. From transmission station TS, a number of so-called trunk cables TC extend, each carrying a multiplicity of program channels. At appropriate points along the length of each trunk cable, so-called feeder cables FC are connected and these extend to switching substations SS which serve to switch selected program channels into so-called drop cables DC which extend to individual dwellings. The trunk and feeder cables may typically comprise highcapacity co-axial cables, and the drop cables may comprise optical fibre cables.

Fig. 2 shows a length of feeder cable and a number of drop cables installed in sewagedraining pipes. A section is shown of a pipe 20, accessible at A and B through respective manholes: pipes D1-D7 drain sewage from individual buildings and form side-connections into main pipe 20 at different points. For pipe Dl, there is shown the typical inspection chamber IC adjacent the building served, and to which the drop cable is to extend for connection into the building. A feeder cable 21, in the form of a multi-channel coaxial cable of 1 8mm diameter, is installed straight along the main pipe 20 to a switching substation SS mounted above ground at location B.

From this switching substation optical fibre drop cables are installed along the main pipe 20 and up the respective side-connecting pipes D1-D7 to the individual buildings, providing to the individual buildings selected ones of the program channels of the feeder cable, under the control of the switching substation. Fig. 2 is diagrammatic in that in practice the feeder cable 21 will vary its path to lie appropriately close to the junction of each of pipes D1-D7 with the main pipe 20.

There will now be described an example of a procedure for installing the cables according to a system as illustrated in Fig. 2, reference being made to Fig. 3. Firstly, a closed circuit television survey is carried out along the main pipe 20 to determine the positions of all the side connecting pipes. From this a plan is made of the desired path for the feeder cable(s) along the pipe.Then a transporting line 22 is threaded through main pipe 20 from A to B and, at B, a machine M1 is disposed in the main pipe 20 and hooked up to the transporting line 22 and this machine M1 is then pulled through the pipe 20 to A, pulling behind it a second transporting line 23 and also the feeder cable 21: at intervals along the pipe 20, machine M1 drills holes in the soffit of the pipe and pushes into each of these holes a clip for securing the feeder cable 20. Machine M1 works from the above-mentioned plan, using its inclinometer and some means of measuring its position along the pipe in order to identify where to drill each time.Thus the machine M1 is controlled in accordance with the survey plan to fix each clip at a desired circumferential point of the main pipe 20 and also at a desired axial position relative to side-connecting pipes D1-D7 in the case of clips immediately adjacent such pipes.

Next, at A, a machine M2 is disposed in the main pipe 20 in place of machine Ml, and is hooked up to the second transporting line 23 at its front and the first transporting line 22 at its rear. The second transporting line 23 is then used to pull machine M2 through the main pipe 20 to B: machine M2 serves to form the feeder cable 21 to a profile appropri ate to its required path along the pipe 20 which is now defined by the installed cable clips. Machine M2 incorporates a closed-cir cuit television camera for the operating personnel to observe the positions of the cable clips and then to control the machine accord ing to the profile to which the feeder cable must be formed over successive portions of its length. This "forming" of the feeder cable 20, prior to engaging it with its cable clips, is particularly advantageous when the feeder cable is a large diameter, metal sheath coaxial cable in view of its inherent stiffness. Machine M2 serves to displace each pre-formed length of cable into engagement with the installed clips, before being advanced to form the next length of cable. In passing through the pipe 20, the machine M2 also draws behind it a metal mesh cover strip, optionally housed within an elongate plastic bag.

Now at A, a machine M3 is disposed in the pipe 20, hooked up to transporting line 22 and has the cover strip engaged with it. Then this machine M3 is pulled through the pipe 20 from A towards B.

Referring to Fig. 4, before the machine M3 reaches the first side-connecting pipe D7, a draw line 28 is passed down the pipe D7 (from the inspection chamber adjacent the building which that pipe serves) and fixed to the soffit of that pipe with a predetermined length of the draw line projecting into the main pipe 20. Conveniently, and as shown, the draw line 28 may be housed loosely within a metal duct 27 and it carries an enlarged head 25 at its end. Two alternative systems for installing ducts, containing draw lines, in the side connecting pipes and secured to their soffits, are described in our patent applications 8404514 and 8404515.

When the leading end of the machine M3 arrives at pipe D7, the projecting end of the draw line 27 is intercepted by a catching arrangement of the machine and the head 25 of the draw line becomes caught in a predetermined position on the machine. As the machine M3 then advances along the pipe 20, it pulls the draw line 27, through its duct 28 and along the main pipe, eventually to B.

In similar manner, the machine M3 catches the leading ends of draw lines projecting into the main pipe 20 from all the successive sideconnecting pipes and pulls these through to B.

Also as it advances along the pipe 20, the machine M3 serves progressively to guide the metal mesh cover strip upwards into covering relation with the installed feeder cable 21, its clips and also the draw lines which the machine is pulling along, and to engage the opposite edges of the cover strip with the successive clips. The plastics bag, which initially encloses the cover strip, is progressively stripped back as the installation of the cover strip proceeds. The cover strip thus becomes fixed in position by engagement of its opposite edges with the clips and is suspended more or less freely between its edges. The draw lines become supported freely upon the upper surface of the cover strip.The draw lines can subsequently be used to pull drop cables through the respective side-connecting pipes (in particular through the respective metal ducts 28) and along the pipe 20 to the switching substation SS. Alternatively the draw lines may be dispensed with, the drop cables themselves (within metal ducts 28) being passed through the side-connecting pipes to project into the pipe 20 and provided with the head 25, for the machine M3 to pick them up as described above.

Fig. 5 shows one of the clips 30 for the feeder cable and also shows the metal mesh cover strip 40. The clip 30 is a one-piece injection moulding of plastics material and comprises an elongate base portion 31 formed with a convex arcuate surface 32 for conforming with the inner surface of the pipe and a pin portion 33 projecting from the surface 32 for interference-fitting within a hole drilled in the soffit of the pipe. The pin portion 33 is formed with annular ribs 33a to aid securement. From the side of the base portion opposite the curved surface 32, two pairs of projections extend to define two circular recesses 34,34 each for snap-engagedly receiving a feeder cable 21 and each with rounded edges 34a,34a.Between the two pairs of projections and opposite the pin 33, a further recess with an abutment surface 35 is provided, for receiving the drill bit of the machine M1 when the clip is being pushed to insert its pin 33 into the drilled hole. At the opposite outer ends of the clip, further projections 36,36 extend from the lower surface of the base portion, defining recesses 37,37 into which respective belts engage (as will be described) for these belts to mount a plurality of such clips side-by-side as a bandolier on the clip installing machine M1. In the opposite outer ends of the clip, circular recesses 38,38 are formed for receiving reinforcing wires 41 which are provided along the opposite longitudinal edges of the metal mesh cover strip 40.The recesses 38,38 are normally closed by spring metal clips 39 (one only shown): each clip 39 comprises a first portion 39a lying against the curved surface 32 and having turned-in edges slidably received in grooves 31 a in opposite sides of the clip base portion, and a second portion 39b which is angled relative to the first portion as to cover the respective recess 38, and extends beyond that recess and curves away from the clip to provide a projecting lead-in tail 39c.

For inserting the reinforcing wires into the recesses 38,38, the machine M3 engages the lead-in tails 39coo bend the clip portions 39b so as to open the recesses, then the machine M3 guides the reinforcing wires into their recesses 38,38 and finally disengages the metal tails 39cto allow these to close the recesses again. The installed position of cover strip 40 is shown in broken lines in Fig. 5 and it will be seen that the strip is suspended more or less freely between its reinforced opposite edge and supports on its upper surface the loosely housed draw lines 27.

The pre-installed condition of the cover strip 40 is shown in full lines in Fig. 5. The preferred strip comprises a tube knitted continuously from wire, which tube is flattened by passing between a pair of rollers as it issues form the knitting head. The reinforcing wires 41 are fed through the knitting head and into the tube as it is formed and the rollers include grooves to accommodate these wires at the appropriate spacing. The wires 41 are retained in their required positions, along the opposite edges of the cover strip, for example by running a line of cotton stitching 42 down the cover strip adjacent each wire. The stitching is only required temporarily, until the cover strip is installed with the wires engaged with the clips 30.

Figs, 6 to 8 show the machine M1 for drilling the holes in the pipe wall and pushfitting the clips 30. Machine M1 has a chassis formed of a pair of parallel spaced-apart skids 101,101 running lengthwise of the machine and serving for resting the machine on, and sliding it along, the pipe bottom. The skids are not straight but raised through the middle section of the machine to minimise tilt when negotiating pipe joints. The chassis further comprises transverse elements 102-107 fixed at their opposite ends to the respective skids.

Adjacent the forward end of the machine Ml, a clamping arrangement is provided for fixing the machine firmly within the main pipe 20 when it has been winched through to the required position for installing a cable clip.

This clamping arrangement comprises an hydraulic rotary actuator 108 mounted to the front of the forward transverse element 102, a drive shaft 109 of this actuator being directed rearwardly through element 102 and having keyed to it a cylindrical member 110 formed with an annular flange 111. Links 112,112 (see Fig. 8) are pivoted to this flange 111 and serve, upon rotation of the actuator 108, to extend pads 114, 114 radially outwards to clamp against the pipe surface: each pad is mounted at one end of an arm 11 5 which is guided in a fixed collar 11 6 and has its opposite end pivoted to the free end of its link 112.

The machine M1 further comprises a body which incorporates the assemblies for drilling a hole and inserting the clip, which body is mounted for turning movement about the lengthwise axis A-A of the machine, under the action of an hydraulic rotary actuator 11 8 fixed between the transverse elements 104 and 105 of the chassis. A saddle arrangement 1 20 is disposed generally over the actuator 11 8 and is fixed to forward and rearward projections 122,123 of the actuator drive shaft. An hydraulic motor 1 24 is provided for the drill, and its mounting arrangements will be described below.At its output end the motor 124 mounts a transmission box 1 30 which houses a bevel gear set for driving a drill bit 1 32 which projects generally upwards and at right angles to the motor axis and also at right angles to the axis B-B of pivoting of the motor. Water feed is provided up through the drill spindle and a flinger, in the form of a disc (not shown) is rotatably carried by the spindle at the top of box 1 30, and serves to throw spoil away from the transmission box under centrifugal action.

A frame structure 128,1 28a is mounted to the saddle 120 and projects rearwardly therefrom and is supported towards the rear of the machine by a bearing 1 26 which is fixed between transverse elements 106 and 107 of the chassis. The drill assembly of motor 1 24 and transmission box 1 30 are mounted by a cranked lever 1 34 and a linkage arrangement 140, 142 as follows. The cranked lever 1 34 is pivoted at its elbow and about an axis B-B to one side member 1 28 of the frame structure 128,128a.This lever has one limb rearwardly and downwardly directed for pivotal connection to a projection 1 36 from the bottom of the box 130, and its other limb forwardly and downwardly directed for pivotal connection to the stroke arm of an hydraulic linear actuator 1 38. The latter actuator is mounted to a downwards extension 11 9 of the foward end of the saddle 120. Referring to Fig. 8, in an intermediate rotary position of the body of the machine (in which position the parts are shown in Figs. 6-8), the linear actuator 1 38 is disposed towards the bottom of the machine and mid-way between the skids 101, 101.Fig. 8 further indicates the positions 138a, 1 38b of the actuator 1 38 when the body is turned fully in one direction or the other from its intermediate position.

The linkage arrangement 140, 142 comprise a first pair of links 140 pivoted to the top of the saddle 1 20 and extending rearwardly to a transverse bar 141 by which they are joined. A further pair of links 142 then extend rearwardly from this bar 141, slightly downwardly inclined relative to the first pair of links 140, and are pivoted to opposite sides of the motor 1 24 at its top and adjacent the transmission box 1 30.

In the rest position of the drill assembly as shown, thus with the actuator 1 38 retracted, the drill is lowered and the drill bit 1 32 disposed on a line inclined somewhat rearwardly relative to a vertical plane transverse of the machine. One of the links 140 abuts a micro-switch 143 (Fig. 6) to give an indication that the drill is lowered. When the machine has been winched along the pipe to the position at which a clip is to be fixed and the clamping arrangement of Fig. 8 has been actuated, rotary actuator 11 8 is powered to turn the body of the machine to an angle appropriate to the circumferential position at which the hole is to be drilled.Then the motor 1 24 is powered to run the drill bit 1 32 and linear actuator 1 38 is extended to raise the drill into engagement with the pipe surface to be drilled. It will be noted that, upon extending the linear actuator 138, the cranked lever 1 34 is turned about its pivotal axis B-B and serves to lift the drill assembly of motor 124 and transmission box 1 30 via the downward projection 1 36 from the latter.

The linkage arrangement 140,142 serves to guide the consequent displacement of the drill assembly such that, as the drill bit is lifted, it moves into the vertical plane transverse of the machine: in particular the drill bit is disposed substantially in this vertical plane over a range of movement at least corresponding to its advance when actually drilling the hole in the pipe surface. Upon completing the hole, the drill assembly is lowered by retracting the linear actuator 1 38 and the motor 1 24 is stopped, in readiness for receiving a clip and push-fitting it into the hole.

Towards its rear and over its top, the frame structure 128, 1 28a mounts a guide tube 144 disposed lengthwise of the machine. This guide tube receives a bandolier of the clips 30 disposed side-by-side with each other, the bandolier of clips being stepped along the tube towards the drill assembly each time a clip is required for push-fitting into a hole just drilled in the pipe. The pin portions 33 of the clips project upwards through a slot 145 in the top of the guide tube 144 and longitudinal ribs 146, 146 on the floor of this tube engage within the cable recesses 34,34 of the clips. The clips are secured together side-byside in the bandolier by a pair of "Min-ebelts" commercially available from Reliance Gear Co.Each of these belts comprises a wire rope provided at regular intervals with plastic bobbles and the respective belts extend through the aligned recesses 37, 37 of the clip (Fig. 5) and are engaged therein by the bobbles. The belts (one of which is diagrammatically indicated at 148 in Fig. 6) extend forwardly of the bandolier within the guide tube and pass around respective guide pulleys 150,150 and rearwardly to toothed pulleys 152, 1 52 which are driven by a reversing rotary hydraulic actuator 1 54 via a sprag arrangement 1 56. Thus, and when the drill assembly is in its lowered position after drilling a hole, actuator 1 54 is powered to cause rotation of sprag 1 56 from a predetermined base position and thus advance the belts 148 and the bondolier of clips until the leading clip is engaged upon and stopped by projections 1 60 of an arm 158, the clip now straddling the drill bit, as shown in Fig. 6.

The guide arm 1 58 is pivoted to the top of the drill motor 1 24 and extends rearwardly and upwardly towards the drill bit, and is spring loaded upwards against a stop 1 62 (so that it contacts the pipe wall when the drill is drilling a hole). This arm is forked at its rear end to provide the projections 1 60, 1 60 to either side of the drill bit, which projections engage within the cable recesses 34,34 of the cable clip when this is advanced into its position straddling the drill bit. For inserting the clip into the drilled hole, the drill assembly is raised again, the drill bit being engaged within the central recess of the clip to abut the surface 35 opposite the pin portion 32.

The upward movement of the drill assembly thus serves to push the clip upwards, firstly pushing it free from the Min-e-belts 148 and then raising it towards the drilled hole and finally push-fitting the clip into this hole. During all this movement, the projections 160, 1 60 of the forked guide arm 1 58 engage the clip and steady it against disorientation. Once the clip has been fixed into position, the drill assembly is lowered and the stop 162, carried by the motor 124, serves to lower the guide arm 1 58 and pull its projections 160, 1 60 free from the clip. The machine M1 is then ready, once its clamping arrangement is disengaged, to be winched along the pipe to the next position at which a clip is to be fixed.

The saddle 1 20 of the machine M1 mounts a close circuit television camera 1 64 directed rearwardly to view the site at which the hole is drilled and the clip inserted. The electronics for this camera are mounted to the machine chassis at 166, above the rotary actuator 108. At the front end of the latter, an inclinometer 1 68 is mounted to generate signals indicating the orientation of the machine chassis. The machine M1 is further provided with a bogie (not shown) coupled to its forward end, which bogie mounts control solenoids for the various hydraulic actuators.

Figs. 9 and 10 show the machine M2 for forming or bending the feeder cable to its required path and engaging this cable with the installed clips. Machine M2 has a chassis formed of a pair of parallel spaced-apart skids 201, 201 running lengthwise of the machine and serving for resting the machine on, and sliding it along, the pipe bottom. Like machine M1, the skids are raised through the middle section of the machine, for the same reason. The chassis further comprises transverse elements e.g. 202, 203 to which the skids are mounted.

At its rear end the machine M2 has a clamping arrangement similar to the clamping arrangement of the machine M1, for fixing the machine against the pipe 20 when it has been winched forward to the required position. This clamping arrangement comprises an hydraulic rotary actuator 204 mounted to the chassis and serving for displacing a pair of clamp pads (one of which is shown at 205 in Fig. 9) which are mounted at the ends of slidingly-guided arms, as in the clamping arrangement of machine M1.

Machine M2 further includes an hydraulic rotary actuator 206 having its output shaft fixed to the chassis such that this actuator is able to turn bodily about a longitudinal axis A-A of the machine. A pair of linkage arrangements are mounted to either side of the rotary actuator for bodily rotation therewith and carry a cable inserter 207, which is made of metal but coated in plastics to minimise friction. One such linkage arrangement (Fig.

9) comprises a cranked lever 208 pivoted at its elbow to a bracket 209 which is mounted to the rear of the actuator 206, the lever 208 having a generally horizontally and forwardly extending arm and also a rearwardly and downwardly extending arm which is pivotally connected to the stroke arm of an hydraulic linear actuator 210. This linear actuator is mounted below the rotary actuator via a bracket 211 which is fixed to the front of the rotary actuator. The linkage arrangement is completed by a link 212 pivoted at one end to the bracket 209 and extending forwardly parallel to the horizontal arm of lever 208, and a link 213 the opposite ends of which are pivoted to the forward ends of link 212 and the parallel arm of lever 208.The corresponding linkage arrangement on the other side of the rotary actuator 206 is identical to that shown except that the lever corresponding to lever 208 has only the horizontal arm. The plastics cable inserter 207 extends transversely of the machine and is fixed at its opposite ends to link 213 and the corresponding links on the other side of the machine.

The cable inserter 207 has a pair of apertures side-by-side for receiving a pair of cables to be formed to profile and inserted into the installed clips. It will be appreciated that as the stroke arm of the linear actuator 210 is pulled in, cranked lever 208 will be pivoted about its elbow thus serving to raise the cable inserter 207, but the two linkage arrangements are such that the two links 21 3 will retain their orientations as they are lifted, thus retaining the orientation of the cable inserter 207 as it is lifted.

A pair of rear view lights 21 5 are mounted to the chassis at the rear of the machine. A television camera 21 6 is also mounted at the rear of the machine but directed forwardly towards the cable inserter: a pair of mirrors 218 are mounted to either side of the camera, and forwardly thereof, to provide a rear view from the machine in addition to the forward view obtained through the space between these mirrors, the rear view serving to ensure that the feeder cable(s) are firmly engaged with the clip, before the machine advances.

A housing 220 is mounted to element 202 to project from the front of the machine and this housing encloses solenoid control valves for the hydraulic actuators. The machine M2 further comprises a forward cable guide bogie 222 which includes a short pair of skids 224 (one shown) mounting a forward viewing camera 226 and also, at its top, a plastics cable guide 228 which is provided with a pair of side-by-side apertures just as the cable inserter 207. The forward bogie 222 is coupled to the main chassis of the machine by two shafts 230, one either side of camera 226, releasably engaged within a respective socket 232 at the forward end of housing 220, so as to prevent rotation of the bogie 222 relative to the main machine chassis. In use, the two parts of the machine M2 are placed separately into the pipe 20 and then coupled together at 230, 232.

The machine M2 may serve for installing two feeder cables at the same time into the respective cable recesses 34,34 of the installed clips. In such case the two feeder cables, having been pulled through the pipe 20 to lie on its bottom, are engaged with the respective apertures of the forward guide 228 and of the cable inserter 207. Instead the machine may be used for installing only a single feeder cable.

In operation, the machine M2 is winched through the pipe 20 until the cable inserter is just beyond the first clip and the clamping arrangement is actuated. Then the rotary actuator 206 is turned until the pair of cables (or the one cable) held by the cable inserter are aligned with the clip recesses 34, 34: the cable inserter is raised by extending linear actuator 210 to thereby snap-engage the cables into the clip. Then all fluid pressure is released from the linear actuator 210 and the rotary actuator 206 and the machine is winched forward again: the cable inserter 207 moves to the lower position under the influence of the cable (which slides through the forward guide 228 and the cable inserter 207) and the cable inserter is also free to turn and follow the cable.When the machine is just ahead of the next clip and after the clamping arrangement is set, the rotary actuator 206 is turned until the cables are aligned with the cable recesses 34,34 of that clip, thus bending or forming the cables to the required path over the length between the two clips. Then the cable inserter is raised again to snap-engage the cables with the second clip.

These operations are repeated for the successive lengths of cables between the successive clips. The forward guide maintains its orientation even as the cable inserter is turned each time, but is found to provide a useful guiding effect upon the length of cable being formed and inserted.

Figs. 11 to 14 show the machine M3 for catching the projecting ends of drop cables (or draw lines therefor) to pull these through the pipe 20, and also for applying the metal mesh cover strip over the feeder cable or cables which have been inserted into the clips by the machine M2. Machine M3 has a chassis which includes a pair of parallel spaced-apart skids 301, 301, running lengthwise of the machine and serving for resting the machine on, and sliding it along the pipe bottom. The machine also comprises a cylindrical main bearing housing 302 extending lengthwise of the machine and to which the skids 301, 301 are mounted via pairs of brackets 303, 303 an 304, 304 at the front and rear ends of the housing 302.

An hydraulic rotary actuator 306 is mounted to the rear of the housing 302 and its output drive shaft 307 is coupled to a cylindrical tube 308 by a splined connection 309. The tube 308 is mounted at its rear end by a bearing 310 to the housing 302. An outer tube 312 surrounds tube 308 and these two tubes are formed with co-operating longitudinal splines at 313 so as to turn together around the axis A-A of the machine. Support for the concentric arrangement of tubes 308, 31 2 is provided by a bearing 314 at the front end of housing 302. The inner tube 308 houses a hydraulic linear actuator 316 which projects from the front end of this tube 308 and is coupled (as will be described) to the forward end of the outer tube 312, so that by extending actuator 316 the outer tube 312 is pulled and extended forwardly out of the housing 302.

A frame structure is mounted to the front end of the sliding outer tube 312 for movement lengthwise of the machine along axis A-A under the action of the linear actuator 316 and for turning movement about axis A-A under the action of the rotary actuator 306. This frame structure carries the catching arrangement for the ends of drop cables (or their draw lines) projecting into the pipe 20 from side-connecting pipes, and also the frame structure carries the arrangement for applying the metal cover strip over the installed feeder cable and engaging that strip with the cable clips.

The frame structure comprises a rear member 320 secured to the front end of the sliding outer tube 312, respective side arms 322, 322 secured to and projecting forwardly from the member 320, and a front member 324 joining the two side arms together. A guide roller 326, with a profile which progressively increases in diameter from its middle towards its opposite ends, is disposed between and journalled at its opposite ends to the opposite side arms 322, 322 of the frame structure adjacent its front. A second, similar guide roller 328 is disposed between and journalled at its opposite ends to a pair of brackets 330 which project forwardly from the carrier 332. This carrier 332 is pivotally connected adjacent its top, and at its opposite sides to the front ends of two links 334, 334 the rear ends of which are pivotally connected to the member 320 at 335, 335.Adjacent its bottom, the carrier 332 is pivotally connected to one end of a cranked lever 336 which is pivoted at its elbow to a bracket 337 carried at the forward end of the linear actuator 316.

The other end of the lever 336 is pivotally connected to the stroke arm of another hydraulic linear actuator 338, lying below the housing 302. The rear end of this actuator 338 is mounted to the sliding outer tube 312 via a bracket 339, an opening 340 being formed in the bottom of the housing 302 to allow for movement of the bracket 339, and hence the actuator 338, with the tube 312 both as the latter is displaced lengthwise and angularly. It will be noted that when linear actuator 338 is extended, it serves to pivot the cranked lever 336 and thus raise the carrier 332, the links serving to guide the carrier so as to maintain it in the same vertical plane transverse of the machine.

At the top of the carrier 332, there is mounted (via a rubber block 341) a generally U-shaped runner 342 for the metal mesh cover strip. The opposite top, side edges of this runner are turned over, as shown at 343 in Fig. 13, to provide channels receiving the reinforcing wires which are secured along the opposite edges of the cover strip.

The metal mesh cover strip is laid along the bottom of pipe 20 before machine M3 is put into operation. Then the machine M3 is disposed in the pipe 20 at one end and the corresponding end of the metal mesh cover strip is threaded over the forward roller 326, under the trailing roller 328 and through the runner 342, with its reinforcing wires received in the channels formed at 343, 343. This end of the cover strip, projecting rearwardly from the runner 342, must be anchored to the pipe or one of the cable clips before the runner 342 can be advanced. The rotary actuator 306 must be turned to align the runner 342 with the installed cable. Then the linear atuator 338 is extended to raise the carrier 332, and with it the roller 328 and the runner 342, so that the runner 342 straddles the installed cable (or cables) and applies over it the length of cover strip 40 disposed in the runner.The machine is now gradually winched forward: the cover strip is progressively lifted from the bottom surface of the pipe and guided over the rollers to the runner 342, which slides along the cover strip, progressively forming it to U-shape and applying it over the installed cable or cables. As this operation proceeds, the rotary actuator 306 is controlled by the operator, using the view provided by a closed circuit television camera 350, to displace the runner 342 so that it follows the varying circumferential position of the cable(s). When the machine arrives at an installed cable clip, the rotary actuator 306 can be used to adjust the circumferential position of the runner 342 if necessary so as to align the opposite sides of the runner with the metal retainers 39, 39 of the cable clip.

The machine is winched along the pipe 20 almost up to the clip, then linear actuator 316 is extended to advance the runner 342 relative to the machine chassis, its circumferential position being adjusted if neccesary. Then using actuator 338, the runner is pushed toward the clip so that the opposite sides of the runner co-operate with the lead-in tails 39b, 39b of the metal retainers of the cable clip, so as to bend these back and open the recesses 38, 38 of the clip: the reinforcing wires of the cover strip are then engaged into these recesses and then the runner 342 is inched forward using actuator 316 to allow the retainers to close across the reinforcing wires. Then the machine is winched forward while retaining actuator 338. These operations are repeated along the length of the pipe 20.

Fig. 14 shows in plan view the arrangement for catching the ends of the drop cables or draw lines projecting into the pipe 20 from the side-connecting pipes: Fig. 1 2 shows the machine M3 with this arrangement removed for clarity. The catching arrangement com prises a plate 352 mounted to the top of the frame structure at the front of the machine, this plate being inclined upwardly from the front towards the carrier 332. A horizontal grill 354 is mounted to and above this plate 352, which grill is formed from wires and comprises two parallel channels 356, 356 towards the rear, which channels align with three further channels 357, 358, 359 at the front. Channel 358 is effectively a forward extension of channels 356, 356 and channels 357 and 359 are inclined in opposite senses relative to channel 358.All three channels are provided with wide mouths 360 which narrow into the respective channels. In Fig. 14 a pair of forwardly-directed lights 362, 362 of the machine are shown.

The catching arrangement is effective, upon advancing through the pipe 20, to intercept a drop cable or draw line projecting from a sideconnecting pipe (see Fig. 4), this drop cable or draw line falling into one or other of the channel mouths 360 with its head element 25 disposed below the grill. The draw line is then guided into one or other of channels 356, 356 and the head element 25 slides up the plate 352, eventually to lodge beneath the grill wires and against an end wall 352a.

Subsequent advancement of the machine causes the draw line to be pulled through the side-connecting pipe and along the main pipe 20. The runner 352, following along immediately behind, serves to entrain the draw line 28 with the metal cover strip, as indicated in Fig. 13.

Once a length of the metal mesh cover strip has been installed over the feeder cable(s) along the length of pipe 20, the reinforcing wires of the cover strip are tensioned from their opposite ends by ratchet device to take up any slack in the cover strip and ensure that its opposite edges will lie close to or in contact with the pipe surface all along the length of the cover strip: the reinforcing wires are not gripped by the mesh or by the clips and are thus always free to slide.

The various machines have been described for installing the cable clips and feeder cable(s) in the pipe 20, for running draw lines through the pipe for pulling through the eventual drop cables, and for installing the metal mesh cover strip. Should it become necessary at a later date to remove the cable installation from the pipe system, then this can be carried out as follows. Firstly, all the drop cables are pulled out. Then one end of the metal mesh cover strip is disengaged from the end cable clip and bend back, then this end of the strip is pulled through the pipe 20 from the other end: this has the effect of peeling back the strip and the arrangement is such that its reinforcing wires will be pulled out of the successive cable clips in turn. Once the cover strip is removed, the machine M2 is passed through the pipe 20 and used to pull the feeder cable(s) from the successive clips, whereafter the feeder cable(s) can be pulled out of the pipe. Finally, machine M1 is passed through the pipe 20 and actuated, at each cable clip, to drill through the clip in alignment with its pin portion, so as to free the clip from the pipe surface.

Claims (14)

1. A cover strip for applying over a cable or cable duct which is secured along the soffit of an underground pipe, said strip comprising a mesh of metal wires sufficiently fine and spaced to enable the strip to flex and to deform in shear, said wires being knitted continuously into a tube which is flattened after two reinforcing wires have been introduced, the reinforcing wires being positioned one along each of the opposite edges of the strip.

2. A clip for securing a communications cable, or a duct for housing a communications cable, to a pipe generally along the soffit of the latter, said clip comprising a base portion with a convex arcuate surface for conforming with the inner surface of the pipe, a pin portion projecting from said arcuate surface for interference-fitting within a hole in the soffit of the pipe, and a recess provided on a side of said base portion remote from said arcuate surface and arranged to snap-engagingly receive and embrace a said cable or duct.

3. A clip as claimed in claim 2, comprising two said recesses whereby two cables may be positioned side-by-side within the pipe.

4. A clip according to either claim 2 or claim 3, wherein opposite ends of the clip are formed with recesses, each for snap-engagingly receiving a respective reinforcing wire of a metal mesh cover strip as claimed in claim 1.

5. Apparatus for installing a feeder cable (or a duct therefor) and drop cables (or draw lines therefor) in an underground pipe system consisting of a main pipe having side-connecting pipes, the apparatus comprising a series of machines for passing successively through the main pipe and arranged to drill holes at intervals, to fix clips into these holes by pushing an interference-fitting projecting pin of each clip into its hole, to bend or form successive lengths of the feeder cable (or its duct) to the required path, to engage the feeder cable (or its duct) with the successive clips, to catch the ends of drop cables (or draw lines therefor) which have been run through the side-connecting pipes to project into the main pipe, to pull these collected drop cables (or draw lines) along the main pipe to a required destination, and to install a metal mesh cover strip over the installed feeder cable (or its duct) and the drop cables (or draw lines) which run alongside it.

6. A machine for passing through an underground pipe and securing cable or duct clips to the pipe generally at its soffit, the machine comprising means for drilling holes at intervals in the soffit of the pipe, at selected circumferential points, and means operable for engaging a clip into each drilled hole by pushing a projecting pin portion of the clip into that hole.

7. A machine as claimed in claim 6, which comprises a chassis slidable along the bottom of the pipe, a body which is mounted to the chassis for controlled rotation about the lengthwise axis of the chassis and a drill carried by the body to be so retractible after drilling a hole as to allow a clip to be stepped into position, the drill being then adapted to be advanced again so as to abut and push the clip to insert its projecting pin portion into the hole.

8. A machine as claimed in claim 7, wherein the drill (including its drive motor and transmission) is mounted to the rotatable body by a linkage arrangement serving to translate the drill generally lengthwise of its drilling bit.

9. A machine as claimed in either claim 7 or claim 8, wherein a plurality of clips are connected together as a bandolier and drive means are provided for advancing the bandolier, when required to place the leading clip thereof into position, for the drill bit to push the clip into its hole.

1 0. A machine for passing through an underground pipe and forming or bending a cable or duct to a predetermined path, the machine comprising an element for engaging the cable or duct and means for turning this element about an axis of the machine which, in use, is substantially parallel to the pipe axis.

11. A machine as claimed in claim 10, further comprising means to engage the cable or duct with successive clips already installed at intervals along the pipe.

1 2. A machine as claimed in claim 11, wherein said means displace said cable- (or duct-) engaging element generally radially of the pipe.

1 3. A machine for passing through an undergound pipe to carry forward and secure drop cables (or draw lines therefor) from sideconnecting pipes, the machine comprising means serving, upon passage of the machine along the pipe, to catch the ends of said drop cables (or draw lines therefor) which have been run through the side-connecting pipes to project into the main pipe, and to pull these drop cables (or draw lines therefor) through the respective side-connecting pipes and along the main pipe as the machine advances, and disposed rearwardly, with respect to the direction of advance, means to lift progressively a metal mesh cover strip into covering relation with the cable or cable duct and its clips and to engage said metal mesh cover strip with said clips.

14. A machine as claimed in claim 13, comprising a chassis slidable along the pipe with its lengthwise axis substantially parallel to the pipe axis, a body mounted for controlled rotation about the lengthwise axis of the chassis and carrying the means for catching the projecting ends of the drop cables (or draw lines therefor) and, rearwardly of the catching means, means to lift progressively the metal mesh cover strip and engaging it with the cable or duct clips.

1 5. A machine as claimed in claim 14, wherein the body is mounted for movement lengthwise relative to the chassis and arranged so that forward movement of the body causes the corresponding length of metal mesh cover strip to be lifted and guided upwards from the pipe floor to its position in covering relation with the cable or duct and with the drop cables (or draw lines therefor).