Replaceable Wear Tooth Assembly

Abstract

An improved tooth 21 and tooth holder 22 assembly for use with a digging implement such as a post hole digger has a first retention member 23 and a second retention member 24 each of which can be used in isolation or in combination. The first retention member 23 comprises a nylon plug having opposed serrated teeth 25 and which is pushed into an opening in the tooth holder 22. The tooth contains rigid profiles 26 and when the tooth is pushed into the tooth holder, the serrations and profiles mesh together to positively retain the tooth within the tooth holder. The second retention means 24 comprises a resilient pin. The tooth and the tooth holder have a positive and negative wedge type shape which allows the tooth to be attached in one orientation only.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application takes the benefit of and in turn claims priority under 35 USC §119 to Australian Provisional Patent Application No. 2015901525 filed on 29 Apr. 2015, the contents of which are herein incorporated by reference.

TECHNICAL FIELD

The present invention is directed to a replaceable wear tooth assembly for a ground digging tool such as a hole digging screw auger an example of which is a post hole digger. Other ground digging tools such as a digging bucket may also benefit from the replaceable wear tooth assembly.

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.

Current practice is that ground engaging tools/wear parts are utilised as consumables and are required by their nature to be replaceable. An example of this type of use is a screw auger that utilises replaceable wear teeth.

Similarly, an excavator bucket, and typically a digging bucket, utilises replaceable teeth on the leading edge.

The purpose of these consumable items is to engage the earth and preferentially wear out to avoid premature damage to the main body of the digging implement. By replacing the teeth, an optimum cutting edge can be maintained.

In the case of a screw auger, the teeth become sacrificial items as opposed to the screw auger itself. In the case of a bucket the teeth on the leading edge are sacrificed as opposed to the main body of the bucket.

An example of an auger is a post hole digger. The auger is usually top mounted to a hydraulic motor which rotates the auger.

FIG. 1 illustrates a hole digging auger which comprises a shaft 11 long enough for the hole to be dug, a helical screw (also called a “flight”) 12 welded to the outside of the shaft, a lower extending head plate 13, a lowermost point (a pilot) 14 and a number of digging teeth 15. The top of the shaft 11 has a mounting 16 to enable it to be connected to and rotated by a motor.

The auger can be mounted to a petrol motor and be a one person or two person auger, these devices being suited for smaller jobs.

For larger jobs, the auger is usually driven by a hydraulic motor supported by a bob cat or other machine.

The teeth are subject to large loads and high abrasion as they are continuously exposed to the elements and high wear environments. The loads apply force to the tooth and attempt to force the tooth into the main body of the screw auger, and cause large amounts of friction on the frontal part of the tooth and high wear on these items is a result.

The teeth are susceptible to wear and tear and need to be replaceable. Thus it is known to provide replaceable teeth for an auger. The head plate is typically provided with tooth holders and digging teeth can be removeably mounted to the tooth holders.

It is known to use a steel retaining pin to hold the tooth to the tooth holder. The pin can be hammered out to release the tooth from the holder. However it is known that the pin can be bent or deformed when the auger strikes a rock or digs into very heavy earth etc., as this transmits an extremely high “shock load” or peak load to the pin. A bent or deformed pin can be difficult to hammer out, and in extreme cases may need to be drilled out. This is a serious disadvantage.

Thus it is known to provide rubber inserts at places between the tooth and the holder to absorb these peak loads and reduce damage to the retaining pin. A disadvantage with this arrangement is in the correct placement of these inserts and ensuring that the inserts remain in place during use of the auger. The inserts are separate items that need to be inspected and possibly replaced and increases the complexity of the tooth holder assembly. For smaller teeth and holders, the inserts need to be smaller and may not be sufficient to properly absorb peak loads.

There would be an advantage if it were possible to retain a tooth in a tooth holder using a pin but without requiring the use of separate resilient inserts to prevent damage to the pin.

It is known to attach teeth to teeth holders without using a steel retaining pin. Thus it is known to use rubber cord or rubber strips or rubber friction members to jam the tooth in the tooth holder. The rubber frictionally engages the tooth to hold the tooth in the holder. This arrangement suffers from disadvantages when a negative force (or a “pulling” force) is applied to the tooth. For instance a sufficiently strong negative force on the tooth can cause the rubber friction members to fail and for the tooth to be inadvertently pulled out of the holder.

In the case of digging augers, when pulling auger out of the hole, forces applied in the opposite direction can easily overcome the friction required to retain the tooth when using rubber only as the retention technique. The result of this is the wear tooth is dislodged from its holder and falls to the bottom of the hole and can be un-retrievable. This is a serious disadvantage.

Furthermore, if the auger becomes stuck in use, the drive unit on top of the auger is capable of reverse function to unstick or dislodge the auger from the spoil. This reverse function can apply a strong negative or “pulling” force on the wear tooth and can cause the tooth to be pulled out of its holder. The potential for dislodgement on this scenario of reversing the screw auger utilising rubber friction retention is very high. This is a serious disadvantage.

There would be an advantage if it were possible to attach a tooth to a tooth holder in a manner to prevent the tooth from becoming detached when subjected to a negative force.

Another disadvantage with many tooth and tooth holder assemblies is the requirement to use specialist tools and equipment to remove the tooth from the holder. For teeth held in place with a steel retaining pin, a pin removing tool is required. When the pin is removed, the tooth is often still held in the holder by contact with the walls of the holder, attached debris, some damage to the tooth, and the like. The tooth then needs to be forced out of the holder.

Conventionally, specifically manufactured wedges are used to force the tooth out of the holder. The wedges are hammered into position and this can damage the tooth and holder. Operators will also attempt to ram any implement in between the wear tooth and tooth holder and in any cavity available and this can also damage the holder and tooth. This operation is also applicable to remove a tooth from the holder when a retaining pin is not present.

There would be an advantage if it were possible to remove a tooth from a holder without specialist equipment and without inadvertent damage to the holder and tooth.

It is an object of the invention to provide a replaceable wear tooth assembly which could overcome at least one of the abovementioned disadvantages or provide a useful or commercial choice in the marketplace.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a replaceable tooth assembly for an auger, the assembly comprising a tooth, a tooth holder, a first retention member to retain the tooth in the holder and a separate second retention member to retain the tooth in the holder,

the first retention member adapted to be mounted to the holder and comprising a plurality of resilient members,

the tooth comprising a plurality of rigid profiles adapted to engage with the resilient members to retain the tooth to the holder,

the second retention member comprising a removable pin.

In this manner a tooth can be mounted to its tooth holder using two retaining members, each member being able to resist a negative or “pulling” force on the tooth. The first retaining member locks the tooth by forcing the resilient members into engagement with the rigid profiles on the tooth. The second retaining member is a removable pin.

To remove the tooth, the pin is removed and the tooth is knocked out of the holder with sufficient force to deform the resilient members to enable the rigid profiles on the tooth to ride past the resilient members to free the tooth from the holder.

FIG. 2 illustrates a non-limiting embodiment of a tooth 21 which is typically formed from steel and has rigid steel profiles 26.

FIGS. 3 and 4 illustrate a non-limiting embodiment of a tooth holder 22 with FIG. 4 (a partially cut away view of FIG. 3) particularly illustrating an internal wall 28 having an opening 29 in which the first retaining member 23 can be fitted. A non-limiting embodiment of the first retaining member is illustrated in FIG. 8.

The tooth 21 can be pushed or hammered into the holder until the profiles on the tooth engage with the members on the first retaining member.

The replaceable tooth assembly finds particular suitability for use with a digging auger such as a posthole digger as this type of tool can be subject to negative or pulling forces. However, the replaceable tooth assembly may also be suitable for use with digging buckets or any other type of engaging tool that can benefit from this type of assembly.

The tooth is typically made from hard rigid material. This material may comprise forged steel, hardened tool steel, high quality alloy steel heat treated to offer maximum resistance to wear and impact, cast iron made from a heat treated ductile iron and the like. The teeth may be forged, cast or fabricated.

The size of the tooth can vary depending on the digging implement to which the tooth is attached. For use with a posthole digger auger, it is considered that the tooth will have a length of between 1-4 inches and a width of between 0.75-2 Inches. For use with a larger digging bucket, it is envisaged that the size of the tooth will be larger.

Suitably, the tooth will comprise a front portion and a rear portion. The front portion will typically comprise or include the leading edge of the tooth. The leading edge may be treated to improve hardness and this may include hard facing and the like. The front portion of the tooth may be substantially rectangular when viewed in plan. The front portion of the tooth may be tapered when viewed in side elevation from a thicker rear portion to a thinner leading edge.

The rear portion of the tooth may be bifurcated when viewed in plan and therefore may comprise a first leg portion and a second leg portion.

At least one (and preferably both) leg portions may include the rigid profiles adapted to engage with the resilient member to retain the tooth to the tooth holder. The rigid profiles are preferably located on inner walls of each leg portion.

The rear portion may include a configuration to allow the tooth to be inserted into the holder in only one orientation. The configuration may include at least one abutment or wedge which will prevent the tooth from being fully inserted and retained in the wrong orientation (for instance upside down).

The rear portion may include a pin retention means to enable a retaining pin to hold the tooth in the tooth holder. The pin retention means may comprise a recess. The recess may comprise a semicircular recess adapted to locate approximately half the circumference of the retaining pin. The recess may be located on one of the leg portions.

The tooth holder is typically adapted to be permanently fixed to the desired type of tool. If the tool is an auger, the tooth holder will typically be welded or otherwise permanently fixed to the head plate (see for instance reference numeral 13 in FIG. 1) of the auger.

The tooth holder suitably comprises a solid rear portion/wall, and a top wall and a bottom wall extending from the rear portion/wall. The tooth holder can therefore have a somewhat C shaped configuration when viewed in side elevation. The top wall and the bottom wall are typically spaced apart by a distance sufficient to enable the rear portion of a tooth to be positioned between the top wall and the bottom wall. It is therefore envisaged that the spacing between the top wall and the bottom wall will typically be between 5-30 mm.

The top wall and the bottom wall may be somewhat rectangular when viewed in plan. The size of the tooth holder will vary depending on the size of the tooth and the size and type of tool to which the tooth holder will be attached. It is envisaged that the top wall and the bottom wall will typically have a length of between 1-4 inches and a width of between 8-30 Inches although this can vary and it is not considered that any particular limitation should be placed on the invention merely by exemplification of certain sizes of the tooth holder.

The tooth holder will typically be manufactured from a strong rigid material such as steel and alloys of steel.

One wall of the tooth holder may be provided with an abutment or step or wedge type configuration adjacent a rear portion of the wall, a purpose of this being to ensure that the tooth is positioned to the tooth holder in the correct orientation and this will be described in greater detail below.

The tooth holder will suitably contain an internal wall extending between the top wall and the bottom wall. The internal wall may have a forward curved configuration.

An opening may be provided through the internal wall. The opening will typically provide a location or mounting area for the first retention member. The opening may have a configuration to hold the retention member in a particular orientation. The opening may have a configuration to prevent the retention member from rotating in the opening. The opening may therefore comprise a somewhat keyhole shaped opening.

The tooth holder may include some form of means to assist in the removal (knocking out) of the tooth from the tooth holder. The means may comprise a knockout recess. The knockout recess may be provided in a front portion of the top wall and/or the bottom wall and it is preferred that the top wall and the bottom wall contain a knockout recess. The knockout recess may be substantially U-shaped when viewed in plan.

The tooth holder may include at least one opening to accommodate a second retention member. Suitably, the top wall and/or the bottom wall contain an opening aligned or otherwise arranged to enable a retention member to pass through or at least into the openings. As it is envisaged that the second retention member will comprise a pin, it is envisaged that the openings will be aligned.

The first retention member functions to retain the tooth in the tooth holder. The first retention member is preferably a separate member which is fixed to the tooth holder and which can hold the tooth in the tooth holder. The first retention member includes a plurality of resilient members to assist in holding the tooth in the tooth holder.

Suitably, the tooth holder includes an internal wall with an opening and the first retention member extends through the opening and is mounted to the tooth holder by the opening.

The first retention member may comprise a solid plug like body. The plug like body may have a shape that prevents the retention member from inadvertent rotation in the opening, and also correctly orientates the resilient members on the first retention member. Suitably, the body may have a cross-section consisting of a larger circle joined by a smaller semicircle such that the body can fit within a keyhole type of opening. Of course, it is envisaged that the body and opening may have other shapes and configurations to ensure that the first retention member is located on the tooth holder in the correct orientation.

The plug like body may include opposed end faces. At least one and preferably both of the end faces contain the resilient members.

The resilient members may be formed integrally with the body or may be formed separately and attached to the body by any suitable means.

If the resilient members are formed integrally with the body, it is envisaged that the body will comprise a resilient material such as a nylon, a rubber, a neoprene, resilient composite materials and the like.

An advantage with the body being formed of resilient material is that the body can also be fixed in the opening by friction engagement between the outer wall of the body and the inner wall of the opening.

However, it is also envisaged that the body may be formed of rigid material such as a hard plastic and the resilient members can be co extruded onto the body, or formed separately and attached to the body by adhesive, plastic welding or other suitable means.

The resilient members may comprise an array of teeth. The teeth may comprise separate elongate tooth like ridges or may comprise an array of separate button like projections.

A second retention means may be provided to further retain the tooth on the holder. The second retention means suitably comprises a removable pin. The removable pin may comprise resilient or plastic material. The resilient material may comprise nylon, rubber, neoprene, composite materials and the like.

In a second aspect of the invention there is provided a replaceable tooth assembly for an auger, the assembly comprising a tooth, a tooth holder, and a first retention member to retain the tooth in the holder, the first retention member adapted to be mounted to the holder and comprising a plurality of resilient members the tooth comprising a plurality of rigid profiles adapted to engage with the resilient members to retain the tooth to the holder.

The tooth, tooth holder, and first retention member may be as described above.

In this aspect of the invention, a second retention member is not provided.

In a third aspect of the invention there is provided a replaceable tooth assembly for an auger, the assembly comprising a tooth, a tooth holder, and a retention member in the form of a resilient removable pin to retain the tooth in the holder,

• a. the tooth holder comprising an top wall, a bottom wall and an internal wall connecting the top wall and the bottom wall,
• b. an opening through the top wall adapted to accommodate the pin,
• c. the tooth having a rear portion adapted to pass into the tooth holder and between the top wall and bottom wall, and,
• d. pin retention means on the rear portion of the tooth adapted to retain the tooth to the holder when the pin is inserted.

In this aspect of the invention, the design of the holder and tooth enables the pin to be resilient. This pin thus functions to retain the tooth to the holder and can also accommodate peak forces without bending or damage to the pin of the type that makes removal of the pin difficult. No additional separate shock absorbing pads or inserts are required making the assembly simpler and easier in use.

In a fourth aspect of the invention there is provided a replaceable tooth assembly for an auger, the assembly comprising a tooth, and tooth holder, the tooth comprising a rear portion adapted for insertion into the tooth holder, the rear portion comprising a configuration to allow the tooth to be inserted into the holder in only one orientation, and at least one retention means to retain the tooth to the holder.

In this aspect of the invention the tooth may be hard faced on only one surface which will dig into the ground. This can save on cost. The tooth can then be inserted into the holder in one orientation only which is the orientation that ensures that the hard face is in the correct position. That is, the tooth cannot be inserted and locked to the holder when in the inverted position.

The configuration may comprise an abutment or wedge which prevents the tooth from being correctly inserted when in the wrong orientation.

In a fifth aspect of the invention there is provided a removable tooth for an auger, the tooth adapted to be attached to a tooth holder on the auger, the tooth comprising a leading edge adapted for ground engagement and a rear portion adapted for insertion into the tooth holder, the rear portion being bifurcated and comprising a first leg portion and a second leg portion, at least one leg portion comprising rigid profiles adapted to engage with resilient members on a retaining member to retain the tooth to the holder.

The tooth may include a configuration to allow the tooth to be inserted into the holder in only one orientation. The configuration may be as described above.

The tooth may include pin retention means on the rear portion of the tooth adapted to retain the tooth to the holder when a retaining pin is inserted.

The tooth may include a knock out point to give a purchase for an external instrument to knock the tooth out of the tooth holder.

In a sixth aspect of the invention, there is provided a retention member to enable a wear tooth to be removably attached to a tooth holder, the retention member comprising a plug like body having opposed faces, least one said face comprising resilient members.

The retention member may be as described above.

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:

FIG. 1. Illustrates a digging auger generally of known design but containing tooth holders and teeth according to preferred embodiment of the invention.

FIG. 1A. Illustrates a tooth attached to a tooth holder.

FIG. 2. Illustrates a plan view of a tooth according to a preferred embodiment of the invention.

FIG. 2A. Illustrates a side elevation view of the tooth of FIG. 2.

FIG. 3. Illustrates a tooth holder according to a preferred embodiment of the invention.

FIG. 4. Illustrates a partially cutaway tooth holder of FIG. 4 to enable the internal wall (28) and the opening (29) in the internal wall to be better illustrated.

FIG. 5. Illustrates a side elevation view of the tooth holder of FIG. 3.

FIG. 6. Illustrates a plan view of the tooth holder of FIG. 3.

FIG. 7. Illustrates schematically a first retention member and a second retention member attached to a tooth (but omitting the surrounding tooth holder).

FIG. 8. Illustrates the first retention member according to a preferred embodiment of the invention.

FIG. 9. Illustrates the second retention member according to a preferred embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the figures, there is depicted a replaceable tooth assembly 20 for an auger 10, the assembly comprising a tooth 21, a tooth holder 22, a first retention member 23 to retain the tooth in the holder and a separate second retention member 24 to retain the tooth in the holder,

• a. the first retention member adapted to be mounted to the holder and comprising a plurality of resilient members 25,
• b. the tooth 21 comprising a plurality of rigid profiles 26 adapted to engage with the resilient members to retain the tooth to the holder,
• c. the second retention member 24 comprising a removable pin.

Auger 10 may be as illustrated in FIG. 1, but it should be appreciated that the tooth assembly need not be limited to this type of auger and there may be circumstances where the tooth assembly can be used on other ground engaging implement such as excavator buckets and the like. However, for the purposes of the detailed description of a preferred embodiment of the invention, reference will be made to auger 10.

The auger 10 conventionally includes a steel shaft 11 which has a length depending on the depth of the hole which is to be dug. Welded to shaft 11 is a steel flight 12. At the lower end of auger 10 is a head plate 13. Longitudinally aligned with steel shaft 11 is a pilot 14 which can also be a replaceable member but pilot 14 does not form part of the present invention and may be a conventional piece. The other end of shaft 11 contains a conventional type of mounting 16 typically to enable the auger to be attached to and rotated by a hydraulic motor which itself is typically attached to a bob cat arm or another type of machine.

The head plate 13 is provided with a plurality of tooth holders 22. Each tooth holder is welded or otherwise fixed to head plate 13. A digging tooth (hereinafter called a tooth) is releasably attached to each tooth holder. Thus, when the digging tooth becomes damaged or dull, it can be replaced. The teeth can also be quickly replaced if the ground composition changes.

Referring now to FIGS. 3-6 and particularly to FIG. 3 and FIG. 4, there is illustrated a tooth holder according to an embodiment of the invention. The tooth holder 22 is made from steel. A rear portion 40 of the tooth holder is welded or otherwise fixed to the head plate 13 of the auger. The tooth holder comprises a thick steel top wall 30 and a thick steel bottom wall 31 which are interconnected to the rear portion 14. The entire tooth holder can be fabricated as a single piece.

An interconnecting steel internal wall 28 extends between top wall 30 and bottom wall 31. Internal wall 28 is best illustrated in FIG. 4 which shows a partially cutaway tooth holder with the top wall 30 of the tooth holder being partially cutaway to better illustrate the internal wall 28. Internal wall 28 is approximately midway between the sidewalls of top wall 30 and bottom wall 31. Internal wall 28 also extends from approximately a front end of top wall 30 and bottom wall 31 to the rear portion 40.

Internal wall 28 has a forward curved configuration 42 (partially visible in FIG. 3) to match a recess 55 in tooth 21 and this will be described in greater detail below.

An opening 29 is provided in wall 28. The function of opening 29 is to locate the first retention member 23 and this will be described in greater detail below. Opening 29 has a particular somewhat keyhole type configuration the reason for which is to prevent unwanted rotation of retention member 23 when the retention member is located within the opening.

The free forward end of top wall 30 and bottom wall 31 is provided with a notch or recess 44 which is a knockout recess to make it easier for the tooth to be knocked out of the tooth holder without the requirements of any specialty tools and this will be described in greater detail below. The recess corresponds to the knock out point 47 located on the wear tooth. This allows for an implement to knock the tooth out when changing.

Top wall 30 is provided with an opening (retaining pin recess) 45 to accommodate the locking pin (the second retention member 24). Bottom wall 31 will also include a similar aligned opening.

Top wall 30 is provided with a welding point locator 49 embedded In the tooth casting to allow quick and accurate alignment of the tooth holder to the head plate 13 of the auger 10.

Bottom wall 31 has a stepped wedge like configuration 41 at a rear portion of the bottom wall and the function of this is to prevent a specially shaped tooth 21 from being inserted the wrong way round into the tooth holder. This will be described in greater detail below.

Referring to FIG. 8, there is illustrated the first retention member 23. Member 23 is substantially plug like in configuration and in the particular embodiment is manufactured from nylon and therefore can also be seen as a nylon retainer. Member 23 has a particular configuration and in cross-section consists of a larger circle 50 joined by a smaller semicircle 51. The cross-section shape of member 23 compliments the particular shape of the opening 29 extending through the internal wall of 28 of the tooth holder 22. Member 23 can therefore be pushed into opening 29 and the size of member 23 is such that the outer wall of the member gripps against the internal wall of opening 29 to firmly locate the member in place. The particular shape of member 23 and opening 29 is such to prevent the member from rotating or turning within the opening. Thus, the member is not entirely circular in design.

Each opposed end face of member 23 contains resilient members 25 which in the particular embodiment comprises an array of serrations or teeth. In the particular embodiment, the resilient members 25 are formed integrally with the member and are therefore made of nylon. The shape and configuration of the resilient members 25 are such that they can slightly deform or be pushed to one side upon insertion of tooth 21 and this will be described in greater detail below.

It can be seen that the orientation of the resilient members 25 and the shape of member 23 is such that when the member is pushed into opening 29 of the tooth holder 22, the serrations will all be substantially vertical (if the tooth holder is held in a horizontal position) and be slightly proud of the opening 29.

Referring now to FIG. 2 and FIG. 2A, there is illustrated a tooth 21 according to a preferred embodiment of the invention. Tooth 21 is formed from strong steel and comprises a front portion 33 containing the leading edge 37 and comprises a rear portion 32. The rear portion 32 (see particularly FIG. 2) is bifurcated and therefore defines a first leg portion 34 and a second leg portion 35. The recess 52 defined between the leg portions has a forward curved configuration and this recess 52 is designed to complement the outer shape of the internal wall 28 of the tooth holder such that the tooth can fit snugly into the tooth holder with each leg portion 34, 35 extending along each opposed side of internal wall of 28 of the tooth holder without unnecessary sideways rocking movement.

The leading edge 37 forms the initial point of contact with the ground and this edge can be hard faced or have tungsten inserts to prolong tooth life.

A knockout notch 47 is provided in tooth 21 and generally in the area in the joining between the leg portions. Notch 47 is designed to align with the knockout recess 44 in the tooth holder (see for instance FIG. 3) when tooth 21 is in place. This makes it relatively easy to knock out the tooth from the tooth holder and against the force of the resilient members 25 on the first retention member 23 and this will be described in greater detail below.

The inner wall of each leg portion 34, 35 is provided with rigid profiles 26 in the form of inwardly pointing serrations. These serrations are formed integrally with tooth 21 and as tooth 21 is formed from steel, the serrations will also be rigid steel serrations.

One of the leg portions (in the embodiment leg portion 35) contains a pin retention means in the form of a recess 38. Recess 38 engages with part of the second retention member 24 to assist in locking the tooth 21 to the tooth holder 24 and this will be described in greater detail below.

FIG. 2A illustrates tooth 21 in side elevation and it can be seen that the front portion 33 tapers from a thinner leading edge 37 to a thicker middle portion. FIG. 2A also illustrates in side elevation leg portion 35. Leg portion 35 (and also leg portion 34) contains an abutment or wedge 36. This wedge acts as a locating shape to prevent the tooth 21 being inserted into the tooth holder in an inverted position. More specifically, and referring to FIG. 3 as well as FIG. 2A, it can be seen that the rear portion of bottom wall 31 in the tooth holder (see FIG. 3) also contains an abutment or wedge arrangement 41 and the shape of this wedge arrangement 41 and wedge 36 on the tooth 21 is such that the tooth 21 can only be inserted correctly in one orientation. If the tooth is attempted to be inserted “upside down”, into the tooth holder, the tooth cannot be fully inserted into the tooth holder and therefore cannot engage with the first retention means 23 and a second retention means 24.

To insert tooth 21 into tooth holder 22, tooth 21 is initially positioned in the correct orientation to ensure that the leading edge 27 is correctly orientated. Tooth 21 is then pushed into tooth holder 22 such that the internal wall of 28 of the tooth holder 22 extends between leg portions 34 and 35 of tooth 21. At some stage, the hard steel profiles 26 on the internal wall of each leg member 34, 35 will contact the resilient members/teeth 25 on the first retention member 23 which is located in opening 29 on internal wall of 28. A resistance will then be noticed. The tooth 21 is then pushed further into the tooth holder and it may be necessary to use a hammer or something similar. This further pushing will cause the inwardly pointing serrations/profiles 26 on each leg portion 34, 35 to push into and deform the resilient teeth 25 on the first retention member 23. Additionally, the abutment/wedge 36 on the end of each leg portion 34, 35 can fit into the abutment/wedge portion 41 in the rear of the tooth holder. When the end of each leg portion 34, 35 abuts against the innermost wall 53 (see FIG. 3), the tooth is fully in place.

In this position, the hard steel inwardly pointing serrations/profiles 26 have meshed into the resilient members/teeth 25 on the nylon first retention member 23. This provides a positive retention of the tooth in the tooth holder and it is difficult to easily pull the tooth out of the tooth holder against the positive retention caused by the inter-engagement of the steel profiles 26 in between the resilient members/teeth 25.

To remove the tooth, it is necessary to use a knockout tool which can be placed in the knockout notch 47 on the tooth (which is aligned with the knockout recess 44 on the tooth holder). Use of the knockout tool will force the hard steel profiles 26 to ride back over the resilient members until such time as the tooth is released. It should be appreciated that the inwardly pointing orientations of the hard steel profiles 26 (see FIG. 2) will make it easier to insert the tooth into the tooth holder and will make it quite difficult to inadvertently remove the tooth from the tooth holder.

FIG. 7 illustrates schematically a tooth 21 positively inter-engaged with the resilient members on the first retention member 23.

When the tooth is in the fully inserted position, the pin retention means 38 on leg portion 35 aligns with the opening 45 in the tooth holder (see FIG. 3). This enables a second retention member in the form of a pin 24 to pass through opening 45 and through pin retention means 38 to further positively retain the tooth in the tooth holder.

An example of a pin is illustrated in FIG. 9. In the embodiment, the pin is a nylon retaining pin. The pin contains a chamfer 54 to allow the pin to seat home in the correct position on the tooth holder, the opening 45 in the tooth holder also containing a chamfer containing a recess to provide a flush finish. This prevents any damage to the head of the pin during use.

To remove the tooth, the nylon retaining pin is knocked out. Thereafter, a simple non-specific knockout tool can be inserted into the knockout recess 44 to engage with the knockout notch 47 on the tooth and the tooth can be knocked out against the positive force of the steel profiles 26 engaging or intermeshing with the resilient members 25.

The first retention member 23 containing the resilient members 25 is a replaceable item and when worn, can be easily removed and replaced with a new retention member. Similarly, the second retention member can also be easily replaced.

The assembly utilises a positive retention technique through the use of positive retention nylon composite or similar compound retainer(s) 23, 24. The first (middle) retainer 23 will be inserted into the internal wall 28 of the tooth holder, and will lock into place by recesses in the tooth holder and corresponding serrated recess in the wear tooth. Once locked in place the tooth 21 cannot be unintentionally dislodged due to the shape of the retainer.

The invention also intends to apply a competitive choice to the market by utilising a rear retaining pin 24 as a secondary retention technique. This rear retaining pin will also be a nylon composite material, not steel. The use of this composite nylon avoids the requirement to utilise guide rails and rubber wedges as shock absorbers.

Both retention members 23, 24 can work independently of each other to retain the wear tooth in the tooth holder. However when working together in the one system it provides a superior lock.

The nylon retention members 23, 24 are an economical consumable product.

This retention assembly allows the replacement of teeth 21 with no speciality tools. The tooth itself can be removed from the tooth holder with any pointed tool as a wedge and with the assistance of the knock out points 44.

The design prevents unwanted dislodgement of the wear tooth when negative pressure is applied in the form of reverse capability and pulling out.

The nylon positive retention members 23, 24 will positively lock the tooth into the tooth holder so that when negative pressure is applied through drilling, the tooth will not dislodge.

The resilient nature of the retention members 23, 24 and their design allows for flex at peak loading when the teeth engage the ground. The first (middle) retention member 23 still gives high retention and does not encounter any problems associated with peak loading or twisting. This retainer on its own will give reversible capabilities but when a tooth is required to be replaced the retainer and tooth can be easily removed.

The composition of the second (rear retainer) being a nylon like material composite and not steel also allows it flex under load and foregoes any requirement to have guide rails or shock absorbing wedges to avoid the pin bending. The rear pin aids in the retention capabilities and on its own will retain the wear tooth with reversing capabilities. The ability to have both systems work independently gives competitive choice and ability to be interchangeable with other systems.

The wedge shaped design on the rear of the tooth allows the tooth to be inserted in one way. Current practice by some other manufacturers is to provide a rubber friction retainer, but this allows the wear tooth to be inserted in either direction. The problem this creates is that the specific hard facing/tungsten tip on the tooth is placed in an inverted position. This can mean the tungsten or hard facing is no longer the leading edge engaging the earth and will wear prematurely and not have full benefit of the hard facing. The wedge shaped design on the rear of the tooth takes away any ability to insert the wear tooth in an inverted position. If the tooth is accidently inserted upside down, the tooth will not fully seat home and engage either of its retainers 24, 25. The operator will have a clear view that the tooth is not correctly seated if placed in the wrong way.

Prior Art tooth and holder design causes the entire load that is applied on the wear tooth to be transferred directed through the U-Shape of the wear tooth and corresponding central point in the tooth holder. This can see premature wear applied to this area. The wedge shaped design on the rear of the tooth gives a secondary benefit in that is disperses the load and spreads it between the U-Shape and both legs of the wear tooth giving prolonged wear tooth life.

The knockout points 44, 47 embedded into the tooth and tooth holder allow for quick interchangeability. Prior Art designs require specifically manufactured wedges used to force the wear tooth out of the tooth holder. It also allows an operator to attempt to ram any implement in between the wear tooth and tooth holder in any cavity available. The knockout points 44, 47 embedded into the tooth and tooth holder give clear and safe points that the user can insert a punch or similar to knock the wear tooth out of the tooth holder in an effective and efficient manner. The knockout points that are designed for that purpose and allow for wear tooth removal without specifically manufactured tooling.

The above description identifies at least one specific, substantial and credible use for the invention. In particular, the specification describes an improved tooth and tooth holder assembly which uses a first retention member and a second retention member each of which can be used in isolation or in combination and provides a means to prevent the tooth from being inserted the wrong way round into the tooth holder.

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 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

1. A replaceable tooth assembly for an auger, the assembly comprising a tooth, a tooth holder, a first retention member to retain the tooth in the holder and a separate second retention member to retain the tooth in the holder,

the first retention member adapted to be mounted to the holder and comprising a plurality of resilient members,

the tooth comprising a plurality of rigid profiles adapted to engage with the resilient members to retain the tooth to the holder,

the second retention member comprising a removable pin,

whereby the first retaining member locks the tooth by forcing the resilient members into engagement with the rigid profiles on the tooth.

2. An assembly according to claim 1, wherein the tooth comprises a front portion and a rear portion with a leading edge of the tooth located on the front portion.

3. An assembly according to claim 2, wherein the front portion of the tooth is rectangular when viewed in plan and tapered when viewed in side elevation from a thicker rear portion to a thinner leading edge.

4. An assembly according to claim 2, wherein the rear portion of the tooth is bifurcated when viewed in plan and comprises a first leg portion and a second leg portion.

5. An assembly according to claim 4, wherein the leg portions include the rigid profiles adapted to engage with the resilient member to retain the tooth to the tooth holder.

6. An assembly according to claim 5, wherein the rigid profiles are located on inner walls of each leg portion.

7. An assembly according to claim 2, wherein the rear portion includes a configuration comprising at least one abutment or wedge to allow the tooth to be inserted into the holder in only one orientation.

8. An assembly according to claim 4, wherein the rear portion includes a pin retainer to enable a retaining pin to hold the tooth in the tooth holder.

9. An assembly according to claim 8, wherein the pin retainer comprises a semicircular recess adapted to locate approximately half the circumference of the retaining pin.

10. An assembly according to claim 9, wherein the recess is located on one of the leg portions.

11. An assembly according to claim 1 in combination with an auger wherein the tooth holder is permanently fixed to the auger.

12. An assembly according to claim 1, wherein the tooth holder comprises a solid rear wall, and a top wall and a bottom wall extending from the rear wall.

13. An assembly according to claim 12, wherein the top wall and the bottom wall are typically spaced apart by a distance sufficient to enable a rear portion of a tooth to be positioned between the top wall and the bottom wall.

14. An assembly according to claim 13, wherein one wall of the tooth holder includes an abutment or step or wedge type configuration adjacent a rear portion of the wall to ensure that the tooth is correctly orientated in the tooth holder.

15. An assembly according to claim 12, wherein the tooth holder has an internal wall extending between the top wall and the bottom wall.

16. An assembly according to claim 15, wherein an opening is provided through the internal wall for locating the first retention member.

17. An assembly according to claim 16, wherein the opening is keyhole shaped.

18. An assembly according to claim 1, wherein the tooth holder includes a knockout recess to assist in removal of the tooth.

19. An assembly according to claim 1 wherein the tooth holder includes at least one opening to accommodate a second retention member.

20. An assembly according to claim 1 including a plurality of resilient members to assist in holding the tooth in the tooth holder.

21. A removable tooth for a replaceable tooth assembly for an auger, the tooth adapted to be attached to a tooth holder, the tooth comprising a leading edge adapted for ground engagement and a rear portion adapted for insertion into the tooth holder, the rear portion being bifurcated and comprising a first leg portion and a second leg portion, at least one leg portion comprising rigid profiles adapted to engage with resilient members on a retaining member to retain the tooth to the holder.