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[0001]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[0002]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[0003]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.[0004]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 replace...

AI Technical Summary

Benefits of technology

The invention has several advantages. The body of the device is made of resilient material, which means it can be securely fixed in the opening by friction between its outer wall and the inside wall of the opening. This design allows the device to absorb peak forces without getting bent or damaged, which means it can withstand a lot of pressure without breaking. Additionally, the design of the holder and tooth allows the pin to be resilient, which means it can also retain the tooth and absorb peak forces without getting bent or damaged. This eliminates the need for separate shock absorbing pads or inserts, making the device simpler and more user-friendly.

Problems solved by technology

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.

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.

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.

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.

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.

The potential for dislodgement on this scenario of reversing the screw auger utilising rubber friction retention is very high.

This is a serious disadvantage.

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.

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 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.

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