AU2015100869A4 - An Excavator Bucket - Google Patents

Abstract

An excavator bucket having an open front and a guide means (61-64) associated with an upper periphery of the open front to guide material into the bucket; a horizontally disposed lower lip holding spaced digging teeth (66-70); the lip having a ground contact surface (65a) with a stepped or raised profile in relation to the floor (60a) of the bucket wherein frictional drag on the bucket is reduced by the lip on penetrating the ground. mD r+ ol

Description

1 AN EXCAVATOR BUCKET TECHNICAL FIELD The present invention is directed to improvements to excavator buckets and particularly to larger excavator buckets that can have a weight of over 10 tons and a capacity of about 20-40 cubic meters. However, the invention may also find suitability in respect of smaller buckets of between or about 1-5 cubic meters or medium-size buckets of between or about 10-15 cubic meters. The larger buckets can be attached to the arm of a large apparatus such as a power shovel or hydraulic excavator. The smaller buckets can be attached to the arm of a hydraulic excavator or other type of digging apparatus. BACKGROUND Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge. Excavator buckets (sometimes called machine buckets) are well known and can vary from extremely large buckets weighing over 20 tons and used in the mining industry and especially with power shovels and hydraulic excavators to smaller buckets that can be attached to a smaller type of hydraulic excavator or backhoe style machine. These buckets are made of steel which may comprise cast members, or rolled steel members attached together usually by welding. The buckets typically comprise a top wall, sidewalls, a rear wall and a floor. The buckets are usually curved. The front of the floor of the bucket is usually provided with digging teeth or an edge blade (for a batter or a mud bucket).

2 A disadvantage with existing buckets is the weight and the capacity of the bucket. Any ability to reduce the weight of the bucket and increase the cubic capacity to improve the flow into and out of the bucket, increase the payload, lessen the cycle times, lower the digging forces, reduce fuel consumption, lessen the strain on the digging tool components, etc. without compromising the strength would be a distinct advantage. There would be a particular advantage if the weight of the bucket could be reduced in the order of 30% without appreciably affecting the bucket performance. Another disadvantage with existing buckets is that many buckets do not fill in an optimum manner. That is, the material is forced into the bucket in a manner that does not readily cause the bucket to be quickly filled with minimum required force. Another disadvantage is that conventional buckets typically fill between 80% 90% of their rated capacity. There would be an advantage if it were possible to provide a bucket design that will fill to its full capacity. Another disadvantage with existing buckets is that as the bucket digs into the material, an appreciable amount of material is dislodged and cast to the outside of the bucket and does not flow into the bucket. Material is also lost as the bucket is lifted. There would be an advantage if it were possible to minimize this lost material. Yet a further disadvantage with bucket designs is that if a bucket of larger capacity is required, it is usually necessary to change buckets. This requires a number of buckets to be fabricated which can increase cost. There would be an advantage if it were possible to enable the volume of the bucket to be varied. Further Conventional Bucket issues. Prior art conventional buckets of most if not all models and sizes traditionally have a horizontal / flat lip with weld on teeth adaptors, including / Ground Engaging Tools (GET) and or as the machines become larger, can have a 3 cast lip arrangement wherein tooth adaptors are cast in to the lip which are also typically horizontal or flat to take the GET. Conventional buckets typically have straight vertical front side walls with a front cheek plate outer edge that allows material to fall out of the bucket when the bucket is filled. In addition, on packing the bucket, material that has already been excavated and not retained due to prior art side wall design has to be double handled and recovered again which all adds to the operational costs. Conventional buckets typically have a front opening comprised of the lip, two side walls and a top hitch plate that are in a square or rectangular relationship to each other. This square or rectangle shape can restrict filling and discharge of material in some applications. Typical conventional buckets have the side walls tapering from the front to the rear of the bucket i.e. the rear section of the bucket is somewhat narrower than the front opening of the bucket. This arrangement can lead to material clogging the rear of the bucket at the wall joins causing the bucket to have a reduced payload cubic capacity as well as promoting premature wear. Conventional buckets typically have a flat floor with side walls that join at the base of the floor forming right angled flat surface areas at these sections. This arrangement has a number of issues and typically can result in almost if not all of the flat bucket floor in contact with earth. In operation this creates substantial drag and wear on the bucket floor and the lower to mid sections of the side walls. Given the significant amount of surface area that is in contact with the earth, this drag can also substantially increase the filling and emptying cycle times of the excavator. It can also introduce a substantial imposition added weight to the bucket if heavy wear plates are fitted to protect the wearing surfaces. This arrangement increases the need for more horsepower to pull the bucket through the earth which leads to more maintenance downtime and additional costs to maintain the underside of the floor and side walls of the buckets inevitably increasing overall operating costs.

4 Conventional buckets are typical heavy due to their design and for the need to fit excessive and expensive wear plating to stop premature wear Conventional bucket designs typically allow a lot of drag on the floor and side walls of the bucket creating slower cycle times and premature wear with areas that are contacting the ground. It is an object of the present invention to provide an improved bucket that may overcome at least some of the above-mentioned disadvantages or provide a useful or commercial choice in the marketplace. It is also an object of the present invention to provide the end user with a more productive, high performance, lower maintenance and less expensive tool to purchase and use to improve ever tightening operating margins facing the mining and construction industries globally. SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided an excavator bucket having an open front and at least one guide means associated with an upper periphery of the open front to guide material into the bucket. With conventional buckets, as the bucket digs into the material, an appreciable amount of material is dislodged and cast over the top of the bucket rather than into the bucket. The design of the top of the bucket (with the lifting hitch etc.) provides a profile that does not facilitate entry of material into the bucket. Reference numeral 15 in Figure 1 illustrates such a profile. The guide means can function as a guide to capture this otherwise lost material into the bucket. The guide means may comprise at least one material capture plate. Suitably, a plurality of plates is provided. The guide 5 means is suitably formed separately and attached to the bucket. Suitably, the guide means is attached to the hitch of the bucket. The guide means may be inclined to guide material into the bucket. The guide means may also function to reduce spillage of material over the top of the bucket as the bucket moves through its lift phase. Thus heaped material in the bucket may be better retained during the lifting phase. According to a second aspect of the present invention there is provided an excavator bucket comprising a material payload system adjacent at least one side wall edge of the bucket, the material payload system adapted to guide material into the bucket. Suitably the payload system is adjacent each side edge wall. Suitably, the material payload system is removeably attachable to the bucket. The material capture plate can be attached to the bucket by at least one bolt or pin or clip The material payload system may be made of cast metal or metal plate. The material payload system may comprise one or more plate members. The plate member may comprise a slotted plate or plate of any suitable profile. The plate member may function to increase or expand the capacity of the bucket with little increase in bucket weight. The plate member can be customised in shape and size to suit a particular bucket or excavation. The plate member may diverge outwardly from the side edge of the bucket. According to a third aspect of the invention there is provided an excavator bucket comprising sidewalls which are at least partially curved inwardly from a lower part of the bucket to an upper part of the bucket. In this aspect of the invention, the sidewalls are not flat. Instead, at least part of each side wall is curved inwardly. It is found that this particular 6 configuration facilitates movement of material to the centre of the bucket which promotes ease of bucket filling. The configuration may provide improved strength and stiffness to the bucket. The configuration may improve filling and discharge performance to the bucket. The configuration may reduce wear on the external surface of the bucket. Each sidewall may comprise a substantially planar central portion and a curved part peripheral portion. The central portion may comprise a cheek plate or portion. According to a fourth aspect of the invention there is provided an excavator bucket comprising sidewalls, a floor, and a corner connector connectible to a side sidewall and the floor. Suitably, a corner connector is provided at each sidewall. The corner connector may have a design to suit standard digging teeth, lip and cheek shrouds. The corner connector suitably includes an adaptor to support a digging tooth. The adaptor may comprise a standard adaptor such that a standard tooth may be attached to the corner connector via the adaptor. The adaptor may be configured to support the digging tooth above other middle or intermediate digging teeth on the front of the bucket. This arrangement may improve digging and filling of the bucket by having the middle teeth initially breaking up the material and having the outer or corner tooth able to penetrate the material with greater ease to facilitate flow of material into the side of the bucket and over the corner connector with reduced restriction. Suitably, the adaptor is configured to position an attached tooth towards the outside of the sidewall to minimize interaction between the tooth and material not captured by the bucket.

7 In another aspect of the invention there is provided an excavator bucket comprising digging teeth, the outermost tooth on each side being raised relative to the remaining teeth. Suitably, the bucket is provided with a hitch assembly. Suitably, the hitch assembly is cast. Suitably, the bucket comprises a rear wall which is curved about an axis extending between the sidewalls. Suitably, the rear wall is curved in one direction only. Suitably, the bucket is a large bucket having a capacity of between 15-45 cubic meters. In a most preferred aspect of the invention there is provided an excavator bucket having an open front and a guide means associated with an upper periphery of the open front to guide material into the bucket; a horizontally disposed lower lip holding spaced digging teeth; the lip having a ground contact surface with a stepped or raised profile in relation to the floor of the bucket wherein frictional drag on the bucket is reduced by the lip on penetrating the ground. Preferably, the lip has upturned end portions to further reduce the frictional drag. In a preferred embodiment, the floor of the bucket is angled or slopes downwards from opposite sidewalls of the bucket towards a midline of the floor. The bucket can have substantially a wedge shaped configuration wherein the mouth of the bucket is wider at the top when compared to the bottom of the bucket and wherein the configuration continues into the collection basket area of the bucket.

8 The bucket can also have continuous internally beveled or conical transitional corner sections between the roof, rear wall, floor and the sidewalls of the bucket. Suitably there are guide means which are removable material capture plates adapted to be fitted to the mouth of the bucket to increase capacity and/or retain excavated material in the bucket. In another preferred embodiment, the side walls of the bucket are substantially perpendicular to the rear wall, top wall plate and bottom floor of the bucket. BRIEF DESCRIPTION OF THE DRAWINGS Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows: Figure 1. Illustrates a perspective view of a bucket. Figure 2. Illustrates a rear view of the bucket of Figure 1. Figure 3. Illustrates a side view of the bucket of Figure 1 Figure 4. Illustrates a top view of the bucket of Figure 1. Figure 5. Illustrates a front view of the bucket of Figure 1. Figure 6. Illustrates a front view of the bucket of Figure 1 with the curved side wall portions in shaded outline for reasons of clarity.

9 Figure 7. Illustrates a side view of the bucket of Figure 1 with the curved side wall portions in shaded outline for reasons of clarity. Figure 8. Illustrates a corner connector of the bucket of Figure 1. Figures 9-11. Illustrate various views of the corner connector of Figure 8. Figure 12. Illustrates a close-up view of the material payload system attached to the sidewalls of the bucket of Figure 1. Figure 13. Illustrates the angled floor of a bucket wedge shaped bucket with internal conical transitional corner sections. Figure 14. Illustrates side walls which are substantially perpendicular to the rear wall, top wall plate and bottom floor of the bucket. Figures 15 and 16. Illustrate horizontally disposed lower lips having a stepped ground contact surfaces relative to the floor of the bucket. Figure 17. Illustrates a perspective representation of a preferred bucket of the invention showing essential features. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring initially to Figures 1-3, there is illustrated an excavator bucket 10 which can have a capacity of between 15-45 cubic meters although this can vary. Referring initially to Figure 1 and Figure 2, the bucket comprises a floor 11, opposed sidewalls 12, 13, a rear wall 14 (see particularly Figure 2) and a top wall 15. The top wall is provided with a cast hitch assembly 16. The bucket generally has an open front or mouth defined by the front edges of floor 11, sidewalls 13 and top wall 15. Attached to the front edge of floor 11 is a plurality of digging teeth 17. The teeth 17 are usually fitted to a front plate which is cast or welded to the remainder of the bucket.

10 Floor 11 of the bucket curves upwardly from the front mouth of the bucket to the rear wall 14. Rear wall 14 is curved (arcuate) in one direction only being about an imaginary transverse axis extending between the sidewalls. That is, rear wall 14 is not curved in two directions. The top wall 15A curves from rear wall 14 to the front of the bucket. Indeed the rear of bottom floor 11, the rear wall 14 and much of top wall 15A form a continuous curve. A hitch assembly 16 is attached to the top part of the bucket. The sidewalls 12, 13 are conical plate side walls and comprise a central planar "cheek" portion 20 and a partially surrounding inwardly curved conical portion 21 which connects to the bottom ( floor) 11, rear wall 14 and top wall 15. The planar cheek portions are parallel to each other and do not taper from the front "mouth" of the bucket to the rear of the bucket. This curved portions 21 allows a more efficient flow and direction of material both into and out of the bucket and will reduce wet type material build up because there are no right angled corners. Even if there is some material build up it will not stay in this area given the shape, and the more material that would build up on this, the heavier it will get and fall away. A conventional bucket in this area will not allow the build-up to discharge. If material is allowed to build up in this area the more material that gets stuck there will add weight to the buckets RSL and lessen the actual payload going into the truck per bucket pass which will in turn lower production and substantially increase cost. Additionally, the intermediate conical sidewalls 21 provide a major strength and stiffness benefit when compared to conventional bucket designs. The conical shape improves bucket filling and discharge and reduces wear on the 11 external surface of the bucket. The rated volume of the bucket is also more indicative of the amount of material moved per pass due to the reduced chance of material carryback. Gussets 22 are provided in the top outside section of the bucket and add superior strength to this part of the bucket. Referring to Figure 1, the bucket is provided with guide means in the form of material capture plates 23. These plates are welded or otherwise fixed to the lifting hitch 16. These plates are inclined towards the inside of the bucket (see figure 1) and it can be seen that material striking these plates 23 will be deflected into the bucket rather than carried over the top of the bucket. It can also be seen from Figure 1 that the profile 15 in the upper part of the bucket is such that material can quite easily pass over the top of the bucket rather than into the bucket. A function of the material capture plates 23 is to guide this otherwise lost material into the bucket. Another advantage is that when the bucket has finished digging the material and passes through the lifting phase, the material the plates can function to prevent material from spilling from the bucket. Referring to Figure 1 and Figure 12, there is provided a customisable payload management system in the form of extension plates 24, 25. The plates can be customised to suit and are removably attached to the edge of a respective side wall of the bucket. In the particular embodiment, plates 24, 25 can be bolted onto each side wall via bolts 60 (see particularly Figure 12). The function of extension plates 24, 25 is to allow the bucket to have an increased cubic capacity without having excessive weight added to the bucket to increase capacity. Thus, it is now possible to have one bucket to do multiple tasks and instead of requiring a large bucket and a separate small bucket, the customisable payload management system can be attached and removed to increase or decrease the capacity of a single bucket. Below the payload management system 24, 25 is provided a material capture plate 26, 27 adjacent each side wall of the bucket, the material capture plate 12 adapted to feed material into the bucket. The material capture plate is removably attachable to the bucket. The material capture plate can be attached to the bucket by at least one bolt or pin. The material capture plate is positioned adjacent and on the outside of the outside tooth 28. The function of the material capture plate is to recover dirt dug up by the outermost tooth 28 and guide this material into the bucket. Conventionally, much if not most of the material dug up by the outermost tooth passes along the outside of the bucket as the bucket is dragged through the dirt. This is inefficient. The material capture plate guides this dug material back into the bucket to provide greater efficiency in the operation of the digging process. The material capture plates 26, 27 are partially attached to a cast curved and raised corner connector 29, 30 and the sidewall 12.13 this being best illustrated in Figure 12. The corner connectors 29, 30 are best illustrated in Figures 8-11. Each corner connector is a cast piece and is designed to provide a smooth transition between the lip plate, the sidewall, and the intermediate conical sidewall to improve material flow. The design of the cast corners also increases the strength of the bucket. The smooth transition (see Figure 8) occurs by having the internal walls 31 is formed without any abrupt corners. The internal walls 31 also provide a good strong thick connection between the bottom lip (floor) plate and the side (cheek) walls. The connector is provided with an adapter 18 on which a conventional digging to 17 can fit in the usual manner. Figure 8 illustrates the adapter 18 without an attached tooth and figure 9 illustrates the adapter 18 with an attached tooth. In the present embodiment, the adapter (and therefore the tooth) has a particular orientation. Firstly, the adapter points slightly outwardly towards the bucket and therefore the tooth will be similarly inclined slightly outwardly towards the bucket, this being best illustrated in Figure 11 which shows the 13 inclined tooth. Secondly, the adapter is located on the connector such that the attached tooth extends slightly above the remaining "middle" teeth 32 on the bucket. Referring to Figure 1, the teeth 28 attached to the corner connectors (also known as the outside teeth) are slightly raised above the remaining middle teeth 32. The reason for this is that the initial penetration on digging and breaking up of material is done with the middle set of teeth 32. The outside teeth 28 will penetrate the material with great ease and allow the outer material to flow into the sides of the bucket and over the corner connectors without restriction. Referring to Figure 13 there is shown a rear elevation illustrating the angled floor of a wedge shaped bucket 34 with internal conical transitional corner sections 35, 36. Also partially are shown are removable material capture plates 37, 38 adapted to be fitted to the mouth of the bucket to increase capacity and/or retain excavated material in the bucket. The use of an angled floor 39, 40 that meets in the midline 41 of the bucket when compared to a flat floor results in far less drag on the bucket as it only has a very small section of the underside of the floor in contact with the earth. It is estimated that this feature will reduce the surface area of the bucket floor being in contact with the earth by up to eighty percent (80%). This design results in both outer areas of the floor either side of the middle of the bottom of the bucket not being in contact with the earth. It substantially reduces the cycle times of the excavator and importantly lowers the wear on the underside of the floor thereby decreasing costs and the penalty of additional weight of protective wear plates. This floor design also allows for a slight increase in cubic capacity of the bucket without adding weight and promotes easier flow of material into and out of the bucket. If required, there is only a need for small and light wear plates to be fitted to the central area of the floor thus substantially decreasing costs and man hours to fabricate. The feature of an opening that is wider at the top 42 when compared to the bottom 43 being carried through into the material collection basket area of the 14 bucket 34 i.e. a wedge shape allows for material entering the bucket to roll easily into the bucket as it is not restricted by square shaped side or cheek plate walls. This arrangement allows for faster filling and discharge times as well as giving some extra capacity without adding substantial weight to the bucket. Referring to Figure 14 there is shown a plan or overhead view wherein the side walls 45, 46 of the bucket are substantially perpendicular to a rear wall 47, top wall plate 48 and bottom floor 49 of the bucket. Square side walls of the bucket that angle down to the floor but are square to the rear wall, the top wall plate and bottom floor of the bucket allow for a larger capacity without adding extra weight to the bucket. This design also restricts clogging of material in the corners and also reduces drag on the outsides of the side walls thereby reducing wear by facilitating easier flow of material both into the bucket on filling and on emptying. Referring to Figures 15 and 16 there is shown horizontally disposed lower lips 50, 51 having stepped ground contact surfaces relative to the floor 52, 53 of the bucket wherein frictional drag on the bucket is reduced by the raised profile of lip as the bucket penetrates the ground. Figure 16 shows the embodiment wherein the lip has upturned end portions 51a, 51b to further reduce the frictional drag. The stepped ground contact surface relative to the floor allows for less drag on the bucket lip on penetrating the ground which increases the productivity of the excavator, i.e. less drag and less hydraulic horsepower required to break the earth which can reduce cycle times, lower fuel burn and operational costs. The lips are shaped to marry up the innovative angled floor and conical transition side walls 54, 55 and 56, 57. Further it needs to be noted that a lip whether it is a fabricated plate lip or a cast lip can be used with the angled centre floor and conical transition side wall design. It may be of interest in certain mining operations there is a necessity for the lip of a bucket to be a full horizontal / flat style arrangement where there is an 15 ongoing need to trim high walls and wall batters and benches. In these applications the upturned corner lip is not suitable. Finally in reference to Figure 17, there is illustrated a perspective representation of the bucket 60 of the invention showing the essential features of an open front wherein the guide means are removable material capture plates 61-64 associated with an upper periphery of the open front to guide material into the bucket; a horizontally disposed lower lip 65 holding spaced digging teeth 66-70 ; the lip 65 having a ground contact surface 65a stepped relative to the floor 60a of the bucket wherein frictional drag on the bucket is substantially reduced by the lip on penetrating the ground. Also shown are continuous internally beveled or conical transitional corner sections 71, 72 between the roof 73, rear wall 74, floor 60a and the sidewalls 75, 76 of the bucket. The bucket can be used by an excavator or other digging or loading apparatus. The bucket will typically have a capacity of between 15-45 cubic meters. The bucket has many advantages over conventional bucket designs. These include, but are not limited to: * Fabrication at less cost; * About 30% lighter than conventional buckets in the same class; * Improved bucket strength due to the shape of the bucket; * Can fill to 100% of capacity as opposed to an 80%-90% maximum capacity for conventional bucket designs; . Easier flow of material into/from the bucket; 16 * Easier digging into material due, inter alia, to the raised outside teeth design; * Reduced cycle time on loading; * Reduced number of passes per load; * Providing mechanical component improvements and structural advantages to any excavator using the bucket; * Reduced weight reduces wear on the machine boom, stick and swing ring; * Not exceeding the OEM machines ASL; * The material payload system is very light and allows for the bucket to have an increased capacity without significantly increasing the weight of the bucket; * A single bucket able to carry out multiple tasks by attaching/removing /changing the material payload system, * Better flow into the bucket and retention of heaped material when raising the bucket due to the material capture plates on top of the bucket. Not only will the above advantages substantially increase the production rates on a mining site and reduce the actual daily or yearly production costs per BCM / TONNES but they will also have a significant effect on reducing the overall running costs. Specifically, this will be a result of less on-board hydraulic horse power required to run the digging tool e.g. the hydraulic excavator. This in turn will lessen the impact on the machine's fuel burn, lower CO emissions and duty cycles, increase the life of major machinery components, lessen the cost of repairs and potentially extend component hours which can be a massive saving to any mining operation. In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term "comprises" and its variations, such as "comprising" and "comprised of" is used throughout in an inclusive sense and not to the exclusion of any additional features. It is to be understood that the invention is not limited to 17 specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art. Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms. Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.

Claims (21)

1. An excavator bucket having an open front and a guide means associated with an upper periphery of the open front to guide material into the bucket; a horizontally disposed lower lip holding spaced digging teeth; the lip having a ground contact surface with a stepped or raised profile in relation to the floor of the bucket wherein frictional drag on the bucket is reduced by the lip on penetrating the ground.

2. The bucket of claim 1, wherein the lip has upturned end portions to further reduce the frictional drag.

3. The bucket of claim 1 or claim 2, wherein floor of the bucket is angled or slopes downwards from opposite sidewalls of the bucket towards a midline of the floor.

4. The bucket of any one of claims 1-3, having substantially a wedge shaped configuration wherein the mouth of the bucket is wider at the top when compared to the bottom of the bucket and wherein the wedge configuration continues into the collection basket area of the bucket.

5. The bucket of any one of the preceding claims wherein there are continuous internally beveled or conical transitional corner sections between the roof, rear wall, floor and the sidewalls of the bucket.

6. The bucket of any one of the preceding claims wherein the guide means are removable material capture plates adapted to be fitted to the mouth of the bucket to increase capacity and/or retain excavated material in the bucket.

7. The bucket of any one of the preceding claims wherein the side walls of the bucket are substantially perpendicular to a rear wall, top wall plate and bottom floor of the bucket. 19

8. An excavator bucket having an open front and a guide means associated with an upper periphery of the open front to guide material into the bucket.

9. The bucket of claim 8, wherein the guide means comprises material capture plates.

10. An excavator bucket comprising a material payload system adjacent at least one side wall edge of the bucket, the material payload system adapted to guide material into the bucket.

11. The bucket of claim 10, wherein the payload system is adjacent each side edge wall.

12. The bucket of claim 10 or claim 11, wherein the material payload system is removeably attachable to the bucket.

13. The bucket of any one of claims 10-12 including the guide means of claim 8 or claim 9.

14. An excavator bucket comprising sidewalls which are at least partially curved inwardly from a lower part of the bucket to an upper part of the bucket.

15. The bucket of claim 14, wherein each sidewall comprises a substantially planar central portion (cheek plate) and a curved part peripheral portion.

16 An excavator bucket comprising sidewalls, and a floor, and a corner connector connectible to a side sidewall and the floor.

17. The bucket of claim 16 wherein a corner connector is provided at each sidewall. 20

18. The bucket of claim 16 or claim 17, wherein each said corner connector includes an adaptor to support a digging tooth.

19. The bucket of claim 18, wherein the adaptor is configured to support the digging tooth above other middle digging teeth on the front of the bucket.

20. The bucket of claim 19, wherein the adaptor is also configured to position an attached tooth towards the outside of the sidewall to minimize interaction between the tooth and material not captured by the bucket.

21. An excavator bucket comprising digging teeth, the outermost tooth on each side being raised relative to the remaining teeth.