AU717522B2 - Bucket clamp for excavator - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT *.o Invention Title: "BUCKET CLAMP FOR EXCAVATOR" The following statement is a full description of this invention, including the best method of performing it known to me: 2

TITLE:

"BUCKET CLAMP FOR EXCAVATORS" FIELD OF THE INVENTION THIS INVENTION relates to a clamping device adapted for fitment to earthmoving equipment incorporating a working tool, such as a bucket, for working and/or shifting earth or other material. The invention is particularly concerned with a bucket clamp for use with an excavator, which excavators are generally characterised by an articulated arm including a boom and a dipper arm and having a bucket or other tool mounted on the dipper arm.

BACKGROUND TO THE INVENTION In general, bucket clamps comprise a jaw or clamping member mounted on a distal end of a dipper arm in opposable relation to a bucket member also mounted thereon. Bucket clamps provide a 15 measure of added versatility to bucket type earth moving machines, such as front-end loaders, backhoes and excavators, allowing such machines to grasp larger objects like logs, rocks and pipes rather than merely operate to dislodge and shift material using a scooping action. Existing bucket clamps are available in a variety of different configurations, each 20 with their own particular drawbacks and problems.

US Patent No. 4285628 to Jankowski describes a grapple attachment for the buckets of front-end type loaders. The grapple S•attachment is pivotally mounted upon the bucket and actuated by hydraulic cylinders also mounted on the bucket. The additional componentry added to the bucket may necessitate actuators of upgraded capacity for both the boom and the bucket. The normal scooping action of the bucket would clearly be compromised by the addition of the generally unwieldy grapple mechanism. Furthermore, the grapple system is generally limited to grasping objects which have a clear path on at least one side thereof, to allow ready access for the loader bucket.

US Patent No. 4770597 to Powers describes a detachable, folding clamping device attached to the dipper arm of a backhoe. In contrast to the Jankowski grapple device, the clamping device of the Powers specification is very simple. A serrated jaw member is merely attached adjacent to the pivot of the bucket on the free end of the dipper arm, and extending laterally therefrom. The jaw member is braced in a position on the dipper arm and thus fixed in relation to the bucket, which severely curtails its versatility and utility.

An earlier US Patent, No. 3807589 in the name of Shovick, describes an auxiliary bucket mounted adjacent the primary bucket of a backhoe for cooperation therewith in gripping and moving materials, akin to a "clam bucket" arrangement. As with the Powers device, the auxiliary bucket is rigidly positioned on the dipper arm for selective engagement by the primary bucket. Likewise, the versatility of the rigid bucket attachment is limited and it must be removed to avoid compromising the normal scooping action of the primary bucket.

20 US Patent No. 5111602 to Risch describes a backhoe **9999 clamping device designed for retrofitting to existing standard backhoe equipment. The clamp arms of the clamping device are pivotally attached to a dipper arm of the backhoe. The clamp arms are also attached, via links, to the bucket actuator so as to move in conjunction with the bucket to achieve a clamping effect. Accordingly the interconnection with the bucket actuator tends to limit the range of angular movement of the clamping operation. Furthermore, the clamp links must be manually 4 disengaged in order to store the clamp arms to thereby facilitate the full range of excavating operations by the bucket. The requirement for manual disengagement is generally inconvenient and results in the backhoe being periodically out of service whilst the operating mode is changed.

US Patent No. 3273729 to Holopainen describes an earlier clamping device for a backhoe. The clamping device includes a clamping arm pivotally mounted on the free end of a dipper arm on a common pivot with a bucket. The clamping arm and dipper arm are actuated by respective hydraulic actuators mounted on opposite sides of the dipper arm. However the clamping arm actuator is pivotally mounted directly to an intermediate portion of the clamping arm, which tends to limit the clamping force able to be applied by the clamping arm. Furthermore, this arrangement does not permit the clamping arm to pivot past the 15 longitudinal axis of the dipper arm thereby limiting the range of movement of the clamping device.

Turning to those clamping arrangements particularly adapted for use with excavators, United Kingdom Patent Application No.

2043586 in the name of Ogawa describes a convertible bucket attachment comprising a bucket and a complementary sub-bucket connected to a dipper arm of an excavator. The bucket and sub-bucket are pivotally connected to one another at a common pivot on the dipper arm and pivoted by link members. Certain link members are pivotally connected at one end to the distal end of a plunger rod of a cylinder actuator which actuates both bucket and sub-bucket to perform both excavation and grabbing operations. However, the sub-bucket is prone to interfering with the scooping action of the bucket during excavating r operations and the range of relative movement of the bucket and subbucket is limited by the geometry of the links interconnecting each with the cylinder actuator.

German Patent Application No.- 4108315 in the name of Maier which describes an excavator having a boom and a working appliance in the form of a bucket at an end thereof. A grab jaw is pivotally mounted on the bucket in opposition thereto for independent pivotal movement by a drive element also mounted on the bucket.

However, the mounting of the grab jaw and drive element on the bucket leads to interference with normal excavating operations. Consequently the entire grab bucket would need to be removed and replaced with a standard bucket in order to enable normal excavating operations. This unnecessarily adds to costs in applications where both a grabbing type action and scooping type action is called for in particular applications; such as demolition or land clearing.

OBJECT OF THE INVENTION o0*o ~It is an object of the present invention to provide a clamping device for an excavator which ameliorates or overcomes at least some of the problems associated with the prior art.

It is another object of the present invention to provide a clamping device for an excavator which provides an improved range of pivotal movement during grabbing operations, yet capable of being *oco conveniently drawn back near a dipper arm of the excavator so as to a minimise interference with a bucket scooping action during excavating oooo operations.

It is a further object of the present invention to provide a clamping device for an excavator which may be conveniently retro-fitted to existing excavator machines for providing added flexibility of operations.

It is yet another object of the present invention to provide a method for retro-fitting a clamping device to an excavator which minimises alterations and/or additions to the excavator.

Further objects will be evident from the following description.

DISCLOSURE OF THE INVENTION In one form, although it need not be the only or indeed the broadest form, the invention resides in a bucket clamp for an excavator includinga rotatable-support frame, a boom extending generally forwardly of said frame, a dipper arm generally depending from a distal end of said boom and a bucket member pivotally mounted on a distal end of the dipper arm, which bucket member may be moved relative to said dipper arm by bucket actuating means; said bucket clamp comprising: a clamping member including a plurality of tine portions; the clamping member pivotally mounted on the distal end of the dipper arm, whereby said clamping member is movable in opposition to said bucket member; clamp actuating means mounted on the dipper arm for moving the clamping member relative to said dipper arm; characterised in that the clamping member is adapted to S* partially cover a mouth portion of the bucket member; the clamp actuating oogo means is coupled to the clamping member via crank means; and wherein the crank means includes one or more intermediate links associated with the clamp actuating means and the clamping member, and one or more radial links associated with the clamp actuating means and the dipper arm.

The crank means may be arranged such that each intermediate link interconnects the clamp actuating means and the clamping member, whilst each radial link interconnects the clamp actuating means and the dipper arm.

Suitably a first end of each intermediate link is pivotally mounted on the clamping member, a first end-of each radial link is pivotally mounted on the dipper arm and respective second opposite ends of each intermediate link and of each radial link are coupled to a common pivot.

In preference, the common pivot is connected to a-distal operative end of said clamp actuating means.

In a preferred form, the clamping member is pivotally mounted on the dipper arm via the pivotal mount for the bucket member.

Suitably, bucket actuating means and clamp actuating means are mounted on said dipper arm, most preferably on opposite sides thereof.

Preferably bucket actuating means and clamp actuating means each comprise fluid actuated cylinders having associated fluid pressure lines for connection to fluid pressure control means.

20 The clamping member may comprise a clamping frame S* including the plurality of tine portions.

Preferably the tine portions of the clamping member are arranged to cooperate with any teeth provided on a leading edge of the bucket member.

In a further form, the invention resides in a working implement for an earthmoving machine having an articulated arm, said I3 working implement comprising: oz.

8 a tool means for earth working pivotally mounted proximate a distal end of the articulated arm, which tool means is moveable relative to said articulated arm by a tool actuating means mounted on said articulated arm; a clamping member including a plurality of tine portions; the clamping member pivotally mounted proximate a distal end of the articulated arm, whereby said clampingmember is moveable in opposition to said tool means clamp actuating means mounted on the articulated arm for moving the clamping member relative to said articulated arm; characterised in that the clamping member is adapted to partially cover a mouth portion of the bucket member; the clamp actuating means is coupled to the clamping member via crank means; and wherein the crank means includes one or more intermediate links associated with the clamp actuating means and the clamping member, and one or more gg:. radial links associated with the clamp actuating means and the dipper arm.

The crank means may be arranged such that each .i intermediate link interconnects the clamp actuating means and the clamping member, whilst each radial link interconnects the clamp actuating means and the dipper arm.

00 Suitably a first end of each intermediate link is pivotally mounted on the clamping member, a first end of each radial link is pivotally mounted on the articulated arm and respective second opposite ends of each intermediate link and of each radial link are coupled to a common pivot.

9 In preference the common pivotal interconnection comprises a pin, which pin is further pivotally connected to a distal operative end of said clamp actuating means.

Preferably the tool means comprises a bucket member, but may otherwise comprise a jack-hammer or a further clamping member.

In another form, the invention resides in a method of fitting a bucket clamp to an-excavator, which excavator includes a rotatable support frame, a boom extending generally-forwardly of said frame, a dipper arm generally depending from a distal end of said boom and a bucket member pivotally mounted proximate a distal end of the dipper arm, which bucket member may be moved relative to said dipper arm by bucket actuating means; said method including the steps of: providing a clamping member including a plurality of tine portions; mounting the clamping member pivotally on the dipper arm o•;o ~proximate the distal end thereof, thereby facilitating movement of said S. clamping member-in opposition to said bucket member; e r .mounting a clamp -actuating means on the dipper arm for o moving the clamping member relative to said dipper arm; and 20 coupling the clamp actuating means to said clamping member by means of crank means including one or more intermediate *fee.: S" link(s) and one or more radial link(s).

ooo.

S

Preferably the step of mounting the clamping member on the .dipper arm includes the common pivotal mounting of the clamping member with the bucket member.

Suitably the step of coupling the clamp actuating means to said clamping member includes the steps of: 1. Y mounting a first end of each intermediate link pivotally on the clamping member; mounting a first end of each radial link pivotally on the dipper arm; and coupling respective second opposite ends of the intermediate link(s) and of the radial link(s) to a common pivot.

Preferably the step of mounting the clamping member on the dipper arm includes the common pivotal mounting of the clamping member with the bucket member.

Preferably the step of mounting the clamp actuating means on the dipper arm further includes the step of mounting one end of the clamp actuating means pivotally on the dipper arm.

Preferably the method of mounting the clamp actuating means further includes the step of connecting a second operative end of the clamp actuating means to said common pivot.

i ~BRIEF DETAILS OF THE DRAWINGS To assist in understanding the invention preferred embodiments will now be described with reference to the following figures in which FIG. 1 is a diagrammatic representation of an excavator including a bucket clamp of a first embodiment; FIG. 2 is a side elevational view of the first embodiment of a bucket clamp; FIG. 3 is a perspective view of the first embodiment of a bucket clamp; FIG. 4 is an exploded perspective view of a bucket clamp of a second embodiment; and 11 FIG. 5 is a perspective view of a clamping member for a bucket clamp of a third embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIG. 1, the excavator 10 shown is of the selfpropelled type having a propulsion frame 11 resting on a pair of caterpillar tracks 12. Other ground engaging members, such as pneumatic tyred wheels, may be substituted for caterpillar tracks in some applications. A support frame 13 is mounted on the propulsion frame 11 by a king pin 17, whereby the support frame is rotatable about an upright axis 14. The support frame 13 carries typical superstructure elements, including an operators cab 15 and a housing 16 for the excavator's power unit.

The excavator 10 also includes an articulated arm 20 for carrying a working implement 30. The articulated arm 20 is pivotally S•mounted on the support frame 13 by a bearing (not shown), such that the articulated arm may be alternately raised and lowered by a pair of main actuators 18. The articulated arm 20 includes a boom 21 and a dipper arm 22, which dipper arm carries the working implement 30. The main actuators 18, which are disposed laterally of the boom 21, extend between the boom and the support frame 13; whilst the dipper arm is S. 20 pivotally mounted by a bearing 23 on a distal end of the boom 21. The dipper arm 22 may be moved relative to the boom by a dipper actuator 24 extending therebetween. The actuators of the embodiment are conveniently of the fluid pressure type. Note that the fluid pressure lines for the actuators, which are of a conventional design, are not shown on some of the drawing figures for reasons of clarity.

The working implement 30 includes a bucket 31, pivotally mounted proximate a distal end of the dipper arm 22, and an opposable 12 clamping member 32 mounted on a common pivot 33 with said bucket.

The bucket 31 is moveable relative to the dipper arm 22 by a bucket actuator 25 mounted on the dipper arm by a bracket 29. The bucket actuator 25 typically operates the bucket via an arrangement of a pivot pin 26, radial links 27 and intermediate links 28.

The bucket clamp arrangement of the present embodiment includes a clamping member 32, moveable relative to the dipper arm 22 by a clamping actuator 34, which clamping actuator operates the clamping member via a further pivot pin 35, pairs of radial links 36 and pairs of intermediate links 37. The links 36, 37 comprise a crank means coupling the clamping actuator 34 to the clamping member 32, which crank means will be further described in relation to FIGS. 2 and 3.

In the embodiment, the radial links 27 for the bucket 31 and the radial links 36 for the clamping member 32 are mounted on the dipper arm 22 by a common pivot 38. However, this arrangement may be V9606. substituted by separate pivotal mounting points as required. Similar considerations apply to the common pivotal mounting 33 of the bucket 31 and clamping member 32. It will be appreciated that the use of the preexisting mounting points assists in minimising the effort and cost involved in adding a bucket clamp.

FIG. 2 depicts the working implement 30 disposed on the dipper arm 22, showing the bucket clamp of the embodiment in each of two extreme operative positions. In a first position (indicated by full lines), the clamping actuator 34 is fully extended showing the ability of the clamping member 32 to pivot to a position past the longitudinal centre-line of the dipper arm 22, whereby the clamping member 32 is able to engage the bucket 31 when the bucket is in a retracted position. This particular ability is facilitated by the crank means coupling the clamping actuator 34 to the clamping member 32. The clamping actuator 34 of the embodiment includes a body, a first end of which body is pivotally mounted on the dipper arm 22 by means of a bracket 39, and a piston rod protruding from a second end of said body. The distal end of the piston rod is coupled to the crank means via a pivot pin The crank means includes, in the present embodiment, a pair of intermediate links 37 each pivotally connected, at a first end to the clamping member 32 and, at a second opposite end, to the distal end of the piston rod of the clamping actuator 34. The crank means also includes a pair of radial links 36, each pivotally connected at a first end to the dipper arm 22 and similarly at respective second opposite ends to the aog.

distal end of the piston rod. The pivotal connection of the distal end of the opiston rod and respective second opposite ends of the intermediate links and radial links is facilitated by the pivot pin In a second position (indicated by phantom lines in FIG. 2), when the piston rod of the clamping actuator 34 is fully retracted, the clamping member 32' is drawn back near the dipper arm 22. The secondary positions of the radial link 36' and the intermediate link 37' are 20 similarly indicated. When in the retracted position, the pivot pin 35' abuts a rest 40 provided on the dipper arm. The arc of travel of the pivot pin from first position 35 to second position 35' shown in the drawing assists in illustrating the operation of the crank means.

The ability of the clamping arm to be drawn back in this manner, as shown in FIG. 3, allows the excavator to be used to undertake conventional digging and/or scooping operations, with minimal hindrance from the clamping arm. It will thus be appreciated that the provision of a 14 crank means interconnecting the clamping actuator 34 and the clamping arm 32, in accordance with the invention, provides an enhanced range of pivotal movement for the bucket clamp along with flexibility and ease of use not available with existing clamping devices for excavators. When it is desired to change the mode of operation of the excavator from digging or scooping to grasping, the requirement for manually engaging linkage arrangements in order to use a bucket clamp or for dismounting a bucket and remounting a grabbing tool is obviated.

It will be further appreciated that the selection of the relative lengths of the links included in the crank means will dictate the particular arc of operation of the clamping member 32. Particular arcs of operation may be required for specific clamping members, such as a plate-like configuration arranged for closing a mouth portion of a bucket.

FIG. 4 shows a second embodiment of the present o:o• invention, which will be described in relation to a method for retro-fitting a clamping device 50 to an excavator or like earth moving machine. The drawing shows a dipper arm 41, a tool actuator 42, a linkage means 43 and a tool means 44 of an existing earth working machine. In the embodiment, the tool means comprises a bucket having a plurality of 20 tooth portions 45 on a leading edge thereof. The clamping device of course may be adapted to suit other tool types, such as a jack-hammer for demolition type jobs (see for example the disclosure in US Patent No.

4466494 in the name of Hanson) or a further cooperating clamp member.

The tool means 44 is pivotally connected to a distal end of the dipper arm 41 by a tool pivot pin 46. The linkage means 43 is pivotally connected to the dipper arm 41 by a linkage pivot pin 47. Typically the pivot pins 46, 47 are located in suitable bearings provided in the dipper arm.

4 i The method associated with the second embodiment includes the steps of fixing a bracket 51 to the dipper arm 41, which bracket cooperates with an actuator pivot pin 52 for pivotally mounting a first end of a clamping actuator 53 thereto. The bracket 51 may be fixed to the dipper arm 41 by welding, bolting or other suitable fixing techniques. A clamp member 54 comprises, in the second embodiment, a clamping frame including a plurality of fork-like tine portions 55. The ends of the tines 55 are suitably arranged to mesh with the teeth 45 on the bucket 44 for providing an improved gripping action when handling a group of loose items.

The clamp member 54 further includes main bearing means S.56 for pivotal mounting of the clamp member on the dipper arm 41. The ;V clamp member 54 is mounted, via the tool pivot pin 46 which passes through the main bearing, on a common pivot with the tool means 44. In some cases, the existing tool pivot pin may need to be exchanged with a lengthened and/or strengthened pin to accommodate the clamp member and to cope with any additional loading requirements above its specification.

There is further provided a crank means which, in the 20 present embodiment, includes a pair of radial links 57, an intermediate link

SSS

S 58 and cooperating pivot pins 59, 61. In a similar fashion to the tool pivot pin 46, the linkage pivot pin 47 is used to pivotally mount respective first ends of the pair of radial links 57 on the dipper arm 41. Again an exchange linkage pivot pin may be specified as required. The intermediate link 58 is pivotally connected at a first end to auxiliary bearing means 60, provided in the clamp member 54, by means of an intermediate pivot pin 61. The crank pin 59 then couples the respective second opposite ends of each of the radial link pair 57, the intermediate link 58 and an operative end of the clamping actuator means 53.

Although, for convenience, the steps of retro-fitting the clamping device are described in a particular sequence, the described sequence is not to be considered as limiting in any way. Other assembly sequences will suggest themselves to those having the appropriate skill in the present field. A particular advantage of the preferred method is that minimal alterations need be made to the dipper arm 41 where existing mounting points 46, 47 are used for common pivotal mounting of the clamping member 54 and associated crank means 57, 58. The bracket 51 for mounting the clamping actuator 53 and the addition of a suitable clamping actuator control sub-system (not shown) are the only substantial modifications otherwise required.

S-A third embodiment of a bucket clamp uses a clamping member 65 which includes a plate portion 66, for partially covering the mouth of the bucket, is shown in FIG. 5. The embodiment includes removable tine portions 67 secured in sockets 68 on the leading edge of :the plate 66. The tine portions are suitably arranged to cooperate with the teeth provided on an excavator bucket. The clamping member includes side plates 69 extending longitudinally of the plate portion 66, which side plates include main bearing means 70 for common pivotal mounting with the bucket and auxiliary bearing means 71 for radial links of the crank means, similar to that of earlier embodiments.

The clamping member 65 is specially extended for operational mounting on the dipper arm of an excavator using a known quick release type hitch arrangement, and includes notches 72 providing clearance for the hitch. The bucket clamp of the embodiment has been found to be particularly useful in manipulating conduits.

Turning to the clamping actuator control sub-system, it is presently envisaged that there could be three optional modes of operation, as follows: the clamp member and bucket being independently operated; the respective actuators being arranged to operate the clamp member and bucket in opposition to one another, for grasping or releasing an object; or (once an object has been grasped), the respective actuators being arranged to operate the clamp member and bucket in cooperation with one another (ie. pivot on the dipper arm in the same direction) so as to facilitate manipulation of the object being grasped, whilst maintained a constant grasp pressure on the object.

Each mode may be selectively engaged by the operator as desired. In a preferred embodiment, wherein the actuators comprised fluid pressure cylinders, a suitable fluid pressure control circuit could be a" i integrated with that already existing on an excavator or similar earthmoving machine.

Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment, specific collection of features or sequence of method steps.

Claims (23)

1. A bucket clamp for an excavator including a rotatable support frame, a boom extending generally forwardly of said frame, a dipper arm generally depending from a distal end of said boom and a bucket member pivotally mounted on a distal end of the dipper arm, which bucket member may be moved relative to said dipper arm by bucket actuating means; said bucket clamp comprising: a clamping member including a plurality of tine portions; the clamping member pivotally mounted on the distal end of the dipper arm, whereby said clamping member is movable in opposition to said bucket member; clamp actuating means mounted on the dipper arm for moving the clamping member relative to said dipper arm; characterised in that the clamping member is adapted to 900* 15 partially cover a mouth portion of the bucket member; the clamp actuating means is coupled to the clamping member via crank means; and wherein the crank means includes one or more intermediate links associated with the clamp actuating means and the clamping member, and one or more *O9O radial links associated with the clamp actuating means and the dipper 9o9oo9 S• 20 arm.

2. A bucket clamp as claimed in claim 1 wherein the crank means is arranged such that each intermediate link interconnects the *°o9 clamp actuating means and the clamping member, whilst each radial link interconnects the clamp actuating means and the dipper arm.

3. A bucket clamp as claimed in either claim 1 or claim 2 wherein a first end of each intermediate link is pivotally mounted on the clamping member, a first end of each radial link is pivotally mounted on 19 the dipper arm and respective second opposite ends of each intermediate link and of each radial link are coupled to a common pivot.

4. A bucket clamp as claimed in claim 3 wherein the common pivot is connected to a distal operative end of said clamp actuating means.

A bucket clamp as claimed in any one of claims 1 to 4 wherein the clamping member is pivotally mounted on the dipper arm via the pivotal mount for the bucket member.

6. A bucket clamp as claimed in any one of claims 1 to wherein the bucket actuating means and the clamp actuating means are mounted on opposite sides of the dipper arm.

7. A bucket clamp as claimed in any one of claims 1 to 6 wherein the bucket actuating means and the clamp actuating means each comprise fluid actuated cylinders having associated fluid pressure lines 15 for connection to fluid pressure control means.

8. A bucket clamp as claimed in any one of claims 1 to 7 wherein the clamping member comprises a clamping frame including the plurality of tine portions.

9. A bucket clamp as claimed in any one of claims 1 to 7 wherein the clamping member comprises a plate portion carrying a plurality of tine portions removably mounted on a edge of said plate portion.

A bucket clamp as claimed in either claim 8 or claim 9 wherein the tine portions of the clamping member are arranged to cooperate with any teeth provided on a leading edge of the bucket member.

11. A working implement for an earthmoving machine having an articulated arm, said working implement comprising: a tool means for earth working pivotally mounted proximate a distal end of the articulated arm, which tool means is moveable relative to said articulated arm by a tool actuating means mounted on said articulated arm; a clamping member including a plurality of tine portions; the clamping member pivotally mounted proximate a distal end of the articulated arm, whereby said clamping member is moveable in opposition to said tool means; clamp actuating means mounted on the articulated arm for moving the clamping member relative to said articulated arm; characterised in that the clamping member is adapted to partially cover a mouth portion of the bucket member; the clamp actuating 15 means is coupled to the clamping member via crank means; and wherein the crank means includes one or more intermediate links associated with .o the clamp actuating means and the clamping member, and one or more radial links associated with the clamp actuating means and the dipper arm. S00o0 20

12. A working implement as claimed in claim 11 wherein the crank means is arranged such that each intermediate link interconnects S the clamp actuating means and the clamping member, whilst each radial link interconnects the clamp actuating means and the dipper arm.

13. A working implement as claimed in either claim 11 or claim 12 wherein the crank means is arranged such a first end of each intermediate link is pivotally mounted on the clamping member, a first end U, of each radial link is pivotally mounted on the articulated arm and 21 respective second opposite ends of each intermediate link and of each radial link are coupled to a common pivot.

14. A working implement as claimed in claim 13 wherein the common pivotal coupling comprises a pin, which pin is further pivotally connected to a distal operative end of said clamp actuating means.

A working implement as claimed in any one of claims 11 to 14 wherein the tool means comprises a bucket member.

16. A working implement as claimed in any one of claims 11 to wherein the tool means comprises a jack-hammer or a further clamping member.

17. A method of fitting a bucket clamp to an excavator, which excavator includes a rotatable support frame, a boom extending generally forwardly of said frame, a dipper arm generally depending from a distal 9o99 ~end of said boom and a bucket member pivotally mounted proximate a distal end of the dipper arm, which bucket member may be moved relative to said dipper arm by bucket actuating means; said method including the •too; steps of: providing a clamping member including a plurality of tine portions; o -20 mounting the clamping member pivotally on the dipper arm proximate the distal end thereof, thereby facilitating movement of said clamping member in opposition to said bucket member; mounting a clamp actuating means on the dipper arm for moving the clamping member relative to said dipper arm; and coupling the clamp actuating means to said clamping member by means of crank means including one or more intermediate link(s) and one or more radial link(s).

18. A method of fitting a bucket clamp to an excavator as claimed in claim 17 wherein the step of coupling the clamp actuating means to said clamping member includes the steps of: mounting a first end of each intermediate link pivotally on the clamping member; mounting a first end of each radial link pivotally on the dipper arm; and coupling respective second opposite ends of the intermediate links and of the radial links to a common pivot.

19. A method of fitting a bucket clamp to an excavator as claimed in claim 17 or claim 18 wherein the step of mounting the clamping member involves the common pivotal mounting of the clamping member with the bucket member.

20. A method of fitting a bucket clamp to an excavator as ~9O* 15 claimed in any one of claims 17 to 19 wherein the step of mounting the ".**clamp actuating means further includes the step of mounting one end of the clamp actuating means pivotally on the dipper arm.

21. A method of fitting a bucket clamp to an excavator as claimed in any one of claims 17 to 19 wherein the step of mounting the clamp actuating means further includes the step of connecting a second operative end of the clamp actuating means to said common pivot. *0*

22. A bucket clamp for an excavator substantially as hereinbefore described with reference to the accompanying drawings.

23. A method of fitting a bucket clamp to an excavator substantially as hereinbefore described. DATED this Seventh day of January 2000. PHILLIP V BOWMAN i>P By his Patent Attorneys ,FISHER ADAMS KELLY