FIELD OF THE INVENTION The present invention relates to wear plates of the type used as a sacrificial lining or surface on heavy equipment, and particularly (although not exclusively) in the field of mining and quarrying.

BACKGROUND TO THE INVENTION

Mining and quarry operations requires thousands of tons of abrasive and heavy rock material to pass through chutes on the way to processing crushers. The impact and wear of the rock material results in extensive damage to the chute walls in a short time. While such chutes may be fabricated with very thick walls, when the wear becomes excessive the operation of the processor must be halted while the expensive, time consuming and arduous repair or replacement efforts are undertaken.

Various attempts have been made to protect rock-contacting surfaces of chutes and other items of mining equipment in an effort to avoid the need to replace an entire part due to the inevitable damage. For instance, the prior art provides wear elements that can be secured to the surface of mining equipment to protect that surface. However, many of these elements are welded or bolted on to the surface of the equipment and can be difficult to replace once worn through. In wear elements which have bases and attachable wear plates, when the abrasive wear plate is worn, the engagement means securing the base to the surface is often also damaged, which requires that the entire base be ground or cut off and replaced.

A further problem of the prior art is that where the engagement means is a bolt, a nut must typically be used on the reverse side of the wear plate to prevent loosening the bolt. This requires the wear element installer to have clear access to both sides of the wear plate such that rotation of the bolt can be prevented while the nut is tightened. In some circumstances, it is impossible to access both the front (lining) side of the wear plate and also the rear side. For example, a chute used to convey mined rock may be of solid concrete construction, there being no means by which a bolt may be applied from the rear of the rock contact face of the chute.

Even where rear access is provided, the need to access from and rear surfaces complicates installation of a wear plate. Another problem is that some means for engaging a wear element do not allow for the complete wearing of the element. Accordingly the wear material of the element is not completely sacrificed before the element is replaced, this being economically wasteful.

It is an aspect of the present invention to overcome or alleviate a problem of the prior art by providing an improved system for attaching a wear element to heavy equipment. It is a further aspect to provide an alternative to prior art building systems for attaching a wear element to heavy equipment.

The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

SUMMARY OF THE INVENTION In a first aspect, the present invention provides a wear element assembly comprising: a wear element comprising an aperture, a fastener configured to be inserted into the aperture of the wear element and also an aperture of a substrate underlying the wear element such that when the fastener is inserted into the wear element aperture and the substrate aperture, a first surface of the fastener contacts a wear element aperture wall and a substrate aperture wall and a space is formed (a) between a second surface of the fastener and the wear element and substrate aperture walls or (b) between the fastener and another structure within the wear element or substrate apertures, and urging means configured to be inserted (a) between the second surface of the fastener and the wear element and substrate aperture walls, or (b) between the fastener and another structure within the wear element or substrate aperture, or (c) within the fastener, wherein, in use, the urging means exerts a force against the second surface of the fastener to urge the first surface of the fastener to frictionally engage with the wear element and substrate aperture walls.

In one embodiment, the wear element assembly comprises two fasteners, the two fasteners configured such that when inserted into the aperture and the fasteners contact an aperture wall, a space is formed between the fasteners, and the urging means is configured to be inserted between the two fasteners, wherein, in use, the urging means urges the fasteners to frictionally engage with the aperture wall.

In one embodiment the upper region at least of the fastener(s) is/are fabricated from a material the same or similar to that of the wear element.

In one embodiment the upper region of the fastener(s) is/are fabricated from a material that wears at a similar rate to that of the wear element. In one embodiment the fasteners are substantially a mirror image of each other.

In one embodiment each of the two fasteners is substantially wedge-shaped.

In one embodiment the fastener surfaces forming the space between the two fasteners are substantially planar.

In one embodiment the fastener surfaces forming the space between the two fasteners are substantially parallel. In one embodiment the fastener(s) has/have a protuberance extending from a lower region, the protuberance configured to engage with a substrate to resist removal of the fastener(s) from the aperture.

In one embodiment the fastener(s) is/are configured such that upper surface of the fastener(s) is/are substantially flush with the surrounding upper surface of the wear element.

In one embodiment the upper region of the fastener(s) is/are configured to extend superior to the surrounding upper surface of the wear element. In one embodiment the upper region of the fastener(s) is/are configured to block or divert rock travelling over the upper surface of the wear element.

In one embodiment the urging means is fabricated from a resiliently deformable material. In one embodiment the urging means comprises a protuberance extending from a lower region, the protuberance configured to engage with a lower external surface of the fastener. In one embodiment the aperture has a tapered upper region.

In one embodiment the tapered upper region of the aperture is not of round cross-section. In one embodiment the tapered upper region of the aperture has an internal corner in cross- section.

In one embodiment the tapered upper region of the aperture is generally triangular, square, rectangular, pentagonal, hexagonal, octagonal, round or ovoid in cross-section.

In one embodiment the tapered upper region of the aperture is generally square or rectangular in cross-section, two opposing sides of the square or rectangular are tapered, and the remaining opposing sides being non-tapered. In one embodiment the upper region of the fastener(s) has/have a thickness equal to or greater than the thickness of the wear element such that the wear element can be substantially or completely worn before the upper region of the fastener is substantially or completely worn. In another aspect the present invention comprises a fastener configured to secure a wear element to a substrate, the fastener comprising a tapered surface and an opposing untapered surface of an upper region, the tapered surface configured to be urged against an aperture wall of a wear element, the untapered surface configured to be urged by an urging means.

In one embodiment the fastener has a protuberance extending from a lower region, the protuberance configured to engage with a substrate to resist removal of the fastener(s) from the aperture. In one embodiment the upper region at least of the fastener is fabricated from a material the same or similar to that of a wear element.

In one embodiment the upper region of the fastener wears at a similar rate to that of a wear element. In one embodiment the wear element comprises an aperture adapted to receive a fastener, the aperture having a tapered upper region.

In one embodiment the tapered upper region of the aperture is not of round cross-section.

In one embodiment the tapered upper region of the aperture has an internal corner in cross- section.

In one embodiment the tapered upper region of the aperture is generally, square, rectangular, pentagonal, hexagonal, octagonal, round or ovoid in cross-section.

In one embodiment the tapered upper region of the aperture is generally square or rectangular in cross-section, two opposing sides of the square or rectangular are tapered, and the remaining opposing sides being non-tapered.

In a further aspect, the present invention provides a kit for fastening a wear element to a substrate, the kit comprising at least one or two fasteners as described herein and an urging means. In one embodiment of the kit the urging means is fabricated from a resiliently deformable material.

Yet a further aspect of the present invention provides a method of securing a wear element to a substrate, the method comprising the steps of locating the wear element as described herein about a substrate, and securing the wear element to the substrate using the fastener as described herein.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 A is a plan view of a preferred wear plate assembly of the present invention. The upper two apertures of the wear plate have fasteners inserted therein, while the lower two are empty, awaiting the insertion of fasteners.

Fig. 1 B is a cross-sectional view through the line A-A' of Fig. 1 A. Fig. 2A is a plan view of a preferred assembly of the present invention, although devoid of the wear plate and fastener to more clearly show the structures in the assembly which are not configured to wear, and upon which the wear plate is secured. Figs. 2B and 2C are cross-sectional views through the lines B-B' and C-C of Fig. 1 A.

Fig. 3A shows a fastener of the present invention having an extended upper region. This type of fastener is used in the assembly shown in Fig. 1 A and 1 B (left hand embodiments, the fasteners marked 20).

Fig. 3B shows a fastener of the present invention, having an upper region designed to be flush with surrounding wear plate fastener. This type of fastener is used in the assembly shown in Fig. 1 A and 1 B (right hand embodiments, the fasteners marked 18). Fig. 3C shows an urging means having protuberances from the lower region.

For each of Figs 3A, 3B and 3C, the drawings shown on the right hand side have been rotated 90 degrees from the drawings shown on the left hand side of the page.

DETAILED DESCRIPTION OF THE INVENTION

After considering this description it is apparent to one skilled in the art how the invention is implemented in various alternative embodiments and alternative applications. However, although various embodiments of the present invention is described herein, it is understood that these embodiments are presented by way of example only, and not limitation. As such, this description of various alternative embodiments should not be construed to limit the scope or breadth of the present invention. Furthermore, statements of advantages or other aspects apply to specific exemplary embodiments, and not necessarily to all embodiments covered by the claims.

Throughout the description and the claims of this specification the word "comprise" and variations of the word, such as "comprising" and "comprises" is not intended to exclude other additives, components, integers or steps.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. The present invention is predicated at least in part on Applicant's discovery that insertion of a fastener and an urging means into a wear plate aperture is capable of securing the wear plate to a substrate, and without the need for access to the rear of the wear plate or any structure behind the wear plate including the structure upon which the wear plate is mounted. In a first aspect, the present invention provides a wear element assembly comprising: a wear element comprising an aperture, a fastener configured to be inserted into the aperture of the wear element and also an aperture of a substrate underlying the wear element such that when the fastener is inserted into the wear element aperture and the substrate aperture, a first surface of the fastener contacts a wear element aperture wall and a substrate aperture wall and a space is formed (a) between a second surface of the fastener and the wear element and substrate aperture walls or (b) between the fastener and another structure within the wear element or substrate apertures, and urging means configured to be inserted (a) between the second surface of the fastener and the wear element and substrate aperture walls, or (b) between the fastener and another structure within the wear element or substrate aperture, or (c) within the fastener, wherein, in use, the urging means exerts a force against the second surface of the fastener to urges the first surface of the fastener to frictionally engage with the wear element and substrate aperture walls. .

In prior art systems for securing of a wear plate to an underlying structure requiring sacrificial protection, it is typically necessary for the insertion of a bolt through the wear plate and through the underlying structure. Generally, a nut is applied to the terminus of the nut and tightened. The present invention is a significant departure from such systems by avoiding the need for a bolt (or similar fastening means), and therefore the need to secure the bolt by application of a nut (or similar) on the reverse side. Avoidance of a bolt further allows for more complete wearing of the wear plate before changing of the plate is required and also the complication which arise where a bolt is along with the wear plate in use.

The fastener may be configured or dimensioned in any way to provide for the required engagement with the wear element aperture and a substrate aperture. Similarly, the urging means may be configured or dimensioned in any way so as to provide the required force to urge the fastener into engagement with the wear element aperture. Typically, the fastener has a wall which is configured so as to properly contact the wall of the aperture to thereby provide for significant engagement (such as frictional engagement) between the two components. Where the fastener wall is configured to contact a planar surface, the fastener surface is typically planar. Where the fastener wall is configured to contact a curved surface, the fastener surface is typically curved accordingly.

The urging means may be any means capable of urging the fastener firmly against the aperture wall. The urging fastener may be substantially non-deformable, and may be a wedge-shaped steel element configured to be forcibly inserted in a space formed between a rear face of the fastener and the aperture wall (or other structure within the aperture), with driving of the wedge into the space forcing the front face of the fastener against a wall of the wear element aperture. As another example, the urging means may be a liquid or a gel which is disposed between the fastener and the aperture wall (or other structure within the aperture), and which expands upon curing to urge the fastener against the aperture wall.

In a preferred embodiment, the urging means is a resiliently deformable material which may be configured to be compressed during insertion of the fastener, and then expands once the fastener is in place. Such materials are well known to the skilled artisan and include rubberized materials, compressible cellular materials, foam-like materials, and the like. Where the urging means is a resiliently definable material, the means may be a generally sheet-like in form configured to make broad contact with a face of a fastener. The urging means may further comprise a protuberance (which is typically integral to the means) configured to extend about a lower surface of fastener thereby providing some resistance to pulling out.

While the assembly may have a single fastener, it is more typical that two fasteners are used with the urging means interposed between the two fasteners such that the means urges the fasteners away from each other and toward opposing walls of the aperture. In such embodiments, the fasteners may be mirror images of each other.

In some embodiments, three, for five, six, seven or eight fasteners are included in the assembly. Where greater that two fasteners are used, the fasteners when correctly disposed define a central space into which an urging means may be disposed. The urging means (and there may be multiple urging means) in such embodiments urge the fasteners against the aperture walls. In some embodiments, at least the upper regions of the fastener(s) (and in some case the entirety of each fastener) is fabricated from a material having a similar hardness, or wears at a similar rate to the material of the wear element. Typically, the fastener(s) are fabricated at least in part from the same material as the wear element.

The fastener(s) of the assembly is/are wedge-shaped in some embodiments. Preferably, the wedge-shaped fasteners have an internal angle of 90 degrees. Thus, where two wedge- shaped fasteners are used, two substantially parallel faces may oppose while the adjacent faces of each fastener face outwardly and toward tapered walls of the aperture.

The fastener(s) may have one or more protuberance which act to secure the fastener(s) in place, and therefore secure the wear element in place. The protuberances may be configured to engage under on into a structure of the aperture to provide resistance from pulling out. Where two fasteners are used, the protuberances may generally extend in opposing directions, and generally from a lower region of each fastener.

The upper region(s) of the fastener(s) may be configured so as to sit substantially flush with the upper surface of the wear element. In some embodiments, the upper regions of the fastener(s) extend significantly above the upper surface of the wear element.

In one embodiment, the aperture is of cross-section which is not round. Furthermore, the upper region of the fastener is not round in some embodiments. Avoidance of a round aperture and/or avoidance of a round fastener upper region prevents (or at least limits) rotation of the fastener within the aperture.

In another embodiment, the aperture is of cross section which is round. Such embodiments may be useful for fastening wear elements to existing chutes, which typically have pre- existing round apertures and/or depressions configured to receive prior art wear plate fasteners (which are typically round). In embodiments having a round aperture, there may be no requirement for a backing plate (marked as 24 in the drawings) and/or the spacer plate (marked as 26 in the drawings) given that round fastener(s) (which are configured to be inserted in the round aperture of the wear element) may be capable directly engaging with structures already present in a chute. Indeed, the backing plate and/or spacer plate may not be required where the structure to which the wear element is secured to an underlying structure which is constructed so as to engage with a rectangular, square or any other shape of fastener/aperture combination.

Preferably the aperture has two opposing tapered walls, and two opposing non-tapered walls. Typically the aperture is square or rectangular in this arrangement. Apertures having non-tapered wall(s) provide for greater resistance to rotation of the fastener. As will be appreciated, the head region of the fastener in such embodiments will has non-tapered wall(s) to abut the non-tapered wall(s) of the aperture. The very tight nature of the coupling between the fastener and the wear element (and therefore the substrate and the wear element) is of significant advantage in the present applications given the significant forces acting on a wear element subject to constant abrasion and impact of rock during service. The coupling between the tapered surfaces of the aperture and the fastener is improved where the taper angle is not equal. It is preferred that the taper angle of the fastener upper region is slightly smaller than the taper angle of the aperture, this allowing a more complete seating of the fastener into the wear element aperture. In one embodiment, the taper angle of fastener upper region is between about 0.5 degrees to about 5 degrees smaller than the taper angle of the wear element apertures. More preferably, the angle is about 2 degrees smaller.

Suitable taper angles for the wear element aperture may be about 1 19 degrees, with the taper of the fastener head region being about 1 17 degrees. Other taper angles of about 1 10, 1 15, 120, 125, 130, 135, 140, 145, 150, 155 or 160 degrees are further contemplated to be useful in some applications.

As used herein, the terms "upper" when used in respect of wear elements and fasteners is intended to mean in the direction of the sacrificial surface. For example, for a wear element, the upper surface is that which is intended to contact rock passing over the wear element. The taper of the tapered region is broad toward the upper surface of the wear element, narrowing toward the lower surface of the wear element. Where the wear element is a wear plate, the lower surface is that which abuts the substrate. Similarly, the upper region of a fastener is that region which (in use) is about the upper surface of the wear element.

The upper region of the fastener may be fabricated from a material that wears at a similar rate to that of the wear element. Thus, where the upper surface of the fastener is exposed to rock or other abrasive material, the upper region of the fastener is sacrificed in a similar way to the surrounding upper surface of the wear element. In that way, the wear surface (being comprised of the upper surface of the wear element and the upper surface of the fastener) wears evenly, with the upper surface of the fastener region being substantially flush with the upper surface of the wear element.

In some embodiments, the upper region of the fastener is configured to extend superior to the surrounding upper surface of the wear element. The superior portion of the fastener may be generally block shaped, wall shaped, dome shaped, pyramidal, or any other geometry considered useful by the skilled person. In such cases the extended upper region may be fabricated from a material that wears at a similar rate or a lesser rate to that of the wear element. It will be appreciated that where the fastener upper region extends above the wear element upper surface, significantly greater forces may be encountered given the greater opportunity for collision with rocks travelling over the wear element.

The use of an upper region extending superior to the surrounding upper surface of the wear element allows for the disposition of barriers, walls, channels and other structures on the wear element surface. For example, extended upper regions of a plurality of fasteners may form two parallel walls along the longitudinal edges of a chute. The walls may be capable of preventing (or at least limiting) the loss of rock over the edge of the chute. Alternatively, converging walls may be established to channel rock toward the centre of the chute. Given the benefit of the present specification, the skilled person is enabled to define wall dimensions suitable for a given application. In some embodiments, the wall may be at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90 or 100 cm high. In terms of wall thickness, this will typically be a function of height (a greater wall height requiring a greater wall thickness). In some embodiment, the wall thickness is at least about 20, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 35, 37, 38, 39 or 40 cm.

The fastener(s) may be fabricated from any material capable of resisting wear or capable of wearing at a desired rate. For example, where the upper region comprises a wall a very hard steel such as high carbon steel (600 grade, for example) may be used. The hardness of the wall significantly limits wear of the wall, and may act to limit the ability of rocks to contact the main wear surface. Any wear element, or part of a wear element, fastener, or part of a fastener required to have a particular hardness, a material having a Brinell hardness of at least about 100, 150, 200, 250, or 300 HB may be used. Preferably, the material has a Brinell hardness of at least about 300 HB.

It is contemplated that fastener or unitary construction may be cast, moulded, stamped, forged or otherwise formed from a single material. Composite constructions are also contemplated, however. For example, in come embodiments the urging means is integral with a fastener, and so a fastener may be comprised of both steel and a resiliently deformable material. In one embodiment, the upper region head region of the fastener(s) may have a depth equal to, or preferably greater, than the thickness of the wear element. By this arrangement, the wear element can be substantially or completely worn before the fastener upper region is substantially or completely worn. This embodiment provides that all, or substantially all, of the wear element is worn down without the wear element being dislodged from the substrate. In prior art wear plate assemblies, at least part of the bolt fastening the plate to the substrate is disposed within the sacrificial material of the wear plate. Accordingly, where the sacrificial material is worn too far the ability of the bolt to secure the plate is compromised and the plate may dislodge from the substrate. Accordingly, it is standard practice in the art to avoid that situation and to replace a wear plate when some sacrificial material is remaining. The present invention avoids the waste associated with that approach of the prior art.

In another aspect, the present invention provides a fastener configured to secure a wear element to a substrate, the fastener comprising a tapered surface and an opposing untapered surface of an upper region, the tapered surface configured to be urged against an aperture wall of a wear element, the untapered surface configured to be urged by an urging means.. In one embodiment, the fastener is configured so as to be operable as a fastener is any wear element assembly as described herein. The fasteners of the present invention may have any one or more of the features as discussed herein with reference to the assembly, with such features expressly incorporated at this point of the specification in connection with the fasteners.

In another aspect the present invention provides a wear element (such as a wear plate) having an upper region which is tapered. The wear elements of the present invention may have any one or more of the features as discussed herein with reference to the assembly, with such features expressly incorporated at this point of the specification in connection with the wear elements. Another aspect of the present invention provides a kit of parts comprising any one or more components of the assembly, viz: the wear element and/or the fastener(s), and/or the urging means. The present kits may further comprise instructions (in video, printed, graphical, or audio form) to assemble the kit component(s) into an assembly as described herein.

In another aspect, the present invention provides a method of securing a wear element to a substrate, the method comprising the steps of locating the wear element as described herein about a substrate, and securing the wear element to the substrate using the fastener as described herein. Typically, a single fastener is inserted through the wear element aperture and through the substrate aperture, with the urging means being co-inserted, or separately inserted. Where two fasteners are used, the first fastener may be co-inserted with the urging means and then the second means being forcefully inserted (assisted by the use of a hammer, for example) thereby compressing the urging means until the two fasteners and the urging means and the aperture walls are frictionally engaged so as to secure the wear element about the substrate.

The present invention will now be further described by way of the following non-limiting preferred embodiments.

PREFERRED EMBODIMENT OF THE INVENTION

Turning to the Figures, in Fig. 1 A there is generally shown a plan view of a wear plate assembly 10 comprising a wear plate 12, having a total of four apertures 14. The two upper apertures 14 are shown having fasteners inserted therein, while the two lower apertures 14 are empty, and ready for fasteners to be inserted therein. Each aperture 14 is generally rectangular and has opposing tapered walls 16 (not visible in the two upper apertures). The remaining opposing walls of the aperture (not marked) are not tapered.

Two types of fasteners are shown. The first type of fastener has an upper region 18 of low profile, while the second type has a walled upper region 20 extending above the upper surface of the wear plate 12. For each aperture, there are two fasteners which together act to engage with the underlying substrate and also the wear plate.

Fig. 1 B is a sectional view through the line A-A' of Fig. 1 showing more clearly the mechanism by which the wear plate 12 is secured to a chute wall 22 in need of the sacrificial protection. A backing plate 24 (fabricated from mild or hardened steel plate) is welded to a spacer plate 26 (fabricated from mild steel plate), both being permanently attached (by bolting or welding) to the chute wall 22, thereby forming a substrate upon which the wear plate 12 is mounted. In use, the backing plate 24 and spacer plate 26 do not wear, with the wear plate 24 intended to be changed before the backing plate 24 is exposed to rock.

It will be noted that the spacer plate 26 comprises elongate depressions, which form the aperture floor and walls. The backing plate 24 forms protrusions 30 extending over the underlying depression in the spacer plate 26.

Urging means 31 is a resiliently deformable polymer disposed between the paired fasteners 18 and 20. It will be noted that the urging means 31 has protuberances 31 A which sit under the paired fasteners 18 and 20. For the extended fasteners 20, a plate 33 is inserted between the fasteners. The plate 33 is fabricated from the same material as the fasteners 20.

Fig. 2A shows a plan view of an empty aperture 14, and without any wear plate in place. Thus, the backing plate 24 is exposed. The protrusions 30 (the limits defined by the dashed outline) extend over the short edges of the depression 28, but not over the long edges.

Fig. 2B is a cross-sectional view taken through the long axis of the depression 28 through the line B-B' of Fig. 3A, showing the protrusions 30 over the short edges. Also shown are the rounded corners formed at the intersections between the walls and floor of the depression on the long axis.

Fig. 2C is a cross-sectional view taken along the short axis of the depression 28 along the line C-C of Fig. 3A. It will be noted that the backing plate edge 24 is flush with the underlying depression wall. It will be further noted that squared corners are formed at the intersection with the depression wall with the floor.

Referring back now to Fig. 2 the relevance of the protuberances 29 protrusions 30 will be apparent in light of their function for the engagement of the paired fasteners 18, 20. In particular, it will be noted that the protuberances 29 extending from the lower regions of the fasteners 18, 20 act to insert under the protrusions 30 formed by the backing plate 24. Given that the upper region of the fasteners 18, 20 are tapered so as to frictionally engage the tapered walls of the aperture 14 of the wear plate 12, the protrusions also serve to secure the wear plate 12 to the backing plate and spacer plate, and in turn to the underlying chute wall 22. Thus, the wear plate can wear down, but remains engaged given the complementarity of the tapered regions of the wear plate aperture 24 and the fasteners 18, 20.

It will be appreciated from Fig. 3 that the two fasteners 18, 20 must be dimensioned such that they can inert into the aperture 14 and depression 28, but then urged away from each other such that the protuberances 29 insert under the protrusions 30. This urging is provided in this preferred embodiment by a resiliently deformable rubberized polymer 31 disposed between the paired fasteners 18, 20. When installed between the fasteners, the polymer urging means 31 is in a compressed state and thus in the uncompressed state the urging means 31 has a depth which is greater than the space formed between the two fasteners when each fastener is abutted against the protrusions 30 of the backing plate 24. The protuberances 31 A are configured so as to resist pulling out from between the space formed by the two fasteners. As will be appreciated (and particularly in relation to the low profile embodiment shown on the right hand side of Fig. 2) the urging means 31 is directly exposed to rock moving over the surface of the wear plate 12 and is therefore prone to dislodgement. If dislodged, the urging of the fasteners 18, 20 against the aperture 14 and depression 28 is lost, and the fasteners will become loose. Upon loosening, the fasteners may fall out of the depression 28 and therefore fail to maintain the wear plate in position.

The protuberances 31 A are further configured such that the urging means 31 is nevertheless intentionally removable by a user when the wear plate is substantially worn and the fasteners 18, 20 need be removed to allow installation of a fresh wear plate. The dimensions of the protuberances 31 A of the urging means 31 may be adjusted in order to achieve a balance between the need for the urging means 31 to remain in place during passage of rock over the wear plate 12 surface, and the need to be intentionally removable by a user.

For the embodiment where the upper region of the fasteners provides for a walled portion extending above the upper surface of the wear plate 12 (see the left hand embodiment of Fig. 1 B) the urging means 31 may extend upwardly only so far as level of the surface of the surrounding wear plate 12. A plate 33 may be interposed between the fasteners 20 to provide a flush upper surface of the fasteners 20, this lessening the opportunity for rock to enter the space and dislodge the fasteners 20. The plate 33 is fabricated of hardened steel so as to have the same wear characteristics as the fasteners 20. Fig. 3 shows more clearly the fasteners of this embodiment. Fig. 4A shows one of the pair of fasteners 20 having a walled extension of the upper region (shown installed in Fig. 2, left hand side), while Fig. 4B shows the lower profile version (shown installed in Fig. 2, right hand side). Both versions have a tapered face 50, and an opposing non-tapered face 52. Fig. 3C shows the protuberances 31 A of the urging means.

While the present invention is described mainly by reference to the attachment of a wear plate onto a chute, it will be appreciated that this is not intended to limit the ambit of this application.

It should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof, for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as falling within the scope of the invention. For example, components and functionality may be added or deleted from diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.