FEDERAL COURT OF AUSTRALIA PAC Mining Pty Ltd v Esco Corporation [2009] FCAFC 18 INTELLECTUAL PROPERTY – Patents – Claims, construction of – Need for practical understanding of claims in context of relevant field of art – Whether purely grammatical approach sufficient. INTELLECTUAL PROPERTY – Patents – Validity – Obviousness – Evidence of inventor – Whether entitled to special weight – Expert evidence that solution generally along the lines of apparatus claimed to be inventive would have been readily apparent to someone skilled in the art – Expert supplied with patent before expressing opinion – Whether value of evidence diminished because expert informed of problem and solution – Whether broad identification of generic solution meant invention itself was obvious. Patents Act 1990 (Cth) s 7(2) Aktiebolaget Hassle v Alphapharm Pty Ltd (2002) 212 CLR 411 Decor Corp Pty Ltd v Dart Industries Inc (1988) 13 IPR 385 Interlego AG v Toltoys Pty Ltd (1973) 130 CLR 461 Insta Image Pty Ltd v KD Kanopy Australasia Pty Ltd [2008] FCAFC 139 Kinabalu Investments Pty Ltd v Barron and Rawson Pty Ltd [2008] FCAFC 178 Lockwood Security Products Pty Ltd v Doric Products Pty Ltd (No 2) (2007) 235 ALR 202 Meyers Taylor Pty Ltd v Vicarr Industries Ltd (1977) 137 CLR 228 Olin Mathieson Chemical Corporation v Biorex Laboratories Ltd [1970] RPC 157 Pfizer Overseas Pharmaceuticals v Eli Lilly & Co (2005) 225 ALR 416 Wellcome Foundation v VR Laboratories (Aust) Pty Ltd (1981) 148 CLR 262 Woven Plastic Products Ltd v British Ropes Ltd [1970] FSR 47 PAC MINING PTY LTD (ABN 11 007 694 895) and CENTRAL QUEENSLAND MINING SUPPLIES PTY LTD (ABN 11 010 402 990) v ESCO CORPORATION and BRADKEN RESOURCES PTY LTD (ABN 82 098 300 988) NSD 1076 of 2008 SUNDBERG, JESSUP & MIDDLETON JJ 4 MARCH 2009 SYDNEY IN THE FEDERAL COURT OF AUSTRALIA NEW SOUTH WALES DISTRICT REGISTRY NSD 1076 of 2008 ON APPEAL FROM A SINGLE JUDGE OF THE FEDERAL COURT OF AUSTRALIA BETWEEN: PAC MINING PTY LTD (ABN 11 007 694 895) First Appellant CENTRAL QUEENSLAND MINING SUPPLIES PTY LTD (ABN 11 010 402 990) Second Appellant AND: ESCO CORPORATION First Respondent BRADKEN RESOURCES PTY LTD (ABN 82 098 300 988) Second Respondent JUDGES: SUNDBERG, JESSUP & MIDDLETON JJ DATE OF ORDER: 4 MARCH 2009 WHERE MADE: sydney THE COURT ORDERS THAT: 1. Orders 1, 2, 3, 4 and 8 of the orders made by the court on 4 July 2008 be set aside. 2. In place of Orders 1, 2, 3 and 4, it be ordered that the Application be dismissed. 3. Save as aforesaid, the appeal be dismissed. 4. The cross-appeal be dismissed. 5. Each party have leave to file and serve, within 14 days, a memorandum as to – a) the order, if any, to be made in place of Order 8 made by the court on 4 July 2008; and/or b) the costs of the appeal and/or of the cross-appeal; and if any party does so – c) each other party have leave, within 14 days of service on it of such memorandum, to file and serve a memorandum in response thereto; and d) the firstmentioned party have leave, within 7 days of service on it of such memorandum in response, to file and serve a memorandum in reply thereto. Note: Settlement and entry of orders is dealt with in Order 36 of the Federal Court Rules. The text of entered orders can be located using eSearch on the Court's website. IN THE FEDERAL COURT OF AUSTRALIA NEW SOUTH WALES DISTRICT REGISTRY NSD 1076 of 2008 ON APPEAL FROM A SINGLE JUDGE OF THE FEDERAL COURT OF AUSTRALIA BETWEEN: PAC MINING PTY LTD (ABN 11 007 694 895) First Appellant CENTRAL QUEENSLAND MINING SUPPLIES PTY LTD (ABN 11 010 402 990) Second Appellant AND: ESCO CORPORATION First Respondent BRADKEN RESOURCES PTY LTD (ABN 82 098 300 988) Second Respondent JUDGES: SUNDBERG, JESSUP & MIDDLETON JJ DATE: 4 march 2009 PLACE: SYDNEY REASONS FOR JUDGMENT INTRODUCTION 1 This is an appeal, by leave granted on 16 July 2008, from declarations and orders made by a single Judge of the court on 4 July 2008 in a patent infringement proceeding commenced in the court on 6 June 2006. The first respondent, Esco Corporation, is the patentee of the two patents in suit. The second respondent, Bradken Resources Pty Ltd, is the registered exclusive licensee of those patents. They were the applicants in the proceeding below. The appellants, PAC Mining Pty Ltd and Central Queensland Mining Supplies Pty Ltd, were the respondents below. The primary Judge held that they had infringed one of the patents in suit, but not the other. They appeal against that judgment. The respondents cross-appeal against his Honour's dismissal of their application with respect to the other patent in suit. The primary Judge also dismissed the appellants' challenges to the validity of both patents, and they appeal against that dismissal also. Further, in one respect the appellants contend that his Honour's order dismissing the respondents' application with respect to one of the patents might be upheld on grounds other than those upon which his Honour relied, and have filed a Notice of Contention in this regard. 2 The field of engineering with which the patents in suit are concerned is that of wear assemblies mounted on the digging edges of excavator buckets. Such buckets are the working components of mechanical excavators, and have the function of digging into, and thereafter collecting, soil, rock, and other like material. It is the leading, or digging, edge of an excavator bucket that has the function of effectively carving into the material to be excavated. Over a period of time, this edge will suffer wear to an extent that may once have required replacement of the bucket. Over the years, various means have been devised to protect the leading edge of excavator buckets by the use of shrouds and other fittings placed over the edge which may be more simply, and more cheaply, replaced as the need arises. 3 One kind of device referred to in the evidence below is that referred to as a "shroud". As the name suggests, a shroud is a covering adapted to be fitted over the digging edge of an excavator bucket, and protecting the edge from contact with the material being excavated. In some cases, it seems, the shroud will be no more than just described, extending laterally from one extremity of the digging edge to the other. In other cases, the digging edge of the bucket will be fitted with "teeth", spaced at intervals and shrouds will then be used to protect the otherwise exposed portions of the edge which lie between these teeth. A second kind of device is the fitting which attaches to the digging edge to support each of the teeth. Such a fitting is generally elongated in shape, is mounted on the surface of the excavator bucket immediately to the rear of the digging edge or thereabouts, and has a forwardly-protruding section onto which a cutting tooth might be mounted. This fitting was referred to in the evidence below as an "adapter", and we shall continue that terminology. It will be apparent that a tooth, when worn, might be replaced on its adapter, and that an adapter, when worn, might be replaced on the excavator bucket. THE PATENTS IN SUIT 4 The patents in suit are: · Australian Patent No. 696355, granted on 24 December 1998, referred to as "Jones II". · Australian Patent No. 743348, granted on 9 May 2002, referred to as "Jones III". The shorthand references are derived from the name of one of the inventors, Mr Larren Jones, who was also an inventor named in an earlier US patent, referred to as "Jones I". The priority date for both Jones II and Jones III is 6 November 1995. 5 Each of the patents in suit is entitled "wear assembly for a digging edge of an excavator". The expression "wear assembly" is a generic one, and is capable of referring either to a shroud or to an adapter, as the context requires. Notwithstanding that title, the present controversy is concerned not with wear assemblies as such, but specifically with the means by which such assemblies are attached to excavator buckets. The respondents contend that the wear assemblies supplied by the appellants, which are shrouds, infringe the patents because of the means employed to attach them to, or in the vicinity of, the digging edge of excavator buckets. 6 Save for the terms of the claims, the complete specifications for Jones II and Jones III are the same. Each of the specifications refers to the "field of the invention" as follows: The present invention pertains to a wear assembly for the digging edge of excavating equipment, and in particular, to an adapter which is mechanically attached to such excavating equipment. Each of the specifications explains the "background of the invention" in the following terms: Excavating teeth and other wear members have long been mounted along the digging edge of buckets and other excavating equipment to break up the ground and enhance the digging operation. As can be appreciated, the wear members used along the digging edge are often placed in harsh working conditions and are thus subjected to a high degree of wearing. In order to minimize the size of the part needing frequent replacement, excavating teeth are ordinarily formed as a plurality of integrally connected parts. An excavating tooth usually comprises an adapter, a point, and a lock pin for securing the point to the adapter. The adapter has a rear mounting end which is configured for attachment to the digging edge of an excavator and a forwardly projecting nose for mounting the point. The point is a tapered member provided with a forward earth-penetrating end and a rearwardly opening socket adapted to be received over the adapter nose. Although the points wear out more frequently, the adapters are also subjected to wearing and periodic replacement. As can be appreciated, the adapters must not only be capable of being firmly secured to the excavator to prevent undesired loss of the tooth during use, but it is desirable that they also be capable of being readily removed and installed by operators in the field. The complete specifications then refer to different approaches which have been developed for securing wear members to the digging edges of excavator buckets. One such approach was to weld the wear member to the lip of the bucket. Another approach was to attach the adapter mechanically, by a combination of a C-shaped clamp and a wedge. A third approach was that taken in Jones I, to which we shall refer further below. As the complete specifications explain, each of these approaches had its problems. 7 The "abstract of the disclosure" set out in Jones III is as follows: A wear assembly for attaching to a digging edge of an excavator includes a boss, a wear member and a lock. The boss is fixed to the excavator and defines a T-shaped coupling structure. The adapter includes a rearwardly extending mounting leg and a forwardly extending working end. The leg includes a T-shaped slot adapted to be received over the T-shaped structure of the boss. The adapter leg further includes an opening for receiving a lock. The lock includes an adjustment assembly for eliminating any looseness which may exist between the adapter and the boss. The same abstract appears in Jones II, save that the different components referred to therein are matched, by a series of numbers, to an accompanying diagram. 8 Each of the specifications sets out the "summary of the invention" as follows: The wear assembly of the present invention enables the wear member to be securely attached to the digging edge of an excavator without the need for welding of the wear member or, in the preferred construction, forming a hole in the excavator's edge. Moreover, the assembly has sufficient stability to amply support adapters on a bucket lip formed with a beveled ramp. Nevertheless, despite the durability of the wear assembly, the wear members can still be easily removed or installed when replacement of the member becomes necessary. In accordance with one aspect of the invention, a wear assembly includes a wear member which releasably attaches to a boss that is fixed to an excavator. The wear member includes a leg which extends rearwardly over the front edge of the excavator. A T-shaped structure is formed along the inner side of the leg for attachment to the boss. The complementary T-shaped coupling structures of the wear member and the boss prevent dislodgement of the wear member under load. The wear member also has front and rear bearing surfaces for resisting the applied loads during use. In another aspect of the present invention, the boss is formed with a first surface which lies against the excavator and a second surface which forms a T-shaped coupling structure for receiving a wear member. The boss further includes a front bearing face for bracing the wear member and a rear bearing face for abutting a lock member to prevent removal of the wear member. In the preferred construction, a clamp section is formed along the first surface to wrap about the front digging edge of the excavator. In accordance with another aspect of the invention, an opening for receiving a lock is formed through the leg of the wear member. The opening has a generally T-shaped configuration with a stem portion and a cross-portion. The stem portion extends longitudinally from the rear end of the leg to the lateral cross portion of the opening. The body of the lock sets between the rear end of the boss and the rear wall of the cross portion in order to prevent removal of the wear member from the boss. An adjustment assembly extends through the body to eliminate any looseness which may exist between the wear member and the boss. In accordance with another aspect of the invention, a deflector can be fixed to the excavator at a position behind the wear member. The removal of a wear member from the boss can frequently be a difficult task due to the compaction of fines around the parts. However, a lock member with an adjustment assembly can be easily used with a deflector to slide the wear member forwardly from the boss. As is apparent from the above summary, there are four aspects of the inventions. The first aspect is the wear assembly itself, which extends rearwardly from the front, or digging, edge of the bucket, and which has on its inner side (ie the side which lies along the surface of the bucket) a T-shaped structure. The second aspect is the boss which is securely fixed to the surface of the bucket and which has a T-shaped structure onto which the corresponding T-shaped structure of the wear member might be received. The mating of the wear member to the boss by their respective T-shaped structures inhibits the former from moving upwards and away from the surface of the bucket. The "rear bearing face" of the boss is an important characteristic of the inventions, but its role does not call to be described at this stage. The third aspect is the opening in the "leg" of the wear member, the purpose of which is to receive a component described as a "lock", which prevents removal of the wear member from the boss. As will appear, the function of the lock is to retain the wear member at its rearmost extremity and thus prevent it from sliding forward along the axis of the T-shaped structure of the boss. An important feature of the lock is that it incorporates an adjustment assembly to eliminate any looseness which may exist between the wear member and the boss, thereby ensuring that the wear member is held securely to the rear. The fourth aspect, the deflector, was not controversial in the proceeding, but it might usefully be noted at this stage that it is fixed to the bucket in a position to the rear of the wear member (ie the shroud or adapter). 9 The claims which were controversial below are claims 1 and 51 of Jones II and claim 1 of Jones III. Claim 1 of Jones II reads as follows: A wear assembly for attachment to a digging edge of an excavator, the digging edge having an inside face and an outside face, said wear assembly comprising: a boss having a first surface adapted to be fixed to the digging edge, a second surface adapted to be positioned remote from the digging edge and having a T-shaped structure, and a bearing face extending between said first and second surfaces; a wear member having at least one rearwardly extending leg and a forwardly projecting working end, said leg having a T-shaped structure releasably coupled to said T-shaped structure of said boss, said leg further including an opening extending therethrough; and a rigid lock received into said opening, said lock having a first face adapted to oppose and engage said bearing face of said boss and a second face adapted to oppose and engage a wall of said opening whereby said lock secures said wear member to said boss, said lock further including an adjustment assembly selectively movable to vary the relative positions of said first and second faces to eliminate looseness which may exist in mounting said wear member to the digging edge. Claim 51 of Jones II reads as follows: A wear assembly for attachment to a digging edge of an excavator comprising: a wear member having a rearwardly extending leg and a forwardly projecting working end, said leg having a longitudinal slot which opens in an inner side of said leg, said slot having an internal shoulder, and an opening extending through said leg and in communication with said slot, said opening including a bearing face; a boss adapted to be fixed to the digging edge, said boss including a bearing face and a longitudinal tongue, said tongue being axially received into said slot of said wear member and including a shoulder to engage said internal shoulder of said slot to prevent relative movement between said wear member and said boss in directions other than longitudinal; and a rigid look received into said opening and including a first face engaged with said bearing face of said opening, a second face engaged with said bearing face of said boss, and an adjustment assembly selectively movable to vary the relative positions of said first and second faces to eliminate looseness which may exist in mounting said wear member to the digging edge. Claim 1 of Jones III reads as follows: A wear assembly for an excavator having a lip with a digging edge, the wear assembly comprising: a mount adapted to be fixed to an excavator lip, the mount including a first shoulder spaced from the lip and a first bearing surface; a wear member including a second shoulder that engages the first shoulder between the first shoulder and the lip to hold the wear member to the mount and prevent release of the wear member from the mount in a direction generally perpendicular to the lip, and an opening equipped with a second bearing surface, wherein the first and second bearing surfaces face in opposite directions when the first and second shoulders are engaged; and a lock received into the opening in the wear member between the first and second bearing surfaces to prevent disconnection of the first and second shoulders from each other and thereby retain the wear member on the mount, the lock having a first lock surface to oppose the first bearing surface, a second lock surface to oppose the second bearing surface, and an adjustment assembly selectively movable to vary the relative positions of the first and second bearing surfaces to thereby apply forces to the wear member and the mount that tend to tighten the mounting of the wear member on the mount. THE APPELLANTS' SHROUD ASSEMBLIES 10 As we have explained above in relation to shrouds generally, the appellants' shroud is adapted to fit around, and thus to protect, a section of the leading edge of the excavator bucket which lies between any two teeth (or mountings for teeth). It may be described as having a "leg" which is in contact with the inside face of the bucket, and a "leg" which is in contact with the outside face. The inside-fitting leg is the longer of the two, giving the shroud a general "J" shape when viewed in profile. The shroud is fitted onto a boss fixed to the surface of the bucket by being slid from front to rear. The boss includes, on each side, a short extension or tab in a horizontal plane, slightly above the surface of the bucket (thus giving the boss, when viewed longitudinally, a very approximate "T"-shaped profile). The shroud includes, on each side, an internal, horizontally-oriented, slot, into which the corresponding tab on the boss is matingly received when the shroud is slid on to the boss from front to rear. Each of the top of the boss and the underside of the shroud contains a longitudinally-oriented semi-circular groove, such that, when the shroud is fully in position on the boss, there is a circular groove running along the centre line of, and internal to, the combined fitting. This groove receives a bolt, the purpose of which is to secure the shroud to the boss, and thus to the face of the bucket. At its rear end, the upper portion of the boss becomes effectively circular such that, over a short distance, the semi-circular groove becomes a circular aperture in the body of the boss (giving this aspect of the boss something of the appearance of a donut). When the shroud is received on to the boss, it slides home against this structure, wherein the circular aperture provides, in effect, a short continuation of what we have described as the now circular groove in the combined fitting. 11 The appellants have two shroud assemblies which were the subject of controversy in the infringement proceeding below. Each conforms broadly to the description above. They differ in point of detail in relation to the bolt which sits in the circular internal groove. In what has been described as the "T-bolt" assembly, the bolt has a straight shaft, with a conventional hexagonal head at one end and a threaded tail at the other. Before the shroud is fitted on to the boss, the bolt is placed in the semi-circular groove in the shroud. The head sits in a cavity internal to the body of the shroud, at the forward end of the groove. The shroud, with bolt in place, is fitted on to the boss as described above. The bolt then lies in the circular groove referred to and, when the shroud is fully to the rear, the tail of the bolt extends through, and beyond, the rear-end circular aperture in the boss. At this point, as we have described, the shroud itself is against the structure defining this aperture. Then, a flat washer, a lock washer and a nut are fitted to the threaded end of the bolt. At the front of the bolt, the underside of the head bears against the internal shoulders of the cavity. At the tail end of the bolt, the flat washer bears against the rear end of the boss. As the nut is tightened, the shroud is drawn (ie by the action of the head of the bolt on the internal shoulders of the cavity) rearwards and is thus secured in place on the boss. 12 What has been described as the appellants' "J-bolt" assembly works according to the same principle as the T-bolt assembly, and is generally as described above, with the following variations. Instead of terminating in a cavity in the shroud, the front end of the longitudinal groove in the shroud turns through 90 degrees towards the top of the shroud (ie the side not in contact with the face of the bucket) and there terminates. Over that short distance, the groove is circular, not semi-circular (it being wholly within the body of the shroud itself). The bolt itself is in the shape of a "J". It is inserted in the hole (ie the upper termination of the groove) in what we have called the top of the shroud, threaded end first. This may best be imagined by considering the "J" as being upside-down, and (at this stage) as looking rather like the periscope of a submarine. As the bolt is lowered into the hole, it is swivelled, as it were, through 90 degrees so that the longer part of the shaft of the bolt is now horizontal, and lies within the longitudinal semi-circular groove in the shroud. The shorter part of the bolt – that containing the head – is now vertical, and terminates in what appears (from the diagrams which were tendered) to be a small recess in the body of the shroud, corresponding with the shape of the underside of the head of the bolt. The shroud, with bolt in place, is then fitted on to the boss by sliding as described above. The head of the bolt sits securely in the recess in the top of the shroud, such that, when the nut on the threaded end is tightened, the shroud is drawn to the rear and secured in place on the boss. In the diagrams which were tendered, the fittings on the tail of the bolt were more involved than in the case of the T-bolt assembly (seemingly consisting, respectively from the head end, of a flat washer, a spring, another flat washer, a nut and a "jam nut"), but such variations are not material for present purposes. THE PROCEEDING AT FIRST INSTANCE 13 Before the primary Judge, the respondents contended that the appellants' shroud assemblies infringed each of claims 1 and 51 of Jones II and claim 1 of Jones III. They led evidence from Mr J M Alden, a structural engineer with extensive experience in relation to industrial settings in which excavators and like equipment are used. In an affidavit sworn on 15 May 2007, Mr Alden compared the claims, phrase by phrase, with the appellants' assemblies. He found every integer of each claim present in both the J-bolt and the T-bolt assemblies. 14 Relying on the evidence of Prof A C Wightley, a mechanical engineer with extensive experience in the design and manufacture of fixed and mobile machinery for mining facilities, the appellants contended that their assemblies fell outside the claims in three broad areas. The first area concerned the opening referred to in Jones II. The appellants said that their assemblies did not have an "opening extending therethrough" as required by claim 1, or an "opening extending through said leg" as required by claim 51. The point here was whether these words required that the opening extend all the way through the leg, or whether it was sufficient if the opening extended partly or substantially through the leg. The primary Judge accepted the following evidence of Prof Wightley, which was given in answer to the question "Why does it follow that [the opening] has to extend right through the leg axially?": The key has a certain depth and has to convey transfer of force from the wear member to the boss to stop the boss slipping off the wear member. So the key has to be deep enough from the top of the wear member to the bottom of the boss or very close to the bottom of the boss. That requires an opening extending all the way through. [Emphasis added by his Honour.] His Honour said that this was "consistent with the geometric logic of the claims in suit", and concluded on the point as follows: In my view, the correct construction of the expressions "opening extending therethrough" or "opening extending through said leg" is that advanced by Professor Wightley on behalf of the respondents. I find that a proper construction of the claims requires that the opening must extend all the way through the leg; an opening which extends only partly or substantially through does not fall within the terms of the claims. Such an interpretation accords with the ordinary meaning of the expression "through", corresponds with the preferred embodiment of Jones II and Jones III, and matches the engineering logic behind the design of such a wear assembly. His Honour observed that it was common ground that the appellants' assemblies did not have an opening which extended all the way through the leg. Accordingly, the appellants were successful in their defence of the infringement cases under Jones II. The respondents have cross-appealed against this aspect of his Honour's judgment. 15 The second area concerned the connotation of the term "digging edge" in each of claims 1 and 51 of Jones II. The appellants said that the term connoted the foremost extremity of the flat surface of an excavator bucket, so that the boss had to be fixed there at least, even if it was also secured further back along the surface. This point was important because the boss in each of the appellants' assemblies was attached to the flat surface a short distance back from the front extremity of the bucket. The primary Judge favoured the view for which the respondents contended, namely, that the "digging edge" as referred to in the claims included some part of the flat surface. His Honour said: … I am persuaded that for the wear assembly to work in a practical manner and withstand the forces brought to play on it, it would be impractical to require the boss to be attached only to the front face or bevelled ramp. The expression "digging edge" should not be interpreted so narrowly. In a notice of contention in support of his Honour's conclusion of non-infringement of Jones II, the appellants maintain that he was in error to have accepted that view, and should have held that it was a requirement of claims 1 and 51, that the boss be fixed to the front extremity of the bucket. 16 The third area related to the lock which, according to each of the claims in suit, was received into the opening in the wear member. Here his Honour described the appellants' case thus: In essence, the respondents' case is that, to constitute an infringement, the lock in its products must (i) have a body; (ii) act as a shear member; (iii) be received into the axial opening in the wear member; and (iv) sit between the rear end of the boss and the rear wall of the axial opening. Without any one of these characteristics, it is said, a product cannot be said to infringe the claims in suit. Elaborating on these characteristics, his Honour noted the appellants' submissions that the purpose of the lock was to act as a "jamming device"; that the lock had to be positioned between the boss and the wear member and, as such, was subjection to compression; that the lock had to be "rigid" at the point of being received into the opening (rather than being made rigid at some later stage); and that the whole of the lock had to be received into the opening. In the appellants' case below, this point involved a crucial distinction between the inventions claimed and their assemblies. It will be recalled that the appellants' assemblies are held in place on the boss by a bolt, with a head and a nut, which is tightened. They contended that the lock referred to in all the claims held the wear member in place by sitting between, and thus by holding apart, the forward-facing part of the rear wall thereof and the rear-facing part of the boss. This, they contended, connoted a mechanism quite different from either of their bolts. 17 The primary Judge dealt with this issue at two levels. He first held that the lock referred to in claims 1 and 51 of Jones II was not required to be "rigid" at the point of being received into the opening. His Honour said: In my view, to determine whether the lock used in the respondents' products is properly described as "rigid", one must take as the point of analysis the moment when the lock is assembled, inserted, adjusted and ready for use. At that time, although the lock may be comprised of several component parts, in my view it can be properly described as a rigid lock falling within the terms of the claim in suit. On a proper construction, it is not necessary for the lock to contain a single and solid piece of metal, as proposed by Professor Wightley. Once the variety of parts of the lock are assembled and thereby made rigid, that is sufficient to fall within the claims in suit. It followed that the bolt, washer and nut arrangements in the appellants' assemblies could be viewed as rigid locks. His Honour secondly held that it was not necessary for the whole of the lock to be received into the opening. His Honour said: In my view, the expression "received into the opening" does not mandate that the whole of the lock must be so received. The normal meaning of "received into" can include receiving part of a lock, and the example of a door lock (in which the lock is received into an opening notwithstanding that its latches, handle and shaft may project outside that opening) given by the applicants demonstrates this point. Neither the language of the claims in suit, nor the functions of the lock in the relevant wear assemblies support the restrictive interpretation of the term proposed by the respondents. There is no reference in the claim to the "whole" or the "entirety" or the "essential parts" of the lock being so received, and in my view, the use of the word "between" does not require that the whole lock should be contained within the opening defined by the first and second bearing surfaces. Moreover, the operation of the lock does not call for a restrictive interpretation because its purpose, which is to prevent detachment of the wear member as a result of the movement of the wear assembly, does not depend on the lock being entirely encased within the first and second bearing surfaces. Professor Wightley accepted this point in cross-examination. Finally, the preferred embodiment depicted in various figures attached to the specifications of the patent does not indicate that the whole lock is contained within the two specified surface areas. Again, this is a matter which Professor Wightley acknowledged in cross-examination. Accordingly, in my view, the proper construction of the claim is that it is not necessary for the whole of the lock to be received into the opening between the first and second bearing surfaces. In addition, having regard to the language used in the claim and the preferred embodiment, I am not persuaded that every critical part of the lock must be received into the opening. No support for this alternative construction can be derived from the terms of the claims in suit, nor is there sufficient evidentiary basis to support such an interpretation. It followed that the circumstance that a section of each of the J-bolt and the T-bolt lay outside the opening in the shroud was not disqualifying. 18 There was another integer of these claims that, according to the appellants, was not to be found in their J-bolt and T-bolt assemblies. They contended that the "adjustment assembly" referred to was not intended to be an essential part of the lock, but may facilitate improved performance under some conditions. The point of this contention was to contrast the role of a nut threaded on to a bolt (which was to be understood as an integral part of the locking action as such) with that of a device intended only to take up slack. On this point his Honour held that the adjustment assembly referred to in the claims was part of the lock itself, and not merely an addition. He said: In my view, it is also clear from the language of the claims that the rigid lock must further include an adjustment assembly as part of it. This further inclusion is not merely as an optional addition to the lock itself. By being selectively moveable, the adjustment assembly is able to vary the relevant positions of the first and second bearing faces and thereby eliminate looseness. This, to my mind, is an essential part of the lock itself which enables it to perform its contemplated function of securing the wear assembly to the bucket. The expression "further including" indicates that the adjustment assembly, in order to achieve its stipulated purpose of eliminating looseness, is seen as necessary to the practical operation of the lock and is therefore part of the lock itself. 19 Thus his Honour held for the respondents with respect to the "lock" aspects of the construction of the claims. The result was a finding that the appellants had infringed claim 1 of Jones III. They appeal against that finding. They also put in issue his Honour's corresponding conclusion with respect to claims 1 and 51 of Jones II in their notice of contention. 20 The appellants' cross-claim on validity had three aspects. First, they said that the invention in Jones III was not novel. The primary Judge held against the appellants on this point, and they have not appealed against that holding. 21 Secondly, the appellants said that the inventions as claimed in claims 1 and 51 of Jones II, and in claim 1 of Jones III, were obvious within the meaning of s 7(2) of the Patents Act 1990 (Cth) and, therefore, did not involve an inventive step. Here it is necessary to return to Jones I. That patent was applied for in 1991 and granted in 1992. Some indication of its relevance to the present question may be gathered from the following paragraph in the specification for that invention: According to the invention, these disadvantages have been overcome through the provision of a generally U-shaped wear member having a T-shaped slot in one of the legs of the U-shape for rearward sliding engagement with a complementarily shaped boss on a face of the excavator and wherein the wear member is equipped with a transversely enlarged, keeper-equipped opening adjacent the rear end for the receipt of an essentially non-compressible lock which resists forward or disengaging movement and which is not subject to deterioration due to heavy, cyclic loading. 22 According to the primary Judge, the commercial embodiment of Jones I, a product marketed by the first respondent as "Toplok", was first sold in Australia in 1991. By 6 November 1995 – the priority date for Jones II and Jones III – Toplok had been sold in large quantities and was used on excavators operating in mines around Australia. The respondents accepted that the technology used in Toplok (effectively that of Jones I) was common general knowledge in Australia. His Honour also noted that the respondents accepted that the introduction of the adjustment assembly into the lock in Jones II and Jones III was the only respect in which, so far as the claims in suit were concerned, those patents involved a potentially inventive departure from Toplok. The question for his Honour on the matter of obviousness, therefore, was whether it would have been obvious to the notional skilled person in the art that an improvement could be made to Toplok by the utilisation of the adjustment assembly claimed in the claims in suit. 23 The primary Judge accepted that each of the expert witnesses called by the parties on the question of obviousness had sufficient expertise to express the opinions that he did as "a person skilled in the relevant art". The opinions relied upon by the appellants were those of Prof Wightley. Before expressing those opinions, Prof Wightley was shown Jones I, and each of the patents in suit. He was also asked to assume that, at the priority date, it was well-known that the "Toplok" apparatus had a problem in that the lock itself "was prone to work loose and fall out thereby allowing the wear member to slide off the boss attached to the excavator bucket". He expressed the opinions that this problem was a "design flaw" and that the use of a screw adjustment to take up any looseness which existed "would immediately come to mind" to a mechanical engineer. The appellants called Mr Robert McClanahan on the questions of obviousness. He was one of the inventors of Jones II and Jones III. He was well-qualified in mechanical engineering, and had been employed by the first respondent since 1982. He gave evidence of the steps taken by the inventors, in the course of devising what became Jones II and Jones III. We shall return in more detail to the evidence of these witnesses in due course. 24 The primary Judge accepted Mr McClanahan's evidence, and, while he did not in terms reject that of Prof Wightley, his Honour did not accept Prof Wightley's conclusion on the matter of obviousness. In par 80 of his reasons, his Honour said: It is also important in this case to note that when deciding whether there has been an inventive step the courts have attached considerable weight to the evidence of the inventor: see Terrell, The Law of Patents (3rd ed., 1994) at [5.92]. In this respect I give weight to the evidence of Mr McClanahan, who was one of the named inventors of Jones II and Jones III, that the solution of the adjustment assembly was not perceived by the inventors for some time until after about mid-1995. Mr McClanahan said that the skilled person would be unlikely to use a bolt and nut assembly because of expected problems such as rusting and deformation of the thread. He also stated that the looseness in Toplok was not a "design flaw" because that wear assembly was expressly designed to permit looseness, a design characteristic which could be tolerated in a shroud and which carried the advantage of being relatively cheap and simple to manufacture. In Mr McClanahan's view, the problems which arose in relation to Toplok were related chiefly to large buckets, and were often cured by a variety of methods which did not involve an adjustment mechanism such as the one which is included in Jones II and Jones III. This, says Mr McClanahan, along with the commercial success of the Toplok shroud, runs contrary to the suggestion that Jones I suffered from a design flaw. The fact that there were some problems does not necessarily indicate that there was a design flaw in the Toplok wear assembly. The primary Judge took the view that Prof Wightley's conclusion was "reduced in weight by hindsight assumptions related to the nature of the problem, the need for a new design and the solution ultimately developed." His Honour did not accept that the problems associated with Jones I "admitted of an obvious solution which would have been readily perceived as a matter of course by a person skilled in the art at the relevant time." Thus his Honour decided the obviousness point against the appellants. They have appealed against that decision. 25 Thirdly, the appellants said that each of the relevant claims was not fairly based on the matter described in the specification to which that claim related. Their case was expressed in their outline of submissions as follows: If the applicants' construction of the relevant claims is accepted then the respondents contend that they each lack fair basis. This is because the whole of the description of the invention in the specification of Jones I and Jones II is confined to a description of a rigid lock which is subjected to compression between the rear bearing face of the boss and the rear wall of the opening. There is no real or reasonable disclosure in the specification that provides any basis for claims which extend to attachment mechanisms that function as tension members (eg. nut and bolt arrangements) which are neither received nor compressed between the bearing face of the boss and the rear wall of the opening. The primary Judge did not accept that case. His Honour said: For reasons given above, I consider the disclosure is not limited to a rigid lock which operates as a "shear" member. Rather, it includes a lock with an adjustment assembly which in fact operates in the way claimed. Accordingly, the specification provides a sufficient disclosure for the adjustment assembly in the terms of the claim. The appellants have appealed against that aspect of his Honour's reasons. INFRINGEMENT 26 In a number of respects the infringement questions which arise on appeal require a construction of the claims in suit, which will also provide a basis for our consideration of the matters of validity to which we shall turn later. Although not, as a matter of principle at least, controversial as between the parties, we should commence by referring to the approach which the court takes to such questions. It is useful to do this by reference to the summary provided by the Full Court in Pfizer Overseas Pharmaceuticals v Eli Lilly & Co (2005) 225 ALR 416, 467-469. 27 The Full Court noted, apparently with approval, the ten principles of construction set out by Sheppard J in Decor Corp Pty Ltd v Dart Industries Inc (1988) 13 IPR 385, 400; 225 ALR at 468 [249]: (1) The claims define the invention which is the subject of the patent. These must be construed according to their terms upon ordinary principles. Any purely verbal or grammatical question that can be answered according to ordinary rules for the construction of written documents is to be resolved accordingly. (2) It is not legitimate to confine the scope of the claims by reference to limitations which may be found in the body of the specification but are not expressly or by proper inference reproduced in the claims themselves. To put it another way, it is not legitimate to narrow or expand the boundaries of monopoly as fixed by the words of a claim by adding to those words glosses drawn from other parts of the specification. (3) Nevertheless, in approaching the task of construction, one must read the specification as a whole. (4) In some cases the meaning of the words used in the claims may be qualified or defined by what is said in the body of the specification. (5) If a claim be clear, it is not to be made obscure because obscurities can be found in particular sentences in other parts of the document. But if an expression is not clear or is ambiguous, it is permissible to resort to the body of the specification to define or clarify the meaning of words used in the claim. (6) A patent specification should be given a purposive construction rather than a purely literal one. (7) In construing the specification, the court is not construing a written instrument operating inter partes, but a public instrument which must define a monopoly in such a way that it is not reasonably capable of being misunderstood. (8) The body, apart from the preamble, is there to instruct those skilled in the art concerned in the carrying out of the invention; provided it is comprehensible to, and does not mislead, a skilled reader, the language used is seldom of importance. (9) Nevertheless, the claims, since they define the monopoly, will be scrutinised with as much care as is used in construing other documents defining a legal right. (10) If it is impossible to ascertain what the invention is from a fair reading of the specification as a whole, it will be invalid. But the specification must be construed in the light of the common knowledge in the art before the priority date. As will appear, Nos. (1) – (6) and (9) on Sheppard J's list have the potential to be important in the present appeal. 28 In Pfizer, the Full Court also noted that the "clear words of a claim are not to be distorted by importing passages from the specification" and that "when a claim is clear it is not to be glossed or obscured by reference to the specification" (225 ALR at 467 [247]). In this respect their Honours referred to the words of Barwick CJ and Mason J in Interlego AG v Toltoys Pty Ltd (1973) 130 CLR 461, 478 that "it is not permissible to vary or qualify the plain and unambiguous meaning of the claim by reference to the body of the specification" (225 ALR at 467 [247]). However, as their Honours in Interlego also pointed out, where an expression is not clear "it is…permissible to resort to the body of the specification to define or clarify the meaning of words used in the claim…" (225 ALR at 468 [248]). 29 The correct approach to the construction of claims has been referred to in two recent judgments of the Full Court. In Insta Image Pty Ltd v KD Kanopy Australasia Pty Ltd [2008] FCAFC 139, [82] the Full Court said: Construction of claims is a matter for the Court: Minnesota Mining & Manufacturing Co v Tyco Electronics Pty Ltd (2002) 53 IPR 32 at [92]; Fresenius Medical Care Australia Pty Ltd v Gambro Pty Ltd (2005) 67 IPR 230 at [34], and other authorities. When claims are being construed, the specification is to be read as a whole in order that the necessary background to the invention may be known and words or expressions used in the claims may be understood: British Thomson-Houston Co Ltd v Corona Lamp Works Ltd (1922) 39 RPC 49 at 67; Rosedale Associated Manufacturers Ltd v Carlton Tyre Saving Co Ltd [1960] RPC 59 at 60, cited with approval by Sheppard J in Decor Corp Pty Ltd v Dart Industries Inc (1988) 13 IPR 385 at 399. However, where a claim is clear and unambiguous, it is not permissible to resort to the specification in order to qualify it: Welch Perrin & Co Pty Ltd v Worrel (1961) 196 CLR 588 at 610; Interlego AG v Toltoys Pty Ltd (1973) 130 CLR 461 (Interlego) at 478; Atlantis Corp Pty Ltd v Schindler (1997) 39 IPR 29 at 35, 48; Kimberly-Clark Australia Pty Ltd v Arico Trading International Pty Ltd (2001) 207 CLR 1 (Kimberly-Clark)at [15]. It may, however, be possible to resolve any ambiguity or lack of clarity by reference to the body of the specification; cf Interlego at 479; Kimberly-Clark at [15]. In Kinabalu Investments Pty Ltd v Barron and Rawson Pty Ltd [2008] FCAFC 178, [44]-[45] the Full Court said: The principles of construction applicable were not in dispute. When determining the nature and extent of the monopoly claimed, the specification must be read as a whole. But as a whole it is made up of several parts which have different functions. The claims mark out the legal limits of the monopoly granted. The specification describes how to carry out the process claimed and the best method known to the patentee of doing that. Although the claims are construed in the context of the specification as a whole, it is not legitimate to narrow or expand the boundaries of monopoly as fixed by the words of a claim, by adding to those words glosses drawn from other parts of the specification. If a claim is clear and unambiguous, it is not to be varied, qualified or made obscure by statements found in other parts of the document. It is legitimate, however, to refer to the rest of the specification to explain the background of the claims, to ascertain the meaning of technical terms and resolve ambiguities in the construction of the claims. See Flexible Steel Lacing Co v Beltreco Ltd (2000) 49 IPR 331 at [73]‑[75] (Hely J). Other more specific principles of construction collected in Flexible Steel at [81] are: · a specification should be given a purposive construction rather than a purely literal one; · the hypothetical addressee of the specification is the non‑inventive person skilled in the art before the priority date; · the words used in a specification are to be given the meaning the hypothetical addressee would attach to them, both in the light of the addressee's own general knowledge and in the light of what is disclosed in the body of the specification; · as a general rule, the terms of the specification should be accorded their ordinary English meaning; · evidence can be given by experts on the meaning those skilled in the art would give to technical or scientific terms and phrases, and on unusual or special meanings given by such persons to words which might otherwise bear their ordinary meaning; · however, the construction of the specification is for the court, not for the expert. In so far as a view expressed by an expert depends upon a reading of the patent, it cannot carry the day unless the court reads the patent in the same way. 30 Turning to the infringement issues which are controversial in the present appeal, we commence with so much of the appellants' notice of contention in the cross-appeal as is concerned with the term "digging edge" when used in claims 1 and 51 of Jones II. The appellants submitted that the digging edge was the very front extremity of the face of the bucket, like the cutting edge of a knife, for example. They then pointed to the circumstance that the boss in their T-bolt and J-bolt assemblies is fixed (eg by welding) onto the flat surface of the excavator bucket, a small distance back from the edge as so understood. No part of the boss is attached to, or fixed to, the edge as such. The respondents submitted that the digging edge was the front portion of the digging face of the bucket, including the extremity thereof, but extending also a short distance back therefrom. They submitted that the appellants' construction would make a nonsense of the claims, since (and this was common ground) an apparatus subjected to the kind of stresses to which components made in accordance with the claims would inevitably be subject could never have worked if fixed or attached on the extremity only. In the respondents' submission, therefore, the appellants' boss was "fixed to the digging edge" notwithstanding that it was located some short distance back from the extremity and that no part of it was in contact with the extremity. The primary Judge upheld that submission, and held that the appellants' assemblies fell within these words in claims 1 and 51 of Jones II. 31 On appeal, the appellants submitted that his Honour had misunderstood the position for which they contended. They did not contend that claims 1 and 51 should be construed so as to imply an attachment on the extremity of the flat surface of the bucket only, but contended rather that the claims required at least that the boss be fixed, in the sense of secured, to that extremity notwithstanding that it would, for the sake of strength and stability (and quite obviously so, in the submission of the appellants) also be fixed further back along the flat surface. They submitted that this interpretation of the expression "digging edge" found support, including diagrammatic support, in the detailed description of the invention contained in the complete specification. Here the appellants were referring to a design and configuration of the boss which is given pre-eminence in the detailed description, and which fits over the leading extremity of the bucket, having a leg extending back along each of the upper and lower faces of the flat surface of the bucket. Being held in place by weld beads or similar, the boss is, according to the appellants, adapted to be fixed to the digging edge. 32 Quite apart from the considerations of structural strength to which his Honour referred, however, there are clear indications in the claims in Jones II that the expression "digging edge" includes a reference to the flat surface of the bucket somewhat to the rear of the extremity as such. A number of claims (6, 10, 20, 26, 34, 40) refer to "the digging edge having an inside face and an outside face". A number of claims refer to a leg of the wear member extending "rearwardly over the digging edge" (10, 20, 26). Claims 5 and 9, in referring to the "deflector", requires it to be fixed "to the digging edge rearward of the said boss". Claim 34 refers to a boss with a surface which has "a clamping section adapted to wrap around the digging edge and engage front portions of the inside face and the outside face". It is as clear as may be from these uses of the expression "digging edge" in various claims that the expression is to be understood as including a general reference to the flat structural portion of the bucket lying immediately to the rear of, and not being confined to, the front extremity thereof. 33 That conclusion is not contradicted by a consideration of other provisions of the complete specification. The appellants' construction of claim 1 is, it seems, influenced by what the complete specification refers to as "the preferred construction", that is, one in which "a clamp section is formed along the first surface to wrap about the front digging edge of the excavator". Such a construction is the subject of much, but not all, of the detailed description and, as the appellants pointed out, of many of the accompanying diagrams. However, as counsel for the respondents pointed out, the detailed description also provides an example of the invention in which the adapter (ie the wear assembly itself) wraps around the leading edge of the bucket, but the boss does not. Rather, the boss is fixed only to the flat surface of the bucket, a little distance to the rear of the front extremity thereof. 34 For those reasons, we reject the appellants' proposition that the "digging edge" referred to in claims 1 and 51 of Jones II is a reference to the front extremity of the bucket. It follows that we do not accept that a configuration in which the boss is placed somewhat to the rear of the front extremity, and does not wrap around it, lies outside those claims. 35 We turn next to the point arising on the cross-appeal as such, namely, whether either of the appellants' shroud assemblies incorporates an opening extending "through" the rearwardly extending leg of the wear member, as required by claims 1 and 51 of Jones II. The primary Judge held that it was common ground that neither the T-bolt assembly nor the J-bolt assembly incorporated an opening which passed the whole way through the body thereof. On the cross-appeal, the appellants conceded that his Honour had been mistaken in saying that it was common ground that the opening in the J-bolt assembly did not pass the whole of the way through the body thereof. Indeed, the appellants conceded that it did. This point, therefore, was controversial only with respect to the T-bolt assembly, in relation to which it was, and it remains, common ground that the opening does not pass the whole way through. That is because the groove in the shroud which contains the bolt terminates, at one end thereof, in the form of a cavity adapted to receive the head of the bolt. There is, therefore, no "opening" at that end. 36 The point on the cross-appeal with respect to the T-bolt assembly is, therefore, as it was before his Honour: should claims 1 and 51 of Jones II be construed so as to require that the opening there referred to pass the whole way through the body of the assembly – in the sense of having an opening at each end joined by a continuous open passage – or will it be sufficient if the opening passes some distance only through the body? The Oxford English Dictionary (2nd Ed) gives the signification of "through" as "the preposition expressing the relation of transition or direction within something from one limit of it to the other: primarily in reference to motion in space …." The sense most relevant to the present context is "from one end, side, or surface to the other or opposite end, side or surface of (a body or a space) by passing within it; usually implying into, at one end, side etc and out at the other." In the context of, say, a person or object in motion, passage "through" a body or space does usually imply an entry into, and an exit from, that body or space (such as, for example, a train passing through a tunnel). However, where the context is not one of motion, but involves the definition of a space by reference to an object by which it is generally enclosed, it makes little sense to envisage the actions of entry and exit. In such a context, to say that the opening extends "through" the body is, in our opinion, clearly to say that it commences at one side, end or extremity, and ends at another. 37 This understanding of "through" in the present context is confirmed by the sense conveyed by the word "extending". That word implies that the opening passes wholly through the object referred to. It is confirmed also by the concept of an "opening" as such. When used with respect to an otherwise generally solid object, an "opening" connotes a gap, hole, passage or aperture. On the respondents' construction of "through", there would be such an opening at one end only. The other end of the cavity referred to would not be "open". For an opening to extend through an object requires, in our view, that each end be open. 38 For those reasons we uphold the respondents' point that the appellants' J-bolt assembly incorporates an opening which extends through it as required by claims 1 and 51 of Jones II; but we reject their like point with respect to the T-bolt assembly. 39 That leaves what is probably the most difficult aspect of the respondents' infringement claims, namely, the question whether the appellants' shroud assemblies incorporate a lock with the features required (in the case of the J-bolt assembly) by claims 1 and 51 of Jones II and/or (in the case of both assemblies) by claim 1 of Jones III. We shall commence with the question whether the J-bolt assembly falls within the terms of claim 1 of Jones II, in the course of which we shall resolve the constructional issues which are effectively common to all these questions. We shall then turn to the remaining questions. 40 The respondents say that the J-bolt itself, together with its washers and nuts, is the lock referred to in claim 1 of Jones II. They say that, when tightened and ready for operation, the bolt is properly described as "rigid". They say that the bolt is received into the opening in the shroud, in the sense of lying substantially within the confines of the semi-circular longitudinal groove contained therein. They say that the first face of the lock is constituted by the inside surface of the washer on the threaded end of the bolt, which face bears against (ie, in the words of the claim, opposes or engages) the rear end (ie the bearing face) of the boss. They say that the second face of the lock is the underside of the head of the J-bolt, which face is drawn (by tightening the nut) into (ie, in the words of the claim, opposes and engages) the corresponding recess in the body of the shroud (ie a wall of the opening referred to in the claim). They say that the nut on the threaded shaft of the J-bolt is an adjustment assembly which may be tightened as the occasion demands to eliminate any looseness which may arise. 41 In par 16 above, we have identified the respects in which the appellants contended at trial that their shroud assemblies (including the J-bolt assembly) did not infringe this aspect of claim 1 of Jones II. We have also identified how the primary Judge dealt with the appellants' points. On appeal, the appellants submitted that his Honour's analysis did not "reflect a commonsense and practical approach to the interpretation of the claim" and was "based upon an over-meticulous and fragmentary analysis of language used in the claim". In our respectful view, there is some justification in these criticisms. To an extent, his Honour's approach was influenced by the way the appellants arranged their submissions before him. In their closing outline dated 14 December 2007, the appellants dealt with the "lock" aspects of the case in the following way. They had a section headed "A rigid lock received into said opening", in which they commenced by setting out the summary referred to by his Honour in the passage we have set out at par 16 above. They proceeded to deal with each of the characteristics there referred to in the some detail. As the wording implies, those aspects were concerned with Jones II. The next main section of the appellants' outline was headed "A lock 'received into the opening between the first and second bearing surfaces'" – a reference to Jones III. The final section of the outline was headed "Further includes an adjustment assembly" – a reference in terms to Jones II, but the text of the outline dealt also with corresponding provisions of Jones III. 42 As appears from what we have set out in pars 17-18 above, the primary Judge dealt with these aspects of the appellants' case as though they involved pure questions of construction, and even then his Honour appears not to have dealt with so much of that case as characterised the lock as one which acted as a shear member or, in the case of Jones III, as involved the requirement that the lock be set between the two bearing faces referred to. We shall return to Jones III, but, in the context of the present discussion (ie Jones II and the J-bolt), it does appear that his Honour did not come to grips with a central aspect of the appellants' case that required an identification of the basic mechanical principles involved in Jones II namely, the means of operation of the lock, and specifically the fact that the claim, properly understood in a practical and not merely a grammatical sense, is concerned with a lock which is set between slightly offset faces which would otherwise move towards each other, thereby operating as a shear member. As noted elsewhere in these reasons, when dealing with the question whether the opening had to extend "through" the wear member claimed in Jones II, his Honour was alive to what he described as the "geometric logic" of the claims, and the "engineering logic behind the design" of the wear assembly. However, his Honour did not, at least apparently, carry that logic forward into his consideration of the "lock" aspects of the claim. 43 It is, in our opinion, almost impossible to render a practical meaning to this aspect of claim 1 of Jones II without bringing to the task at least a general understanding of the invention as a whole and of the field of engineering in which it is said to be useful. The meaning of the word "lock" (relevantly to the present matter, ie excluding such things as a lock of hair) is based upon function rather than upon appearance or attributes. That is to say, a device or apparatus is a lock because it locks. Use of the word "lock" in the claim, therefore, reveals little about the essence of the invention, and invites further inquiry. The word is then qualified by the requirement that it be "rigid", but, out of context, that requirement may go no further than to exclude devices which are flexible or pliable in some sense. It is really the further characteristics of the lock, and how they operate in co-operation with the boss and the wear member to achieve locking, that illuminate what it is the inventors had in mind and thus the true scope of the claim in relevant respects. In other words, to know what is here claimed by the inventors, one needs to understand how it is proposed that the lock should work. 44 This brings us to the expert evidence in the proceeding below. What the words of a claim convey to an experienced professional in the relevant art is, of course, most relevant to the present question, although, as has frequently been stressed, the construction of a claim is ultimately a matter for the court to be done according to conventional legal principles. In the present case, each of Mr Alden and Prof Wightley expressed his understanding of what was conveyed by the claims in the patents in suit. They did not agree. They were extensively cross-examined, in the course of which reference was made to the complete specifications, particularly to the consistory clauses, and to the detailed descriptions of the inventions. In his reasons for judgment, the primary Judge said that, "[g]enerally, Mr Alden's evidence was not significantly shaken on cross-examination". His Honour also said that Prof Wightley's evidence "was tested but…not materially undermined". 45 In order to understand the point of departure as between the evidence of Mr Alden and that of Prof Wightley, it is useful to refer first to their affidavits in the order in which they were filed, as this illuminates the way the argument developed. In his affidavit of 15 May 2007, Mr Alden said that he had read the specifications in each of the patents in suit. From that, he understood that the inventions (ie Jones II and Jones III) had three main features, namely: (a) a boss (or mount) which is fixed to the lip or digging edge of the excavator, having an external, or male, structural shape for attachment of a wear member and a prevention of movement of the wear member upwards and away from the inside surface of the bucket; (b) a wear member having a complementary internal, or female, structural shape that attaches to the boss (or mount) by sliding over the male structural shape of the boss, and which by encompassing the boss, protects it from wear; and (c) a lock that is received into an opening in the wear member, that acts against both the boss (or mount) and the wear member, preventing (longitudinal) removal of the wear member from the boss. The lock has facility for adjustment which enables tightening of the wear member onto the boss and/or digging edge. Mr Alden reached that understanding without any knowledge of the infringements alleged by the respondents. He then considered the appellants' shroud assemblies, and expressed the view, with respect to the "lock" aspects with which we are presently concerned, that they fell within the claims in suit. In relation to the J-bolt assembly in the context of claim 1 of Jones II, Mr Alden's view was substantially as set out in par 40 above. He expressed like views with respect to the other claims in suit, and with respect to the T-bolt assembly under all three claims in suit (a matter to which we shall turn later). 46 In an affidavit sworn on 25 May 2007, Prof Wightley referred first to Jones I. In that patent, the disadvantages of the then prior art were referred to, and a summary of the invention was provided (as set out in the extract from Jones I in par 21 above). Referring to the lock in Jones I as a "key", Prof Wightley said: A key is received into a cavity in the wear member extending at right angles to the centre line of the wear member. The key bears against the vertical bearing surface of the cavity in the wear member at the top half of the key. The bottom half of the key bears against the rear vertical bearing surface of the boss. In this assembly, the key acts as a shear member preventing forward movement of the wear member which, if permitted, would allow the wear member to slide off and detach from the boss. I refer to the key as a "shear member" because it is subjected to shearing forces from the bearing surfaces of the wear member and the boss in that: (a) the bearing surface of the boss exerts a force on the lower half of the front surface of the key; and (b) the bearing surface of the wear member exerts a force on the top half of the rear surface of the key in the opposite direction. 47 In a further affidavit sworn on 16 August 2007, Prof Wightley turned his attention to Jones II and Jones III. He referred to his earlier affidavit and continued: I consider that the "rigid lock" referred to in claims 1 and 51 of Jones II and the "lock" referred to in claim 1 of Jones III perform the same function as the key (or "lock") in Jones I. Both are shear members and are subjected to shear forces of the kind I have described in paragraphs 16 and 17 of my First Affidavit. The language used in the claims to describe the function of the lock and the use of the word "boss", make it clear to me that the lock is a shear member. In particular, I refer to those words: "…said lock having a first face adapted to oppose and engage said bearing face of said boss and a second face adapted to oppose and engage a wall of said opening whereby said lock secures said wear member to said boss". In my opinion, these words describe the function of a shear member. Other examples of shear members familiar to a mechanical engineer include lock plates, dowels, and key and keyways. In all these cases, they prevent one member sliding sideways relative to the adjacent member. If sliding occurs, the bearing faces in the members set up shear stresses in the shear members in a scissor-like action. In most cases, the fit of the shear member in the grooves in the adjacent member is not a tight fit and some form of tightening arrangement is also required. Shear (or compressive) forces may be contrasted to tension (or elongation) forces. A member is subjected to tension forces when it is subjected to equal forces acting in opposite directions away from each other down the axis of the member. Examples of tension members are tie rods, bolts, friction grip joints and steel cables and rope. Prof Wightley referred to Mr Alden's affidavit of 15 May 2007 and made four points in opposition to Mr Alden's opinion that the appellants' assemblies were covered by the claims in suit. First, he said that the claims required the lock to be "a single member and not a collection of component parts". Secondly, he said that the lock described in the claims was "in the nature of a rigid block which functions as a shear member", whereas the "so-called lock" in the appellants' assemblies "is only rigid when all of the identified constituent parts are assembled and tightened". Thirdly, he said that the forces applied (in the appellants' assemblies) when those components were assembled and tightened were "tensile forces, rather than shear forces", as required by the claims. Fourthly, he said that the adjustment assembly described in the claims was "an addition to the lock", not part of the lock itself. 48 In an affidavit sworn on 18 October 2007, Mr Alden referred to Prof Wightley's affidavit of 16 August 2007, and said that he did not agree with Prof Wightley's comments about shear forces and shear members. He said that it was "too simplistic and somewhat misleading to simply refer to components such as lock plates as 'shear members'." He said that shear members were "typically installed with a reasonably tight fit". He did not agree that shear forces and compression forces were the same. He exhibited to his affidavit a report in which he explained, with illustrations, the differences between the various forces of tension, compression, shear, bending and torsion. He provided, by reference to a diagram, an explanation of the various forces and stresses that would transfer through the lock assembly described in the preferred embodiment of the inventions in Jones II and Jones III. That diagram demonstrated that the lock, when installed in accordance with the preferred embodiment, would carry tension, compression and shear forces at different points. 49 It is necessary to refer further to Mr Alden's diagram, as it was the focus of much of the cross-examination at trial. The diagram was as follows: Mr Alden's point was that it was compression forces, not shear forces, that operated at the interface between the rear of the boss and the front of the adjustment plug that was threaded into the lock. The tendency of the lock to bend as this compression force was applied induced tensile forces across the rear face of the lock and compression forces across the front face of the lock. The only place at which shear forces arose was through the threaded interface between the lock and its adjustment plug. As we understand the respondents' case, Mr Alden's evidence demonstrates that it cannot be by reference to the absence of tensile forces, or to reliance wholly upon shear forces, that the limits of the claims in suit are defined. 50 Under cross-examination, Prof Wightley was taken to Mr Alden's diagram, but adhered to his view that the forces at work upon a lock constructed in accordance with the claims in suit would, at least very substantially, be shear forces. He pointed out that Mr Alden's diagram had been dimensioned so as to show a fairly narrow plug-head relative to the width of the rear of the boss. Such a representation, according to Prof Wightley, emphasised the tendency of the lock to bend under compression. He said: The rigid lock in Jones 2 and Jones 3 can and will function as a shear member under certain circumstances, and they are either that the adjustment assessment is not screwed up such that it bears against the back of the boss, and then the key – the lock – behaves in the same fashion as a Jones 1-type lock. And under those circumstances, it can fairly be described as a shear member. More than that, the proportions of the bearing area of the bolt or the adjusting assembly, where it pressed on the back of the boss, is very important, because it tells us the clearance between the outside limit of the boss and the inside of the opening in the wear member. That particular area is where shear takes place. If the diameter of the bolt is large, relative to that gap, there will be almost no bending. It would be almost entirely of shear. If it's very narrow, as is shown by Mr Alden's analysis or diagram, then more bending takes place. But whatever happens, whether there's bending or no bending, same amount of shear is always present, and I believe that it's valid to depict – to call a member a shear member by the function it performs and the majority of the stresses that are likely to occur most of the time, during its service life. Mr Alden accepted that, if there were no forwardly-protruding threaded plug in the lock, and the whole of the front face of the lock were in contact with the boss, the forces operating upon the lock would be shear forces. 51 It was no part of the claims in suit that the lock referred to must operate as a shear member. However, the debate between Prof Wightley and Mr Alden as to the engineering concepts was relevant to a practical understanding of the claims in suit. In the passage which we have set out in par 47 above, Prof Wightley quoted from the terms of claim 1 in Jones II. From those words it was clear to him that the claim referred to a lock which operated as a shear member. In contesting that proposition, Mr Alden demonstrated that a lock made in accordance with the claim would be subject, to an extent, to a range of forces including tension forces. However, he did so by reference to a diagram which showed a lock operating substantially in the way to which, in the submission of the appellants, the claim was confined, that is to say, a lock constituted by a block which received pressures from either side. Because the faces upon which the lock bore were offset to a degree, as Prof Wightley pointed out, shear forces were involved. The extent to which other forces were also involved depended upon the extent of bending forces arising from the action of the boss upon the lock, which in turn depended upon the width of the front end of the threaded plug relative to the width of the clearance, or gap, between the outside limit of the boss and the inside of the opening in the wear member. 52 Ultimately, the debate between Mr Alden and Prof Wightley was not to be resolved by determining that one was right and the other was wrong. Each recognised the validity of the position of the other with respect to particular conditions. We can understand why the primary Judge concluded that the evidence of neither was relevantly undermined in cross-examination. However, what his Honour's reasons do not disclose, with respect, is an appreciation that the whole debate was conducted in the context of a lock which sat between faces to be held apart. Relevantly to the present point, his Honour approached the problem as though it required a construction of the phrase "a rigid lock received into said opening" in Jones II and of the phrase "a lock received into the opening" in Jones III. He dealt with the problem as so identified in two stages, namely, the "rigid lock" point and the "received into the opening point". He held that there was no requirement for the lock to be rigid at the point of insertion into the opening, and that a lock could be "received" into the opening notwithstanding that it did not sit wholly therewithin. By dividing the problem up in this way, and by treating it substantially as a grammatical one, his Honour failed to read the relevant paragraphs of the claims as a whole and in practical way with a view to identifying, as a matter of engineering rather than merely of wording, the limits of the invention there claimed. 53 Informed by the practical understandings of Mr Alden and Prof Wightley in the way we have described, we return to words of claim 1 of Jones II. The claim requires that the lock be received into the opening in the leg of the wear member, that is to say, that it be positioned inside the opening. For present purposes, we regard it as immaterial whether the lock is wholly or only partly received into the opening. With the lock in that position (ie in the opening), it is required that the second face of the lock be adapted to oppose and engage a wall of the opening. This suggests that it should be an internal wall of the opening that the face of the lock opposes and engages. At the same time, it is required that the first face of the lock be adapted to oppose and engage the bearing face of the boss. Thus we have a component with two faces sitting inside an opening, where one of the faces opposes and engages an inside wall of the opening and the other opposes and engages the bearing face of a boss. It is the placement of the lock in that position which, of itself, "secures said wear member to said boss" (in which respect we note the use of the word "whereby"). In our view, the most natural thing which the words of the claim convey is a component whose function is to keep things apart. 54 A consideration of the complete specification in Jones II confirms the construction of claim 1 proffered above. The relevant statement in the summary of the invention is, "[t]he body of the lock sets between the rear end of the boss and the rear wall of the cross portion in order to prevent removal of the wear member from the boss". In the detailed description of the invention, various characteristics and intended functions of the lock in the preferred embodiments are provided as follows: · the rear end of the boss "functions to abut lock member …"; · the opening in the adapter "is positioned near rear end … of leg … and rearward of rear bearing face…of boss … when adapter … is assembled on the boss …"; · the lock member "has a rigid block-shaped body … defined by a front wall …, a rear wall …, a first end wall …, and a second end wall …. Body … of lock … is received into cross portion … of opening … such that its front wall … opposes rear wall … of boss …, and its rear wall … opposes rear wall … of adapter .... This engagement structure effectively prevents the adapter from being moved forwardly along the boss."; · if no adjustment assembly is incorporated, the adapter "can be amply secured to boss … by a rigid lock without an adjustment assembly … that simply prevents forward movement of the adapter. Under these conditions, the lock member and corresponding opening would be essentially the same as discussed in [Jones I] …". The specification makes clear that these are the preferred embodiments only, and that other embodiments might be employed. However, every embodiment of the invention described involves the opening being – as stated in the second point above – rearward of the rear bearing face of the boss, and the lock as being received into the opening. It is the rear wall of the lock member that opposes the rear wall of the adapter. This describes a lock that operates by resistance, ie by being set between the faces that would otherwise moves towards each other. 55 We return now to the reasons of the primary Judge as to the "lock" aspects of claim 1 of Jones II. Two of the relevant integers were the requirements that the lock be "rigid" and that it include an adjustment assembly. Clearly the latter was an essential integer of the claim in the sense that a lock without an adjustment assembly would not infringe. To that extent we agree with his Honour. However, the appellants' point was rather different. It at least involved the proposition that the condition of rigidity was different from, and should exist before, any final condition brought about by the process of adjustment. His Honour did not accept the position for which the appellants contended. He took the view that the condition of rigidity was to be determined after the lock had been adjusted. That is to say, a lock which was non-rigid at the point of being placed in position would still be covered by the claim if it were rendered rigid by adjustment. It followed that the nut on the J-bolt served two relevant functions: by being tightened, it made the bolt rigid, and by being (or being able to be) adjusted, it constituted an adjustment assembly. For reasons which follow, we consider that his Honour was in error in these respects. 56 In our view, a critical passage in claim 1 of Jones II is that which states "whereby said lock secures said wear member to said boss". It means that, by reason of the matters stated previously in the relevant paragraph, the lock secures the wear member to the boss. The previously-stated matters are the rigidity of the lock, the fact that the lock has faces as described and the placement of the lock in the described orientation apropos the boss and the wall of the opening in the wear member. The clear sense of the claim is that this combination of matters provides a secure fitting of the wear member to the boss. The appellants' point that claim 1 of Jones II required the lock to be "rigid" at the point of being received into the opening must be correct, since it is that state of rigidity, together with the faces on, and the orientation of, the lock that causes it to secure the wear member to the boss. His Honour's conclusion that the point at which the claim required the lock to be rigid was when it was "assembled, inserted, adjusted and ready for use" was, in our view, only three parts correct. The fourth part is significant. As we have explained, the claim refers to a lock which operates as such when it is assembled and inserted: it is then "ready for use". It may be adjusted as required, but is operational without adjustment. In other words, the state of rigidity claimed for the lock does not come about only by the process of adjustment. 57 The wording of the claim then moves to the adjustment assembly. Here again it is clear that that assembly is not intended to be a component of the lock which is essential to enable it to function as such (ie to secure the wear member to the boss). The lock "further" includes such an assembly; the purpose of the assembly is to "eliminate looseness"; and that looseness is such as "may exist". The clear sense of the relevant paragraph read as a whole is that the lock should work as such whether loose or tight, but that the elimination of looseness – a step which, it is implied, might be desirable in practice – can be done by means of the adjustment assembly. 58 As noted above, an aspect of the appellants' defence to the respondents' infringement case below was that claim 1 of Jones II required the lock to be received (ie located) wholly, or at least very substantially, within the opening referred to. The appellants so contended because important parts of the J-bolt were not, in their submission, within any "opening" when the bolt was assembled, tightened and ready for use. His Honour rejected that contention as a matter of construction of the claim, holding that a lock which was only partly in an opening was nonetheless "received into said opening". He gave the example of a door lock which, in his view, could be said to be received into an opening notwithstanding that its latches, handle and shaft remained outside the opening. In our view, this was, with respect, an inapt analogy. As will be apparent from our reasons set out above, the contribution which the phrase "received into said opening" makes to the construction of claim 1 of Jones II is to inform the reader where the rigid lock should be located and thus (in combination with the references to the faces which it must oppose) to define the way the lock is intended to work. The question whether the lock was wholly or only partly received into the opening was something of a side-issue, although, in defence of his Honour, that matter was squarely put to him by the appellants. 59 The appellants' J-bolt assembly does not incorporate a lock with the characteristics of that claimed in claim 1 of Jones II as we have identified them. The function of the bolt is to hold things together. It sits (to an extent) in an opening in the sense that it must be somewhere, but it does not have the characteristics or the function apropos the opening that are required by the claim (ie to maintain separation generally within the confines of the opening). Further, the J-bolt assembly is not such as could be described as rigid without the nut having been secured tight: indeed, as we read the primary Judge's reasons in relevant aspects, his Honour accepted that proposition. Our point of departure from his Honour is that we consider that the claim is concerned with a lock which operates as such by reason of its initial rigidity and its placement in the opening there referred to, at which point no question of tightening or adjustment arises. Neither do we accept that the nut on the threaded tail of the J-bolt falls within the meaning of an "adjustment assembly" as claimed. Without the nut, the J-bolt itself would not act as a lock in any sense. We cannot imagine a circumstance in which the assembly might be used without the nut – or with the nut being in place but not being secured home – and, in such a condition, being regarded as a lock which "secured" the wear member to the boss, albeit loosely. Rather, the tightening of the nut in the J-bolt assembly is itself what brings about a state of rigidity and provides the secure attachment. Without that, the bolt could not be regarded as a lock at all. It is not merely a matter of adjustment. 60 For the above reasons, we would uphold so much of the appellants' notice of contention in the cross-appeal as relates to the respondents' allegation that the appellants' J-bolt assembly infringes claim 1 of Jones II. 61 To deal with claim 51 of Jones II it is sufficient to adopt what we have said above in relation to claim 1, subject only to the following modifications. Under claim 51, it is what is described as the "first face" of the lock which is engaged with the bearing face of the opening in the wear member and the "second face" of the lock which is engaged with the bearing face of the boss. Thus the first face of the lock is the underside of the head of the J-bolt and the second face of the lock is the inside washer on the threaded end of the bolt. Other than by interchanging the designation of the first and second faces of the lock, claim 51 is, as we read it, indistinguishable from claim 1. Claim 51 does not refer to the bearing and lock faces as "opposing" each other, but in point of substance it is referring to the same locking principle as is claim 1. We would reach the same conclusions with respect to the matter of infringement as we have above in the case of claim 1. 62 Before leaving Jones II, we should say something briefly about the appellants' T-bolt assembly. We have indicated that we propose to dismiss the cross-appeal in this respect because we agree with the primary Judge that the assembly does not include an opening extending through the shroud. However, were it otherwise, it will be clear from what appears above that we would find that the assembly does not infringe claims 1 or 51 of Jones II. The reasoning provided above in relation to the J-bolt would apply likewise to the T-bolt. 63 We turn next to the requirements of claim 1 of Jones III, and shall commence with a consideration of the appellants' T-bolt assembly. The respondents say that the T-bolt itself, together with its washers and nuts, is the lock referred to. They say that the bolt is received into the opening in the shroud in the same way as described above in relation to claim 1 of Jones II. They say that the "first bearing surface" described in claim 1 of Jones III is the rear face of the mount secured to the surface of the bucket (which is the member described in Jones II as the "boss"). They say that the cavity in which the head of the T-bolt is set is part of the opening referred to, and that the internal shoulders of that cavity, in contact with the underside of the head of the bolt, is the second bearing surface mentioned in the claim. Thus the opening is said to be "equipped with a second bearing surface". They say that the first and second bearing surfaces face in opposite directions in the sense that the first bearing surface (on the mount) faces to the rear and the second bearing surface (in the cavity in the shroud) faces to the front. The respondents say that the T-bolt is received into the opening between the first and second bearing surfaces because the shaft of the bolt lies between the rear face of the mount and the cavity in the shroud. They say that the "first lock surface" of the bolt is constituted by the inside surface of the washer on the threaded end of the bolt which bears against (ie "opposes") the rear face of the mount, and that the "second lock surface" of the bolt is the underside of the head of the bolt which bears against (again, "opposes") the internal shoulders of the cavity to which we have referred. As in the case of claim 1 of Jones II, they say that the nut on the threaded shaft of the T-bolt is the adjustment assembly, but here (ie in the context of claim 1 of Jones III) they also point out that the nut may, and will normally, be used to "apply forces to the wear member and the mount that tend to tighten the mounting of the wear member on the mount". 64 Claim 1 of Jones III differs from claim 1 of Jones II in a number of respects, but there are important similarities. Jones III claims what is described as a "mount", but it is clear that this component performs the same function as the "boss" in Jones II. The mount has a "first bearing surface". The wear member has an opening with a "second bearing surface". When the first and second "shoulders" are engaged (ie when the wear member is in position), "the first and second bearing surfaces face in opposite directions". The lock is then received into the opening "between the first and second bearing surfaces". The orientation of the lock apropos the two bearing surfaces is put beyond doubt with the words "the lock having a first lock surface to oppose the second bearing surface [and] a second lock surface to oppose the second bearing surface". The position of the lock in the opening is of itself sufficient for the lock to function as such, as to which we note the expression "…therebyretain the wear member on the mount…" (emphasis added). 65 It is, in our view, central to the scope of claim 1 of Jones III that the lock be received into the opening in the wear member between the first and second bearing surfaces referred to, and that the first and second lock surfaces of the lock oppose those bearing surfaces respectively. In other words, the lock surfaces must necessarily be located internally with respect to the bearing surfaces which they respectively oppose. Inescapably, it seems to us, the operation of the lock must be one which inhibits the bearing surfaces from moving closer towards each other than they otherwise might: they are locked apart, as it were. This understanding of the claim is confirmed by the terms of the complete specification which are, as we have said, the same as those of Jones II. We refer to, and adopt in the present context, what we have said in par 54 above. 66 By contrast with the requirements of claim 1 of Jones III, the surfaces in the appellants' T-bolt assembly which the respondents identify as the lock surfaces (the internal face of the washer and the underside of the head of the bolt) are located outside the bearing surfaces which they presumptively oppose. They are not between them. And neither could they be as a matter of function, as their purpose is not to keep those bearing surfaces apart – it is to hold them together. The same conclusion applies in the case of the J-bolt assembly. Here the second bearing surface of the wear member is the recess in the top of the shroud (at the forward termination of the opening which extends through the shroud) and the second lock surface of the bolt is the underside of the head of the bolt which sits in that recess. Otherwise, and relevantly to the present question, the assembly is indistinguishable from the T-bolt assembly. 67 The "adjustment assembly" provisions of claim 1 of Jones III differ from the corresponding provisions of claim 1 of Jones II in respects which may be important. The provisions are not introduced by the adverb "further". The faces which are, by adjustment, varied in their relative positions are the bearing surfaces of the mount and of the opening, rather than (as in Jones II) different faces of the lock. The action of the adjustment assembly is such as would "tend to tighten the mounting of the wear member on the mount" rather than (as in Jones II) to eliminate looseness which may exist. Particularly with respect to the first and third of these differences, the case for regarding the adjustment assembly as an essential part of the locking action is somewhat stronger in Jones III than in Jones II. 68 It is to be recalled that because of the primary Judge's findings as to the need for the "opening" to extend the whole way "through" the wear member (which effectively led to the rejection of the respondents' case in relation to Jones II), the only sense in which his Honour's reasons for concluding that the adjustment assembly was an essential part of the lock, set out in par 18 above, was part of the ratio decidendi of the judgment below was in relation to Jones III. Yet, in a number of respects at least, the terminology used by his Honour is that of Jones II, not of Jones III. Only the reference to the selective movability of the first and second bearing faces appears to have been taken from Jones III. To the extent that his Honour was here construing Jones III, he appears to have been working from the wrong text, or at least from a text which was a kind of admixture of the wording of the different patents. 69 We shall say nothing further on this aspect, since it was the subject neither of a ground of appeal nor of any submission made on behalf of the appellants. We consider that the consistency of the appellants' assemblies with claim 1 of Jones III may be determined without reference to the "adjustment assembly" aspects of the debate. 70 For reasons stated in pars 63-67 above, we would uphold so much of the appellants' appeal as relates to the respondents' allegation that the appellants' T-bolt and J-bolt assemblies infringe claim 1 of Jones III. obviousness 71 In their submissions on appeal, the appellants attacked his Honour's conclusion that considerable weight should be attached to the evidence of the inventor (see par 24 above). They submitted that the reference to Terrell was mistaken, and that the proposition was, in any event, wrong. They submitted also that his Honour was in error to have attributed the evidence about the unlikelihood of a bolt and nut assembly being used to Mr McClanahan. Finally in this respect, they submitted that his Honour failed to refer to other evidence by Mr McClanahan which was much more on point, and was wholly consistent with the evidence given by Prof Wightley in support of the appellants' case. 72 It appears that the reference by the primary Judge to the third edition of Terrell on The Law of Patents was in error. The edition published in 1994 was the fourteenth edition, but in other respects his Honour's citation was accurate. The relevant text read as follows: In coming to a conclusion as to whether or not a claim contains a real inventive step over what was previously known or used, the court in the past has attached considerable weight to the evidence of the inventor himself. Counsel for the appellants criticised his Honour's recourse to Terrell at two levels. First, they pointed out that the proposition had been omitted from the next edition of Terrell, the fifteenth published in 2000. Secondly, they submitted that the primary Judge overlooked what the High Court had to say with respect to the proposition as it appeared in the fourteenth (and earlier) editions of Terrell. A similar proposition in the eleventh edition was relied upon by Edmund Davies LJ in Woven Plastic Products Ltd v British Ropes Ltd [1970] FSR 47, 58. In the course of a systematic review of the authorities in Wellcome Foundation v VR Laboratories (Aust) Pty Ltd (1981) 148 CLR 262, Aickin J (with the assent of other members of the court) referred to Woven Plastic and continued (at 280): The mode of expression makes it clear that this observation was obiter. The paragraph in Terrell on The Law of Patents,11th ed. (1965) to which his Lordship referred (par. 322) refers only to Lightning Fastener Co. Ltd. v. Colonial Fastener Co. Ltd. (1934) 51 R.P.C. 349 and Howaldt Ltd. v Condrup Ltd. (1936) 54 R.P.C. 121. Cases to the contrary effect are not referred to. Neither of the other members of the Court of Appeal adverted to the point. Contrast the view in Blanco-White, Patents for Inventions, 3rd ed. (1962), p. 144, where he refers to cases which say that such evidence is "not of great weight", a comment repeated in the 4th ed. (1974) par. 4–228. According to the appellants, it is as clear as may be that Aickin J rejected the proposition stated in the eleventh edition of Terrell, and preferred the view expressed in Blanco White, namely, that the evidence of the inventor should not be regarded as having "great weight". 73 Wellcome was a case which concerned the obligation of the patentee to give discovery of documents which included those "relating to research and development and experimental work on the claimed invention both before and after the priority date of the subject letters patent" (148 CLR at 269). Both the Supreme Court of New South Wales and, on appeal therefrom, the Full Court of the Federal Court, had ruled that such discovery should be given. An appeal to the High Court was unsuccessful. After a review of the authorities, which he found to be conflicting to an extent, Aickin J said (at 287): If evidence of the failure of other attempts to solve a well-known problem, i.e. to satisfy a "long-felt want", is admissible in support of the inventive nature of a successful solution to such a problem, as it undoubtedly is, it is difficult to see why the patentee's own lack of success in earlier attempts would not also be admissible for the same purpose. It may well be that the use of such evidence by the patentee would involve some risk because it would no doubt be used to support an argument that the last and successful step was by then obvious, though such an argument would require careful examination to see whether or not it was an illegitimate use of hindsight. … In the result, therefore, I have concluded that evidence of research and experiments (if any) of a patentee leading up to his claimed invention is generally admissible, though not always likely to be helpful. The fact that in a particular case there may not have been any research or experiment involved in the making of an invention does not require the conclusion that evidence relating to research and experiments, where they took place, will not be admissible. The question in the present case relates not to admissibility (nor even to discoverability) but to utility. It is clear from Wellcome, however, that there is no general proposition of law that, when questions of obviousness are in issue, considerable weight should be given to the evidence of the inventor. 74 The appellants next pointed out that Mr McClanahan had not given evidence that "the skilled person would be unlikely to use a bolt and nut assembly because of expected problems such as rusting and deformation of the thread." The respondents accepted that Mr McClanahan gave no such evidence, and that his Honour had erred in relevant respects. They submitted, however, that the error was inconsequential, since evidence to the same effect had been given by another witness, Mr Anthony Ashworth. Mr Ashworth was called by the appellants. His cross-examination by counsel for the respondents contained the following passages: Is there any inherent disadvantage of [threaded] assemblies such as the Paige and Hendricks assemblies?---Threads. Threads always cause a problem in terms of degradation in operation and, yes, that's – that is a concern. What's the nature of the degradation that they suffer?---It can be anything from rusting through to [fines] packing within them. When you get wear or [deformation] of the thread during operation it makes it difficult for the thread to act as a thread in terms of removing the nut and like type [deformation]. To the extent that the primary Judge did, in par 80 of his reasons, attach "considerable weight" to this evidence because of his mistaken belief that it had been given by an inventor (which Mr Ashworth was not), his Honour's error should not be regarded as inconsequential. 75 The final basis upon which the appellants attacked par 80 of the primary Judge's reasons requires us to deal with the respects in which they asserted that the inventions, so far as claimed in claims 1 and 51 of Jones II and in claim 1 of Jones III, were obvious to a person skilled in the relevant art in the light of the common general knowledge as it existed in the patent area before the priority date. The appellants' case at trial was that a mechanical engineer equipped with an understanding of Jones I and of its commercial embodiment (Toplok) would regard the tendency towards looseness of the wear member as an obvious shortcoming, and would likewise regard it as obvious that such looseness might be removed by the utilisation of a threaded adjustment means. On this subject, Prof Wightley said: In my opinion, the inability to tighten the wear assembly described in Jones I is a design flaw. Wear assemblies made from cast parts that are to be used in high impact and high load applications (eg. on an excavator bucket) must have a rigid assembly if frettage corrosion and fatigue is to be avoided. Looseness in the assembly will not only reduce the life of the replaceable wear member, but also the boss welded to the excavator bucket. This is a particularly significant problem because the bucket would then need to be taken to a maintenance workshop to grind off the weld before the boss can be replaced. This defeats the purpose of having field replaceable wear parts. To a mechanical engineer trying to overcome the problem of the Jones I design, it would be readily apparent that some mechanism to tighten the assembly was required. One measure that would immediately come to mind is the use of a screw adjustment which could be used to take up any looseness around the key. This is a basic practical measure that is routinely used by mechanical engineers to eliminate looseness in applications that require rigid assemblies. I believe a screw adjustment which could be used to take up the looseness is a solution that would be readily apparent to any reasonably competent mechanical engineer and certainly one that he or she would be led to try. On appeal, it was submitted on behalf of the appellants that Mr McClanahan's affidavits did not address this evidence given by Prof Wightley, and that the respondents did not call any other expert witness on the subject of obviousness. 76 The appellants draw attention to certain evidence given under cross-examination by Mr McClanahan, which, they contend, was effectively the same as that of Prof Wightley in relevant respects, and to which the primary Judge did not refer in his reasons. In his affidavit sworn on 14 September 2007, Mr McClanahan said that he was one of the inventors for the patents in suit. He explained the means by which, commencing with Jones I and its perceived shortcomings, the inventors eventually came up with an adjustment assembly of the kind referred to in the claims in suit. The project given to the inventors was "to create a mechanically attached adapter system" for excavator bucket lips. They spent some time considering different ideas on how to develop the Toplock shroud into an adapter system. Their aim was to have an adapter that would stay on as long as possible, and would not wear loose. They identified a number of key issues, not all of which related to aspects that were ultimately carried forward into the three claims in suit. One of the issues, however, did so relate. It was "the appropriate choice for the locking mechanism for the Toplok adapter". There was a concern that the "fit relationship" would become too loose with wear, when used on adapters as distinct from shrouds. The inventors considered, and rejected, a number of approaches such as tighter manufacturing tolerances and self-adjustment mechanisms. In his affidavit, Mr McClanahan continued: We then turned to considering several types of adjustable bolt arrangements without springs. There was a lot of discussion around how to allow access to the threaded piece for tightening the lock in a TOPLOK Shroud design. The original design had the same shape as the TOPLOK Shroud, however this allowed only limited, awkward access. Eventually we settled on the current design, by opening up the back of the adapter for ease of access to the threaded piece. 77 Mr McClanahan was cross-examined by counsel for the appellants with respect to the process by which the inventors eventually settled upon a threaded adjustment mechanism. Relevantly to the point the appellants make on appeal, that cross-examination proceeded as follows: Now, when you decided, as I say, for whatever reason, not to utilise the self-adjusting approach, then who took the decision to simply use a bolt threaded through the back of the rigid block?---It would have been a group decision. The engineers would have taken recommendations to the audit managers and there would have been discussions and agreement on what direction we took. Now, after you had determined not to pursue the self-adjusting approach tell us what particular alternatives were taken to those people in relation to what I'll call the non-self-adjusting approach?---Well, non self-adjusting – by the time we got to that aspect of the design as I recall we focussed on a threaded bolt arrangement. There were no other options considered, I want to suggest to you?---I don't recall any. And the reason for that is that once you decide that it's impractical, whether it be for cost or other purposes, to go down the self-adjusting route the decision to be taken is a perfectly obvious one, isn't it?---I don't know whether it's completely obvious, but as a mechanical engineer the choice of a threaded option is one of the first that would spring to mind. Mr McClanahan also accepted that the marketing people within the first respondent expressed a preference for a take-up mechanism which operated automatically, ie for a mechanism which did not require manual adjustment to eliminate looseness. When it was put to Mr McClanahan that "virtually all of the time" of the inventors was spent on attempts to come up with such an automatic system, he responded: "the large chunk of the time, yes." Using this evidence as a starting point, the appellants submit that little or no inventive effort went into the development of the threaded adjustment option which was ultimately adopted. Indeed, they say that, once a self-adjusting system was rejected, the threaded option was obvious. 78 As will be apparent from the foregoing, this was not a case in which the content of common general knowledge in the patent area before the priority date was controversial. It was also accepted that both Mr McClanahan and Prof Wightley were persons skilled in the relevant art in the light of the common general knowledge. Rather, the controversy surrounded the factual question of whether the inventions in Jones II and Jones III, so far as claimed in the claims in suit, were properly to be regarded as obvious to persons such as they. The question, of course, was not whether the inventions were in fact obvious to Mr McClanahan or to Prof Wightley, but whether they would have been obvious to the notional person skilled in the relevant art, looking at the matter immediately before the priority date. 79 In a context such as the present, the connotation to be given to the word "obvious" is that proposed by Graham J in Olin Mathieson Chemical Corporation v Biorex Laboratories Ltd [1970] RPC 157, 187-188, approved by the High Court in Aktiebolaget Hassle v Alphapharm Pty Ltd (2002) 212 CLR 411, 433: Would the notional research group at the relevant date, in all the circumstances, which include a knowledge of all the relevant prior art and of the facts of the nature and success of chlorpromazine, directly be led as a matter of course to try the –CF3 substitution in the '2' position in place of the –C1 atom in chlorpromazine or in any other body which, apart from the –CF3 substitution, has the other characteristics of the formula of claim 1, in the expectation that it might well produce a useful alternative to or better drug than chlorpromazine or a body useful for any other purpose? [emphasis added] (ie added by the High Court) In the context of the present case, the question was whether the notional mechanical engineer, at the priority date, in all the circumstances, including a knowledge of Jones I and of Toplok, would directly be led as a matter of course to try an adjustment assembly of the kind described in the claims in suit, in the expectation that it might well produce an improvement in the attachment means previously employed. 80 The burden of persuading the court that an affirmative answer should be given to this question lay upon the appellants. In relevant respects, they relied upon the extract from Prof Wightley's affidavit which we have set out at par 75 above. He said that "the use of a screw adjustment" would "immediately come to mind". He said that such an adjustment was a solution which "would be readily apparent to any reasonably competent mechanical engineer and certainly one that he or she would be led to try". The primary Judge took the view that the value of Prof Wightley's evidence was compromised by reason of the circumstance that, from the outset, he had been exposed to the shortcoming to which Toplok was perceived to be subject, and to the terms of Jones I, as well as to those of the patents in suit. In other words, Prof Wightley, from the outset, knew the problem, and he knew the solution. The authorities make it clear that the caution with which his Honour approached the evidence of Prof Wightley was both justified and desirable: Meyers Taylor Pty Ltd v Vicarr Industries Ltd (1977) 137 CLR 228, 242; Alphapharm 212 CLR at 423-424 [21]; Lockwood Security Products Pty Ltd v Doric Products Pty Ltd (No 2) (2007) 235 ALR 202, 215 [46]. At this level of analysis, nothing put on behalf of the appellants on appeal has cast any doubt upon the approach which his Honour took. Within the confines of that approach, the matter of obviousness was essentially one of fact. We are not persuaded that his Honour erred in declining to be satisfied that Prof Wightley's evidence, of itself, warranted the conclusion that the adjustment assembly introduced by Jones II and Jones III was obvious. 81 As we have said, the focus of the appellants' case on appeal was upon par 80 of his Honour's reasons, and upon what they contended was his Honour's error in according considerable weight to the evidence of the inventor (effectively that of Mr McClanahan). It does appear that his Honour placed "considerable weight" on the evidence of Mr McClanahan. In addition to par 80 of his reasons (see par 24 above), his Honour had earlier said (in his discussion of Mr McClanahan's evidence): Mr McClanahan was cross-examined at some length, however, in my view, his evidence was not materially disturbed. As I note below at [80], the evidence of an inventor of a patent in suit is given a particular form of weight, and I am satisfied that Mr McClanahan's evidence attracts that weight in this case. That Mr McClanahan's evidence should have been given special weight, by reason only of the fact that he was the inventor, was inconsistent with Wellcome and was, therefore, an error on the part of his Honour. However, it remains to consider whether that error materially affected his Honour's conclusion, and if so whether we should reach a different conclusion on appeal. 82 In paragraph 80 of his reasons, his Honour referred to the following aspects of Mr McClanahan's evidence: · his conclusion that the skilled person would be unlikely to use a bolt and nut assembly because of expected problems such as rusting and deformation of the thread; · his opinion on the question whether the tendency towards looseness in Toplok was a design flaw; · his explanation of the operational contexts in which that tendency expressed itself, why, and how it was remedied in various ways. 83 As to the first point, when his Honour actually came to determine whether a threaded adjustment apparatus would have been an obvious means of overcoming such shortcomings as there were in Toplok, he said: To a large extent it is common ground that there were problems in the operation of Toplok. As to the extent to which those problems were known at the priority date, while I accept that it was common general knowledge among mechanical engineers that problems arising as a result of looseness between the different parts of the wear assembly could be reduced by the use of adjustment assemblies (such as a screw adjustment), I cannot go further and accept Professor Wightley's evidence that it would be readily apparent to a mechanical engineer considering the problems in the Jones I design that the use of a screw adjustment would be an obvious solution. Professor Wightley's evidence must be approached with some caution because he was simultaneously informed of both the nature of the problem encountered by the Jones I design and also the solution ultimately supplied by the patentee in this case. Having been shown all of Jones I, Jones II and Jones III at the time he was instructed, Professor Wightley was aware of the solution at the time he was asked to express his opinion about its obviousness, which in my view reduces the weight of his evidence on this point. The difficulty with both the problem and its solution being presented to Professor Wightley as part of his instructions was that he did not seek to identify the causes of the problem because there was no need to do so. Although Professor Wightley may have been able to go beyond his instructions and investigate this issue independently, he understandably did not do so. As a consequence of these circumstances, Professor Wightley did not consider any possible alternative solutions. His instructions were only to comment on the obviousness or otherwise of the threaded adjustment set out in the patent, which meant that he did not consider the possibility that looseness of wear members could be overcome by adjusting tolerances or using rails or shins which were adopted as temporary fixes. We do not believe that his Honour based his final determination of the point upon his initial view that Mr McClanahan's evidence was to be given considerable weight. The aspect which most strongly bore upon his thinking was that Prof Wightley's opinion had to be discounted because it was formed with the advantage of hindsight. 84 As to the second point, it does appear that the primary Judge preferred Mr McClanahan's opinion that the tendency to looseness in Jones I was not a design flaw. But whether such a flaw existed was not the factum probandum in the present case. It was because Prof Wightley recognised the existence of a design flaw that he the more readily perceived the solution. It was how he, as a mechanical engineer, came to the opinion that the solution was obvious. Mr McClanahan, by contrast, gave evidence that Toplok worked well in the field save when used on the larger buckets. On this point, the primary Judge said: In addition, I am not persuaded that Professor Wightley was correct in describing the problems arsing from looseness in the Toplok product as being a "design flaw". Although the evidence could be understood to establish that some recurrent difficulties plagued the usage of Toplok, it did not go so far as to establish the existence of a design flaw in Jones I. The problems regarding looseness were problems which arose from the increase in size of the buckets in specific instances, and these problems were alleviated by a variety of practical means which did not involve any adjustment mechanism. There was also evidence that considerable numbers of the Toplok shrouds had been sold and that they had some commercial success. In such a context, a conclusion that the inventive step in Jones II and Jones III was obvious cannot, in my view, be sustained. It will be noted that his Honour's emphasis here was upon the respondents' experience with Toplok in practice. This was a substantially factual matter from which his Honour drew his own inferences as to the absence of a design flaw and on the subject of obviousness. It seems to us that his Honour's conclusions in relevant respects were uninfluenced by the special weight he may have accorded to the evidence of Mr McClanahan. In any event, they reflect the conclusions we would ourselves reach in relevant respects. 85 As to the third point, this is to an extent covered by the paragraph from the primary Judge's reasons most recently set out above. As it seems to us, it involves pure questions of fact upon which Mr McClanahan was best placed to give evidence. In accepting that evidence, his Honour was not involved in any kind of exercise which required him to accord a particular weight to that evidence. The fact is that the thrust of his Honour's reasons was to reject the evidence of Prof Whiteley because his opinion had been inappropriately tainted, from the outset, in the way we have described. As we have said, nothing put to us on appeal persuades us that his Honour was in error to have proceeded in this way. 86 It should not, in our view, be overlooked that the inventors were employed by, or associated with, the commercial enterprise which was responsible for Toplok, and thus had every incentive to devise an improvement for that apparatus. The fact that they did so only after a considerable period of giving attention to the problem speaks against the proposition that the solutions which they found would have been obvious to the notional mechanical engineer. The appellants would have us discount matters of this kind, relying upon the evidence given by Mr McClanahan under cross-examination to which we have referred at par 77 above. They submit that most of the effort put in by the inventors was devoted to attempts to devise a self-adjustment mechanism at the behest of the respondents' marketing people. In our view, however, this criticism does not meet the point. It commences from a standpoint at which the inventors had both identified the problem and resolved that an adjustment mechanism in the lock, whether automatic or manual, was the solution most likely to yield a useful result. We do not accept that the mere fact that Mr McClanahan conceded that, having investigated self-adjusting options at length, and having discarded them, "the choice of a threaded option is one of the first that would spring to mind" is effectively the same as a concession that the adjustment assemblies incorporated into the inventions as registered would have been obvious, from the outset, to the notional mechanical engineer knowledgeable in the relevant field. 87 There is a further difficulty with the appellants' reliance upon the answer from Mr McClanahan to which we have referred, and upon the corresponding passage in the affidavit of Prof Wightley. Mr McClanahan referred only to "a threaded option". Prof Wightley referred only to "a screw adjustment". Neither witness went to the point of saying that, at the priority date, he (or any mechanical engineer knowledgeable in the field) would have been directly led, as a matter of course, to try the very adjustment assembly incorporated into Jones II and Jones III in the expectation that it might well produce an improvement on Toplok. This is more than a pedantic distinction. Relevantly to the present debate, the claims in suit are much more specific than mere requirements that threaded options or screw adjustments be employed. Claim 1 of Jones II requires that the lock include an adjustment assembly which selectively varies the relative positions of the two faces of the lock. Claim 51 says much the same thing. Claim 1 of Jones III requires that the adjustment assembly be able to vary the relative positions of the bearing surface on the mount and the bearing surface on the opening in the wear member. These are quite specific requirements, and the obviousness of them is not, in our opinion, established merely by the suggestion that threaded options or screw adjustments (otherwise unparticularised) would readily spring to mind. 88 The matter of obviousness was one for the appellants to establish. His Honour was, in our view, correct to hold that they had not done so. We would dismiss so much of the appeal as relates to the primary Judge's rejection of the appellant's case on obviousness. fair basis 89 As is apparent from the submissions made before the primary Judge to which we have referred in par 25 above, the thrust of the appellants' case with respect to fair basis was that, if the claims in suit were sufficiently wide to cover nut-on-bolt arrangements such as the T-bolt and J-bolt assemblies, they were not fairly based in the specifications. We have held that the claims are not that wide. In their outline of submissions on appeal, the appellants pointed to other respects in which, they contended, the claims were not fairly based. At the hearing of the appeal their counsel made it clear that their position was that "if we don't infringe it we are not officious enough to sue the claim for a finding of invalidity on fair basis at least". In the circumstances, there is no call for us to address the appellant's invalidity case to the extent that it relies upon s 40(3) of the Patents Act. Their appeal should, in this respect, be dismissed. DISPOSITION OF THE APPEAL AND THE CROSS-APPEAL 90 It follows from the above reasons that we should uphold so much of the appeal as is concerned with infringement, and dismiss the balance (ie so much as is concerned with the validity of the patents in suit). We should dismiss the cross-appeal. We shall lay out a timetable for the parties to make written submissions on the question of costs, both of the proceeding below and of the appeal/cross-appeal. I certify that the preceding ninety (90) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justices Sundberg, Jessup & Middleton. Associate: Dated: 4 March 2009 Counsel for the Appellants/Cross-Respondents: Mr JV Nicholas SC with Mr HPT Bevan & Ms J Beaumont Counsel for the Respondents/Cross-Appellants: Mr RC Macaw QC with Mr SCG Burley SC Solicitor for the Appellants: DLA Phillips Fox Solicitor for the Respondents: Mallesons Stephen Jaques Date of Hearing: 11 & 12 November 2008 Date of Judgment: 4 March 2009