NZ209339A - Interactive tensioner for cable laying apparatus - Google Patents

Description

209339 No.- 209,339 Date: 24th August 1984 NEW ZEALAND PATENTS ACT, 1953 COMPLETE SPECIFICATION "APPARATUS FOR USE IN PLOUGH LAYING OF CABLE OR PIPE" l/SJBC ROGER MURRAY MAHAN, a British subject and New Zealand citizen, of 21 R.D. , Sercombes Road, Geraldine, New Zealand, hereby declare the invention for which I /MW* pray that a patent may , be granted to pie&DB, and the method by which it is to be performed,^ to be particularly described in and by the following statement: - " * - W, It, X 2 09339 The present invention relates to improvements in or relating to cables.

In my New Zealand patent specification Nos. 190015/190552, 190016 and 190017 there is disclosed and claimed novel apparatus and methods relating to the plough laying of advance jointed pipeline or cable.

The full content of these specifications is hereby here incorporated by way of reference. In my New Zealand patent No.198104 there is disclosed means and methods whereby during such plough laying of pipeline or cable a metal tracer for the pipeline can be laid. The disclosure of that specification is also hereby here incorporated by way of reference.

With the development of fibre optic cables there is a need for vast distances of new cable lines to be laid. The difficulty with fibre optic cables however is that joins must be carefully made to ensure the light signals pass through the join without any undue interference or loss and therefore it is essential that as few joins as possible be made in any cable. With that in mind it can be envisaged that large reels of fibre optic cable can be moved substantially synchronously with apparatus referred to in my above mentioned patent specifications in lieu of the advance jointed pipe or cable. Even so, and irrespectively of whether or not the rearward urging apparatus of my New Zealand patent specification No.190015/190552 is employed, there is still a significant risk of damage owing to stretching or v. i'J kinking of the cable line. a"» «■ 18 FEB 1986 209339 3 - It is therefore an object of the present invention to provide apparatus means and/or methods which will allow the plough laying of cable such as fibre optic cable with a plough laying technique.

Accordingly in one aspect the present invention consists in apparatus for plough laying cable comprising self propellable apparatus capable of advancing and having provision for the carriage of an operator of its advancement at a riding position, a trench forming plough carried or trailed by said self propellable apparatus to create a cable receiving trench behind said self propellable apparatus, guide means that moves synchronously with said plough within a trench section just formed thereby to guide cable being laid without kinking to the bottom of such trench as the whole apparatus advances, cable reel supporting means dependent from said self propellable apparatus in advance of said riding position to rotatably support such a reel which is to supply cable therefrom, means behind said riding position and above said plough to receive cable prior to its entering into the guide means, a pivoted structure dependent from the self propellable apparatus and over which the cable being fed from the reel can move, said pivoted structure normally having the cable contacting surface thereof disposed in other than a direct line between the take-off point of the feeding reel (or any guide for the cable between such take-off Doint 209339 of the feeding reel in advance of the pivoted structure) and said means behind said riding position and above said plough to receive cable, means to bias at least the cable contacting surface region of said pivoted structure upwardly, means to rotate a reel rotatably supported by said cable reel supporting means so as to feed cable therefrom, and interactive means between said pivoted structure or extensions thereof and said means to rotate said cable reel, said interactive means being operable such that when the pivoted structure is raised above a datum position in its normal operative locus of movement under reduced tension in cable passing over the pivoted structure, and under the action at least in part of said means to bias, rotation of the cable reel is reduced or halted and such that when the pivoted structure is lowered below said datum and still within its normal operative locus of movement under the action of the cable passing thereover against said means to bias owing to increased tension, the rotation, if any, of the cable reel to feed cable therefrom is increased.

Preferably said pivoted structure is in the form of a mast angled rearwardly or forwardly with respect to said self propellable apparatus .

Preferably said mast is directed rearwardly.

Preferably said mast includes at the distal end region thereof a reel or pulley over which the cable can ride.

.V 18 FEB J986* 209339 - Preferably said means to bias is at least a spring in tension or compression acting on said mast.

Preferably said means to rotate a reel is hydraulically actuable and said interactive means includes a hydraulic circuit including a valving mechanism controlled by movement of said pivoted structure.

Preferably said self propellable apparatus is a crawler tractor.

While in the preferred form of the present invention hydraulic means is preferred insofar as the interactive means is concerned, a person skilled in the art will appreciate how alternative arrangements using electrical or even mechanical means can be employed.

What is apparent from the application of the present invention is the disposition of the cable during feed-out in a position (preferably alongside the operator) where the operation of the tension control system of the invention can be readily reviewed with any failure becoming immediately apparent by a lowering of the pivoted structure more than momentarily or more than a small distance. This would therefore allow the operator to take action to minimise risk to expensive fibre optic cables(should that be the form of cable being laid)by simply slowing or halting the advancement of the crawler tractor or other self propellable apparatus.

A person skilled in the art will appreciate the arrangement of such pulleys or other systems as may be appropriate to ensure the smooth movement of cable from a reel into the bottom of a trench being formed by a mole plough or the equivalent arrangement and subsequently \ 11 >,v ^ 209339 buried.

Preferably the method is performed using apparatus in accordance with the present invention.

One preferred form of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a diagrammatic view of apparatus in accordance with the present invention showing in outline a crawler tractor pulling plough laying apparatus and showing with a horizontal broken line the ground level and also showing with a broken line the locus of feed of the cable from a reel which in the form illustrated is arranged to feed cable to the pivoted structure in the direction of the arrow, it being appreciated that the plough laying apparatus preferably is substantially as depicted and described in detail in my aforementioned New Zealand patent specifications and Figure 2 is a similar view to that of Figure 1 but showing the preferred "tell tale" mast moved downwardly as a result of tension increase and showing means including at least one pulley or a roller which is the preferred means to receive the cable (such as for example a form of rearwardly urging mechanism for example as disclosed in my New Zealand patent specification No. 190015/190552) before it is fed to guide means to the bottom of the trench just formed.

In the preferred form of the present invention the crawler tractor 1 pulls the plough laying apparatus 2 which includes a plough 3 trailed preferably by a trailer unit 4 pulled by a draw bar 5. The_—.^ > » E N r 209333 cable shown by the broken line 6 is preferably received by cable receiving apparatus 7 (preferably substantially as disclosed in my aforementioned New Zealand patent specification No. 190015/190552).

From the apparatus 7 the cable 6 passes down into guide means preferably comprising a series of linked trench wall shoring apparatus which includes guide or a series of guides therein to smoothly lay the cable into the bottom of the trench that has been formed and which trench preferably self closes upon the passage of the last of the linked shoring and cable guiding apparatus. Preferably such apparatus is as disclosed in my New Zealand specification No. 190017.

Preferably the means to feed the cable is a reel or spool 8 carried preferably on the front of crawler tractor 1.

Preferably the spool 8 is adapted to rotate in the arrowed direction under the action direct or indirect of a hydraulic motor which is controlled by a hydraulic flow divider (not shown) which in turn is controlled by the rotational position of the tell tale mast 9 about its pivot 10. Preferably a compression spring or other resilient means 11 is provided to return the tell tale mast to its condition as shown in figure 1 which is or substantially is the datum condition that it may assume when there is some synchronosity between the feed of the cable from the reel with the demands for cable in the trench.

In use therefore any momentary shock loading of the cable is avoided by virtue of the depression of the cable between the condition shown in Figure 1 and 2 which shortens the locus from the reel to,the^N ./ v -« *8 FEB 1966* 209339 means for receiving the cable (whether it be the apparatus 7 or the guide chute). With a view to restoring the mast back to its condition in figure 1 it is necessary therefore to speed the feed of the cable or to slow the movement of the crawler tractor 1 until such time as more cable is made available. Ideally therefor the interactive means is such that the speed of rotation of the reel 8 is increased when the mast or other pivoted structure moves below its datum against its bias under an increase in tension in the cable 6 and such increased rate of feed is reduced when there is a return of the mast to the condition as shown in Figure 1 and indeed preferably stopped if it rises still further.

Persons skilled in the art therefore will appreciate how the use of the tell tale mast provides for minimal shock loading of the cable and at the same time ensures that when ever the tell tale mast has been deflected, deformed or otherwise moved by the cable the mast can be returned substantially to its initial condition so as to be available for any future shock loading because interactive means causes an increase in the feed of cable.

Claims (8)

- 9 - £09339 WHAT I CLAIM IS: ; J

1. Apparatus for plough laying cable comprising self propellable apparatus capable of advancing and having provision for the carriage of an operator said operator being carried in a riding position, a trench forming plough carried or trailed by said self propellable apparatus to create a cable receiving trench behind said self propellable apparatus, guide means that moves synchronously with said plough within a trench section just formed thereby to guide cable being laid without kinking to the bottom of such trench as the whole apparatus advances, cable reel supporting means dependent from said self propellable apparatus in advance of said riding position to rotatably support such a reel which is to supply cable therefrom, means behind said riding position and above said plough to receive cable prior to its entering into the guide means, a pivoted structure dependent from the self propellable apparatus and over which the cable being fed from the reel can move, said pivoted structure normally having the cable contacting surface thereof disposed in other than a direct line between the take-off point of the feeding reel (or any guide for the cable between such take-off point of the feeding reel in advance of the pivoted structure) and said means behind said riding position and above said plough to receive - 10 - 209139 means to bias at least the cable contacting surface region of said pivoted structure upwardly, means to rotate a reel rotatably supported by said cable reel supporting means so as to feed cable therefrom, and interactive means between said pivoted structure or extensions thereof and said means to rotate said cable reel, said interactive means being operable such that when the pivoted structure is raised above a datum position in its normal operative locus of movement under reduced tension in cable passing over the pivoted structure, and under the action at least in part of said means to bias, rotation of the cable reel is reduced or halted and such that when the pivoted structure is lowered below said datum and still within its normal operative locus of movement under the action of the cable passing thereover against said means to bias owing to increased tension, the rotation, if any, of the cable reel to feed cable therefrom is increased.

2. Apparatus as claimed in Claim 1 wherein said pivoted structure is in the form of a mast angled rearwardly or forwardly with respect to said self propellable apparatus.

3. Apparatus as claimed in Claim 2 wherein said mast is directed rearwardly.

4. Apparatus as claimed in Claim 2 or Claim 3 wherein said mast includes at the distal end region thereof a reel or pulley over which the cable can ride - 11 - 209339

5. Apparatus as claimed in any one of Claims 2 to 4 wherein said means to bias is a spring in tension or compression acting on said mast.

6. Apparatus as claimed in any one of the preceding claims wherein said means to rotate a reel is hydraulically actuable and said interactive means includes a hydraulic circuit including a valving mechanism controlled by movement of said pivoted structure.

7. Apparatus as claimed in any one of the preceding claims wherein said self propellable apparatus is a crawler tractor.

8. Apparatuses claimed in any one of the preceding claims substantially as hereinbefore described with reference to either or both of the accompanying drawings. ; -t *r^orcU" ^;s/<j7h&*A&r^