AU2013245564B2 - A guard - Google Patents

Abstract

A guard including: a body having an external face and an opposing internal 5 face, and a plurality of replaceable wear elements, each having at least one free end portion, said wear elements being retained in an operative attitude by said body in a manner whereby said free end portions project beyond said external face, said free 10 end portions defining a plurality of tortuous pathways between opposing edge portions of said body. .- Af2

Description

2013245564 21 Oct 2013 P/00/011 Regulation 3.2 Australia

Patents Act 1990

COMPLETE SPECIFICATION STANDARD PATENT

Invention Title: A guard

The following statement is a full description of this invention, including the best method of performing it known to us: ΙΑ 2013245564 21 Oct 2013

A GUARD

This invention relates to a guard that in use is adapted to protect articles to which it is attached against wear, such 5 as wear caused by abrasion due to contact with abrasive materials and as a consequence of friction.

This invention has particular, but not exclusive, application to a guard for a dragline bucket and wherein LO reference will be made to same. However it will be appreciated that the invention may be used in other applications where there is excessive wear as a consequence of contact with particulate materials passing thereover, such as dirt chutes and hoppers, and sugar mill washers. 15

Dragline excavators typically include a dragline bucket system comprising a large bucket which is suspended from a long boom by a plurality of wire ropes. Dragline excavators are used in strip-mining operations to move large quantities 20 of overburden, namely unwanted material lying above mineral deposits in open cut mines. This is achieved by dragging the bucket substantially horizontally over the overburden in a manner whereby some of this unwanted material is collected by the bucket, said material entering the bucket via the bucket's 25 open front end. By skilful operation of the bucket, the waste material contained therein is subsequently dumped on a spoil. This leaves the mineral deposit exposed so that it can be loaded into dump trucks and taken to a Raw Stockpile. 30 Due to the coarse nature of the waste material, the dragging of the bucket over the overburden is typically quite abrasive and whereby as a consequence portions of the bucket that are in contact with said overburden are subject to considerable wear. For this reason portions of the bucket pMIN07101 2 2013245564 21 Oct 2013 that are prone to wear are usually covered by a sacrificial wear component, such as a plate manufactured from hardened steel. These steel wear plates are usually welded to the bucket. 5

When a wear plate requires replacing due to excessive wear, the welds holding the wear plate in place must be gouged away so that the wear affected wear plate may be removed and a fresh wear plate welded in its place. 10

It is estimated that the overhaul of a 90 cubic meter dragline bucket, during which numerous worn wear plates are removed and subsequently replaced by new wear plates, may take four boilermakers, working twelve hours a day, forty-two days 15 to complete. Further, the overhaul of the dragline would typically be undertaken in a workshop located remote from the mine site where the dragline excavator was operating. Consequently, large vehicles are required to transport the bucket to and from the workshop. 20

In order to minimise disruption caused by the overhaul and/or repair of a dragline bucket, operators of the dragline excavator will most likely own two or three dragline buckets with the view that they have a spare bucket to replace the 25 bucket currently in service if required, while the third bucket is currently offsite being overhauled.

It will be appreciated that the costs of overhauling/repairing a dragline bucket are quite 30 considerable, as too is the revenue that is lost due to a cessation of production while buckets are replaced. pMIN'07101 3

It is therefore an object of the present invention to provide a guard which may alleviate at least some of the deficiencies of the prior art and which will be reliable and efficient in use.

With the foregoing and other objects in view, this invention in one aspect relates to a guard including: A body having an external face and an opposing internal face, and A plurality of replaceable wear elements, each having at least one free end portion, said wear elements being retained in an operative attitude by said body in a manner whereby said free ned portions project beyond said external face, said free end portions defining a plurality of tortuous pathways between opposing edge portions of said body.

In one embodiment of this aspect there is provided a guard for a dragline bucket that in use has at least one wear susceptible portion that is subject to wear as a consequence of impact with particulate overburden material, the guard including; a body having an external face that in use comes into contact with particulate overburden material, an opposing internal face and opposing edge portions, and a plurality of wear elements that are replaceable relative to the body, each wear element having at least one free end portion that includes a circumferential flange, the wear elements are retained in an operative attitude by the body in a manner whereby the free end portions project beyond the external face and the wear elements are arranged such that the free end portions of the wear elements define a plurality of tortuous pathways between

3A the opposing edge portions such that in use impacted particulate overburden material builds up between the wear elements so as to at least partially cover the external face of the body and the circumferential flanges are adapted to assist with retention of particulate material.

According to another embodiment there is provided a guard for a dragline bucket that in use has at least one wear susceptible portion that is subject to wear as a consequence of impact with particulate overburden material, the guard including; a body having an external face that in use comes into contact with particulate overburden material, an opposing internal face and opposing edge portions, said body also including a plurality of apertures extending between the external face and the internal face, and a plurality of replaceable wear elements, each retained within a respective one of said the plurality of apertures and whereby a portion of each wear element projects beyond the external face, the wear elements being located between opposing portions of the body and arranged in a manner such that the wear elements define a plurality of tortuous pathways between the opposing portions of the body, wear elements are arranged such that the free end portions of the wear elements each include a circumferential flange and define a plurality of tortuous pathways between the opposing portions of the body such that in use impacted particulate overburden material builds up between the wear elements so as to at least partially cover the external face of the body and the circumferential flanges are adapted to assist with retention of particulate material.

3B

According to a further embodiment there is disclosed a dragline bucket having a body with an outer face and an inner face and least one wear susceptible portion on the outer face, said dragline bucket including: at least one guard as disclosed herein, releasably secured to the outer face.

There is further disclosed a method of extending the working life of a dragline bucket that in use has at least one wear susceptible portion that is subject to wear as a consequence of impact with particulate overburden material, the method including: releasably securing at least one guard as disclosed herein on at least one of the wear susceptible portions and using the dragline bucket in the manner in which it would normally be used such that impacted overburden particulate material shall cover at least a substantial portion of the external face of the body of the at least one guard, the impaction of the particulate overburden material and its retention against the external faces of the at least one body aided by the wear elements, and whereby the impacted particulate overburden material is combination with the at least one guard shall protect the dragline bucket from significant wear arising from use of the dragline bucket.

The body may be substantially plate like and may have any suitable shape. For example, the body may be round, square or polygonal.

Further, the body may be manufactured either entirely or substantially from one material, such as hardened steel. Alternatively, the body may be constructed from two or more materials. For example, the body may comprise a skeleton or 2013245564 02 Aug 2017

3C frame manufactured from hardened steel and may include one or more recesses or such like that are filled with an alternative material, such as aluminium. As a consequence, the composite body may weigh less than a body that is constructed solely or 5 substantially from hardened steel.

The body may include attachment means for facilitating the releasable attachment of said body to a structure, such as a dragline bucket. For example, the attachment means may 10

The rest of this Page is intentionally left Blank 4 2013245564 21 Oct 2013 include mechanical attachment means that is adapted to mechanically engage with the structure, such as one or more tapered keys. Alternatively the attachment means may include a plurality of apertures formed in the body through which a 5 stem of a threaded fastener in use may extend and whereby in some embodiments the apertures may be threaded. Further, there may be provided an enlarged opening or recess associated with each aperture, said enlarged opening being formed in the external face of the body and being adapted in use to receive 10 either a nut or a head of a threaded fastener.

However, it will be appreciated that in other embodiments the body may in use be releaseably secured to the structure using a suitable adhesive or a welding process, (to install a 15 keeper system).

The body may also include retaining means for retaining the wear elements in an operative position relative to the body. For example, in one embodiment the retaining means may 20 include a plurality of apertures through which there may extend a stem of a threaded fastener used to releasably secure the wear element to the body. Alternatively, the retaining means may include an aperture formed in the body through which the free end of the wear element extends and whereby an 25 opposing portion of the wear element may be retained behind said body.

Where the retaining means includes an aperture formed in the body through which the wear element extends, in one 30 embodiment both the aperture and the wear element may be configured such that there will be little, if any, rotational movement of the wear element relative to said body. For example both the aperture and the wear element may each have a pMIN07101 5 2013245564 21 Oct 2013 substantially rectangular shaped cross section and the fit between the two components may be either a close fit or a frictional fit. Further, preferably both the aperture and the wear element include one or more tapered side walls and 5 whereby the wear element in use will be retained within the aperture by friction.

The wear element is preferably manufactured from a material that is harder than the material used in the 10 construction of the body. For example, the body may be constructed from a weldable material, such as mild steel, while the wear elements may be constructed from a heat treated steal of much greater hardness. 15 The wear elements may be any suitable shape. For example, the wear elements may generally have a prismatic shape, such as that of a cylinder. Alternatively, the wear elements may resemble a truncated pyramid, such as a square or round based pyramid. 20

Further, the tip of the free end portion of the wear element may include a barb or a barb like circumferential flange that is adapted to assist with the retention of particulate material between adjacent wear elements and/or 25 between wear elements and an external face of the body. In one embodiment, the barb like circumferential flange may resemble a cap that is placed over the free end portion of the wear element. 30 As stated previously, it is preferred that the pathway between free end portions of adjacent wear elements is a tortuous one. For example, the wear elements may be arranged in rows and within each row adjacent wear elements may be pMIN07101 6 2013245564 21 Oct 2013 equally spaced from one another, but wherein the wear elements of two adjacent rows may be offset such that a wear element of one row is not located directly behind a wear element of an adjacent row. In particular, the orientation, size and 5 proximity to one another of the wear elements will be such that the wear elements collectively will promote "packing", namely the build up therebetween of particulate material, which in turn it is believed will enhance the longevity of the wear components. For example, it is believed that filling the 10 void between adjacent wear elements with particulate material will protect leading portions of these wear elements during subsequent use from direct impact with particulate material.

In another aspect, this invention relates to a guard 15 including: a body having an external face and an opposing internal face, said body also including a plurality of apertures, and a plurality of wear elements each retained within a respective one of said apertures and whereby a portion of each 20 of said wear elements projects beyond said external face, said wear elements being located between opposing portions of said body and arranged in a manner such that said wear elements define a plurality of tortuous pathways between said opposing portions of said body. 25

In still yet another aspect, this invention relates to a structure having at least one wear susceptible portion, said structure including: a body that is releasably secured to the structure so as 30 to cover the wear susceptible portion, said body having an external face and an opposing internal face, said external face forming an external face of the structure, and pMIN07101 7 2013245564 21 Oct 2013 a plurality of replaceable wear elements, each having at least one free end portion, said wear elements being retained in an operative attitude by said body in a manner whereby said free end portions project beyond said external face, said free 5 end portions being located between opposing edge portions of said body and whereby said free end portions define a plurality of tortuous pathways between opposing edge portions of said body. Preferably the structure is a dragline bucket and the wear susceptible portion is a portion of the bucket 10 that under normal working conditions is susceptible to wear due to contact with overburden, such as the external faces of the heal, bottom and side walls of the bucket.

In still yet another aspect, this invention relates to a 15 method of extending the working life of a structure that includes at least one wear susceptible portion that is subject to wear as a consequence of contact with a particulate material, such as overburden; said method including: (a) releasably securing a guard to the structure such 20 that the guard covers the wear susceptible portion, said guard including a body having an external face and an opposing internal face, and a plurality of replaceable wear elements, each having at least one free end portion, said wear elements being retained in an operative attitude by said body in a 25 manner whereby said free end portions project beyond said external face, said free end portions defining a plurality of tortuous pathways between opposing edge portions of said body; (b) using the structure in the manner in which it would normally be used such that impacted particulate material shall 30 cover at least a substantial portion of the external face of the body, the impaction of the particulate material and its retention against the external face of the body being aided by the wear elements, and whereby the impacted particulate pMIN07101 8 2013245564 21 Oct 2013 material in combination with the guard shall protect the structure from significant wear arising from use of the structure . 5 Preferably the structure is a dragline bucket and whereby the guard is employed to extend the operable life of the dragline bucket and/or increase the time between successive overhauls of the dragline bucket. 10 In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate preferred embodiments of the invention and wherein: 15 Fig. 1 is a pictorial view showing the underside of a dragline bucket;

Fig. 2 is a cross-sectional side view of a portion of a guard that is constructed in accordance with the present invention, said guard being secured to a bottom wall of a 20 dragline bucket of the type shown in figure 1;

Fig. 3 is a detailed side cross-sectional view of the guard shown in figure 2;

Fig. 4 is a plan view of a portion of the guard shown in figure 2; 25 Fig. 5 is a plan view showing an alternative pattern of wear elements to that shown in figure 4;

Fig. 6 is a side view of an alternative wear element constructed in accordance with the present invention;

Fig. 7 is a side cross-sectional view of an alternative 30 wear body constructed in accordance with the present invention;

Fig. 8 is a side cross-sectional view of yet another wear body constructed in accordance with the present invention; pMIN07101 9 2013245564 21 Oct 2013

Fig. 9 is a side cross-sectional view of a portion of an alternative guard constructed in accordance with the present invention, and

Fig. 10 is a side cross-sectional view of yet another 5 guard constructed in accordance with the present invention.

Figure 1 shows a typical dragline bucket 300 that is inverted and wherein the bucket includes a bottom wall 301, two opposing side walls 302 that extend upwardly from the 10 bottom wall 301, said side walls and said bottom wall all being connected to a rear wall 303. The bottom wall 301, side walls 102 and the rear wall 303 define an open topped receptacle that further includes an open front end 304, opposite the rear wall 303. 15

The bucket 300 includes three wear susceptible portions that are protected by hardened steel plates that are welded to the bottom wall 301 and the two side walls 302. These wear plates are commonly referred to as heel wear plates 305 and a 20 front heel wear bar 306. The inventor proposes to replace the aforementioned wear plates with a guard of the type shown in figures 2 to 10.

Figures 2 to 4 show a guard 10 that includes a plate like 25 wear body 11 and a plurality of wear elements 12.

The wear body 11 may be constructed from any suitable material, including a material having good wear resistant characteristics, such as a steel material having a hardness 30 between 250 and 300 BN, and may take any suitable shape. For example, if the guard is intended to replace one of the heal wear plates 305, the body may be constructed from a substantially rectangularly shaped piece of steel that has ρΜΓΝ0710Ι ίο 2013245564 21 Oct 2013 been rolled or bent into the "L" shape of the heal wear plate as shown in figure 1.

The wear body 11 includes an external face 13 that in use 5 shall come into contact with overburden, and an opposing internal face 14.

The wear body 11 also includes a plurality of substantially square shaped, wear element apertures 15, each 10 defined by four inclined, interconnected, side walls 16, (see figures 3 and 4) . Further, the enclosed area of the opening formed in the external face 13 is smaller than the enclosed area of the opening formed in the internal face 14 and whereby the taper preferably lies between one degree and four degrees. 15 However, in other embodiments the taper may be reversed and whereby holding bolts that extend through a central portion of each wear element may be employed to retain the wear elements in place. 20 The apertures 15 are preferably arranged in rows 17 and, within each row, the apertures 15 are equally spaced from one another. Further, the apertures 15 of every second row are not located directly behind or in front of adjacent apertures 15 in these rows. As a consequence the apertures 15 in every 25 second row are offset from the apertures 15 contained in adjacent rows 17.

It will also be observed that the orientation of the apertures in every second row differs from the apertures 30 contained in adjacent rows. In the embodiment shown in figures 2 to 4, the apertures contained in the second row appear to have been rotated through an angle of 45 degrees when compared to the apertures contained in adjacent rows. pMIN07101 11 2013245564 21 Oct 2013

The body 11 also includes a plurality of square shaped recesses 18 formed in the internal face 14. The recesses 18 are each coaxial with an associated aperture 15 and whereby 5 each recess includes four inclined, interconnected side walls 19. Further, the taper of these side walls 19 is preferably the same as the taper of the side walls 16.

Each recess 19 also includes a substantially flat 10 enclosed wall 20 that surrounds the opening to the associated aperture 15.

The body 11 further includes attachment means 21 for facilitating the releasable attachment of said body to a 15 structure, such as a dragline bucket 300. The attachment 21 includes mounting apertures 22 extending through the body and whereby the external face 14 includes a plurality of circular shaped mounting recesses 23, each being concentric with an associated mounting aperture 22. The mounting recess is large 20 enough to receive a nut 24 and the head of a socket, (not shown), that may be used to disengage the nut from the threaded stem 25 of a bolt that is used to secure the body 11 to the dragline bucket 300. Further, as can be seen in figure 3, there is a washer 26 located between the nut and a flat 25 wall 27 of the recess.

The wear elements 12 are preferably constructed from a material that is harder than the material that is used in the construction of the body 11. For example, the wear elements 30 may be constructed from a steel material having a hardness in the range of 400 BN to 500 BN. pMIN07101 12 2013245564 21 Oct 2013

Each of the wear elements 12 resemble a truncated, square based, pyramid comprising a base portion 26 and a free end portion 27 interconnected by four inclined side walls 28 and whereby the angle of inclination is the same as the taper of 5 the side walls 16 of the wear element apertures 15.

The aforementioned base portion 26 is integrally connected to a much larger square shaped locking portion 29 and whereby the base portion 26 is adapted to fit frictionally .0 within a respective one of the apertures 15 and the locking portion 29 is adapted to frictionally fit within a respective one of the recesses 18.

In use a plurality of sacrificial wear elements 12 may 15 each be inserted into a respective one of a plurality of apertures 15 such that the tapered side walls 28 of the wear element 12 frictionally engage with the side walls 16 of said aperture 15 of a plate like body 11 having a shape that is adapted to cover a wear susceptible portion of a structure, 20 such as the dragline bucket 300. The wear elements 12 are prevented from rotational movement relative to the body by the aforementioned frictional engagement of the side walls 28 and 16, and by the location of the locking portion frictionally within the recess 18. Further, it will be appreciated that 25 the frictional fits will most likely alleviate any problems that may arise when fitting the body 11 to the structure caused by wear elements 12 becoming detached or separated from the base. 30 The base 11 is secured to a wall of the structure using a plurality of bolts 30 and whereby each bolt includes a nut 24 locatable within a mounting recess 23 and a threaded stem 25 pMIN07l01 13 2013245564 21 Oct 2013 having a free end that is adapted to engage said nut. The opposite end of the stem 25 is attached to a head portion 31.

In use, each threaded stem 24 extends through a mounting 5 aperture 22 and aligned apertures formed in the structure, such as a bottom wall 301 of the dragline bucket 300 and a liner plate 310. Further, the liner plate includes a plurality of recesses each adapted to receive a respective one of the bolt heads 31. 0

It is believed that when the guard is dragged across overburden, particulate material will, due to the tortuous paths existing between adjacent wear elements 12 contained in adjacent rows of wear elements, become trapped there between. 15 Further, it is believed that the layer of impacted particulate material 200 covering the external face 13 of the body 11 will protect the body from wear and shall shield the nuts 24, said layer of impacted particulate material being retained in its operative attitude by the combined effect of the wear elements 20 12.

Figure 5 shows a portion of an alternative guard and whereby the arrangement of wear elements 12 is different to that shown in figure 4. 25

Figure 6 shows an alternative wear element 50. Like the wear element 12, the wear element 50 is preferably constructed from a material that is harder than the material that is used in the construction of the wear body 11. For example, the 30 wear elements 50 may be constructed from a steel material having a hardness in the range of 400 BN to 500 BN. pMIN07101 14 2013245564 21 Oct 2013

The wear element 50 includes a substantially square shaped base portion 51 and a coaxial, substantially cylindrically shaped, free end portion 52 which are interconnected by first and second intermediate portions 53 5 and 54 respectively.

The base portion 51 includes a square shaped external face 55 and an opposing internal face 56, interconnected by four side faces 57. 10

The free end portion 52 includes a circular shaped bottom face 58 and an opposing, circular shaped, top face 59, interconnected by a continuous side wall 60. 15 The first intermediate portion 53 extends upwardly from the face 56 and is coaxial with the base portion 51. The first intermediate portion includes a continuous side wall 61 that is tapered inwardly in the direction away from the base portion 51. 20

The second intermediate portion 54 depends from the bottom face 58 and is coaxial with the free end portion 52. The second intermediate portion resembles a truncated square based pyramid with four substantially rectangular shaped side 25 walls 62 that diverge away from the bottom face 58 and whereby the base of the truncated pyramid sits on top of, and is connected to, a top wall 63 of the first intermediate portion.

Further, the transverse cross-sectional area of the top 30 of the second intermediate portion is less than the transverse cross-sectional area of the free end portion. Consequently, the circumferential edge portion 64 of the bottom face 58 of pMIN0710l 15 2013245564 21 Oct 2013 the free end portion 52 may function in use like a barb behind which particulate material may become trapped.

Figure 7 shows a portion of an alternative wear body 65 5 that is constructed from a suitable material, including a material having good wear resistant characteristics, such as a steel material having a hardness between 250 and 300 BN, and may take any suitable shape. 0 The wear body 65 includes an external face 66, that in use will come into contact with overburden, and an opposing internal face 67.

The wear body 65 also includes a plurality of wear i5 element apertures 68, each having a square shaped recess 69 defined by four, slightly inclined, interconnected, side walls 70 and a coaxial, substantially cylindrical, bore 71 having a slightly tapered, continuous, side wall 72. The bore 71 includes an opening in the internal face 67 that is slightly 20 larger than the opening in the external face 66 and whereby the taper may lie between one degree and four degrees.

The wear element apertures 68 are preferably arranged in rows and, within each row, the apertures 68 are equally spaced 25 from one another. Further, the wear element apertures 68 of every second row are not located directly behind or in front of adjacent wear element apertures 68 in these rows. As a consequence the wear element apertures 68 in every second row are offset from the wear element apertures 68 contained in 30 adjacent rows. A guard of the type shown in figure 9 may be assembled by locating a wear element 50 in each of the wear element pMIN07101 16 2013245564 21 Oct 2013 apertures 68 from behind, as indicated by arrow 75. In this way, the first intermediate portion 53 forms a press fit with the tapered side wall 72 of the bore 71. Likewise, the base portion 51 is located within the square shaped recess 69 and 5 is retained therein by the press fit between the side walls 57 and abutting side walls 70. Further, it will be appreciated that the engagement of the side walls 57 with abutting side walls 70 shall, in use, prevent rotational movement of the wear element about its longitudinal axis relative to the wear 10 body 65.

As shown in figure 9, the second intermediate portion 54 and the free end portion 52 extend outwardly from the external face 66 of the wear body 65. 15

It is envisaged that the wear elements in every second row, when compared with the wear elements in adjacent rows, will be rotated through an angle of 45 degrees. 20 When the wear body 65 is secured to a structure, the base portions 51 of the wear elements 50 will be sandwiched between the structure and the wear body 65.

Figure 8 shows a portion of an alternative wear body 85 25 that is constructed from a light weight material, such as aluminium, and may take any suitable shape.

The wear body 85 includes an external face 86, that in use will come into contact with overburden, and an opposing 30 internal face 87.

The wear body 85 also includes a plurality of wear element apertures 88, each having a square shaped recess 89 pMIN07101 17 2013245564 21 Oct 2013 defined by four, slightly inclined, interconnected, side walls 90 and a coaxial, substantially cylindrical, bore 91 having a continuous side wall 92. 5 The wear element apertures 88 are preferably arranged in rows and, within each row, the apertures 88 are equally spaced from one another. Further, the apertures 88 of every second row are not located directly behind or in front of adjacent apertures 88 in these rows. As a consequence the wear element 0 apertures 88 in every second row are offset from the wear apertures 88 contained in adjacent rows.

Each of the wear element apertures 88 is lined with a steel bush 93 having a substantially square shaped base 15 portion 94 and a substantially cylindrically shaped top portion 95.

The base portion 94 includes an external top wall 96 and four interconnected external side walls 97 that depend from 20 said top wall. The top wall 96 and the four side walls 97 are locatable within the square shaped recess 89, their profile complimenting the shape of the recess 89 and forming with said recess a press fit. 25 The base portion 94 includes a square shaped recess 101 defined by four, slightly inclined, interconnected, side walls 102 .

The top portion 95 includes a continuous external side 30 wall 98 and an upwardly and inwardly tapered internal wall 99 which forms a bore 100 that is coaxial with the square shaped recess 101. The top portion 95 is locatable within the bore 91 and whereby the side walls 92 and 98 preferably form a pMIN07101 18 2013245564 21 Oct 2013 press fit. The taper of the internal wall 99 preferably lies between one degree and four degrees. A guard of the type shown in figure 10 may be assembled 5 by locating a wear element 50 in each steel bush 93 from behind, as indicated by arrow 75'. In this way, the first intermediate portion 53 forms a press fit with the tapered side wall 99 of the bore 100. Likewise, the base portion 51 is located within the square shaped recess 101 and is retained 10 therein by the press fit between the side walls 57 and abutting side walls 101. Further, it will be appreciated that the engagement of the side walls 57 with abutting side walls 101 shall, in use, prevent rotational movement of the wear element about its longitudinal axis relative to the wear body 15 85.

As shown in figure 10, the second intermediate portion 54 and the free end portion 52 extend outwardly from the external face 86 of the wear body 85. 20

It is envisaged that the wear elements in every second row, when compared with the wear elements in adjacent rows, will be rotated through an angle of 45 degrees. 25 When the wear body 85 is secured to a structure, the base portions 51 of the wear elements 50 will be sandwiched between the structure and the wear body 85.

The wear body 65 and the wear body 85 may each be secured 30 to a wall of the structure using a plurality of bolts and whereby each bolt may include a nut locatable within a mounting recess, not shown, and a threaded stem that is ρΜΓΝ07101 19 2013245564 21 Oct 2013 connected to the bolt's head, said stem having a free end that is adapted to engage said nut.

It is anticipated that the embodiments shown in figures 9 5 and 10 will function in a manner similar to the embodiment shown in figures 2 to 5. However, it is believed that by making the body 85 from a light weight material the resulting saving in weight compared to the embodiment shown in figure 9 will mean that the dragline bucket will be able to carry more 10 overburden.

In particular, It is believed that when the guard is dragged across overburden, particulate material will, due to the tortuous paths existing between adjacent wear elements 50 15 contained in adjacent rows of wear elements, become trapped there between. Further, it is believed that the layer of impacted particulate material covering the external face 66 or 86 of the body 65 or 85 will protect the body from wear and shall shield the bolts used to secure the wear body to the 20 structure. Further, it is believed that the somewhat enlarged free end portion will assist with the trapping and retention of particulate material between adjacent wear elements and between the external face 66 or 86 and the free end portion 52. 25

It will be appreciated that the embodiments that are shown in figures 1 to 10 demonstrate one method by which the wear elements may be retained within the body and how the body may be secured to the structure. In alternative embodiments, 30 a retaining plate may be placed between the structure and the body such that the wear elements are sandwiched between the retaining plate and the body. Further, a suitable adhesive or binding agent may be placed between the retaining plate and pMIN07101 20 2013245564 21 Oct 2013 the body such that said adhesive/binding agent shall fill any voids between the wear elements and the body, between the wear elements and the retaining plate and between the body and the retaining plate. The adhesive/binding agent once set will 5 further assist with the retention of the wear elements within respective apertures in the body.

It is further believed that the due to the hardness of the wear elements, these components will be slow wearing in 10 comparison to prior art wear plates. Further, it will be appreciated that when one or more wear elements are damaged or show signs of significant wear, the body may be detached from the structure by unscrewing the nuts 24 thereby allowing the damaged and/or worn wear elements 12 or 32 to be replaced by 15 fresh wear elements.

It is believed that the modular guard 10 and 30 will, due to their construction, provide longer lasting protection for the wear susceptible portions of the dragline bucket and will 20 require less time to maintain.

It will of course be realized that while the foregoing description has been given by way of example of this invention, all other modifications and variations thereto as 25 would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as herein defined in the appended claims. pMIN07101

Claims (14)

1. CLAIMS:

   1. A guard for a dragline bucket that in use has at least one wear susceptible portion that is subject to wear as a consequence of impact with particulate overburden material, the guard including; a body having an external face that in use comes into contact with particulate overburden material, an opposing internal face and opposing edge portions, and a plurality of wear elements that are replaceable relative to the body, each wear element having at least one free end portion that includes a circumferential flange, the wear elements are retained in an operative attitude by the body in a manner whereby the free end portions project beyond the external face, the wear elements are arranged such that the free end portions of the wear elements define a plurality of tortuous pathways between the opposing edge portions such that in use impacted particulate overburden material builds up between the wear elements so as to at least partially cover the external face of the body and the circumferential flanges are adapted to assist with retention of particulate material.
2. 2. The guard of claim 1, wherein the body includes a plurality of apertures and each wear element is retained with a respective one of the apertures.
3. 3. A guard for a dragline bucket that in use has at least one wear susceptible portion that is subject to wear as a consequence of impact with particulate overburden material, the guard including; a body having an external face that in use comes into contact with particulate overburden material, an opposing internal face and opposing edge portions, the body also including a plurality of apertures extending between the external face and the internal face, and a plurality of replaceable wear elements, each retained within a respective one of the plurality of apertures and whereby a portion of each of the wear elements projects beyond the external face, the wear elements being located between opposing portions of the body and arranged in a manner such that the wear elements define a plurality of tortuous pathways between the opposing portions of the body, the wear elements are arranged such that the free end portions of the wear elements each include a circumferential flange and define a plurality of tortuous pathways between the opposing portions of the body such that in use impacted particulate overburden material builds up between the wear elements so as to at least partially cover the external face of the body and the circumferential flanges are adapted to assist with retention of particulate material.
4. 4. The guard of claim 3, wherein the apertures are arranged in rows and the apertures within each row are equally spaced from one another .
5. 5. The guard of claim 3 or claim 4, wherein each aperture is substantially square shaped.
6. 6. The guard of claim 5, wherein the orientation of the aperture in every second row differs from the apertures contained in adjacent rows.
7. 7. The guard of claim 5 or claim 6, wherein each aperture has a substantially square recess formed in the internal face that are each coaxial with an associated aperture and are each defined by four inclined, interconnected side walls.
8. 8. The guard of claim 7, wherein each wear element has a substantially square base complimentary to the recess so as to prevent rotational movement of the wear element relative to the body.
9. 9. The guard of claim 7 or claim 8, wherein each wear element has an intermediate portion intermediate the base and the free end portion that has an external surface complimentary to each aperture .
10. 10. A dragline bucket having a body with an outer face and an inner face and least one wear susceptible portion on the outer face, said dragline bucket including: at least one guard of any one of claims 1 to 9, releasably secured to the outer face.
11. 11. The dragline bucket of claim 10, wherein the dragline bucket body has a plurality of mounting apertures between the outer face and the inner face and the guard is releasably secured to the dragline bucket by a plurality of bolts extending through the mounting apertures.
12. 12. The dragline bucket of claim 10, further including at least one liner plate located on that part of the inner wall that is opposite a guard secured onto the outer wall, the liner plate include mounting apertures coaxial with the mounting apertures through the bucket body each bolt extends into a mounting aperture .
13. 13. The dragline bucket of claim 11, wherein the liner plate includes a recess associated with each mounting aperture for receiving a bolt head.
14. 14. A method of extending the working life of a dragline bucket that in use has at least one wear susceptible portion that is subject to wear as a consequence of impact with particulate overburden material, the method including: releasably securing at least one guard of any one of claims 1 to 9 on at least one of the wear susceptible portions and using the dragline bucket in the manner in which it would normally be used such that impacted overburden particulate material shall cover at least a substantial portion of the external face of the body of the at least one guard, the impaction of the particulate overburden material and its retention against the external faces of the at least one body aided by the wear elements, and whereby the impacted particulate overburden material is combination with the at least one guard shall protect the dragline bucket from significant wear arising from use of the dragline bucket.