The invention has particular but not exclusive application to hydraulic excavator assemblies having means for extending the reach of the excavator, and to a method and a stick therefor.

Background of Invention Typically as seen in FIG 1, hydraulic excavators have a control station 10, a boom 11 elevated and lowered by a pair of boom rams 12 mounted on the control station 10, and a stick 13 pivotally connected proximate its inboard end by a first stick pin 14 to the outboard end of the boom 11 and pivoted in relation thereto by a stick ram 15 mounted on the boom 11 and connected to the inboard end of the stick 13 by a second stick pin 16. A bucket 17 is pivotally connected to the outboard end of the stick 13 by a head bracket 18 mounted on the bucket 17. The head bracket 18 has a first bracket pin 19 to which the outboard end of the stick 13 is pivotally connected and the bucket 17 is pivoted or "crowded"in relation to the stick 13 by a bucket ram 29 (or"crowding"ram) mounted to the stick 13 proximate its inboard end and connected via a link 20 to the bucket head bracket 18 proximate the first bracket pin 19 by a second bracket pin 21.

As used herein the expressions"inboard"and"outboard"refer to the ends of the stick and boom which when connected are respectively closest to and furthest from the control station.

The standard arrangement on the outboard end of the stick 13 described above for mounting the bucket 17 to the stick 13 can be varied as seen in FIG 2 by attaching a so called"quick hitch"mechanism 22 to the outboard end of the stick 13. The quick hitch mechanism 22 which is seen in outline in greater detail in FIG 3 provides a fixed first journal bearing 24 adapted to house the first bracket pin 19 and an articulated tongue 25 adapted to pivot around the second bracket pin 21 to form a second journal bearing 26 for housing the second bracket pin 21. A locking pin (not seen) engages the tongue 25 to keep the second bracket pin 21 locked in the second journal bearing 26. Pins 27 and 28 are connected to stick 13 and link 20 as bracket pins 19 and 21 were previously.

It is known if excavators of the above type are found to having a reach less than is required, for them to be replaced by another excavator having an increased length boom and a correspondingly increased length stick to which the bucket is attached.

Summary of Invention The present invention aims to provide an alternative to known excavators to allow the reach of an excavator to be extended without the necessity to replace the excavator with another having longer boom and stick.

This invention in one aspect resides broadly in an hydraulic excavator having a control station, a boom, a first stick attached to the boom and a bucket attached to the first stick, and hydraulic means under the control of an operator at the control station for operating the boom, stick and bucket and including two-way hydraulic means for providing a hammer function to the bucket, the excavator including:- a second stick connectable between the first stick and the bucket for extending the reach of the excavator, the second stick having a head bracket at the inboard end adapted for connection to a quick hitching mechanism.

In another aspect this invention resides broadly in a stick for extending the reach of an hydraulic excavator having a control station, a boom, a first stick attached to the boom and a bucket attached to the first stick, and hydraulic means under the control of an operator at the control station for operating the boom, stick and bucket and including two- way hydraulic means for providing a hammer function to the bucket, the stick being connectable between the first stick and the bucket and including:- a head bracket at the inboard end adapted for connection to a quick hitching mechanism.

It is preferred that the head bracket is releasably affixable to the inboard end of the second stick whereby the second stick is attachable to a plurality of different model excavators or different model quick hitches by changing the head bracket.

In one embodiment the head bracket has a pair of fixed pins receivable in respective journal bearings on a quick hitch mechanism. Alternatively the head bracket may have a pair of slidably mounted pins such that the head bracket can be attached to the first stick by sliding the pins in journal bearings at the outboard end of the first stick and at the outboard end of hydraulic means mounted on the first stick.

The outboard end of the second stick can carry a quick hitching mechanism for connection to the bucket.

It is also preferred that the second stick includes hydraulic ram means mounted thereon for pivoting the bucket, the hydraulic ram means being connected to the two-way hydraulic means.

In another aspect this invention resides broadly in a method of extending the reach of an hydraulic excavator having a control station, a boom, a first stick attached to the boom and a bucket attached to the first stick, and hydraulic means under the control of an operator at the control station for operating the boom, stick and bucket and including two- way hydraulic means for providing a hammer function to the bucket, the method including:- locating a second stick between the first stick and the bucket, the second stick having a head bracket at the inboard end adapted for connection to a quick hitching mechanism; connecting the head bracket to the outboard end of the first stick or to a quick hitch mechanism attached thereto, and connecting the outboard end of second stick, or connecting a quick hitch mechanism attached thereto, to the bucket..

It is preferred that the method also includes:- connecting hydraulic ram means mounted on the second stick to the two-way hydraulic means for pivoting the bucket.

Description of Drawings In order that this invention may be more easily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention, wherein:- FIG I is a side view of a known excavator; FIG 2 is the excavator of FIG 1 showing the stick connected to the bucket by a known quick hitch mechanism; FIG 3 illustrates the quick hitch mechanism in greater detail; FIG 4 is a schematic diagram of a boom and known stick with a quick hitch attached for connection to a bucket in known manner;

FIG 5 is a schematic diagram illustrating a stick in accordance with the present invention for extending the reach of the excavator, and FIG 6 is a schematic diagram illustrating the stick of the present invention connected between a"standard"stick and a bucket to extend the reach of the excavator.

Description of Preferred Embodiment of Invention An understanding of the prior art outlined above with reference to FIGS 1-3 will assist in appreciating the present invention illustrated in greater detail with reference to FIGS 4-6.

As can be seen in FIG 4, a boom 40 is connected at its outboard end to a stick 41 in known manner with stick ram 42 connected to stick 41 at pin 49 to pivot it about pin 39.

Quick hitch mechanism 43 is connected in known manner to pin 44 at the outboard end of stick 41and to bucket ram 45 by link 46.

An extending stick 50 in accordance with the present invention is illustrated in FIG 5 and has a head bracket 51 at the inboard end which is adapted in the manner to be described to be affixed to quick hitch mechanism 43 in similar manner to that in which quick hitch mechanism 43 attaches to a bucket.

Head bracket 51 has a pair of pins 52 and 53 which are received in the journal bearings 47,48 of quick hitch mechanism 43 (see FIG 4) in the same manner that bracket pins 21 and 19 were received in journal bearing 24,26 as descibed previously with reference to FIGS 2 and 3.

It will be appreciated that in a manner not shown the head bracket 51 can be releasably affixed to the inboard end of the extending stick 50 so that it can be attached to different model excavators or to different model quick hitches, simply by changing the head bracket.

The assembled boom 40, stick 41, extending stick 50 and bucket 54 are illustrated in FIG 6.

As can be seen in FIG 4, a two-way hydraulic hose 56 is fitted to boom 40 and stick 41 for providing percussive or hammer functioning to bucket 54 in known manner.

This line is utilised in accordance with the present invention to operate ram 55 mounted on the extending stick 50 in conventional manner to crowd bucket 54.

It will be appreciated that in a manner not shown, a quick hitch mechanism can be connected to the outboard end of extending stick 50. Similarly in a manner not shown, head bracket 51, whilst adapted to be connected to a quick hitch mechanism, could also be connected to the standard outboard end of stick 41 by connecting pin 52 to the outbound end of stick 41 at 44 and connecting pin 53 to link 46.

Thus it will be appreciated that in one aspect of the present invention, a hydraulic excavator has a control station, a boom 40, a first stick 41 attached to the boom and a bucket 54 attached to the first stick, and hydraulic means under the control of an operator at the control station for operating the boom, stick and bucket and including two-way hydraulic means 56 for providing a hammer function to the bucket. The excavator also includes a second stick 50 connectable between the first stick 41 and the bucket for extending the reach of the excavator, the second stick having a head bracket 51 at the inboard end adapted for connection to a quick hitching mechanism 43.

Similarly in another aspect the present invention resides in a stick 50 for extending the reach of an hydraulic excavator having a control station, a boom 40, a first stick 41 attached to the boom and a bucket 54 attached to the first stick, and hydraulic means under the control of an operator at the control station for operating the boom, stick and bucket and including two-way hydraulic means 56 for providing a hammer function to the bucket.

The extending stick 50 is connectable between the first stick 41 and the bucket 54 and includes a head bracket 51 at the inboard end adapted for connection to a quick hitching mechanism 43.

In use in accordance with the method of the present invention, the reach is extended of an hydraulic excavator having a control station, a boom 40, a first stick 41 attached to the boom and a bucket 54 attached to the first stick, and hydraulic means under the control of an operator at the control station for operating the boom, stick and bucket and including two-way hydraulic means 56 for providing a hammer function to the bucket.

The method includes locating a second stick 50 between the first stick 41 and the bucket 54, the second stick having a head bracket 51 at the inboard end adapted for connection to a quick hitching mechanism 43. Head bracket 51 is connected to the outboard end of the first stick 41 or to a quick hitch mechanism attached thereto. The outboard end of second stick 50 (or a quick hitch mechanism attached thereto) is connected to the bucket 54.

Hydraulic ram means 55 mounted on the second stick 50 is connected to the two-way hydraulic means 56 for pivoting the bucket 54.

It will be appreciated that the apparatus and method of the present invention has a number of advantages over known excavators and in particular enables the reach to be extended without having to use a larger excavator.

It will of course be realised that whilst the above has been given by way of an illustrative example of this invention, all such and other modifications and variations hereto, as would be apparent to persons skilled in the art, are deemed to fall within the broad scope and ambit of this invention as is herein set forth.