GB2294910A - Apparatus for use in clearing land mines - Google Patents

Abstract

Apparatus for clearing land mines comprises a plurality of rollers (40) carried on parallel arms by a common support frame (61 - 77) attachable to the front of a drive vehicle which can push the apparatus over the ground in front of it. The rollers are displaceable individually in a vertical direction on the support frame so that they all remain in rolling contact with the ground, exerting their weight thereon, despite variations in the ground surface, enabling the entire width of a band of ground in front of the vehicle to be swept. <IMAGE>

Description

APPARATUS FOR USE IN CLEARING LAND MINES The present invention relates generally to apparatus for use in clearing land mines.

In many theatres of conflict throughout the world combatant parties have sought to defend sensitive areas by sowing mine fields in an attempt to dissuade their opponents from advancing towards certain sensitive positions. Although mine fields particularly those comprising anti-personnel mines, may be a legitimate, if distasteful means of waging war, they present a particular problem when the conflict is over because, due to the very nature of the mine, its presence just below the surface of the ground is not in any way marked.

Indeed, the army laying the mines will have gone to some trouble to conceal their exact presence even though the general area of the mine field may be marked out for strategic or tactical purposes. There are, therefore, many large tracts of land throughout the world where, despite the cessation of hostilities, it is still unsafe to travel, newspapers carry regular reports of innocent civilians injured or killed by inadvertently straying into a mine field and stepping on a land mine.

Rendering a mine field secure involves either locating and disabling each mine, a time consuming and dangerous task, or deliberately setting out to explode every mine in the mine field by passing and repassing the area with a suitably armoured vehicle, normally a tank, which is fitted with a heavy roller usually made of cast iron.

Land mines intended to cause damage to personnel are generally relatively small and insufficiently powerful seriously to damage an appropriately armoured vehicle, and various designs of armoured vehicle for this purpose are known.

The vehicle used for this purpose must be effectively mine proof. Known vehicles comprise a heavily armoured track laying locomotive component having two forwardly extending arms between which is mounted a heavy roller which rolls over the ground as the vehicle advances and acts to detonate the majority of mines before the vehicle itself passes over the ground. A rigid roller, however, cannot follow closely the minor variations in terrain resulting in some mines being passed without detonation, and resulting in detonation by the pressure exerted by the tracks of the vehicle. Although the tracks in the main resist damage from such detonations, sufficient distortion can occur to make smooth operation of the vehicle difficult, necessitating changes to the track.

Likewise, if a larger-than-average mine should be detonated by the pressure of the roller, or if the position is such that it is in very close proximity to the roller upon detonation, damage to the roller can occur, resulting in the need for repairs. Such repairs require dismantling the vehicle, discontinuing the mineclearing operation and despatch of the components to repair workshops where they can be worked on for repair.

In severe cases complete replacement of components and/or assemblies may be required, which is expensive and in any event time consuming.

The present invention seeks to provide apparatus for use in mine-clearing operations, which will be free from many of the disadvantages suffered by the roller-type clearing apparatus previously known. Embodiments of the invention will be cheaper, lighter and easier to transport.

Embodiments may also be mounted on lighter vehicles, for example, the Smith African Kasper armoured car.

According to one aspect of the present invention, therefore, apparatus for use in clearing land mines comprises at least one hollow wheel or roller which can contain bulk material such as a granular or particular solid and/or a liquid, means for mounting the said wheel or roller such that it can be guided to roll over the surface of the ground whilst being free to displace vertically such that the ground-contact pressure is always determined by the weight of the wheel or roller despite variations in the terrain.

In use of the apparatus of the invention, therefore, the free vertical displacement of the roller allows it to rise and fall over small irregularities in the terrain without at the same time requiring displacement of a boom or arm from by which it is supported for rolling movement.

In a preferred embodiment of the invention the wheel or roller is made from two halves which can be secured together with the filling material in place, and secured to a fixed axle rotatable in journals or bearings with respect to the wheel or roller, or mountable in journals or bearings for rotation with respect thereto.

Preferably the axle of the wheel or roller is guided vertically (and in this context "vertical" will be understood to refer to departures from the line strictly perpendicular to the horizontal which will allow the wheel or roller to rise or fall in the vertical direction, and will include inclination of some magnitude in achieving this result). In such a way that the weight of the wheel or roller is always applied to the ground and supported thereby without any residual or subsidiary support from the mechanism or framework from which the wheel or roller is suspended.

In practice, of course, the wheel or roller may have a relatively short axial extent in relation to its diameter, and apparatus for clearing mines may include a plurality of such rollers mounted for turning motion about a common axis, and each individually guided for vertical displacement.

Of course, in practice, a single row of wheel or roller elements will be separated by clearances sufficient to allow mounting of each individually on a suspension or a support framework which allows the "vertical" displacement to take place, and to counteract the possibility that land mines of sufficiently small size to pass between two adjacent rollers should be encountered, it is preferred that the apparatus of the invention includes two sets of wheels or rollers, a first set mounted for rotation about a first common axis of rotation, and each individually displaceable in a vertical direction with respect thereto, and a second row turnable about a second axis, parallel to the first, and again each being individually displaceable.Naturally, the second row of wheels or rollers will individually be offset by half of the separation between adjacent wheels or rollers of the first set so that each wheel or roller of the second set certainly extends over any interspace between the adjacent two rollers immediately in advance of it during use.

One particularly preferred embodiment of the invention comprises two rows of rollers suspended from a common transverse frame borne at each end by a respective boom or arm projecting forwardly from a locomotive vehicle.

A cross frame is preferably pivotally mounted on the supporting boom or arm end so as to be turnable about an axis parallel to but offset from either of the two axes about which the respective sets of wheels or rollers turn.

In any event, the or each wheel or roller may be guided between two downwardly projecting support guide arms depending from the or a transverse member of the frame.

Embodiments of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of an individual roller mounted on a transverse member; Figure 2 is a generalised perspective view of an assembly comprising two sets of rollers; Figure 3 is a side view of the embodiment of Figure 2; and Figure 4 is a plan view of the configuration of rollers illustrating the relative positions thereof; Figure 5 is an exploded, partly sectioned view of an alternative embodiment similar to that of Figure 1.

Figure 6 is a perspective view of an assembly of rollers in a different configuration from that shown in Figure 2; Figure 7 is a side view of the assembly shown in Figure 6; Figure 8 is a plan view of the assembly shown in Figure 6; Figure 9 is a perspective view of a further embodiment of the invention; and Figure 10 is a slide view of the embodiment of Figure 9 provided with means for removing unwanted vegetation in the path of the machine.

Referring now to Figure 1 to 4 of the drawings, an individual sacrificial wheel or roller generally indicated 11 comprises a plastics moulded structure having integral spindles 12, 12. The structure of the roller 11 can be seen from the partially sectioned roller to the left of Figure 1, and comprises a main, shallow, cylindrical or cup shape body 14 having a circular base disk 15 and a cylindrical skirt wall 16. Projecting away from the skirt wall 16 and centrally of the main disk 15 is a stub axle 12 integrally moulded with the disk 15, and on the opposite face of the disk 15 from the stub axle 12 is a cylindrical boss 17.

Fitted into the circular rim of the skirt portion 16 is a second disk 18 held in position, for example by heat welding the plastics material around its perimeter to the rim of the skirt 16, such that the disk 18 lies parallel to and coaxial to the disk 15 of the cup shape portion of the roller.

The stub axle 13 integral with the disc 18 is coaxial with the stub axle 12, and is reinforced by a corresponding inwardly projecting stub 19 coaxial with the stub 13 and which enters the boss 17. Upon manufacture the cup-shape body is held with the circular rim of the cup-shape portion upwards to allow a particulate material, such as sand, to be introduced into its interior, whereupon the disc 18 is then positioned in alignment with the rim of the skirt 16 and heat welded in position to complete the roller structure. The plastics material from which the roller is made maybe any suitable impact-resistant plastics such as polyethylene or polypropylene, and may be reinforced with fibres or other strengthening material such as carbon fibres or glass fibres as appropriate.Typically, the wall thickness of the roller may be of the order of 2.5 centimetres, whilst the roller itself may be anything between 50 centimetres in diameter and 1 metre in diameter. Other sizes are possible depending on the nature of the mine field to be cleared, and these dimensions, given by way of example only, are not to be taken as limitative.

As can be seen in Figure 1 the oppositely directed coaxial stub axels 12, 13 are each located in respective generally upright guide slots 21, 22 formed in downwardly depending guide members 23, 24 connected to a rigid connection beam (19) which in turn is carried on a rigid transverse support beam 25. The depending guide members 23, 24 are spaced from one another by a distance slightly greater than the thickness of the roller 11 so that it has no tendency to rock about a longitudinal axis, and any tendency to move about a vertical axis is resisted by the rigidity of the depending guide members 23, 24 in which the stub axels, 12, 13 are a relatively firm sliding fit.

If the transverse support beam 25 is displaced forwardly, therefore, the roller 11 is urged by its contact with the ground to roll over the surface of the ground turning about the axis defined by the two stub axels 12, 13, and any variations in the height of the ground are accommodated by vertical displacement of the stub axels 12, 13 themselves up or down the guide slots 21, 22.

As can be seen in Figures 2 and 3, the transverse beam 25 forms part of a rectangular support frame 26 having a second transverse beam 27 and two triangular end frames 28, 29. The triangular end frames 28, 29 have pivotal attachments 30, 31 at their lower apices 32, 33 respectively, connected to forwardly extending booms 34, 35 of a track-laying armoured vehicle (not shown) adapted to carry the mine-clearing roller structure and to resist the impact of blast caused by detonation of any mines over which the rollers 11 are caused to roll.

As will be seen from Figures 2 and 3 the second transverse beam member 27 carries a similar array of downwardly depending channelled supports 36 each having respective guide slots 37, 38 (only one of which is visible in Figure 3) within which individual rollers 38 of a second row are guided for vertically displaceable movement.

In use of the apparatus described, the two sets of rollers 11, 38 are caused to roll over the ground by driving the armoured vehicle forwardly, transferring the forward motion via the booms 34, 35. Any general inclination in the ground is accommodated by rocking motion of the whole guide frame 26 about the pivots 30, 31 to the booms 34, 35, whilst more local variations in the terrain are accommodated by individual rollers 11 or 39 rising up the slots 21, 22 or 37, 38 so that the full weight of the roller is always borne on the ground to ensure that sufficient pressure is applied to the ground to cause certain detonation of any mine buried in the path of the apparatus.The rollers 39 of the second row are offset by half the separation of the rollers 11 in the first row so that the space between two adjacent rollers if the first row is contacted by the roller immediately behind it in the second row.

Should a mine'be contacted and detonate, the force of the detonation is at first absorbed by the plastics material deforming and, subsequently, upon rupture of the container defined by the cylindrical housing by dispersal of the granular or particulate material housed in it.

Because of the particulate material is finely divided the blast is disbursed in such a way that each particle receives only a relatively small amount of energy and is thus not sufficiently energetic seriously to damage the mine-clearing vehicle carrying the booms 34, 35 should it impact thereof. Naturally, no other vehicle or personnel will be in the vicinity while mine clearing is taking place and the force of the explosion is therefore harmlessly dissipated when the fragments of the plastics shell of the roller 11 or 39 and the granular material fall to earth.

All of the components of the apparatus described above are held together by bolted connections so that replacement of a roller destroyed by detonation can be effected quickly and easily, and the mine-clearing vehicle may carry a sufficient supply of replacement rollers to allow it to operate for some considerable time without leaving the mine-clearing site.

Referring now to Figure 5, the alternative embodiment shown comprises a roller generally indicated 40 which, in this embodiment, comprises first and second clam shell halves 41, 42 each of which has a generally cup-shaped configuration comprising a circular base 43, 44 with a cylindrical wall 45, 46 upstanding from its periphery.

The free end of each cylindrical wall 45, 46 has a respective radially inwardly or radially outwardly facing peripheral annular rebates 47, 48 so as to define outer peripheral edges 49, 50 of approximately half the thickness of the cylindrical wall portion 45, 46 itself.

Respectively each of which occupies about one half of the thickness of the cylindrical wall 45, 46 and is the same length as the other axially of the cylindrical wall such that, when the two cup-shape clam shell halves 41, 42 are fitted together the outer peripheral edges 49, 50 of the cylindrical walls 45, 46 engage respective rebates 47, 48.

Centrally of each of the circular bases 43, 44 are respective central, frusto-conical hollow bosses 51, 52 which, when the two clam shell halves 41, 42 are fitted together to define a roller 40, receive opposite ends of a central reinforcing axle member 53.

Finally, the cylindrical walls 45, 46 each have a respective semi circular notch 54, 55 at a point in the periphery, to define an opening through which, when the two clam shell halves 41, 42 are fitted together as shown in Figure 5 to define a roller 40, constitutes an opening through which particulate material can be introduced entirely to fill the interior space 56 within the roller 40 as in the embodiment of Figures 1 to 4. A suitable plug (not shown) is also provided, which may be fixed in place after assembly and secured, for example, by heat or solvent welding. Likewise, upon assembly the outer peripheral edges 49, 50 of the cylindrical walls 45, 46 are secured together by heat or solvent welding, rivets or any other suitable fixings.

As can be seen in Figure 5 the two frusto-conical bosses 51, 52 effectively act as the two oppositely directed stub ends of an axle which, as in the embodiment of Figure 1, can be received in channels 57, 58 of respective downwardly depending guide members 59, 60 held by upper forwardly projecting fixed channel-section supports 61, 62.

Referring now to Figure 6, the alternative configuration of the roller assembly can be seen. Here, as in the embodiment of Figures 1 to 4, there are five rollers 40, individually identified 40a - 40e coaxially arranged in a row turnable about a common axis x-x and each individually supported by its respective stub axels in channels of respective downwardly depending guide members such as the members 59, 60 illustrated in Figure 5. The row of rollers 40 is carried on a transverse beam 67 by an array of upper forwardly projecting fixed channel supports like the supports 61, 62 illustrated in Figure 5 and identified individually with the reference numerals 63, 64,, 65 and 66.Unlike the embodiment of Figure 2, however, the upper fixed supports 61-66 are carried by a single beam 67 which is itself pivotally mounted at its opposite ends, by pivots 68, 69 to booms 70, 71 of a suitable vehicle (not shown).

Projecting rearwardly from the transverse beam 67 are five further upper supports 72-76 which carry respective downwardly projecting guide members, only one of which can be seen in Figure 6 identified with the reference numerals 77. These carry four rollers 40f-40i identical in all respects to the rollers 40a-40e in the forward row, located in register with the spaces between the five rollers 40a-40e of the forward row.

As will be appreciated from Figures 7 and 8, the forwardly projecting supports 61-66 and the rearwardly projecting supports 72-76 are aligned with one another, of the same length such that, as the rollers 40 roll over the ground the supports 61-66 and 72-76 can apply turning moments to the transverse beam 67 to allow the forward or rearward row of rollers to rise and fall respectively.

In this embodiment the booms 70, 71 are pivoted at their connection to the vehicle and allowed to turn under their own weight (anti clockwise as shown in Figure 7) about the pivot point generally indicated A so that the rollers 40 in their normal position of use are located with the respective axel stubs 51, 52 at the upper ends of the channels 57, 58. Any depression in the terrain over which the roller 40 passes will then be followed by the individual roller, with the axels sliding down the channels 57, 58 as far as the length of these channels will allow, whilst any rise in the terrain will cause the individual roller engaging the rise to follow the ground, whilst the remaining rollers will fall, with respect to their supports, allowing them to follow the level of the ground over which they roll.

As in the embodiment of Figures 1 to 4, should the row of rollers strike a land mine, the individual roller 40 affected may be distorted, or even destroyed with the interior filling of particulate material absorbing the force, or at least the majority of the force of the detonation without causing damage to the remaining rollers. Because, as mentioned above, the individual elements of the support structure are all fixed together releasably, for example by bolts, the individual damaged roller (or rollers if more than one is damaged by the explosion) may be removed and replaced with a fresh roller from a supply carried on the vehicle. In appropriate circumstances the particulate material, such as sand, may be taken from the site rather than carried with the vehicle.

The pivot axis defined by the two pivots 68, 69 lies in the plane defined by the two common axes of the two sets of rollers 40. The advantage of this configuration lies in the fact that should the front or rear set of rollers experience a force greater than that which can be absorbed by disintegration of one or more of the rollers, the whole assembly of rollers will be lifted from the ground, and, in this case, by turning around the pivot axis defined by the pivot 68, 69 can rotate through 180" so that the front roller array moves to the position previously adopted by the rear roller array, and vice versa. This may also be the case if terrain of particular irregularity is encountered, and increases the versatility of the machine.

Referring now the Figure 9 there is shown a modified embodiment similar to that of Figures 6, 7 and 8, but in which the two booms 70, 71 are not directly pivoted to the vehicle as in the embodiment of Figures 6, 7 and 8, but rather are pivotly connected to a transverse beam 80 at pivotable connections 81, 82 allowing the roller configuration to behave as in the previous embodiment.

The beam 80 itself, however, is pivotally connected to the vehicle via a central vertical pivot 83 allowing the framework comprising the booms 70, 71 the beam 80 and all the rollers carried thereby to pivot about the vertical axis of the connection 83 to the vehicle to effect steering of the roller assembly without requiring it to be lifted in any way from the ground surface. This is of particular advantage in dealing with twisting narrow roads. Steering can be achieved by use of two fluid pressure actuators 84, 85. These are preferably located at the end of the armoured vehicle furthest from the steering wheels so that there is less likelihood of the wheels touching ground which has not been cleared of mines and the path of the vehicle will remain in the track of the clearing equipment.For vehicles in which the steering wheels are normally the front wheels this will mean that the frame of rollers will be attached to the rear of the vehicle and clearing will take place by reversing the vehicle. Modifications to the vehicle for this purpose, including the fitting of a second steering wheel and controls in the rear of the vehicle to allow the driver better vision over the clearing equipment may naturally be effected.

The embodiment of Figures 9 and 10 is further provided with means for combating the difficulty encountered when land mines have been in the ground for so long that metallic parts have become corroded. The result of such corrosion can be that detonation does not necessarily immediately follow depression of the pressure plate because, for example, the spring which should propel the firing pin in to the detonator may be jammed. It has been known for such mines to explode long after a clearing operation has been undertaken. To combat this a vibratory engine 86 is mounted on the cross beam 67.

Such vibratory engines are known in the construction industry and are used, for example, to compact wet concrete. The action of this engine 86 on the frame of rollers results in the transmission of vibrations which it is believed should be sufficient to dislodge any corroded parts of mines and allow them to detonate properly. In this embodiment the engine 86 is air powered using a supply of compressed air generated by a compressor mounted in the vehicle on which the frame of rollers is mounted. The engine itself is protected by a casing of armour plate against blast damage. Other suitable vibratory engines may, of course, be provided.

The embodiment of Figures 9 and 10 is also fitted with means for removing unwanted vegetation such as trees and other plants which may spring up on roads which have fallen into disuse because of the presence of land mines.

To combat this an additional frame comprising two forwardly projecting members 88, 89 and a transverse beam 90 is mounted in advance of the forward set of rollers 40a-40e. An appropriate disc cutter 91 suspended from a displaceable support 92 is carried by the transverse beam 90. The disc cutter may, like the vibratory motor 86, be driven by compressed air from a source on the vehicle or otherwise driven as appropriate. On seeing vegetation in the path of the clearing equipment the driver may position the disc cutter 91 appropriately such that the vegetation is cut through as the vehicle advances. Means (not shown) for displacing the carrier 92 and therefore the disc cutter 91 laterally from side to side of the clearing equipment along the beam 90 may be provided.

Claims (19)

1. Apparatus for use in clearing land mines, comprising at least one hollow roller which can contain bulk material and means for guiding the roller for rolling movement over the ground whilst allowing it to be displaced vertically to accommodate variations in the surface of the ground in such a way that the groundcontact pressure is determined by the weight of the roller.

2. Apparatus as claimed in Claim 1 including a plurality of the hollow rollers mounted for rotation about a common rolling axis or parallel rolling axes for rolling in the same direction on adjacent paths, the rollers being movable individually relative to each other in the vertical direction to enable each roller substantially to maintain ground contact when encountering variations in the ground surface in its path of movement.

3. Apparatus as claimed in Claim 2, in which the plurality of rollers is arranged in at least two sets, the rollers in each set being arranged with their rolling axes in a common vertical plane and being spaced laterally in the direction of their axes, the rollers in the respective sets being staggered relative to each other in the direction of their axes, such that the rollers sweep the entire width of a band of ground over which they are rolled in use.

4. Apparatus as claimed in any one of Claims l to 3, in which the means for guiding the or each roller comprise a guiding and supporting structure adapted to receive drive at a position remote from the roller for moving the roller across the ground in a generally horizontal direction perpendicular to its rolling axis, the roller being movable vertically relative to the drive-receiving position to maintain ground contact during movement by the drive means, which contact causes the roller to roll over the ground.

5. Apparatus as claimed in Claim 4, in which the guiding and supporting structure includes upright support means for the or each roller on which the respective roller is movable in a generally vertical direction in use, the upright support means being carried by a structural member or structural members having a horizontal extent and including the drive-receiving position remote from the roller.

6. Apparatus as claimed in Claim 5, in which the or each roller has axle members projecting from opposing side faces thereof, the axle members being engaged in respective vertical guide channels of the upright support means which guide the vertical movements of the roller in use, the or each roller being carried by the upright support means such that its entire weight rests on the ground between upper and lower end positions of its vertical movement.

7. Apparatus as claimed in Claim 5 or Claim 6, in which the guiding and supporting structure comprises or includes a support arm or arms adapted at or adjacent one end for attachment to a drive vehicle so as to project forwardly of the direction of movement of the vehicle in use and carrying the upright support means at or adjacent its opposite, forward end in use.

8. Apparatus as claimed in Claim 7 as dependent on Claim 2, in which the support arm or arms carry a transverse support structure at the forward end thereof, the transverse support structure carrying respective upright support means for the plurality of rollers.

9. Apparatus as claimed in Claim 8, in which the transverse support structure is pivotally mounted on the or each support arm for pivoting about an axis parallel to the rolling axes of the rollers.

10. Apparatus as claimed in Claim 9 as dependent on Claim 3, in which the rollers are arranged in two sets and the pivot axis of the support structure is located between the rolling axes of the two sets of rollers in the direction of movement of the rollers relative to the ground in use.

11. Apparatus as claimed in Claim 10, in which the planes containing the rolling axes of the two sets of rollers are equally spaced from the pivot axis of the transverse support structure and the transverse support structure can pivot through 180" about its pivot axis between two positions in which the positions of the two sets of rollers are reversed relative to the direction of movement of the apparatus, in use, and in both of which positions the rollers can contact the ground.

12. Apparatus as claimed in any one of the preceding claims, in which the or each roller is releasably attached to its guiding means and readily replaceable in the event of damage.

13. Apparatus as claimed in any one of the preceding claims, in which the roller comprises a plastics shell.

14. Apparatus as claimed in Claim 13, in which the shell is moulded in two parts which are subsequently joined together.

15. Apparatus as claimed in any one of Claims 7 to 14, in which the or each support arm is adapted for pivotal attachment to a drive vehicle for pivoting about an upright axis in use to allow the apparatus to be steered.

16. Apparatus as claimed in any one of the preceding claims, further including vibratory means carried by the guiding means for vibrating the at least one hollow roller, in use.

17. Apparatus as claimed in any one of the preceding claims, further including cutter means carried by the guiding means for cutting vegetation in front of and/or laterally of the land-mine clearing apparatus in use.

18. Apparatus substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

19. A vehicle equipped with apparatus for clearing landmines according to any one of Claims 4 to 11 or Claims 12 to 14 as dependent on Claim 4, in which the apparatus is attached to the vehicle by the supporting structure with the or each roller locatable in rolling contact with the ground in front of the vehicle in its direction of travel in use.