US3886755A

US3886755A - Method for locating an underground cable

Info

Publication number: US3886755A
Application number: US367425A
Authority: US
Inventors: Holger Alexander Lundin
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 1972-06-21
Filing date: 1973-06-06
Publication date: 1975-06-03
Anticipated expiration: 1992-06-03
Also published as: GB1432256A; AU5613273A; AR202896A1; CA978379A; FR2189904A1; FR2189904B1; DE2329521A1; JPS4957387A; CH558602A; ES416108A1

Abstract

There is disclosed an assemblage for laying an underground cable. This assemblage includes a movable but stationarily operated power plant, a digging tool and a cable laying tool. The digging tool and the cable laying tool are connected to the power plant so that they can be extended from the power plant to a selected distance and are then pulled back to the power plant. While being so pulled back the digging tool digs a trench and the cable laying tool feeds cable to be laid into the trench as the same is being formed. A brake is mounted on the cable laying tool and co-acts with the same so as to avoid slack in the cable while the same is being laid.

Description

0 United States Patent 1 1111 3,886,755

Lundin June 3, 1975 [54] METHOD FOR LOCATING AN 3,497,016 2/1970 Ryan 61/726 X 9 3,726,099 4/1973 Ruge 75 :JNDERGRgliND Z L d E k d 3,747,357 7/l973 Erickson et al 6l/72.6 355; H e FOREIGN PATENTS OR APPLICATIONS 4l0,900 5 1934 U 't d K' d 61 72.6 [73] Assignee: Telefonaktiebolaget L M Ericsson, m e mg 0m Stockholm Sweden Primary ExaminerJacob Shapiro 22 Filed; June 1973 Attorney, Agent, or Firm-Harte, Baxley & Spiecens [21] Appl. No.: 367,425 [57] ABSTRACT There is disclosed an assemblage for laying an under- [30] Foreign Application Priority Data ground cable. This assemblage includes a movable but June 21, 1972 Sweden 8164/72 stationarily Operated power p a gg g tool and a Feb. 20, 1972 Sweden .1 23400 72 cable y g tool. The digging tool and the cable laying tool are connected to the power plant so that they can [52] U5. C1. 61/72.6; 37/193; 172/700 be nded from the power plant to a selected dis- [51] Int, Cl, A011 3/64; F161 1/00; A011 13/08 tance and are then pulled back to the power plant. [58] Field of Search 61 /72.6, 72.5, 72.7, 72.1, While eing so pulled back the digging tool digs a 6l/72.2; 37/193; 172/700 trench and the cable laying tool feeds cable to be laid into the trench as the same is being formed. A brake is [56] References Cit d mounted on the cable laying tool and co-acts with the UNITED STATES PATENTS same so as to avoid slack in the cable while the same 1,854,617 4 1932 Maloon 61/726 ls bemg 3,406,525 10/1968 Kinnan 61/726 7 Claims, 8 Drawing Figures Pmwanms mm 11886755 SHEET 1 FATE .TEB 3 SHEET aassflss METHOD FOR LOCATING AN UNDERGROUND CABLE The present invention relates to a method for locating an underground cable, consisting in opening a track in the ground and to place the cable in the opened track and then to refill the track over the cable.

As cables which shall be located in the ground become cheaper all the time and the working costs for the location increase. work is carried out in several places with development of different machines for such location. A great number of such machines have already been constructed and used to a great extent abroad. Machines have even been developed in Sweden, and these are specially adapted to the ground conditions in Sweden. The fastest and therefore cheapest method for cable location seems to be direct location by means of a cable plough, which after one or more drivings along the same distance locates the cable at the correct depth in the ground.

In practice, however, it has appeared that it is difficult even with very expensive machines to plough in cables into wooded ground, especially coarse roots effectively stop the cable-laying.

One has earlier tried to use different equipment for cable ploughing, where in. very big machines of the caterpillar type with a non-vibrating plough have been used. Such equipment would probably be too expensive and besides, it can only be used when the ground conditions are good, i.e. in arableand meadow ground. Even plough equipment with a four-wheel driven tractor and with a vibrating plough has been used. The vi brating plough increases the practicability in spite of the limited tractive force from the wheels, for which reason location can take place in rather stony ground since the plough several times has been driven without cable. Even with this machine the practicability is limited regarding wooded ground, where first and foremost coarse roots provide hindrance. At practically all ploughing a hydraulic excavator is necessary as a complement when forcing hindrance as larger ditches, roads, ground with roots and/or big stones and so on.

Up to now known methods used when ploughing down cables have the advantages that in suitable ground the expenses become low and the ground damages get considerably less than with other methods. However, they have also some disadvantages, i.a. high expenses for the equipment and bad exploitation of the equipment included in the plough and excavator. Another essential disadvantage in earlier known machines is that the cable, when the location process has started, only with difficulty can be separated from the pulling machine and that the location only can be continued after manual excavation. If the plough with the cable layer which is fixed to the pulling machine is stopped by hindrance during the cable-laying, consequently quite time-wasting steps must be taken.

Furthermore, the previously known arrangements for ploughing down cables are dependent on the evenness of the ground as the cable layer is wheel carried. in consequence of which damages on the cable easily arise. if the driver can not operate the cable layer so that the movements of the machine over stones, roots and other unevennesses do not influence the cable.

Fromthe above mentioned it appears that there is a need of developing new methods and machines for a faster and cheaper location ofunderground cables. The

Cables should preferably be placed at requested depth without the need of a cable ditch beeing opened and then refilled after that the cable has been drawn out. The intention with the present invention is to provide such method and tools suitable for carrying out the method.

The invention will be described more in detail in connection with the enclosed drawings where diagramatically;

FIG. 1 shows the final stage during ploughing a track or a cable trench,

FIG. 2 shows the starting stage during location of a cable in an earlier ploughed track,

FIG. 3-6 show different views of a location tool,

FIG. 7 shows a further embodiment of a location tool from the side and FIG. 8 shows the same tool from above.

In FIG. 1 is diagramatically shown an excavator (pulling vehicle) 10 with a hinged digging arm 11, in the end of which remote from the excavator a plough tool or a rasp or digger tool 12 is attached, furthermore, a location tool 13 and a piece of cable 14. The digging machine has two supporting legs 15 by means of which the excavator stands steadily on the ground. The figure shows the final phase of a working stage in which a track 16 has been loosened in the ground from the place where the location tool 13 is to the immediate proximity of the machine 10.

In FIG. 2 the machine 10 and the tool 13 are shown in the same position as in FIG. 1 but the arm 11 has been extended so that it has been possible to stick in rasp 12 into a fastening means 131 on the upper part of the tool 13 on the side turned towards the machine 10. Cable 14 is passed through the tool 13 so that when tool 13 is drawn in the earlier loosened track 16 by the stationary machine 10 the cable 14 will be gradually located in the bottom of thetrack. As the tool 13 is pulled towards the machine 10 the track is refilled behind the tool and the cable 14 is thus located in the requested depth.

FIG. 3 shows the tool 13 from the side. It consists of two spaced plane-

parallel walls

31 and 32, see also FIG. 4 which shows the tool from behind and FIG. 5 which shows the tool from above. These walls form together a unit similar to a plough in the forward direction and backwards open and downwards closed with a strip 34 placed between the

walls

31 and 32 for steadily the unit and steering the passing cable through the tool. FIG. 6 shows a cut through the tool along the line AA in FIG. 3, with the oblique wall 34 for steering the inserted cable.

By means of a rasp 12, which in mounted position is bent towards the excavator 10 and has an edge in the same direction it is quite easy to loosen the ground where the cable later will be placed. The shape of the rasp 12 and the mobility and strength of the arm 11 and the fact that the excavator is not moved during the stage of loosening allow that all ground which can be dug also can be rasped. Furthermore, big stones can be broken and heavy roots torn off. During particularly difficult circumstances the rasp can be brought to carry out a loosening work around the stones and stubs in order to facilitate the finishing of a track with loose substances.

Rasp 12 has a shape and thickness which suits to the fastening means 131 on the location tool 13. The distance between

sheets

31 and 32 in this tool corresponds to the diameter of the largest cable which is to be located. When the tool 13 is pulled forward, the cable can gradually be passed between the

sheets

31 and 32 and be placed in the same depth in the track in which the bottom of the tool is driven.

Summing up the location or laying of the cable takes place in the manner that the cable first is pulled out along the desired cable length whereupon a track is loosened in steps of about two meters, i.e. as far as the movable arm of the pulling vehicle reaches, and the lo cation tool is then put down in the loosened track and pressed down by means of the arm to required depth. The cable is placed on the bottom and against the base wall of the location tool and as the tool gradually is moved in the loosened track, the cable is gradually fed in and through the location too]. At the same time as loosening of a two meter distance takes place in front of the location tool by means of the rasp the track can be refilled behind the location tool with a spade by the same person who attends to the supplying of the cable.

In accordance with the description the location of a given cable length takes places in steps of about two meters. It is of course possible that first loosening of the whole cable length takes place and that the cable thereafter is located in the whole length without interruption. It is of course also possible that the transportation of the rasp 12 respectively location tool 13 takes place by means of a fixed arm or with a connection 11 on the drawing vehicle which during the working stages is moved along the cable length. Whether the one or the other method is choosen depends on the ground conditions. As the rasp can be substituted by a digging bucket there will be no need of an extra machine during specially difficult conditions.

Two plane-

parallel walls

70 and 71 according to FIG.

7-8 spaced from each other provide a unit similar to a plough in the forward direction and opened on the backside and having a strip 72 inserted between the walls for staying the tool and steering the cable 14 passing through tool upon location of the cable.

At the plane-parallel walls there is attached a turnable drum holder 74 one end 141 of which supports a rotatable drum 75 arranged for the cable 14 which has to be located and the other end 142 of which is shaped as a guiding means for steering the cable 14 winded from the drum 75 together with the strip 72. As appears from FIG. 7 end portion 142 is bent in abouth right angle to the other part of the drum holder and directed down in about the same direction as the strip 72, so that the cable 14 easily can be steered by the end portion by the strip 72 at the passage through the tool. In FIG. 7 is indicated that the lower part of the end portion 142 has a track, in which the cable 14 runs.

The drum holder 74 has two rectangular taps 143 for supporting in the corresponding recesses in

walls

70 and 71, and a through shaft 77 for supporting two holders 160. The rectangular taps 142 and the recesses in the walls have been shaped so that the drum holder can move enough in order to obtain braking effect and free sliding respectively against a brake plate 76 which is attached to the holder 160. On the other hand, greater movements are prevented.

- The holders 160 of the brake plate 76 consist of two arms which are fixed outside of the

walls

70 and 71 and seating on the through shaft 77 on which the arms are maintained by a cotter or another suitable arrangement. The height of the brake plate 76 is regulated in proportion to the diameter of the cable drum 75 by means of a shaft 78, which has two lockable eccentrics against the walls and 71.

When the tool is standing still, the different parts take the positions which appear in FIG. 7, i.e. the drum rests against the brake plate 76 due to the influence of the force of gravity. and hereby the cable 14 is prevented to be wound off from the drum, but when the tool is moved forward, (i.e. to the right in FIG. 7) pulling takes place in the cable 14 in consequence of which the drum holder 74 is turned clockwise so that the drum is lifted from the plate 76 and the cable can be wound up from the drum in accordance with the movement of the tool.

When locating an underground cable it is often desirable that a protective strip of for example plastic is placed over the cable. For this purpose a roll 79 with plastic band 191 is arranged which is turnable between the two arms which hold the brake plate 76.

A strip guide 20 is attached to the

walls

70 and 71 and guides the plastic band 191 from the roll 79 over the free part of the cable 14 outside the tool.

We claim:

1. A method of laying an underground cable, said method comprising the steps of:

providing a digging assembly including a movable but stationarily operating power plant, a digging tool. a cable laying tool and a pulling mechanism coupled at one end to the power plant and extendable to a selected distance. the extended end of the mechanism being attachable to either tool;

moving the power plant to a location selected for laying an underground cable;

attaching the digging tool to the pulling means and extending the same to a position at which the digging tool is at a selected distance from the power plant;

activating the power plant for pulling back the digging tool to effect loosening of the strip of ground along the withdrawal path of the digging tool to prepare said ground for laying a corresponding length of cable;

detaching the digging tool and attaching the cable laying tool and again extending the pulling means along the length of the strip of loosened ground; and

reactivating the power tool for pulling the cable laying tool back to the power plant while simultaneously paying out cable from the cable laying tool and placing the cable in space cleared by the cable laying tool in the ground by and while pulling back said cable laying tool.

2. An assemblage for laying an underground cable,

said assemblage comprising in combination:

a movable but staionarily operated power plant including a pulling means extendable from a position adjacent to the power plant to a selected extended position, said pulling means being retractable from the extended position to the adjacent position by activation of the power plant;

a digging tool for loosening ground, said tool being attachable to the extended end of the pulling means for pulling the tool from the extended position to the adjacent position to effect loosening of the ground along the path through which the tool is pulled back;

a cable laying tool attachable to said extended end of the pulling means for pulling said tool from the extended position to the adjacent position, said cable laying tool including a space closed off by a ploughshaped wall at the side facing the power plant when the cable laying tool is attached to the pulling means and being open at the side opposite to said plough-shaped wall. said plough-shaped wall displacing loosened ground as the cable laying tool is pulled back towards the power plant. thereby providing a ditch for laying cable fed into the space in the tool and fed out from the cable laying tool through the open side thereof as said tool is being pulled back to the power plant; and

a cable drum for winding thereabout a length of cable to be fed into said space;

holder means supported by the cable laying tool, said holder means including a pivotal two-arm lever, the fulcrum of the lever being mounted on the cable laying tool. one arm of said lever mounting said drum;

the other arm of said lever guiding the cable; and

brake means also mounted on the cable laying tool, said brake means including a bar pivotally mounted on said cable laying tool, and a brake member mounted on said bar and disposed below said drum, said brake means being movable into and out of braking engagement with said cable drum in response to pulling of the cable laying tool towards the power plant;

said holder means being located and balanced so that the drum and the brake means are biased by the gravitational force acting upon the drum into braking engagement when the cable laying tool is at a standstill but are pivoted out of said braking engagement by the pull of the cable against said other lever arm overcoming the gravitational force when the cable laying tool is pulled towards the powers plant.

3. An assemblage according to claim 2, wherein said cable laying tool comprises two spaced apart parallel walls, a base wall, and said plough-shaped side wall adjacent to the base wall, said walls defining said space within the cable laying tool, and guide means for guiding cable fed into the space from the side thereof opposite to the base wall and out of said space through the open side thereof.

4. The assemblage according to claim 2 and comprising a roll of protective strip material rotatably supported on said bar, and guide means guiding the strip material from said roll over cable emerging from the open side of said cable laying tool.

5. An assemblage for laying an underground cable, said assemblage comprising in combination:

a movable but stationarily operated power plant including a pulling means extendable from a position adjacent to the power plant to a selected extended position, said pulling means being retractable from the extended position to the adjacent position by activation of the power plant;

a digging tool for loosening ground. said tool being attachable to the extended end of the pulling means for pulling the tool from the extended position to the adjacent position to effect loosening of the ground along the path through which the tool is pulled back:

a cable laying tool attachable to said extended end of the pulling means for pulling said tool from the extended position to the adjacent position said cable laying tool including two spaced apart parallel walls, a base wall, and a plough-shaped side wall adjacent to the base wall, said walls defining a closed space within the cable laying tool, said plough-shaped wall facing the power plant when the cable laying tool is attached to the pulling means and said space being open at the side opposite to said plough-shaped wall, said plough-shaped wall displacing loosened ground as the cable laying tool is pulled back towards the power plant, thereby providing a ditch for laying cable fed into the space in the tool and fed out from the cable laying tool through the open side thereof as said tool is being pulled back to the power plant;

guide means for guiding cable fed into said space from the side thereof opposite to the base wall and out of said space through the open side thereof;

holder means supported by the cable laying tool, said holder means including a pivotal two-arm lever, the fulcrum of said lever being mounted on the cable laying tool, one arm of the lever mounting said drum; and

brake means also mounted on the cable laying tool and disposed below said drum, said brake means including a bar pivotally mounted on said cable laying tool, and a brake member mounted on said bar, said brake means being movable into and out of braking engagement with said cable drum in response to pulling of the cable laying tool towards the power plant, the other arm of said lever guiding the cable, said drum and said holder means being located and balanced so that the drum and the brake means are biased by the gravitational force acting upon the drum into braking engagement when the cable laying tool is at a standstill but are pivoted out of said braking engagement by the pull of the cable against said other lever arm overcoming the gravitational force when the cable laying tool is pulled towards the power plants.

6. An assemblage according to claim 5 wherein said guide means are curved and positioned to guide cable to and along said base wall prior to leaving the space through the open side thereof.

7. The assemblage according to claim 5 and comprising a roll of protective strip material rotatably supported on said bar, and guide means guiding the strip material from said roll over cable emerging from the open side of said cable laying tool.

Claims

1. A method of laying an underground cable, said method comprising the steps of: providing a digging assembly including a movable but stationarily operating power plant, a digging tool, a cable laying tool and a pulling mechanism coupled at one end to the power plant and extendable to a selected distance, the extended end of the mechanism being attachable to either tool; moving the power plant to a location selected for laying an underground cable; attaching the digging tool to the pulling means and extending the same to a position at which the digging tool is at a selected distance from the power plant; activating the power plant for pulling back the digging tool to effect loosening of the strip of ground along the withdrawal path of the digging tool to prepare said ground for laying a corresponding length of cable; detaching the digging tool and attaching the cable laying tool and again extending the pulling means along the length of the strip of loosened ground; and reactivating the power tool for pulling the cable laying tool back to the power plant while simultaneously paying out cable from the cable laying tool and placing the cable in space cleared by the cable laying tool in the ground by and while pulling back said cable laying tool.

2. An assemblage for laying an underground cable, said assemblage comprising in combination: a movable but staionarily operated power plant including a pulling means extendable from a position adjacent to the power plant to a selected extended position, said pulling means being retractable from the extended position to the adjacent position by activation of the power plant; a digging tool for loosening ground, said tool being attachable to the extended end of the pulling means for pulling the tool from the extended position to the adjacent position to effect loosening of the ground along the path through which the tool is pulled back; a cable laying tool attachable to said extended end of the pulling means for pulling said tool from the extended position to the adjacent position, said cable laying tool including a space closed off by a plough-shaped wall at the side facing the power plant when the cable laying tool is attached to the pulling means and being open at the side opposite to said plough-shaped wall, said plough-shaped wall displacing loosened ground as the cable laying tool is pulled back towards the power plant, thereby providing a ditch for laying cable fed into the space in the tool and fed out from the cable laying tool through the open side thereof as said tool is being pulled back to the power plant; and a cable drum for winding thereabout a length of cable to be fed into said space; holder means supported by the cable laying tool, said holder means including a pivotal two-arm lever, the fulcrum of the lever being mounted on the cable laying tool, one arm of said lever mounting said drum; the other arm of said lever guiding the cable; and brake means also mounted on the cable laying tool, said brake means including a bar pivotally mounted on said cable laying tool, and a brake member mounted on said bar and disposed below said drum, said brake means being movable into and out of braking engagement witH said cable drum in response to pulling of the cable laying tool towards the power plant; said holder means being located and balanced so that the drum and the brake means are biased by the gravitational force acting upon the drum into braking engagement when the cable laying tool is at a standstill but are pivoted out of said braking engagement by the pull of the cable against said other lever arm overcoming the gravitational force when the cable laying tool is pulled towards the powers plant.

5. An assemblage for laying an underground cable, said assemblage comprising in combination: a movable but stationarily operated power plant including a pulling means extendable from a position adjacent to the power plant to a selected extended position, said pulling means being retractable from the extended position to the adjacent position by activation of the power plant; a digging tool for loosening ground, said tool being attachable to the extended end of the pulling means for pulling the tool from the extended position to the adjacent position to effect loosening of the ground along the path through which the tool is pulled back; a cable laying tool attachable to said extended end of the pulling means for pulling said tool from the extended position to the adjacent position, said cable laying tool including two spaced apart parallel walls, a base wall, and a plough-shaped side wall adjacent to the base wall, said walls defining a closed space within the cable laying tool, said plough-shaped wall facing the power plant when the cable laying tool is attached to the pulling means and said space being open at the side opposite to said plough-shaped wall, said plough-shaped wall displacing loosened ground as the cable laying tool is pulled back towards the power plant, thereby providing a ditch for laying cable fed into the space in the tool and fed out from the cable laying tool through the open side thereof as said tool is being pulled back to the power plant; guide means for guiding cable fed into said space from the side thereof opposite to the base wall and out of said space through the open side thereof; a cable drum for winding thereabout a length of cable to be fed into said space; holder means supported by the cable laying tool, said holder means including a pivotal two-arm lever, the fulcrum of said lever being mounted on the cable laying tool, one arm of the lever mounting said drum; and brake means also mounted on the cable laying tool and disposed below said drum, said brake means including a bar pivotally mounted on said cable laying tool, and a brake member mounted on said bar, said brake means being movable into and out of braking engagement with said cable drum in response to pulling of the cable laying tool towards the power plant, the other arm of said lever guiding the cable, said drum and said holder means being located and balanced so that the drum and the brake means are biased by the gravitational force acting upon the drum into braking engagement when the cable laying tool is at a standstill but are pivoted out of said braking engagement by the pull of the cable against said other lever arm overcoming the gravitational force when the cable laying tool is pulled towards the power plants.