GB2355907A

GB2355907A - A blade for digging assembly, and related apparatuses

Info

Publication number: GB2355907A
Application number: GB9925851A
Authority: GB
Inventors: John Robert French
Original assignee: JR French Ltd
Current assignee: JR French Ltd
Priority date: 1999-11-02
Filing date: 1999-11-02
Publication date: 2001-05-09
Also published as: KR20020065506A; CA2390125C; WO2001033158A3; GB9925851D0; IL149452A0; NO20022084L; JP2003513187A; CN1409814A; ZA200204431B; HK1052547A1; AU1157101A; WO2001033158A2; YU33102A; CA2390125A1; EP1228340A2; HRP20020386A2; AU768900B2; NO20022084D0

Abstract

A blade 12 for use in a digging assembly (10, figure 1) having a base 24 and a terminal portion 26, base 24 being wider than terminal portion 26 and blade 12 tapering towards terminal portion 26. Blade 12 has first second and third sharpened edges 28, 30, 32, having flanks 34 that subtend an angle of at least 90{. Each of the flanks 28, 30, 32 are skewed in relation to the others so as to exhibit a lifting effect when blade 12 is rotated through soil in use. In a further aspect, the blade has three limb members (38, figure 4), each limb member (38) having a base (40) and a terminal portion (42), the base being narrower than the terminal portion (42) and the limb member (38) tapering towards the base (40). There are sharpened edges (44, 46, 48). There may be a tine (52, figure 5) associated with each blade 1. In a further aspect still, there is a moveable vehicle (56, figure 7) having a digging assembly 10, a grinding hopper (60) and a magnetic roller (70) for removing ferrous materials from the soil such as landmines, so that they may be safely disposed of.

Description

2355907 A BLADE FOR A DIGGING ASSEMBLY, AND RELATED APPARATUSES This

invention relates to a blade for a digging assembly. Such a digging assembly and related apparatuses are disclosed in our co-pending UK Patent Application No. G139901997.8.

The invention also relates to a moveable vehicle including a grinding hopper and a digging assembly such as the ones disclosed herein and in io GB9901997.8. Digging assemblies and apparatuses such as these are useful in the clearance of landmines and other unexploded ordnance.

According to an aspect of the invention, a blade for use in a digging assembly comprises:

(a) a base portion and a terminal portion remote from the base portion, the base portion being wider than the terminal portion and the blade tapering in width between the base and terminal portions; (b) a first, sharpened, arcuate edge, extending between the base and the terminal portions of the blade; (c) a second, sharpened edge defined by the terminal portion; and (d) a third, sharpened, arcuate edge extending between the base and terminal portions of the blade, each of the first, second and third edges having flanks that between them subtend an angle of at least 0, each of the flanks being skewed in relation to the respective flanks of the other edges.

A blade according to the invention can be mounted at its base on a rotatable shaft in a digging assembly, in either of two orientations. In a first orientation, rotation of the rotatable shaft in a predetermined I direction causes the blade to rotate about the axis of the shaft so that its first edge leads, followed by its second and third edges respectively. In the second orientation, rotation of the rotatable shaft in the predetermined direction causes the blade to rotate about the axis of the shaft so that its 5 third edge leads, followed by its second and first edges respectively.

In use a digging assembly such as the ones disclosed herein and in G139901997.8 may be lain on or inserted into the soil of a minefield or battle area and driven forwardly e.g. by means of a pushing or pulling io vehicle. When a blade according to the invention is mounted in the first orientation on the rotatable shaft of the digging assembly, rotation of the shaft in a predetermined direction causes the first, sharpened edge of the blade to cut through soil and e.g. tree and plant roots, tripwires and cables, thereby freeing any unexploded ordnance such as mines. The trailing second and third, sharpened edges then follow the first, sharpened edge through the cut material.

The angle subtended by the flanks of the first, second and third edges of the blade, the relative orientation of the flanks, and the comparatively wide base portion of the blade, produce comparatively broad flanks on the first and third edges of the blades. As the third, sharpened edge trails the first, sharpened edge through the cut material and other fragments in the soil, the flanks of the third edge provide a lifting effect. This allows any solid objects to be lifted to the surface of the minefield, from where they can be readily removed and destroyed.

If roots or any other vegetation become wrapped around the rotatable shaft in the digging assembly, the rotatable shaft can be rotated in a reverse direction. This causes the third, sharpened edge to cut through the 2 roots or vegetation around the shaft, so removing the entanglement around the shaft.

When a blade according to the invention is mounted in the second orientation on the rotatable shaft of the digging assembly, rotation of the rotatable shaft in the predetermined direction in the digging assembly causes the third, sharpened edge to cut through the soil etc. The trailing second and first edges follow through the cut material, and the orientation of the flanks of the first edge causes the cut material and any solid objects io to be lifted to the surface.

In an embodiment of the invention, the flanks of the second, sharpened edge of the blade subtend an angle of 90'. The flanks of the first and third, sharpened edges may also subtend an angle of 90'.

In other embodiments, the flanks of the first and/or third sharpened edges of the blade are concave.

The depth of the flanks of the second, sharpened edge, when measured along a line perpendicular to the length of the second, sharpened edge, is preferably 25mm.

In a preferred embodiment of the invention a chisel edge is provided at each of the junctions between the flanks of the second and third edges of the blade.

The provision of the chisel edges is advantageous when the blade is used in a digging assembly that is being driven through rocky or stony ground. In such use, the blade is mounted on the digging assembly's rotatable 3 shaft in the second orientation. Rotation of the rotatable shaft in the predetermined direction then causes the third, sharpened edge of the blade to cut through the soil, and the location of the chisel edges is such that during this rotation the chisel edges are also leading edges. Hence the chisel edges can split and chop any rocks and stones that are encountered by the blade.

The second, sharpened edge follows this chisel action and imparts a cutting action on the material that has been split or chopped by the chisel io edge. Finally the first edge follows through the split, chopped and cut material, the orientation of its flanks acting to support the cut material for lifting.

The length of each of the chisel edges may be any value but in a preffred embodiment is preferably 25min.

The width of the base portion of the blade may be any value but in a preferred embodiment is preferably 75mm.

According to a second aspect of the invention, a blade for use in a digging assembly includes three limb members, each limb member including:

(a) a base portion and a terminal portion remote from the base portion, the terminal portion being wider than the base portion and each of the limb members tapering in width between the terminal and base 25 portions; (b) a first, sharpened, arcuate edge extending between the base and terminal portions, (c) a second, sharpened edge defined by the terminal portion-, and (d) a third, sharpened, arcuate edge extending between the terminal 4 and base portions; wherein the three limb members meet and are joined together at their base portions so that they extend away from a central region of the blade at an equal distance to each other.

A blade according to this aspect of the invention may be mounted on a rotatable shaft in a digging assembly by passing the rotatable shaft through the central region of the blade.

io In preferred embodiments, all of the perimeter edges of the blade are sharpened. In combination with the configuration of the limb members of the blade, such sharpened edges create a continuous cutting action when the blade is rotated on a rotatable shaft in a digging assembly.

A digging assembly including one or more of these blades may include a tyne associated with the or each blade. These tynes may be mounted in the digging assembly so that they extend parallel to their associated blade and are offset slightly to one side. In use, rotation of each blade past an associated tyne creates a guillotine effect.

When a digging assembly including one or more blades and associated tynes is driven through the soil of a minefield or battlefield, the guillotine action of the blades, passing the tynes, prevents material such as barbed wire, razor wire and plant roots from becoming wrapped around the 25 rotatable shaft of the digging assembly.

As with the blades of the first aspect of the invention, a blade according to the second aspect of the invention brings solid and large objects, such as stones or unexploded ordnance, to the surface when it is used in a digging assembly being driven through the soil.

As well as including one or more tynes, a digging assembly including one or more blades according to the second aspect of the invention may also include one or more paddle members on the rotatable shaft. The paddle members may extend along the length of the rotatable shaft.

When the digging assembly is driven through the soil of a minefield or a battlefield, the rotatable shaft of the digging assembly passes close to the io top surface of the soil. The soil may provide a degree of resistance to the rotation and any movement of the shaft as the digging assembly moves forwards, i.e. the shaft may dig into the soil and prevent the digging assembly moving forwards. The provision of one or more paddle members on the rotatable shaft reduces the pressure required to force the shaft through the soil. The or each paddle member acts in a similar manner to the paddles on a paddle steamer, and lifts the soil over the top of the shaft, allowing the shaft and the digging assembly to move forward unhindered.

A digging assembly may include a number of blades according to the second aspect of the invention. The precise number of blades, and the distance between the blades on the rotatable shaft, are dependent upon the amount of debris that is likely to be found in soil that a digging assembly is to be driven through. Similarly the diameter of the or each blade, and hence the length of each of the limb members of the or each blade, used in a digging assembly is dependent upon the depth of cut that is required from the digging assembly.

According to a third aspect of the invention, a moveable vehicle 6 comprises:

(a) a digging assembly; (b) a hopper open at one end and having therein one or more moveable grinding elements for grinding, to a predetermined size, material 5 conveyed to the hopper; and (c) a conveyor for conveying material from the digging assembly to the hopper, the conveyor arrangement including a magnet for removing ferrous debris and a sieve for removing loose or small particles from the material before it reaches the hopper. 10 The conveyor arrangement may include a conveyor belt provided with a magnetic roller at an extremity thereof. This allows any ferrous debris contained within material being transported on the conveyor belt to be removed.

The magnetic roller may be a roller that includes a permanent magnet or an electromagnet.

The conveyor arrangement may also include a perforated conveyor belt. 20 Small and loose particles contained 'in material conveyed on the conveyor belt may then fall through the perforations before the material reaches the hopper.

The digging assembly may include a blade according to the first aspect of 25 the invention, and preferably includes a plurality of blades according to the first aspect of the invention.

In other embodiments, the digging assembly may include one or more blades according to the second aspect of the invention. In these 7 embodiments, the digging assembly may include a tyne in association with the or each blade, and may also include one or more paddle members mounted on its rotatable shaft.

The grinding hopper may include a plurality of pivotable hammers and a back plate.

The back plate may include a hardened rotating metal back plate, or it may include two individual plates that follow reciprocating paths in front io of or on either side of the pivotable hammers.

The plurality of hammers may be mounted on one or more rotating flywheels.

The grinding hopper may optionally include a grille between the pivotable hammers and the back plate. Such a grille can be used to ensure that only particles greater than the size of the grille's holes are kept within the grinding hopper, allowing smaller particles to drop under gravity through the grille. This can be used to determine the size of the particles produced by the hopper, because as soon as the particles become small enough, they will pass through the grille away from the pivotable hammers.

The distance between the plurality of pivotable hammers and the back plate may be adjustable. This allows the resultant size of the particles produced by the hopper to be altered.

Preferred embodiments of the invention will now be described by way of non-limiting example, with reference to the accompanying drawings in which:

8 Figure 1 is a side view of a digging assembly according to the invention; Figure 2 is a perspective view of a digging assembly similar to that shown 5 in Figure 1; Figure 3 is a perspective view of a blade according to the invention for use in a digging assembly such as those shown in Figures I and 2; io Figure 4 is a perspective view of a further blade according to the invention for use in a digging assembly such as those shown in Figures I and 2; Figure 5 is a schematic view of a number of the blades shown in Figure 4 mounted on a rotatable shaft in a digging assembly such as those shown in Figures I and 2; Figure 6 is a schematic side elevational view of a moveable vehicle according to the invention; Figure 7 is a perspective view of a moveable vehicle, according to the invention, and similar to that shown in Figure 4; and Figures 8A and 8B are perspective views of internal details of a grinding hopper in accordance with the invention.

Digging assemblies 10, such as the digging assemblies shown in Figures 1 and 2, are described in detail in out co-pending UK Patent Application No. G139901997.8.

9 The digging assembly 10 shown in Figures I and 2, includes a plurality of blades 12 mounted on a rotatable shaft 14. When the digging assembly 10 is driven through soil in a minefield or a battlefield, the rotatable shaft 14 causes the blades 12 to rotate through the soil. Sharpened edges on the blades cut through the soil and any other material such as plant roots and wires. Solid or large objects such as stones or unexploded ordnance are brought to the surface of the soil by the rotating blades. Here they are scooped up and collected by one of a number of buckets 16 passing io around a conveyor path 18 on the digging assembly 10.

The buckets 16 move around the conveyor path 18, carrying objects they have collected from the surface of the soil until they reach an uppermost point 20 on the conveyor path 18. At this point 20, the buckets 16 tip 15 forwards and drop their load into or onto a collecting member.

The buckets 16 then move further around the conveyor path 18 to a position at which they are once again available to collect objects that have been lifted to the surface by the blades 12.

A camera 22 may be provided to observe the buckets 16 travelling around the conveyor path 18. If unexploded ordnance is collected by one of the buckets, the digging assembly 10 can be halted, and the unexploded ordnance can be disposed of safely. The camera allows the digging 25 assembly 10 to be operated from a remote position.

A blade 12 according to the invention, and suitable for use in a digging assembly 10, such as those shown in Figures I and 2, is shown in Figure 3.

The blade 12 includes a base portion 24 and a terminal portion 26 remote from the base portion 24. The base portion 24 is wider than the terminal portion 26, the blade 12 tapering in width between the base portion 24 and the terminal portion 26.

The width of the blade 12 is proportional to the blade's length. Thus when the depth of the desired cut of the blade 12 is 250min, the width of the base portion 24 of the blade 12 is 75mm.

The blade 12 includes a first, arcuate edge 28 that extends between the base portion 24 and the terminal portion 26. The first edge 28 is sharpened and, in the Figure 3 embodiment, is convexly curved.

A second edge 30 extends from the first edge 28, across the terminal portion 26 of the blade 12. The second edge 30 is sharpened and, in the Figure 3 embodiment, is straight.

The blade 12 also includes a third, arcuate edge 32 that extends from the second edge 30 between the terminal portion 26 and the base portion 24.

The third edge 32 extends along an opposite side of the blade 12 to the first edge 28. The third edge 32 is sharpened and, in the Figure 3 embodiment, is concavely curved.

The three sharpened edges 28,30,32 have flanks 34 that between them subtend an angle of at least 90'. On each side of the blade 12, the respective flanks of each of the edges 28,30,32 are skewed one relative to another.

11 The blade 12 may be secured on a rotatable shaft 14 of a digging assembly at its base portion 24. When the blade 12 is rotated by the shaft 14, the relative orientations of the flanks 34 of the edges 28,30,32 enable the blade 12 to support and lift cut material that is encountered by the blade 12.

The flanks 34 of the first.edge 28 and the third edge 32 may optionally be concave.

lo The blade 12 shown in Figure 3 includes a chisel edge 36. The chisel edge 36 is located along the junction between the flanks 34 of the second edge and the third edge 36. A chisel edge 36 is also located between the flanks 34 of the second edge 30 and the third edge 32 of the opposite side of the blade 12 to the side of the blade 12 that is shown in Figure 3.

In preferred embodiments, the chisel edge is 25mm in length.

A further blade 12 according to the invention is shown in Figure 4. This blade 12 includes three limb members 38. Each limb member 38 has a base portion 40 and a terminal portion 42. The terminal portion 42 is wider than the base portion 40, each of the limb members 38 tapering in width between the terminal portion 42 and the base portion 40.

Each limb member 38 includes a first, arcuate edge 44 that extends between the base portion 40 and the terminal portion 42. The first edge 44 is sharpened and, in the Figure 4 embodiment, is concavely curved.

A second edoe 46 extends from the first edge 44 across the terminal portion 42 of each of the limb members 38. The second edge 46 is also 12 sharpened and, in the Figure 4 embodiment, is convexly curved.

Each limb member 38 also includes a third, arcuate edge 48 that extends between the terminal portion 42 and the base portion 40. The third edge 48 extends along an opposite side of each of the limb members 38 to the first edge 44. The third edge 48 is sharpened and, in the Figure 4 embodiment, is concavely curved.

The three limb members 38 meet and are joined together at their base io portions 40, at a central region 50 of the blade 12. The limb members 38 extend away from the central region 50 at an equal distance apart from each other. In the embodiment shown in Figure 4, the limb members 38 lie in generally the same plane as each other.

The blade 12 may be secured on a rotatable shaft 14 in a digging assembly 10, such as those shown in Figures 1 and 2, by passing the shaft 14 through the centre point 50 of the blade 12 and fixing the blade 12 and the shaft 14 to one another. Rotation of the shaft 14 then causes the limb members 38 to rotate about the axis of the shaft 14.

The sharpened edges 44,46,48 of the limb members 38 may form a contiguous series of sharpened edges around the perimeter of the blade 12.

When the blade 12 of Figure 4 is used in a digging assembly 10,- a tyne 52 can be positioned in the digging assembly 10 so that when the blade 12 is rotated by the shaft 14, it passes close to the tyne 52. The arrangement shown in Figure 5 shows a number of the blades 12 of Figure 4 mounted on a rotatable shaft 14. A number of tynes 52 are positioned in the digging assembly 10 so that each of the tynes 52 lies parallel to, and offset to one side of, an adjacent one of the blades 12. When the shaft 14 rotates, each of the blades 12 then passes closely past one of the tynes 52. If items such as barbed wire, trip wire or plant roots are picked up by the limb members 38 of the blades 12, the action of the blades 12 passing the tynes 52 cuts the items so that they do not become wrapped around the rotatable shaft 14.

io The rotatable shaft 14 in Figure 5 also includes a number of paddle members 54. The paddle members 54 are rectangular members that extend along the length of, and away from, the shaft 14.

Combined rotation of the shaft 14 and forward movement of the digging assembly 10 cause the paddle members 54 to lift soil over the top of the shaft 14. This prevents the soil building up and resisting the movement of the shaft through soil.

A moveable vehicle 56 according to the invention is shown in Figures 6 and 7.

Moveable vehicle 56 includes a digging assembly 10, a conveyor arrangement 58 and a grinding hopper 60.

The digging assemblies shown in Figures I and 2, and in co-pending patent application no. GB9901997.8 are suitable for use as the digging assembly 10 of Figure 6.

In the embodiment shown, the conveyor arrangement 58 includes a first 14 conveyor 62 and a second conveyor 64.

The first conveyor 62 comprises an endless, flexible belt 66 moveably entrained about two spaced apart, rotatable rollers 68,70. Roller 68 is positioned below an end of the digging assembly 10. The conveyor belt 66 extends around the first roller 68 and extends horizontally from the first roller 68 to the second roller 70 at a position remote from the digging assembly 10.

io Roller 70 includes a magnet, that can be a permanent magnet or an electromagnet.

Like the first conveyor 62, the second conveyor 64 comprises an endless, flexible conveyor belt 72 moveably entrained around two spaced apart, rotatable rollers 74,76.

Roller 74 is positioned beside, and slightly below, roller 70 of the first conveyor 62. The second conveyor belt 72 extends in the same direction as the first conveyor belt 66. It extends upwardly and around roller 74, and horizontally away from roller 74 towards the second roller 76, remote from the first conveyor 62.

The second conveyor belt 72 is perforated. This allows particles that are smaller than a predetermined size to fall through the belt 72 under gravity.

Two television cameras 22,78 are provided at elevated positions above the moveable vehicle 56. The cameras 22,78 can tilt, swivel and zoom. They allow observation of the material being transported through the moveable vehicle 56, as well as aiding the control of the steering of the vehicle 56.

In particular, one of the cameras 22 observes the material being lifted by the digging assembly 10, whilst the other camera 78 concentrates on the material conveyed through the rest of the vehicle.

Material that is lifted by the buckets 16 of the digging assembly 10 is dropped onto the first end 68a of the first conveyor 62 when the buckets 16 reach the uppermost point 20 of the conveyor path 18.

The thus deposited material is transported towards roller 70, away from io the digging assembly 10. As the material approaches roller 70, any ferrous debris contained within the material is attracted by the magnet incorporated into roller 70 towards the area of conveyor belt 66 surrounding roller 70.

As the conveyor belt 66 travels around roller 70 any non-ferrous material is transported over the end of the first conveyor 62 and falls under gravity onto a first end 74a of the second conveyor 64.

The ferrous debris does not fall off of the end of the first conveyor 62 with the non-ferrous debris due to the attractive magnetic force provided by roller 70. Consequently the ferrous debris remains in contact with the conveyor belt 66 as it travels around roller 70. This effectively separates any ferrous debris from other material being conveyed through the moveable vehicle 56.

The ferrous debris remains in contact with the conveyor belt 66 until the ferrous debris has moved a predetermined distance away from the second roller 70, back towards the first roller 68. At this point, the attractive magnetic force is too weak to keep the ferrous debris in contact with the 16 belt 66. The ferrous debris hence falls under gravity from the belt 66, and is guided to a collection receptacle 80 by a chute 82.

The non-ferrous material that falls onto the first end 74a of the second conveyor 64 is transported away from the first conveyor 62 towards the second roller 76 of the second conveyor 64. As the second conveyor belt 72 is perforated, particles smaller than a predetermined size fall under gravity through the conveyor belt 72.

io When the non-ferrous material that remains on the second conveyor belt 72 reaches the second roller 76, it is transported over the second end 76a of the second conveyor 64 and falls under gravity into the grinding hopper 60.

Internal details of a grinding hopper, according to the invention, are shown in Figures 8A and 8B.

The grinding hopper includes a back plate 84, which in Figure 8A is shown as a hardened metal back plate rotating about two vertically spaced apart rollers 86,88.

A number of flywheels 90 are provided within the area enclosed by the backplate 84. A plurality of pivotable hammers 92 are mounted on each of the rotatable flywheels 90, as shown in Figure 8B..

When material is fed into the top of the grinding hopper, it is crushed or broken between the harniners 92 and the back plate 84.

The hammers 92 are pivotable in order to allow them to bounce off of extremely hard materials. They may be provided in various shapes and 17 sizes, depending on the nature of the material and soil structure of the cut material being fed into the grinding hopper.

The back plate 84 is moveable in order to prevent wet material that may be fed into the grinding hopper from causing a blockage.

In other embodiments, the back plate 84 may be provided by a single plate reciprocating up and down in front of the rotating flywheels 90.

lo The grinding hopper may include a variation of flywheel 90 and pivotable harnmer 92 combinations. The flywheel/hamn-ler assemblies can be moved towards or away from the back plate 84 to allow for different sizes of particle to be produced, and to allow for wear on the pivotable hammers 92.

The size of the particles produced by the grinding hopper can also wholly or partly be determined by the size of the holes provided in a grille 94.

The grille 94 is optional, and when present, it is located between the pivotable hammers 92 and the back plate 84. The provision of the grille 94 between the hammers 92 and the back plate 84 means that particles smaller than a predetermined size fall under gravity through holes in the grille 94.

Particles that are larger than the predetermined size of the holes in the grille 94 are retained between the pivotable hammers 92 and the grille 94 so that they are crushed and broken down further, until they are small enough to fall under gravity through the grille 94, away from the hammers 92.

18 The grille 94 may be produced from hardened metal.

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Claims

I A blade for use in a digging assembly comprising:

(a) a base portion and a terminal portion remote from the base portion, the base portion being wider than the terminal portion and the blade tapering in width between the base and terminal portions; (b a first, sharpened, arcuate edge, extending between the base and terminal portions of the blade; (c) a second sharpened edge defined by the terminal portion; and (d) a third, sharpened edge extending between the base and terminal portions of the blade, each of the first, second and third edges having flanks that between them subtend an angle of at least 90', each of the flanks being skewed in relation to the respective flanks of the other edges.

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2. A blade as claimed in Claim 1, wherein the flanks of the second, sharpened edge subtend an angle of 90'.
3. A blade as claimed in Claiml or Claim 2, wherein the flanks of each of the first and third, sharpened, arcuate edges subtend an angle of 0.
4. A blade as claimed in Claim I or Claim 2, wherein the flanks of at least one of the first and third, sharpened, arcuate edges are concave.
5. A blade as clam-led in Claim 4, wherein the flanks of each of the first and third, sharpened, arcuate edges are concave.
6. A blade as claimed in any preceding claim, wherein the depth of the flanks of the second, sharpened edge when measured along a line perpendicular to the length of the second, sharpened edge is 25mm.
7. A blade as claimed in any preceding claim, further including a chisel edge at each of the junctions between the flanks of the second and third edges.

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8. A blade as claimed in Claim 7, wherein the length of each of the chisel edges is 25mm.
9. A blade as claimed in any preceding claim, wherein the width of the base portion of the blade is 75mm.
10. A blade generally as herein described, with reference to and/or as illustrated in Figure 3 of the accompanying drawings.
11. A blade for use in a digging assembly comprising three limb members, each limb member including:

(a) a base portion and a terminal portion remote from the base portion, the terminal portion being wider than the base portion and each of the limb members tapering in width between the terminal and base portions; (b) a first, sharpened, arcuate edge extending between the base and terminal portions; (c) a second, sharpened edge defined by the terminal portion; and (d) a third, sharpened, arcuate edge extending between the base 21 and terminal portions; wherein the three limb members meet and are joined together at their base portions so that they extend away from a central region of the blade at an equal distance apart from each other.
12. A blade as claimed in Claim 11, wherein the sharpened edges of the limb members form a contiguous series of sharpened edges around the perimeter of the blade.
13. A blade generally as herein described with reference to and/or as illustrated in Figure 4 of the accompanying drawings.
14. A digging assembly including one or more blades each according to :D I'D Claim 11, wherein a rotatable shaft passes through the centre of and is 15 secured to the or each blade.
15. A digging assembly according to Claim 14, further including a tyne associated with the or each blade, the or each tyne extending parallel to ZD and displaced to one side of the or each blade.
16. A digging assembly according to Claim 14 or Claim 15, wherein the rotatable shaft includes one or a number of paddle members extending along the length of the rotatable shaft.
17. A digging assembly generally as herein described with reference to and/or as illustrated in Figure 5 of the accompanying drawings.
18. A moveable vehicle, comprisincl: (a) a digging assembly; (b) a hopper open at one end and having therein one or more 22 moveable grinding elements for grinding, to a predetermined size, material conveyed to the hopper; and (c) a conveyor for conveying material from the digging assembly to the hopper, the conveyor arrangement including a magnet for removing ferrous debris and a sieve for removing loose or small particles from the material before it reaches the hopper.
19. A moveable vehicle as claimed in Claim 18, wherein the conveyor io arrangement includes a conveyor belt provided with a magnetic roller atan extremity thereof.
20. A moveable vehicle as claimed in Claim 19, wherein the magnetic roller comprises a roller that includes a permanent magnet.
21. A moveable vehicle as claimed in Claim 19, wherein the magnetic roller comprises a roller that includes an electromagnet.
22. A moveable vehicle as claimed in any of Claims 18 to 21, wherein the conveyor includes a perforated conveyor belt.
23. A moveable vehicle as claimed in any of Claims 18 to 22, wherein the digging assembly includes one or more blades according to Claim I or any claim dependent therefrom.
24. A moveable vehicle as claimed in any of Claims 18 to 22, wherein the digging assembly includes one or more blades according to Claim 11 or any claim dependent therefrom.

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25. A moveable vehicle as claimed in Claim 24, wherein the diggig assembly is in accordance with any of Claims 14 to 16.
26. A moveable vehicle as claimed in any of Claims 18 to 25, wherein the grinding hopper includes a plurality of pivotable hammers and a back plate.
27. A moveable vehicle as claimed in Clai m 26, wherein the back plate includes a hardened rotating metal back plate.
28. A moveable vehicle as claimed in Claim 26, wherein the back plate includes two plates that follow reciprocating paths in front of or on either side of the pivotable hammers.
29. A moveable vehicle as claimed in any of Claims 26 to 28 wherein the plurality of pivotable hammers are mounted on one or more rotating flywheels.
30. A moveable vehicle as claimed in any of Claims 26 to 29, wherein the grinding hopper further includes a grille between the plurality of pivotable hammers and the back plate.
31. A moveable vehicle as claimed in any of Claims 26 to 30, wherein the distance between the plurality of pivotable hammers and the back plate is adjustable.
32. A moveable vehicle generally as herein described with reference to and/or as illustrated in Figures 6 to 8B of the accompanying drawings.

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