MACHINE FOR PLOUGHING TRENCHES AND LAYING CABLES OR WIRES THEREIN

Abstract: A machine for mole ploughing a flexible cable or conduit (K), said machine including a vehicle, a plough (4) connected to the vehicle and a guide means (5) mounted in connection with the plough, said means feeding the conduit from a rotatably mounted storage reel (R) via a drive means (18) for the conduit and into a ditch formed by mole ploughing during the advance of the vehicle along the dicth. A coupling means (20, 21), engaging with the conduit and actuated by the stress in it, compulsorily slackens or stretches the conduit fed down into the ditch only when the conduit is subjected to the action of a given force.

Description: DESCRIPTION Machine for Ploughing Trenches and Laying Cables or Wires therein Technical Field The present invention relates to a machine for mole ploughing, i.e. simultaneous ploughing up a ditch and laying a flexible cable or conduit in it, the machine including a vehicle, a plough connected to the vehicle and guide means mounted oil the plough for advancing the conduit into the ditch from a rotatably mounted storage reel while the vehicle is advanced along the ditch. The machine is preferably used for electrical and telephone cables, but may also be used for other purposes such as laying water hoses. Background Art A machine is known, from the Norwegian Patent Specification 136 586 for example, comprising a tractor excavator with a plough connected to its excavating bucket, the plough having guide means for the cable. A cable reel is attached to the front blade of the excavator. Such a machine is burdened with a plurality of disadvantages. One disadvantage is that the machine will be encumbered with equipment which is heavy to lift and which is voluminous. Another disadvantage is that the equipment hinders the use of the machine for other purposes, such as other excavation work in conjunction with the removal of boulders and stumps and in connection with landscaping work. A further dis¬ advantage is that the rotational resistance of the cable reel and other friction forces in the equipment will be so large that the cable is stretched, and thus does not follow the contour of the ditch bottom, resulting in that the cable does not obtain a constant laying depth and can be subjected to impermissibly large stresses and exterior damage. The U.S. Patent Specification 3 486 334 teaches a road grader, to which is connected a plough and guide means for a cable, the latter being wound off from a reel carried by the grader for laying in the ditch made by the plough. This road grader has the disadvantages mentioned above with regard to space requirements, use for other purposes as well as stresses on, and damage to the cable. A hand-operated cable layer, connectable to a vehicle and provided with plough and guide means for the cable is known from the U.S. Patent Specification 3 066 491. The cable is fed by a drive means down into the ditch made by the plough at a somewhat greater speed than the vehicle travelling speed. Disadvantages with this cable layer are that it cannot be connected to the arm or bucket of a mechanical excavator, that it does not carry any cable reel, and that no regula¬ tion of the feed speed is possible, which means that an unnecessary excess of cable or a deficient amount of cable, possibly causing damage thereto, is fed into the ditch. Disclosure of Invention One object of the present invention is to improve the known machines of the kind described above and to provide a machine, which primarily allows it to be utilised as an excavator without extensive assembly and dismantling work and also for laying cable without the latter being subjected to impermissibly large stresses, either during laying or after the ditch has been filled. This object is achieved by the invention having been given the distinguishing features disclosed in the characterizing portions of the claims. Description of Figures Figure 1 is a schematic side view of a machine in accordance with an embodiment of the invention. Figure 2 is a view seen from behind of the macnine according to Figure 1 , and substantially along the line II - II in Figure 1. Figure 3 is a schematic side view of another embodiment of a part of a machine in accordance with the invention. Preferred Embodiments The ground surface is denoted by M in Figure 1 , and D denotes a ditch excavated with the aid of the inventive machine and in which a cable K is laid with the aid of this machine. An excavator bucket G attached to an un- illustrated excavator, tractor excavator or the like conventional machine, is provided with a gripping means A comprising two swingable arms, the means otherwise being of a conventional kind. A suitable excavator for the purpose may be that of the type illustrated in the U.S. Patent Specification 4 297 799. A unit 1 is removeably attached to the bucket G by the gripping means R gripping round a bar 2 included in the unit, while a shoe 3 on the unit accomodates the bucket teeth. The unit 1 otherwise comprises a plough 4, a cable guide means 5 attached to the rear of the plough, and a carriage 6 pivotably mounted to the plough. The plough 4 is directed forwards in the mole ploughing direction illustrated by an arrow in Figure 1 , and at its rear portion it is limitedly sw±ngably mounted at 7 in a frame 8 included in the carriage 6. Two posts 9 and 10 are welded to the frame 8, as well as two arms 11. Two wheels 12 are rotatably mounted on the frame 8 at mutual spacing, which exceeds the maximum width of the plough 4. A shaft Ra is rotatably and removably mounted on the upper ends of the arms 11. A shaft 13 is rotatabl mounted at the upper ends of both posts 9 and 10. A belt pulley 14 attached to the shaft 13 is driven by a belt 15, which in turn is driven by a belt pulley 17 attached to a wheel axle 16 connecting the wheels 12. A second belt pulley 18 is attached to the shaft 13. A guide collar 19 is suitably pivotably mounted on the post 9. A cable leader 20 provided with an eyelet is pivotably mounted on the post 9, on which a gas spring 21 is also pivotably mounted, the piston rod end of the spring being pivotably attached to the cable leader 20. The function of the machine described above will now be described. The unit 1 is first connected to the bucket G by the bucket being maneouvered by the machinist so that its teeth are inserted in the shoe 3 and the bar 2 comes into engagement against the back of the bucket. The machinist, then swings the arms A, which were previously moved apart, towards each other for gripping the bar. The bucket G is then moved upwards and is swung clockwise in Figure 1 so that the arms 11 will be substantially horizontal, after which these are moved in under the shaft Ra of the cable reel R. The unit 1 and thus the arms 11 are now lifted so that the shaft Ra is placed in the cradles 11a at the upper ends of the arms 11 in Figure 1. The unit is then swung anti-clockwise so that it assumes the position illustrated in Figure 1, with the wheels 12 on either side of the ditch D which is to be ploughed. When the excavator is advanced in the direction of the arrow, the plough 4 forms the ditch D simultaneously as the cable K wound up on the cable reel R is fed out to the bottom of the ditch via the details mounted on the posts 9 and 10 together with the guide means 5 which includes a pipe stub 5a and a curved duct 5b. If the pull in the cable K does not attain a given limiting value when the cable is fed out, the cable will lie on the bottom of the ditch D and follow its contour. For this purpose the cable is fed from the reel R via the guide collar 19 and through the eyelet of the cable leader 20, which is urged upwards in Figure 1 by the spring 21 , this position of the leader being illustrated by chain- dotted lines in Figure 1 , whereon the cable is at a distance from the rotating belt pulley 18, and further through the guide means 5 and out to the ditch. The cable leader 20 will be affected if the pull on the cable increases for some reason so that it attains a predetermined limiting value, which partly depends on the bias in the spring 21 and partly on the friction forces acting on the reel R and cable K as the cable is fed out to the ditch. Thus the cable leader 20 will be swung anti-clockwise to the position illustrated by full lines in Figure 1 against the bias of the spring 21 by the action of the tensioned cable during continued advance of the vehicle, the cable coming into engagement with the rotating belt pulley 18, which then feeds the cable with a speed somewhat exceeding the normal cable lay- ing speed. This results in that the pull in the cable decreases, the cable slackening off and accompanying the contour of the ditch bottom. As soon as the pull in the cable decreases to a value under the mentioned, predetermined value, the cable leader is swung clock- wise in Figure 1 by the bias of the spring 21 and moves the cable out of engagement with the belt pulley so that the cable will then be wound from the reel without being driven by the belt pulley 18. The cable leader 20 will thus move the cable in and out of engagement with the belt pulley during cable lay¬ ing in response to the pull in the cable. In an obstacle is encountered during mole ploughing, the machinist moves the unit 1 to a suitable position in the already excavated ditch, or to one side thereof, whereupon he releases the unit 1 from the bucket G by swinging the arms A away from each other and thereafter withdrawing the bucket teeth from the shoe 3. He then swings the arms A towards each other and into a space on the bucket where they do not hinder excavation, so that the obstacle can now be excavated with the aid of the bucket G in the usual manner. Subsequent connection of the unit 1 and bucket G takes place in the manner already described. A modified embodiment of a portion of the machine illustrated in Figure 1 is illustrated in Figure 3. Since the embodiment in Figure 3 only differs from the one in Figure 1 in respect of the drive means for the cable, only the parts of the machine according to the -modified embodiment which relates to the drive means and co-acting details are illustrated in Figure 3. Remaining details are identical with those illustrated in Figure 1 , excepting that the carriage 6 is not only swingably connected to the plough 4 but also removably connected to it at 7. The details in Figure 3 which have their counterpart in Figure 1 have been denoted by-the same reference numerals with the addition of a prim sign. A pipe 30 extending up over the belt pulley 18' is attached to the post 9'. Inside the pipe 30 there is a gas spring 31, the lower part of which is pivotably attached to the lower end of the pipe. At the upper end of the gas spring 31 there are a roller 32 and one end of an arm 33 mounted for turning. The other end of the arm 33 is pivotably connected to a bell crank 34, which is pivotably mounted on the outside of the pipe 30 and provided with a handle 34a. The roller 32 bears against the underside of the right hand portion of a guide arm 35, the left hand portion of which is provided with a fork-like end portion 35a. The guide arm 35 is pivotably mounted on the pipe 30 at 36, and a conical rubber wheel 37 is rotatably mounted on the guide arm between 35a and 36. After the cable K * has been inserted in the groove of the belt pulley 18' the required feed force on the cable is adjusted fully variably, this force depending on the type of cable, by swinging the handle 34a so that the gas spring 31 is pivoted and the roller 32 displaced along the underside of the guide arm 35. When the handle 34a is lifted from its position illustrated in Figure 3, the roller 32 is moved closer to the pivoting point 36, while the pressure of the wheel 37 against the cable K' decreases successively, and the wheel 37 is lifted from the cable when.the roller has passed the point 36. If too much cable is fed, the end portion 35a of the guide arm 35 is moved upwards by the cable through the stiffness and larger curvature of the latter forcing the end portion upwards, the friction engagement ceases between the cable K' , the wheel 37 and the pulley 18' rotating with a somewhat higher peripheral speed than the cable laying speed. As soon as the cable is stretched again on continued forward travel of the machine, this friction grip is once again established. The cable is thus fed down into the ditch without being either too taut or too slack. It will be understood that the invention is not limited to the embodiment described above and illustrated on the drawing, but is only limited by the disclosures in the claims.

Claims: CLAIMS 1. A machine for mole ploughing, simultaneously excavating for and laying a flexible conduit or cable, said machine including a vehicle, a plough connected to the vehicle and guide means mounted in connection with the plough for feeding the conduit directly into the ditch from a rotatably mounted storage reel as the vehicle is driven along the ditch, and a drive means for the conduit, mounted between the reel and the guide means, characterized by a coupling means (20, 21; 30 - 37) engaging with the conduit (K) and actuated by the tension therein for moving the conduit to or away from engagement with the drive means (18; 18") for compulsory slacking or stretching the conduit (K) fed out into the ditch only when the condtlit is subjected to the action of a predetermined force. 2. Machine as claimed in claim 1, characterized * in that the feed speed of the drive means (18; 18') is greater than the advancing speed of the vehicle and that said coupling means (20, 21) engaging with the conduit (K) takes the conduit into engagement with the drive means for said predetermined force, which is a tensional force in this case. 3. Machine as claimed in claim 1, characterized . in that the feed speed of the drive means (18; 18') exceeds the advancing speed of the vehicle and that said coupling means (35, 37) engaging with the conduit (K 1 ) takes the conduit out of engagement with the drive means for said force, which is a compressive force in this case. 4. Machine as claimed in any one of the preceding claims, characterized by a means (34) for setting the force with which i-he coupling ra α ans (30 - 37) acts on the conduit. 5. Machine as claimed in any one of claims 2 - 4, charachterized in that the drive means (18, 18') is rotatable and that the coupling means includes a pivot¬ ing means (20, 35) actuable by the conduit (K, K'), said pivoting means taking the conduit to and from engagement with the rotating drive means against the bias of a spring means (21; 31) . 6. Machine as claimed in any one of the preceding claims, characterized in that the drive means (18; 18') and the roller (R) are carried by a carriage (6) which is connected to the guide means (5) and/or the plough (4) which together with these forms a unit which is removably connected to the excavating bucket G of an excavating machine. 7. Machine as claimed in claim 6, characterized in that the unit is provided with a first element (2) grippable by a gripping means (A) on the excavator bucket (G) and a second element (3) to be mounted to a portion of the bucket. 8. Machine for mole ploughing a flexible cable or conduit, said machine including a vehicle, a plough connected to the vehicle and a guide means mounted in connection with the plough for feeding down the conduit into the ditch from a rotatably mounted storage reel during advancing the vehicle along the ditch, characterized in that the plough (4) , guide means (5) and reel (R) are mounted on a structure which is removably coupled to a gripping means (A) on the bucket (G) on an excavating machine. 9. Machine as claimed in claim 8, characterized in that the structure includes a first element (2) grippable by the gripping means (A) on the bucket (G) and a second element (3) which may be applied to a portion of the bucket.

Inventors: SONERUD JOHN TEODOR, SONERUD, JOHN, TEODOR
Applicants: SONERUD JOHN TEODOR, SONERUD, JOHN, TEODOR
Application year: 1985
Main classification: E02F5
IPC codes: E02F3, E02F5