NZ609318A - Cable or Pipe Laying Equipment - Google Patents

Abstract

609318 Cable or pipe laying equipment (10) for attachment to a towing vehicle. The cable or pipe laying equipment includes a mole plough (11), a guide portion (13) associated with the mole plough and incorporating cable or pipe guiding equipment, and a vibrator (14) associated with the mole plough and arranged to vibrate the mole plough at a preselected frequency in use. An isolation unit (15) is also provided between the equipment and towing vehicle to dampen the vibrations transmitted from the vibrator to the towing vehicle. In use the towing vehicle moves the equipment along a desired path while the mole plough is located subsurface, wherein the mole plough creates a trench which enables cables or pipes to be laid behind the plough. h and arranged to vibrate the mole plough at a preselected frequency in use. An isolation unit (15) is also provided between the equipment and towing vehicle to dampen the vibrations transmitted from the vibrator to the towing vehicle. In use the towing vehicle moves the equipment along a desired path while the mole plough is located subsurface, wherein the mole plough creates a trench which enables cables or pipes to be laid behind the plough.

Description

CABLE OR PIPE LAYING EQUIPMENT Field of the Invention The present invention relates to cable or pipe laying equipment which incorporates a mole plough (also known as a subsoiler), for laying deep laid cable/pipe underground.

Background of the Invention Cables supported upon poles are becoming increasingly unpopular:– they are unsightly, and the poles are easily damaged by vehicles and tend to topple in earthquakes. However, although buried cables are preferable, it can prove very difficult to bury the cable to a sufficient depth to prevent accidental damage to the cable, without a major disruption of the area through which the cable is to pass. It can be equally difficult to achieve deep laying of pipe.

As used herein, the term "deep laying" refers to laying cable or pipe at least 1.2 m, and up to 1.5 m, underground.

Digging a trench 1.5 m deep and laying the cable or pipe in the trench from above is slow and time-consuming and causes a considerable disruption of the surrounding area.

It is known to use a mole plough to form an underground trench with minimal surface disruption, and to lay the cable or pipe in the trench by feeding the cable/pipe in behind the plough. However, to date it has not been possible to use this type of equipment for deep laying of pipe or cable in a single pass.

Summary of the Invention An object of the present invention is the provision of cable or pipe laying equipment incorporating a mole plough, which is capable of deep laying pipe or cable in a single pass.

The present invention provides cable or pipe laying equipment including: - a mole plough; - a guide portion associated with the mole plough and incorporating pipe/cable guiding equipment; and - a vibrator associated with the mole plough and arranged to vibrate the mole plough at a preselected frequency in use; - an isolation unit adapted to be connected between the equipment and a towing vehicle, to reduce the vibration transmitted from the vibrator to the towing vehicle.

Preferably the isolation unit includes means for connecting to the towing vehicle, a frame having freedom of movement in at least one plane and buffer means for limiting the freedom of movement of the frame.

Preferably the mole plough is mounted such that the mole plough and the associated guide portion can be raised or lowered vertically in use.

Preferably the guide portion includes a plurality of channels, each channel being adapted to receive a cable, and guide it through the guide portion to emerge from the rear face of the guide portion substantially horizontally.

In a preferred embodiment, the guide portion includes a tape dispenser and a tape channel adapted to receive tape from the dispenser and guide it through the guide portion to emerge from the rear face of the guide portion substantially horizontally.

In a preferred embodiment, the guide portion includes a sediment hopper and a sediment channel adapted to receive sediment from the hopper and guide it through the guide portion to emerge from the guide portion close to where the cable or pipe emerges from the guide portion.

The present invention further provides a method of laying cable or pipe including the steps of: - providing a cable or pipe laying equipment as described above; - connecting the equipment to a towing vehicle; - providing cable or pipe to be laid; - engaging said cable or pipe with the pipe/cable guiding equipment in the guide portion; - activating the vibrator; and - using the towing vehicle to move the equipment along a desired path.

The method may include the steps of digging a preliminary trench and placing the equipment in that trench.

Preferably the method includes the step of altering the height of the mole plough as required during use.

Brief Description of the Drawings By way of example only, a preferred embodiment of the present invention is described in detail, with reference to the accompanying drawings in which:- Figure 1 is a side view of equipment in accordance with the present invention; Figure 2 is a side view of the equipment of Figure 1 at the start of a cable/pipe laying operation; Figure 3 is a view similar to Figure 2, but during a cable/pipe laying operation; Figures 4, 5, & 6 are side views of different configurations of the guide portion of the equipment; Figure 6a is a side view of a hopper component; Figure 7 is a side view of the isolation unit of the equipment; Figure 8 is a plan view of the isolation unit; and Figure 9 is a section on line 9-9 of Figure 8 Detailed Description of Preferred Embodiment Referring to Figures 1 to 3, pipe/cable laying equipment 10 in accordance with the present invention includes a mole plough 11 mounted upon a body 12, a guide portion 13 which incorporates pipe/cable guiding equipment, and a vibrator 14 mounted vertically above the mole plough body 12. The equipment 10 is connected to a suitable towing unit such as a bulldozer (not shown) via an isolation unit 15 as hereinafter described, which isolates the bulldozer from the vibration of the vibrator 14.

The equipment is powered from the bulldozer hydraulics by a hydraulic connections 16, 17.

The guide portion 13 may be any of a variety of designs, some of which are illustrated in Figures 4 to 6, depending upon the type of cable/pipe to be laid and the manner in which it is to be laid, as hereinafter described.

The mole plough 11 may be any of a range of known designs of mole plough. The mole plough illustrated in the drawings is a typical known design and consists of a generally chisel edged tip 11a the outer edge 11b of which provides a thin, relatively narrow leading edge which in use is inclined downwards at a small acute angle to the horizontal. The opposite side 11c is rigidly secured to a roughly cuboid body 12 with an inclined front face 12a. The width of the tip 11a and the width of the body 12 are approximately the same; both are fairly narrow, because the purpose of the mole plough is to form a narrow slot in the ground, no larger than is reasonably required to accommodate the pipe or cable to be laid.

To allow the mole plough to provide a deep trench, the upper edge 12b of the body is rigidly secured to a substantially vertical plate 22, the upper end of which carries the vibrator 14. The width of the plate 22 is less than the width of the body 12, to minimise the drag as the body 12 and plate 22 are pulled through the earth, as shown in Figure 3.

The isolation unit 15 is provided with a pair of pivotal connection eyes 18, for connecting to a tow fitting of known type on the back of a bulldozer. The opposite side of the isolation unit 15 is fitted with a bracket 19 which provides a strong point to which one end of a hydraulic ram 20 is secured. The other end of the hydraulic ram 20 is mounted on a bracket 21 lying underneath the vibrator 14. In the configuration shown in Figures 1 and 2, the hydraulic ram 20 is fully extended and the upper portion of the body 12 of the mole plough lies just beneath the isolation unit 15. This is the normal starting position of the equipment, as shown in Figures 1 and 2.

To lower the mole plough 11 to its full depth, as shown in Figure 3, the hydraulic ram 20 is retracted to the position shown in Figure 3, forcing the mole plough 11 vertically downwards. The isolation unit 15 has a slot through the centre, to enable the support plate 22 which connects the mole plough body 12 to the vibrator 14, to pass through the isolation unit 15 when the mole plough is lowered to the position of Figure 3.

The hydraulic ram 20 is powered from the bulldozer via the hydraulic lines 17. It should be noted that the depth of the mole plough 11 can be altered while the mole plough is in use, simply by extending or contracting the hydraulic ram 20.

The vibrator 14 may be any of a range of known types of vibrator, and also is powered from the bulldozer via the hydraulic lines 16. Typically, the vibrator 14 generates a vibration by the rotation of out of phase weights; the level of vibration can be varied by varying the speed of rotation. For many types of ground, it has been found that a vibration of 700 rpm is optimal.

The isolation unit 15 is shown in greater detail in Figures 7 - 9, and consists of two housing columns 25, 26, each of which provides a pair of opposed supports carrying upper and lower pairs of connecting arms 27, 28. The two upper arms 27 are parallel to each other and spaced apart, one on each side of the isolation unit 15; each of the arms is pivoted at each end, so as to be freely rotatable in bearings 29. The two lower arms 28 also are parallel to each other and spaced apart, one on each side of the isolation unit, and also are pivoted at each end, so as to be freely rotatable in bearings 30.

The forward housing 25 has the connection eyes 18 rigidly secured across the forward face. The rear housing 26 has the strong point 19 for the hydraulic ram 20 secured to the rear face and provides a slot 31 therethrough, allowing the plate 22 to slide freely through the isolation unit 15.

The degree of movement between the cables/pipe laying equipment and the towing vehicle permitted by the isolation unit is limited by the provision of buffers and buffer plates:- a buffer plate 33 is rigidly secured at one end to the forward housing 25, and extends substantially horizontally into the gap between the forward and rear housing columns at about the midpoint of the height of the columns. On either side of the buffer plate 33, heavy duty rubber buffers 34, 35 extend respectively downwards and upwards from support plates (not shown) rigidly secured to the rear housing 26. The ends of the buffers 34, 35 are spaced a short distance away from the buffer plate 33, so as to permit relative movement between the housing columns 25, 26 as the pairs of arms 27, 28 pivot. However, once the ends of either the buffers 34 or the buffers 35 contact the plate 33, further movement is prevented. This effectively isolates the towing vehicle from the vibration of the cable/pipe laying equipment when in use, while still providing a sufficiently positive connection between the equipment and the towing vehicle to allow for positioning and transport.

The guide portion 13 is primarily to guide a pipe or cable smoothly into the slot formed by the mole plough 11. The pipe or cable to be laid is carried on a reel (not shown) supported by the towing vehicle, and is guided between guide rollers 40 mounted on a support 41 above the vibrator 14. Figure 3 shows two cables 42, 43 being guided between the rollers 40, down through the interior of the guide portion 13 and into the trough 44 formed by the mole plough.

The guide 13 may have any of a range of interiors, depending upon whether it is to be used in combination with cable or with pipe, and whether with single or multiple cables.

Basically, each guide 13 provides a hollow structure with an open top 13a providing access from above into the interior of the guide and a series of spaced exits 13b/c/d at the rear of the guide, to allow cable or pipe to exit substantially horizontally. The forward edge 13e of the guide is pivoted to the rear of the body portion 12 of the mole plough, so that it can be towed behind the mole plough.

Figure 4 shows the interior of the guide 13 depicted in Figures 1 to 3. The guide provides three separate channels 45, 46, 47. The channels 45 and 46 are designed to receive cable from the rollers 40, and to guide each cable separately vertically downwards, around a smooth curve to emerge from the rear face 48 of the guide substantially horizontally. The channel 47 is designed to receive marker tape 50a from a tape dispenser 50 provided at the rear of the guide; the marker tape is used to lie in the channel on top of cables or pipes to indicate to subsequent excavators or cable layers that a cable lies underneath.

Figure 5 shows a guide suitable for pipe laying, providing a single, wider, interior channel 51. In Figure 5, the removable end 52 of the guide is shown removed, for clarity.

For some types of cable, there is a requirement for the cable to be laid in a bed of special sand. As shown in Figures 6 and 6a, the guide 13 can be modified so that the sand is dispensed from a hopper 60 which is integrally formed with the rear surface 61 of the guide, so that the sand is laid down into the slot formed by the mole plough simultaneously with the laying of the cable, and only a single pass is required. The hopper 60 is formed as a cone rigidly secured close to the rear edge of the rear surface 61. The hopper 60 opens into a channel 62 and in use the hopper 60 is filled with sand by any suitable means and when the cable laying starts, the bottom of the channel 62 is opened so that the sand is dispensed at the same time as the cable is laid.

The guide portions described above all are formed with removable rear surfaces 52, 61, so that a single guide can be used for different applications simply by fitting a different rear surface. The rear surface is formed with an upper securing point 52a, 61a respectively and is secured to the guide portion 13 by passing a securing bolt 73,74 through the upper securing point and engaging a bolt 52b, 61b with a corresponding hook 59 formed on the rear surface of the guide portion.

As shown in Figures 1 to 4, the rear surface of the guide portion may be formed with a series of spaced hooks 59, 59a, 59b for engaging the rear surface at intervals along its length. However, the rear portion may of course be formed with a permanently fitted rear surface if preferred.

The above described cables/pipe laying equipment is used as follows:- the equipment is connected to a suitable towing vehicle such as a bulldozer by connecting the isolation unit eyes 18 with corresponding towing eyes on the towing vehicle. A coil of the cable or pipe to be laid is supported on the towing vehicle, and the appropriate design of guide portion 13 is selected, to suit the pipe or cable to be laid. If the cable is to be laid in a specified material, the guide portion shown in Figure 6 is selected, and the hopper 60 is filled with the specified material.

At the site where the pipe or cable is to be laid, a preliminary trench 70 (Figure 2) is dug to about half of the desired depth of the cable/pipe, and the equipment is positioned in the trench as shown in Figure 2. The pipe or the or each of the cables is led from the reel, between the rollers 40, down the top 13a of the guide portion 13, until the ends of the cables/pipe travel through the appropriate channels in the guide portion 13 and emerge from the rear of the guide portion as shown in Figure 3.

The towing vehicle is then towed forwards in the direction of Arrow A of Figure 2, while the mole plough 11 is lowered in the direction of Arrow B (by contracting the hydraulic ram 20) thus moving the mole plough in the direction of Arrow C. The vibrator 14 is started, to vibrate the mole plough 11 and facilitate its penetration through the earth.

The amount by which the mole plough 11 is lowered is controlled by the degree of movement of the hydraulic ram 20. The frequency of the vibration supplied by the vibrator 14 may be varied to suit different types of earth.

Claims (9)

Claims:

1. Cable or pipe laying equipment including: - a mole plough; 5 - a guide portion associated with the mole plough and incorporating pipe/cable guiding equipment; and - a vibrator associated with the mole plough and arranged to vibrate the mole plough at a preselected frequency in use; - an isolation unit adapted to be connected between the equipment and a 10 towing vehicle, to reduce the vibration transmitted from the vibrator to the towing vehicle.

2. Cable or pipe laying equipment according to claim 1, wherein the mole plough is mounted such that the mole plough and the associated guide portion can 15 be raised or lowered vertically in use.

3. Cable or pipe laying equipment according to claim 1 or claim 2, wherein the isolation unit includes means for connecting to the towing vehicle, a frame having freedom of movement in at least one plane and buffer means for 20 limiting the freedom of movement of the frame.

4. Cable laying equipment according to any one of the preceding claims, wherein the guide portion includes a plurality of channels, each channel being adapted to receive a cable, and guide it through the guide portion to emerge 25 substantially horizontally from a face of the guide portion which is at the rear in the direction of motion of the equipment in use..

5. Cable or pipe laying equipment according to any one of the preceding claims, wherein the guide portion includes a tape dispenser and a tape channel 30 adapted to receive tape from the dispenser and guide it through the guide portion to emerge substantially horizontally from the face of the guide portionwhich is at the rear in the direction of motion of the equipment in use.

6. Cable or pipe laying equipment according to any one of the preceding claims, 35 wherein the guide portion includes a sediment hopper and a sediment channel adapted to receive sediment from the hopper and guide it through the guide portion to emerge from the guide portion close to where the cable or pipe emerges from the guide portion.

7. A method of laying cable or pipe including the steps of: 5 - providing a cable or pipe laying equipment according to any one of the preceding claims; - connecting the equipment to a towing vehicle; - providing cable or pipe to be laid; - engaging said cable or pipe with the pipe/cable guiding equipment in the 10 guide portion; - activating the vibrator; and - using the towing vehicle to move the equipment along a desired path.

8. The method of claim 7, further including the steps of digging a preliminary 15 trench and placing the equipment in that trench.

9. The method of either of claims 7 or 8, further including the step of altering the height of the mole plough as required during use.