GB2482516A

GB2482516A - Tool coupler with wear indicators.

Info

Publication number: GB2482516A
Application number: GB1013156.3A
Authority: GB
Inventors: Gary Miller
Original assignee: Miller International Ltd
Current assignee: Miller International Ltd
Priority date: 2010-08-04
Filing date: 2010-08-04
Publication date: 2012-02-08
Anticipated expiration: 2030-08-04
Also published as: GB201013156D0; GB2516381A; GB2482516B; GB201414977D0; WO2012017192A1

Abstract

Coupler for attaching a tool to an excavator where the coupler has wear indicators 44/46. The coupler has a first half (12, fig 1) for attachment to an excavator and second half (18, fig 1) for attaching an accessory to the coupler. The erosion indicator 44may be on a surface of the coupler which engages against or faces an attachment pin 24. The wear indicator may be a protrusion 46 extending out of a surface of the coupler or can be cut 46 into the coupler. The indicator may be on a surface of a hook, latch or jaw of the coupler.

Description

Wear Indicators for a Coupler for an Excavator The present invention relates to wear indicators for couplers as used for attaching accessories to an arm of an excavator. Such wear indicators allow an operator easily to determine when the serviceable parts of the coupler may need to be replaced.

Couplers for connecting accessories, such as buckets, to the arm of an excavator are well known. Such couplers comprise a number of moveable parts, at least one of which will be for engaging with or against an attachment pin provided on the accessory. The couplers are also typically attached to the free end of the arm of the excavator by two further attachment pins. They extend through holes in the free end of the arm of the excavator and also through two matching pairs of holes in the top half of the coupler.

Since the coupler will typically be manufactured to fit onto a specific excavator, the positional tolerances of the two matching pairs of holes in the top half of the coupler can be relatively precise, for aligning with corresponding holes in the free end of the arm of the excavator, whereby the two attachment pins used to attach that coupler to the free end of that arm can be engaged through those holes with a relatively tight fit.

This is turn means that there will be only a minimal amount of relative movement between the attachment pins, the pairs of matching holes in the coupler and the two holes in the arm of the excavator. The coupling of the accessory to the coupler, however, is different: The accessory to be coupled to coupler might be an accessory for a different brand of excavator. That is because couplers of this type typically are relatively universal -they can couple onto accessories with a range of different pin spacings (the distance between the axes of the two attachment pins of the accessory). As such, the pin spacing of the accessory, or the diameter of the pins themselves, might not correspond to the distance between the holes in the free end of the arm of the excavator (or the diameter of those holes. The "universal" couplers, therefore, do not use fixed pin holes for attaching the accessory thereto. Instead it uses jaws with a size, shape or orientation suitable for accommodating the range of different pin spacings (or pin diameters). Then, to physically attach the accessory into those jaws, these so-called universal couplers will generally have a number of moving parts to allow a latch to adjustably latch against at least one of those pins for locking that pin within the jaw.

Due to the adjustability of these movable parts, or the somewhat universal nature of the jaws, however, there will inevitably be an absence of a tight, surrounding fit between the retained pin and the jaw. That in turn allows the or each pin in the bottom half of the coupler (i.e. the one(s) in the jaw(s)) to move to a greater degree relative to the jaw(s)/latch(es) than the corresponding pins in the matched pairs of holes in the top half of the coupler. That additional movement will in turn impose additional service loading onto the jaw(s) or latch(es), whereupon there will be a relatively increased degree of wear on those components compared to the matched pairs of holes in the top half of the coupler, yet the adjustable nature of the latch(es) can hide that potentially high degree of wear since the latch(es) can be driven further across the jaw(s) to compensate for the wear.

The knowledge that couplers ultimately wear out, and thus that they need to be serviced to replace worn components, is recognised in the art, and thus many operators would tend to have their couplers serviced at predefined intervals. However, it is not always easy to track which machines have been exposed to the most high-wear operations. Therefore, a regular service interval might become inappropriate where a particular coupler has been exposed to a significant amount of high-wear usage. An operator, however, could easily fail to recognise this, whereupon a coupler could be worn beyond a safe working condition.

Once such safety concern is the fact that the geometry of the coupler changes as components such as the larch/hook or jaws wear down, and that change in geometry can change the loading characteristics on the various components within the coupler.

For example, where a pivoting latching hook is provided for the rear jaw, that pivoting latching hook will experience significant loadings during use of the coupler, such as during digging operations where a bucket is attached to the coupler. With a non-worn coupler, the geometry of the coupler is designed such that those loadings on that hook are designed to be borne primarily by the hook's pivot axle. This is so that the hydraulic cylinder used to drive the pivoting latching hook into a latching position against the bucket's rear accessory pin is not itself overloaded by those digging forces. After all, an overload of the hydraulic cylinder can burst that hydraulic cylinder, and thus lead to a failure of the coupler. This geometry is achieved by having the pin bear against the pivoting latching hook on a lower face of that hook -a pin engaging surface that lies beyond the throat of the hook, rather than on the main shaft of that hook -the pin facing surfaces that occupy the extent of the hookf from the elbow towards the pivot axle of the hook. That distal location of the pin engaging surface of the hook allows the reaction forces arising from the digging operations to be angled away from the axis of the hydraulic cylinder, thereby being borne primarily by the pivot axle of the hook, rather than by the hydraulic cylinder. However excessive wear to either the hook or to the jaw can cause that geometry to change since the hook will be powered into a more rearward condition to compensate, whereupon the pin engaging surface can change its position relative to the throat of the hook, and even pass through that throat to the main shaft of the hook. That in turn changes the loading characteristic of the hydraulic cylinder.

The present invention therefore seeks to provide some form of a wear indicator for a coupler to allow an operator to determine visually whether a servicing of the coupler is required so as to prevent the components from wearing beyond a safe working condition, and so as to prevent too large a change in the geometry of the coupler from occurring. The present invention also seeks to avoid the problem of an operator accidentally allowing a high-usage coupler from exceeding safe wear levels, and secondly to avoid the problem of providing premature servicing to merely part-worn elements -such servicing, after alt, results in unnecessary downtime.

According to the present invention, there is provided a coupler for coupling an accessory to excavator, the coupler comprising a frame with a first half for attachment to the excavator and a second half for attachment to an accessory, the coupler comprising at least one wear indicator provided in or on or behind an attachment pin facing surface of the coupler.

Preferably the wear indicator is provided in or on a surface of the coupler that is adapted to engage against, or to face, an attachment pin. Alternatively the wear indicator can be located behind the pin facing surface, such as in or on a surface that extends from that pin facing surface. Preferably that surface lies perpendicular to the pin facing surface. By "close" we are referring to a distance corresponding to the allowable degree of wear for that surface.

Preferably the coupler is attached to an arm of an excavator, and preferably the first half is a top half of the coupler and the second half is a bottom half of the coupler.

Preferably the wear indicator is moulded onto the surface of the coupler, and preferably that surface is one that is to face the accessory pin once the coupler is in engagement with the accessory pin.

Alternatively, the wear indicator may be cut or etched into the surface of the coupler, that surface preferably being close to a pin facing surface.

The wear indicator may be formed, cut, etched or attached into or onto the surface of the coupler.

The wear indicator will typically be within 3 to 9mm of the pin facing surface.

Preferably the wear indicator provides a protrusion extending out of the surface of the coupler. Where that surface is the pin facing surface of the coupler, such as within a jaw off the coupler, or on a latch of the coupler, that projection will generally be for bearing against the attachment pin in use. That protrusion will then be worn down by the accessory pin as the coupler/excavator/accessory is used. Then, upon wearing that protrusion down to it being generally flush with the surface from which it projected, the operator will know that that worn component will have exceeded its serviceable life.

The degree of wear that can be tolerated, and thus the height of the protrusion, the depth of the cut, or the closeness of the wear indicator to the pin facing surface, can be governed by the degree of wear that would be acceptable without the thickness of the remaining component compromising that component's safe usability (either as a factor of the component's remaining strength or in terms of its capability to fit with the attachment pins of the accessory).

Preferably the height, depth or closeness of the wear indicator from the pin facing surface is set at a distance lying between 2mm and 10 mm, thereby allowing an amount of wear of between 2 and 10mm. Further, different elements of the coupler may be allowed to wear to different degrees to other elements of the coupler.

Preferably height, depth or closeness of the wear indicator from the pin facing surface is about 5 mm.

The wear indicator can have a given width as well. Preferably the width of the wear indicator is between 3 and 15 mm. Most preferably the width is no wider than 10 mm.

The height, depth or closeness of the wear indicator from the pin facing surface can also be set as a factor of the size or capacity of the coupler. For example, a lightweight coupler (e.g. for I tonne loading) might tolerate a degree of wear of only 1, 2 or 3 mm, whereas a 20 tonne coupler might tolerate a degree of wear of between 5 and 10mm.

After all, the overall thicknesses of the components in a larger coupler will themselves be thicker than in a corresponding smaller coupler. Preferably, therefore, the height, depth or closeness of the wear indicator to the pin facing surface is no greater than 30% of the thickness of the material at the location of the wear indicator, and more preferably no greater than 10% of that thickness. This thus allows a component to wear through 10% (or 30% in the larger definition) of its material before the wear indicator suggests that a serviceable repair/replacement is needed.

It is to be understood that the wear indicator could take the form of an inserted material within or behind the pin facing surface, which material would then be revealed upon a sufficient degree of wear occurring to that pin facing surface.

The wear indicators can be attached components or moulded projections, or the wear indicators may be grooves cut into or otherwise formed or etched into the surface of the coupler.

It can be either the wearing down of the projection or the wearing down of the surrounding area, that can provide the indication of an unacceptable degree of wear (such as a wearing of the projection back down to the pin facing surface, or a wearing of the surrounding area down to the base of the groove, or the wearing down of the surface down to the edge of the projection, groove or etching -e.g. when the projection, groove or etching is on the side adjacent to the pin facing surface).

The wear indicator may be provided on the pin facing surface of a latch or on a pin facing surface of a hook.

The wear indicator can be provided at the throat of a pivoting latching hook.

The hook may further comprises a pin engaging surface, the pin engaging surface being a flat surface extending away from the throat of the latching hook, and being the surface of the hook against which the pin will bear in normal, non-worn use.

The wear indicators on the pin facing surface of the latch or hook of the coupler are preferably only contacted by an attachment pin of an accessory attached thereto, during use of the coupler and accessory, upon either that pin facing surface, or a different pin facing surface, wearing down to a sufficient degree.

In a further preferred embodiment, the wear indicator is provided to a side of a jaw of the coupler. The preferred jaw would be the rear jaw of the coupler, or the downwardly facing jaw of the coupler.

The wear indicator might be positioned in or on the side of a hook or latch of the coupler. That hook or latch might be a front or rear latch or hook of the coupler.

More than one wear indicator may be provided, e.g. on both jaws, or on all the hooks/latches, or on both sides of the or each jaw.

More than one wear indicator may be provided for a particular component -for example two wear indicators may be provided on the pin facing surface of the rear hook. By spacing them apart, they function less like a mini-fulcrum for the attachment pin, thereby stabilising the grip of the attachment pin by the hook.

Preferably the wear indicator has a triangular cross-section, either as a projection or as a cut-out. Other cross sections can also be used, such as a rounded cross-section.

The shape of a projection, however, will be worn down if it forms a pin engaging surface.

These and other features of the present invention will now be described purely by way of example with reference to the accompanying drawings, in which: Figure 1 shows a coupler suitable for comprising wear indicators of the present invention; Figure 2 shows the coupler of Figure 1, but now having wear indicators, for example as shown on a side wall of the rear jaw and on the rear jaw's hook; Figure 3 shows a more detailed view of the rear jaw of Figure 2; and Figure 4 shows a pivoting latching hook, such as from the coupler of the preceding Figures, more clearly showing wear indicators on a throat of that latching hook.

Referring first of all to Figure 1, there is shown a coupler 10 for attaching to an arm of an excavator (not shown) via holes 20, 22 in its top half 12 and for attaching an accessory (not shown) thereto via a pair of jaws 14, 16 located in its bottom half 18.

The top half 12 attaches to that arm of the excavator by the use of a pair of attachment pins (not shown). Those pins slide through the paired holes 20, 22 with a tight fit whereupon there is limited relative movement therebetween. This mode of attachment is well known in the art. See, for example, GB2330570.

In the bottom half 18 of the coupler, a different mode of attachment is used (for attaching an accessory to the coupler, and thus also to the arm of the excavator). For that, two jaws 14, 16 are provided, together with a pivoting latching hook 26.

Neither the jaws 14, 16, nor the latching hook 26, closely envelops the respective attachment pins of the accessory (see Figure 2). That is because the jaws 14, 16 are open-mouthed jaws, designed to hook onto their respective attachment pins, one after the other -first the front jaw 14 engages a first attachment pin of the accessory (not shown) and then the second attachment pin 24 is swung into the second jaw (rear jaw 16) before then moving the latching hook 26 into a position of engagement thereagainst by a movement as shown by the arrow 28 in Figure 2. This mode of attachment is also well known. See again, for example, GB2330570.

As is known for this kind of coupler, the pivoting latching hook 26 is adapted to be pivoted about a pivot axle 30, the pivot axle being mounted on or in the frame 32 of the coupler 10. Further, that latching hook comprises a pin latching surface 34, a rear locking surface 36 and a lip 38. That lip 38 is raised so as to provide an additional safety mechanism for the hook, as known from GB 2330569. Likewise the rear of the hook is stepped, as known from both GB 2330570 (mentioned above) and W02008/029112. That stepped arrangement allows a blocking bar (not shown) to engage against the rear of that hook 26 through a variety of different degrees of rotation of that hook 26, as is also known from the above documents.

Referring then again to Figure 1, it can also be seen that a latching mechanism 40 is provided for the front jaw 14. That front latching mechanism could be any one of a number of different forms of latching mechanism known to a skilled person, including those disclosed in the above mentioned PCT application. It will be noted, however, that that latching mechanism 40 also comprises a surface that faces towards an attachment pin (i.e. once an attachment pin has been located within the front jaw 14 -against the pin receiving surface 42 thereof).

The present invention, however, is distinguished over the prior art by the fact that it comprises various wear indicators 44, 46. These will now be further described.

The first wear indicators 44 are shown in Figures 2 and 3, and they comprise a groove provided in at least one of the side surfaces of the rear jaw 16 (there is a corresponding side surface on the other side of the coupler, which may also have such a groove).

The illustrated side surface 48 is typically a finished surface formed within a jaw component of the coupler. That surface might be finished, for example, via a reaming process.

The jaw component may be a part of the frame, i.e. cast or fabricated into the frame 32 at the time of manufacture of the frame. Alternatively it may be a separately produced component that then get fitted/welded into a fabricated or case frame 32. Preferably, and as shown, the frame is a cast frame, with the jaw component being a separately produced component that gets fitted into the moulded frame. This allows a commonly moulded frame to be used for a variety of different jaw forms, such as ones with greater or lesser radiuses of curvature for suiting different attachment pins -ones with different diameters), or with different upper waIl 50 shapes for accommodating different arc radiuses of the pivoting latching hook 26, or wider (or narrower) jaws for suiting different accessory dimensions. This also allows the jaw component to be formed from a different material to the frame -the frame typically needs to be tough or strong, whereas the jaw typically needs to be somewhat harder than the frame since it is the jaw that received the daily impacts from the use of the accessory, thereby ensuring an increased useable life for the coupler compared to a directly moulded or directly cut jaw (i.e. one made from the same material as the frame). It is nevertheless to be appreciated that the jaw can be formed directly in the frame/sidewalls of the coupler.

Where the side surface of the jaw is formed with a finishing process such as reaming, the groove 44 can readily be cut into that side surface 48 by the reaming apparatus.

Alternatively, if the jaw component is moulded, that wear indicator 44 may be moulded into the side surface of the moulded component. However, other methods of manufacturing a jaw component, or a jaw, with a wear indicator of this type will be readily understood by a skilled person.

Instead of a groove, the wear indicator 44 could be a protrusion. Again it could be moulded or reamed onto that side surface (the latter being by reaming away the area surrounding it). An alternative method of forming such a protrusion, however, would be to form it as a weld bead.

The wear indicator could also be etched onto the side surface.

The wear indicator 44 is preferably a solid line along its extent, although it could be intermittently provided.

The wear indicator as shown follows the curvature of the upper wall 50 of that rear jaw 16 along at least a part of its extent. That curvature has a convex section that corresponds to the arcuate path of travel 28 of the hook 26 between a non-latching position (not shown) and a latched position (as shown in Figures 2 and 3). That convex section is thus concentric with the pivot axle 30 of the latching hook 26. The groove or protrusion of the wear indicator 44 thus includes a first arcuate section that is concentric with the pivot axis 30 of the latching hook 26.

That upper wall 50 also has a curvature reversal, past a point of inflexion 58, to a concave curvature on either side of that convex section. Those concave sections define the two end walls 51 of the rear jaw 16. The wear indicator 44, as shown, follows that curvature reversal to just beyond the point of inflexion 58, thereby covering the full extent of the line of probable wear of the rear jaw -the end walls 51, in practice, will not wear to any significant degree since the attachment pin will not bear against them -due to the inturned tips 60 of the jaw 16, accessories with pin spacings (distances between the axes of the two pins) suitable to place the rear pin 24 against one of those end walls 51 will not fit within the coupler via a conventional quick coupling procedure.

Other lengths (extents of correspondence relative to the upper wall 50 of the jaw 16) for the wear indicator can, however, be provided.

From the above description, and from the drawings, it can be seen that the wear indicator generally follows the shape of the curvature of the upper wall 50 of the rear jaw 16. In that regard it is parallel thereto. Preferably, and as shown, the edge of that wear indicator 44 that lies closest to the upper wall 50 of the jaw 16 lies a set distance away from that upper wall (prior to any wear occurring to that upper wall). That distance provides a service limit -that distance will clearly shrink as that upper wall wears away through use of the coupler 10, and upon that distance becoming zero, the product will have to be serviced for repairing or replacing the jaw component. Preferably that distance is between 3 and 9 mm and most preferably it is 5 mm for a typical three tonne coupler. Smaller couplers may require a smaller distance and larger couplers may require a larger distance, depending upon the given service limits for the products (or components) in question. Nevertheless, by making that distance preferably 5mm, a 5mm service limit on the wear of that jaw 16 is provided. As such, upon the upper wall 50 wearing back down to the lower surface (closest edge) of the wear indicator 44, an operator will know that a serviceable pair of the coupler is needed.

The wear indicator 44 has a finite width 62. That width should be wide enough to ensure that the wear indicator is readily visible, even when the coupler is dirty (dusty), or upon a quick inspection following a wipe with a finger. That is because the coupler will typically be used in dirty environments (accessories include buckets that are frequently used to dig dirt, soil, mud, rubble or gravel/quarry products). Preferably that width 62 is no less than 5mm, although preferably it is no more than 15mm wide.

Instead of the 5mm service limit lying at the lower/closest edge of the wear indicator 44, it might alternatively be provided at the middle of the wear indicator, or even at an upper or distant edge thereof, whereupon the wear indicator being worn down or worn out can provide the operator with the required signal to conduct a service repair of the component(s).

The wear indicator could alternatively be just an etched line in the side surface of the jaw 16, whereupon a wearing down of the upper surface 50 of the jaw 16, at any point thereof, up to that line would provide the operator with the required indication of wear.

A similar wear indicator might also be provided on an opposite side surface of the rear jaw (not shown) such that there is a wear indicator on both sides of the coupler. This allows for uneven wear to be identified, or for inspections to be made from either side of the coupler. Likewise, wear indicators might be provided on one or both of the side surfaces 52 of the front jaw 14, in much the same manner as that for the rear jaw 16.

The front jaw 14 can likewise feature finished side surfaces 52. Likewise the front jaw can be formed either as a separate jaw component, or as a moulded or fabricated component of the frame.

A similar wear indicator might also be provided on the side surface(s) of the latching hook. Preferably, however, the latching hook features a different type of wear indicator, as shown in Figures 2 to 4. Bear in mind, however, that the two different forms of wear indicator are potentially interchangeable between the two different side surfaces of the various components, or between the various different pin facing surfaces of those components.

The second form of wear indicator -the second wear indicators 46 -is provided on the pin facing surface 34 of the hook 26 (although as described above they might also or instead be on the pin facing surfaces 42, 50 of the jaws 14, 16, although due to the loading characteristics of the pins against those pin facing surfaces 42, 50 of the jaws 14, 16 during the use of the coupler (and the accessory attached thereto), such wear indicators would be subjected to rapid wear characteristics, which could lead to undesirably frequent service intervals, or overly rapid performance losses (due to the wearing out of those pin facing surfaces). It is thus preferred that this second type of wear indicator 46 be limited to locations on the latching hook(s) 26, 40 of the couplers 10.

The second wear indicators 46, as shown in Figures 2 to 4, comprise ribs or projections on the pin facing surfaces of the component -here the pivoting latching hook 26. As shown, these wear indicators 46 take the form projections that extend upwardly from a throat of the hook 26, on the pin facing surface 34 thereof, As shown, the projections have flat edged ridge, and a generally triangular cross section. Although it is preferred that they have such a generally triangular cross-section (before the edge becomes worn down), it is to be understood that other sections can function equally well. The benefit of the triangular section, however, is that the degree of wear is visible on the basis of the width of the worn-off surface. Likewise the flat edged ridge is preferred. Its uniformity also assists in the determination of any degree of wear thereof.

Preferably the wear indicators, two are shown, are spaced apart along the pin facing surface 34. Further, as shown, they preferably project upwardly from the pin facing surface 34 of the hook 26 by a maximum perpendicular distance 54 (shown schematically in Figure 4) of about 5 mm. Different couplers -e.g. couplers of a smaller size, might have a smaller height, and larger couplers a larger height. Preferred heights are thus 3mm to 9mm, as per the first wear indicators 44.

The ridges of the wear indicators 46, as described above, are shown to be substantially flat, rather than following the curve of the throat of the pin facing surface 34 of the hook 26. Due to the curvature of the throat of the pin facing surface 34, and the flat nature of the ridge of the wear indicators 46, the ends of those wear indicators taper down in height towards their ends. The given projection height 54 is thus a preferred maximum perpendicular projection height.

These second wear indicators can perform their function in either one of two ways, depending upon the geometry of the hook or on the geometry of the jaw with which that hook is associated (and the size of the attachment pin retained thereby. The first, more basic approach, will be described first.

The wear indicators can form the point of contact between the hook 26 and the pin.

Due to the convex curvature of the upper wall 50 of the rear jaw 16, the attachment pin will typically engage against the same part of that wear indicator, irrespective of the pin spacing of the accessory (although that pin spacing will vary the location of the engagement between the attachment pin and the upper wall 50 of the rear jaw). In light of that effectively static location of the pin relative to the wear indicator, a curved wear indicator is not needed. That retention of the pin against the wear indicator will ultimately wear down that wear indicator. Then, upon it wearing down, an operator will know that a service repair is needed for the hook.

The above first mode of operation, however, is typically not to be used since the wear indicator presents too small a surface area of contact against the attachment pin, and as a result both the attachment pin and the wear indicator will wear out overly rapidly.

Nevertheless, it can be used, and its serviceable life can be increased by increasing the number of wear indicators (two are shown, spaced apart from one another, which in turn allow the pin 24 to be more firmly secured by the hook 26 -a single wear indicator could operate like a fulcrum for the pin 24, whereupon the pin would readily wobble relative to the hook 26, whereas two spaced wear indicators 46 mitigate that issue).

More than two wear indicators might also be provided, or the spacing between them might be increased by moving them closer towards the side surfaces of the hook).

The alternative, and more preferred approach for using these second wear indicators 46, however, will now be described in greater detail: As seen in Figure 3, the attachment pin 24 of the accessory (not shown) bears against an underside of the upper wall 50 of the rear jaw 16. Further, the pivoting latching hook 26, upon being powered into a latching position (it is illustrated in a slightly retracted position to allow the wear indicators to be seen) will have its pin engaging surface 54 also bearing against the pin 24. The wear indicators, due to them being provided in the throat of the hook which throat has a lesser radius than the radius of the pin 24, will thus not be in contact with the pin 24 during the normal, non-worn use of the coupler.

Wear to the couplet will thus occur at the two locations of contact -the underside of the upper wall 50 of the rear jaw and the pin engaging surface 64 of the hook.

As that wear occurs, the hook 26 will be able to be further powered backwards towards the pin 24. That is because the point of contact against the pin engaging surface 64 of the hook will slide up the hook (either since the pin engaging surface 64 is being worn down, or else because the wearing down of the upper wall of the jaw allows the pin to sit higher up relative to the jaw, whereupon the hook can move further in the direction indicated by the arrow 28).

Only upon a sufficient wearing down of either or both the pin engaging surface 64 of the hook 26 and the upper wall 50 of the jaw 16 will the pin 24 ultimately come into contact with the wear indicators. The wear indicators therefore can indicate a need for a serviceable repair on the basis of them being a tell-tale", rather than them being something that has to wear down to nothing. That is because if there are any wear marks on the wear indicators (which should not be being worn down during normal use conditions), then there must have been a large enough degree of wear to some other element of the coupler, such as the pin engaging surface 64 of the hook or the upper wall 50 of the rear jaw 16, to render a serviceable repair to be necessary.

It will be appreciated from the above disclosure, therefore, that the wear indicators 46 of this hook 26 provide a tell-tale indication of excessive wear upon the location of the pin engaging surface shifting towards the throat of the hook 26. Such a shift, if it became excessive, would potentially be such as to vary the geometry of the coupler to a sufficient degree to cause a potential overloading of the hydraulic cylinder used to power the hook 26 from a non-latching position into its latching position. The tell-tale is thus not just indicating a degree of physical wear of the component on which it is located, but also potentially a degree of wear on an associate surface -here being the upper wall 50 of the jaw 16.

Although distances (heights, depths or closenesses) have been mentioned above in absolute terms, it should be noted that the height, depth or closeness of the wear indicators to a pin facing surface, prior to any wear occurring, is variable dependent upon the safety factors applied to the relevant components' designs during their design process. The distances can thus alternatively be expressed in percentage terms, dependent upon the thicknesses of the material at the locations in question. Preferably the height or depth or closeness of the wear indicator from the pin facing surface is made to be no less than 10% of the thickness 56 of the component at that wear indicator's location. That relative height/closeness, however, can typically vary from between 5% and 30% of the thickness of the component at that location, gain dependent upon the safety factors employed in the design of that component. After all, it will be appreciated by a skilled person that the height/depth/closeness of the projections, etc, should be sufficient to allow the serviceable part to have had a sufficiently long service life to be practical, prior to an indication of a service need being presented thereby, but without allowing the components to have been worn away beyond a safe working limit, and without them having been exposed to too great a number of oscillatory loadings, which oscillatory loadings could otherwise present a potential risk of a fatigue failure.

The limits will also depend upon the materials used to fabricate the components.

The limits will all be readily determinable through destructive testing of the relevant components.

The wear indicators as provided for the couplers of the present invention therefore provide an operator with a means for allowing that operator to determine the time when a serviceable repair of their coupler, or of a component thereof, is needed since the wear indicator will provide a suitable indication of the degree of wear already encountered -something that is otherwise difficult to ascertain from an inspection of the device since there will be no other indication present on the coupler of the thickness of the components before they were first used (i.e. before any wear had occurred).

The present invention has been described above purely by way of example.

Modifications in detail may be made to the invention within the scope of the claims appended hereto.

Claims

CLAIMS: 1 A coupler for coupling an accessory to excavator, the coupler comprising a frame with a first half for attachment to the excavator and a second half for attachment to an accessory, the coupler comprising at least one wear indicator provided in or on or behind an attachment pin facing surface of the coupler.
2. The coupler of claim 1, wherein the wear indicator is provided in or on a surface of the coupler that is adapted to engage against, or to face, an attachment pin.
3. The coupler of claim 1, wherein the wear indicator is located behind the pin facing surface.
4. The coupler of claim 3, wherein the wear indicator is in or on a surface that extends from that pin facing surface.
5. The coupler of claim 4, wherein that surface lies perpendicular to the pin facing surface.
6. The coupler of any one of the preceding claims, wherein the coupler is attached to an arm of an excavator.
7. The coupler of any one of the preceding claims, wherein the wear indicator provides a protrusion extending out of the surface of the coupler.
8 The coupler of any one of claims 1 to 6, wherein the wear indicator is cut or etched into the surface of the coupler.
9. The coupler of any one of claims I to 7, wherein the wear indicator is moulded onto the surface of the coupler.
10. The coupler of any one of the preceding claims, wherein the height, depth or closeness of the wear indicator from the pin facing surface is set, at the time of its application, at a distance of between 2mm and 10 mm from the pin facing surface.
11. The coupler of any one of the preceding claims, wherein the wear indicator has a given width, at the time of its application, of between 3 and 15 mm.
12. The coupler of any one of the preceding claims, wherein the height, depth or closeness of the wear indicator from the pin facing surface is set, at the time of its application, at a distance of no greater than 30% of the thickness of the material at the location of the wear indicator.
13. The coupler of any one of the preceding claims, wherein the height, depth or closeness of the wear indicator from the pin facing surface is set, at the time of its application, at a distance of no less than 5% of the thickness of the material at the location of the wear indicator.
14. The coupler of any one of the preceding claims, wherein the at least one wear indicator is provided on the pin facing surface of a latch or hook of the coupler.
15. The coupler of claim 14, wherein the at least one wear indicator is provided at a throat of a pivoting latching hook.
16. The coupler of claim 15, wherein the hook further comprises a pin engaging surface, the pin engaging surface being a flat surface entending away from the throat of the latching hook.
17. The coupler of claim 15 or claim 16, wherein the wear indicators on the pin facing surface of the latch or hook of the coupler are only contacted by an attachment pin of an accessory attached thereto, during use of the coupler and accessory, upon either that pin facing surface, or a different pin facing surface, wearing down to a sufficient degree.
16. The coupler of claim 14, claim 15, claim 16 or claim 17, the pin facing surface featuring two wear indicators, the wear indicators being spaced apart from one another.
19. The coupler of any one of the preceding claims, wherein the at least one wear indicator is provided on a side surface of a jaw, or of a hook or latch, of the coupler.
20. The coupler of claim 19, wherein the at least one wear indicator is provided on a side surface of a rear jaw of the coupler.
21. The coupler of claim 20, wherein the wear indicator has a curved shape in plan, following at least a portion of the curvature of the upper wall of the jaw.
22. The coupler of any one of the preceding claims, wherein the wear indicator has a triangular cross-section.
23. A coupler for attaching an accessory to an arm of an excavator, the coupler featuring at least one wear indicator, the coupler being substantially as hereinbefore described with reference to any one or more of the accompanying drawings.
24. A jaw for a coupler, the coupler being for attaching an accessory to an arm of an excavator, the jaw featuring at least one wear indicator, the jaw being substantially as hereinbefore described with reference to any one or more of the accompanying drawings.
25. A wear indicator substantially as hereinbefore described with reference to any one or more of Figures 2 to 4.
26. A pivoting latching hook featuring at least one wear indicator, the pivoting latching hook being substantially as hereinbefore described with reference to any one or more of Figures 2 to 4.