FEDERAL COURT OF AUSTRALIA Esco Corporation v PAC Mining Pty Ltd [2008] FCA 640 PATENTS – infringement – construction – wear assemblies attaching to excavator buckets – meaning of "opening extending therethrough" – meaning of "digging edge" – meaning of "rigid lock". PATENTS – invalidity – novelty – meaning of "shoulders" – whether prior patent had "shoulders". PATENTS – invalidity – obviousness – use of screw to eliminate looseness in earlier wear assemblies – person skilled in the art – common general knowledge – whether starting point of invention obvious – whether looseness in earlier wear assemblies a design flaw – evidence of obviousness given in hindsight – whether evidence should be accepted. PATENTS – invalidity – fair basis – real and reasonably clear disclosure of the invention – lock with adjustment assembly disclosed. WORDS AND PHRASES – "opening extending therethrough" – "digging edge" – "rigid lock" – "shoulders" Patents Act 1990 (Cth) ss 7(1), 7(2) Aktiebolaget Hässle v Alphapharm Pty Ltd (2002) 194 ALR 485 cited Kimberly-Clark Australia Pty Ltd v Arico Trading International Pty Ltd (2001) 201 CLR 1 cited Lockwood Security Products Pty Limited v Doric Products Pty Limited (2004) 217 CLR 274 cited Lockwood Security Products Pty Limited v Doric Products Pty Limited (No. 2) (2007) 235 ALR 202 considered Meyers Taylor Pty Ltd v Vicarr Industries Ltd (1977) 137 CLR 228 considered Populin v HB Nominees Pty Ltd (1982) 41 ALR 471 cited Stena Rederi Aktiebolag v Austral Ship Sales Pty Ltd (2007) 73 IPR 257 cited Technograph Printed Circuits Ltd v Mills-Rockley (Electronics) Ltd [1972] RPC 346 considered ESCO CORPORATION AND BRADKEN RESOURCES PTY LTD (ABN 82 098 300 988) v PAC MINING PTY LTD (ABN 11 007 694 895) AND CENTRAL QUEENSLAND MINING SUPPLIES PTY LTD (ABN 11 010 402 990) NSD 1084 OF 2006 TAMBERLIN J 12 MAY 2008 SYDNEY IN THE FEDERAL COURT OF AUSTRALIA NEW SOUTH WALES DISTRICT REGISTRY NSD 1084 OF 2006 BETWEEN: ESCO CORPORATION First Applicant/First Cross-Respondent BRADKEN RESOURCES PTY LTD (ABN 82 098 300 988) Second Applicant/Second Cross-Respondent AND: PAC MINING PTY LTD (ABN 11 007 694 895) First Respondent/First Cross-Applicant CENTRAL QUEENSLAND MINING SUPPLIES PTY LTD (ABN 11 010 402 990) Second Respondent/Second Cross-Respondent JUDGE: TAMBERLIN J DATE OF ORDER: 12 MAY 2008 WHERE MADE: SYDNEY THE COURT DIRECTS THAT: 1. The parties consult with a view to agreeing upon and sending to my Associate in chambers Short Minutes of Order giving effect to these reasons for judgment. 2. The parties, if unable to agree on Short Minutes of Order giving effect to these reasons for judgment, send to my Associate in chambers competing Short Minutes of Order with brief reasons. THE COURT ORDERS THAT: 3. Costs be reserved. Note: Settlement and entry of orders is dealt with in Order 36 of the Federal Court Rules. IN THE FEDERAL COURT OF AUSTRALIA NEW SOUTH WALES DISTRICT REGISTRY NSD 1084 OF 2006 BETWEEN: ESCO CORPORATION First Applicant/First Cross-Respondent BRADKEN RESOURCES PTY LTD (ABN 82 098 300 988) Second Applicant/Second Cross-Respondent AND: PAC MINING PTY LTD (ABN 11 007 694 895) First Respondent/First Cross-Applicant CENTRAL QUEENSLAND MINING SUPPLIES PTY LTD (ABN 11 010402 990) Second Respondent/Second Cross-Respondent JUDGE: TAMBERLIN J DATE: 12 MAY 2008 PLACE: SYDNEY REASONS FOR JUDGMENT 1 The applicants apply for orders declaring that the respondents have infringed Australian patent numbers 696,335 ("Jones II") and 743,348 ("Jones III") and restraining them from any further infringement. Other orders sought include orders for delivery up, damages or accounts of profits and destruction of materials used to produce the allegedly infringing products. 2 The first applicant ("Esco") is the registered proprietor of both Jones II and Jones III. The inventions contained in the patents can be described as wear assembles which attach to the "digging edge" of an excavator bucket, and thereby protect that portion of the bucket's edge which engages with or digs into the ground. Wear assemblies comprise several parts, including a "shroud", a "weld base", a "lock" and an "adjustment assembly". The priority date of both Jones II and Jones III is 6 November 1995. Jones III is a divisional of Jones II. 3 The second applicant ("Bradken") is the registered exclusive licensee of both Jones II and Jones III. 4 The respondents are alleged to have sold and supplied several wear assemblies which infringe Jones II and Jones III. The wear assemblies produced by the respondents which are said to infringe the applicants' patents are known as the Hensley System, the PAC System and CQMS System. 5 The applicants' allegations of infringement turn on three questions of construction relating to the meaning of certain expressions in the patents' specifications, namely: · "opening extending therethough"; · "digging edge"; and · "a rigid lock received into said opening". 6 The respondents' Defence and Cross-Claim responds to the applicants' allegations of infringement, and pleads that the relevant claims of the applicants' patents are invalid on the grounds that they are not novel, do not involve an inventive step and are not fairly based on the descriptions in the patents' specifications. The respondents seek appropriate declarations of invalidity. BACKGROUND 7 The patents in suit are referred to as "Jones Patents" because they are part of a series of patents of which Mr Larren Jones, a former employee of Esco, is named as an inventor. In addition to Jones II and III, which are the patents in suit, it is also relevant to note the registration of United States Patent number 5,088,214, which is known as "Jones I". This patent is an important piece of prior art that is expressly incorporated by reference into Jones II and Jones III. 8 Jones I was applied for in 1991 and granted in 1992. The corresponding Australian patent was applied for in 1992 and claimed priority based on the 1991 application. The commercial embodiment of Jones I, which was a product known as "Toplok", was first sold in Australia in 1991. By 6 November 1995, which is the priority date for both Jones II and Jones III, Toplok had been sold in large quantities and was used on excavators operating in mines around Australia. It had been advertised and promoted in trade shows and trade publications. The applicants say that, by the priority date of Jones II and Jones III, Toplock's technology was common general knowledge in Australia. 9 One of the problems encountered by the Jones I design was that looseness occurred between the lock, the boss and the inside walls of the opening which extends through to the shroud where it wraps around the digging edge of the bucket. This problem apparently arises both from the fact that cast parts are used in the manufacture of Toplok and also from general wear and tear during operation. 10 As noted above, Jones I, Jones II and Jones III are concerned with wear assemblies for the digging edges of excavators. Wear assemblies are constituted by the combination of several replaceable parts (namely, shrouds, adapters and teeth). Not every wear assembly contains every type of replaceable part. Some configurations of large excavator buckets are fitted with shrouds only, as it is desirable to have a single continuous edge along the excavator bucket. Depending on the nature of the work to be performed by the excavator, however, a combination of shrouds and teeth may be used. In such situations, the teeth are attached to adapters which form part of or are attached to the lip of the excavator bucket. The function of all configurations of wear assemblies is to provide digging edges which can be replaced when damaged or worn. Such functionality avoids the more expensive and time-consuming option of repairing or replacing the whole excavator bucket. 11 In order to accommodate the attachment of shrouds, adapters and teeth, the digging edge of the excavator bucket is usually bevelled or rounded. The adapters are welded onto, or are somehow otherwise attached to, the lip of the bucket at certain intervals along the digging edge. The teeth then fit onto the adapters and are fastened in position by pins extending through the teeth and into the adapters. For the portion of the digging edge exposed between each adapter, a shroud wraps around it. 12 The teeth project out beyond the edge of the bucket, and will generally engage the ground before any other part of the wear assembly. This means that the teeth (and the adapters to which they are fixed) generate larger reaction forces in the bucket than the shrouds. As a consequence, the teeth and adapters have a greater bending movement, that is, greater leverage than the shrouds. 13 The specifications of the patents in suit begin by identifying the field of the invention as relating 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". The specifications draw attention specifically to adapters used in wear assemblies, and to the desirability that they be capable of ready removal and installation by operators in the field. In other earlier patents, the adapter was welded to the bucket and the replacement of such adapters was difficult and time-consuming. Indeed, one such patent described a system comprised of a mechanically attached adapter which is held in place by a combination of a clamp and a wedge, but which required repeated blows with a heavy sledge hammer to insert the wedge upon any replacement of the adapter. In addition to the onerous and time-consuming nature of such a process of replacement, a further disadvantage of this system was that a hole had to be punched through the lip of the excavator bucket which reduced its strength and integrity. 14 The specifications of the patents in suit also refer specifically to some of the problems encountered by the Jones I design. The specifications state that the Jones I design was not suitable for attaching all types of wear members to all types of buckets because, for example, large buckets with bevelled lips tend to generate larger forces on an adapter. In addition, Jones I is said to lack means for eliminating any looseness that may exist between the wear member and the boss to which it is affixed. 15 The specifications of both Jones II and Jones III describe the advantage of the new inventions in those patents over the prior art 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 apply support adapters on a bucket 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.' CLAIMS IN SUIT 16 Only certain claims of Jones II and Jones III are in suit in the present case. They are claims 1 and 51 of Jones II and claim 1 of Jones III. 17 Claim 1 of Jones II is 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 the 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.' (Emphasis added.) 18 Claim 51 of Jones II is 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 lock 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.' (Emphasis added.) 19 Claim 1 of Jones III is 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.' (Emphasis added.) EVIDENCE 20 The evidence from each party was largely directed to the conflict between the different interpretations of the claims in suit favoured by the parties' respective expert witnesses. I found the expert witnesses on both sides to be well-versed in their field. Applicants' evidence 21 Affidavit evidence was filed by the applicants. The deponents whose affidavits were read were Messrs John Alden, Indradeep Battacharya, Robert McClanahan and Ms Karen Gillard. 22 Mr Alden was called by the applicants as an expert. His evidence related chiefly to the interpretation of the specifications of the patents in suit. I accept his qualifications and experience, which were of a high order and not significantly challenged by the respondents, as grounding his expertise in this area. 23 Four affidavits of Mr Alden were read, and his evidence was the subject of detailed cross-examination. Three of his affidavits concerned issues of construction and infringement, while the fourth related to novelty. In relation to construction and infringement, Mr Alden deposed in detail to the differences and similarities he perceived between the claims in suit and the respondents' products, namely the PAC and CQMS Systems, the Hensley System and the CQMS Lower Wing System. In broad terms, Mr Alden concluded that the respondents' products did have the features of the claims in suit. He also gave evidence in response to the evidence of an expert witness retained by the respondents, Professor Wightley. Mr Alden concluded that Professor Wightley erred in his evidence by treating shear forces and compressive forces as interchangeable, and that, in any event, to refer to a "shear member" to describe the lock in the present case is overly simplistic because the forces which are transferred through the lock are not confined to shear forces. In a later affidavit, Mr Alden also took issue with the way in which Professor Wightley defined and used the terms "digging edge" and "opening extending therethrough". Finally, on the issue of novelty, Mr Alden deposed that he is unable to agree with Professor Wightley's conclusion that the invention is novel, and set out in detail the reasons why he reached the opposite conclusion. 24 Generally, Mr Alden's evidence was not significantly shaken on cross-examination. However, on one matter, Mr Alden's evidence did not withstand cross-examination entirely unshaken. His interpretation of the phrase "opening extending therethrough" was largely one of subjective impression and, in my view, was shown to be weak. I do not find Mr Alden's reasoning as to how he reached his interpretation of this expression persuasive. 25 An affidavit of Mr Battacharya was read in this proceeding. He is a legal representative for the applicants. His affidavit exhibited several photographs and a video recording of the installation of the PAC and CQMS Systems onto the lip of an excavator bucket. This affidavit was illustrative because it demonstrated how the attachment of the wear assembly takes place. Mr Battacharya was not required for cross-examination. 26 Mr McClanahan swore two affidavits in this proceeding. He is one of the named inventors of Jones II and Jones III, and is presently a senior engineer in the employ of Esco. His evidence served several purposes. It set out the history of the industry which developed "ground engaging tools", and the purpose which those tools were designed to achieve. It also set out the history of the development of the Toplok shroud, and explained how that led to the need to develop the inventions which are the subject of Jones II and Jones III. Mr McClanahan also deposed in detail to the mode of development of the inventions, the considerations which the inventors took into account, and what problems the inventions were intended to overcome. To assist comprehension, Mr McClanahan exhibited to his affidavits several drawings showing the inventions' appearance, their operation and how they sought to overcome problems with existing ground engaging tools. 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. 27 Ms Gillard, who is the financial systems controller of Bradken, also swore an affidavit. It set out the way in which Bradken maintains records of sales history, and exhibited data and reports relating to the sales success of Toplok as a commercial product. Ms Gillard was not required for cross-examination. Respondents' evidence 28 The respondents read the affidavits of five deponents, Professor Allan Wightley and Messers Thomas Meyers, Anthony Ashworth, Shane Smith and Andrew Calvin. 29 Professor Wightley was an expert witness. His qualifications and experience are impressive and there was no substantial challenge to his expertise. I accept his evidence as that of an expert witness. As is evident from Mr Alden's evidence above, there were disputes between Professor Wightley and Mr Alden regarding the way in which the claims in suit should be construed, whether they had been infringed by the respondents' products, and whether the respondents' products were novel and/or included an inventive step. 30 Six affidavits of Professor Wightley were read in evidence. In relation to the issues of construction, Professor Wightley considered the meaning of references to "rigid lock", "lock", "digging edge" and "opening extending therethrough", and concluded that the respondents' products do not come within those expressions. Professor Wightley's evidence expressly disagreed in substantial part with that of Mr Alden, and is said to substantiate the conclusion that the respondents' products do not infringe the claims in suit. On the issue of novelty, Professor Wightley said that certain patents, and in particular United States Patent number 3,919,792 (also known as "Hahn"), already disclosed all of the essential integers of claims 1 and 51 in Jones II and claim 1 in Jones III. Professor Wightley also gave evidence relevant to the issue of obviousness. His evidence on this aspect described the wear assembly which is contained within the specification of Jones I, and made several observations about the design of Jones I in relation to: the ability to fit the wear member "in the field using hand tools"; the rigidity of the wear assembly; the types of forces which operate; the functionality of the latch; and a minor difference between the Jones I design and the Toplok design. After addressing what he considered to be a design flaw in Jones I, Professor Wightley stated that, to a mechanical engineer trying to overcome this flaw, it would be readily apparent that some mechanism to tighten the wear assembly, such as a screw adjustment, would be required. Finally, on the question of obviousness, Professor Wightley deposed two affidavits which respond directly to evidence adduced by the applicants, and devoted special attention to a particular characteristic of the Hahn patent, which was referred to as the "shoulder" design of the lock. 31 Professor Wightley was cross-examined by counsel for the applicants. His evidence was tested but, in my view, not materially undermined. In particular, I favour the construction which Professor Wightley gave to the phrase "opening extending therethrough". In my view, Professor Wightley's evidence that the phrase bears a meaning that "it's an opening that starts one side and it goes to the other side, all the way through, from one surface to the other", is persuasive. Professor Wightley expressly derived his interpretation from the ordinary meaning of the term "opening extending therethrough", an approach which I find to be stronger than that adopted by Mr Alden. 32 My Meyers is the Managing Director of the first respondent. He swore three affidavits read in this proceeding. He gave evidence of his personal background, the way in which the respondents' business has developed over time, its production of wear assemblies, and the way in which the wear assembly market developed in Australia. Mr Meyers also gave evidence, some of which I allowed over objections, as to matters which he regarded as common general knowledge about the design and manufacture of wear assemblies in Australia at 6 November 1995. Mr Meyers inspected the patent specifications for, among others, Jones I, Jones II and Jones III, before concluding that the original Toplok wear assembly supplied in Australia used a rigid lock as described in Jones I, but without any adjustment mechanism of the kind described in Jones II and Jones III. He considered that the modified Toplok wear assembly supplied in Australia incorporated an adjustment mechanism as described in claims 1 and 51 of Jones II and claim 1 of Jones III. In addition, Mr Meyers exhibited several CD-Rom discs which contained animations depicting the construction of various wear assemblies. 33 Mr Meyers was cross-examined by counsel for the applicants in relation to the records he kept in order to track the performance of certain wear assemblies, the conclusions he drew in relation to the areas in which the designs could be improved, and the reasons for which the wear assemblies regularly failed. The cross-examination clarified, by reference to diagrams already in evidence, what Mr Meyers regarded as the invention in this case, which, in broad terms, was the advantage gained from only requiring a bolt or screw to secure the teeth of the wear assembly to their mounts, without also requiring special tools to achieve the same result. 34 Mr Ashworth, who was called for the respondents, swore one affidavit. At the relevant time, he was an engineer employed by Mason & Cox. His evidence related to the usage and functionality of several different types of locks used in ground engaging tools, such as J-bolts, straight bolts and Toplok. In addition, Mr Ashworth gave evidence of what he considered to be the common general knowledge about the design and manufacture of wear assemblies in Australia at 6 November 1995. While cross-examination of Mr Ashworth elicited some further information about the disadvantages of certain bolts used in wear assemblies and the way in which he became aware of the Toplok product, it did not materially undermine his evidence. 35 Finally, the respondents relied on the evidence of two further witnesses, Messrs Smith and Calvin. Mr Smith gave evidence that a large number of Toplok shrouds supplied to mines in the Hunter Valley had failed prematurely and that some mines were improvising ways in which to fix the shroud and wear assembly in place. Mr Smith was not required for cross-examination. Mr Calvin, a solicitor representing the respondents, gave evidence that, according to the data supplied by Ms Gillard for the applicants, there may have been many more complaints and warranty claims in relation to a certain product supplied by the applicants than the mere two per cent suggested by Mr McClanahan. Cross-examination of Mr Calvin was brief, and sought chiefly to test the basis and correctness of the calculations he had undertaken in relation to Ms Gillard's evidence. Infringement 36 In this case, three issues of construction of the patents' specifications arise out of the contention that the respondents' products infringe the patents in suit. In particular, the phrases which are in dispute are: (i) "opening extending therethrough" in claim 1 of Jones II or "opening extending through said leg" in claim 51 of Jones II; (ii) "digging edge" in claims 1 and 51 of Jones II; and (iii) "a rigid lock received into said opening" in claims 1 and 51 of Jones II or "a lock received into the opening" in claim 1 of Jones III. In this case, the resolution of these three issues of construction will also resolve the question of infringement because the three issues reflect the only points of distinction which the respondents say exist between the patents and the respondents' products. "Opening extending therethrough" 37 The first issue relating to infringement is whether the respondents' products have a wear member with a rearwardly extending leg that includes an "opening extending therethrough" (as in claim 1 of Jones II) or an "opening extending through said leg" (as in claim 51 of Jones II). Given that it is common ground that the respondents' products do not have an opening which extends all the way through the leg, the question which arises is one of construction, namely, whether the opening must go all the way through the leg or whether it is sufficient if the opening goes only partly or substantially through the leg. 38 The applicants say that the expression "therethrough" can include extending partly or substantiallythrough the leg. The word "extending", it is said, is used in the sense of stretching forth over a substantial length, an argument which is said to be supported by the use of the present participle form of the verb. By way of example, the applicants refer to the way in which a tibia can be said to extend through a leg, despite the fact that the tibia does not go all the way through the leg, and the way in which the opening in a collapsible tripod can be said to extend through the leg of the tripod, even though that opening may not go all the way through. 39 The applicants rely on the evidence of Mr Alden that the functions of the opening in the wear member's leg are to receive the lock, to provide a wall to oppose and engage the second face of the lock, and as a result to facilitate the lock (and adjustment assembly) performing its function. These functions, it is said, do not require that the opening should be axial or extend all the way through the leg. Mr Alden's evidence provided examples of an opening which is not axial and may not extend all the way through the leg. Mr Alden referred to cases where the lock could be inserted into the opening from the rear of the leg, an approach which, although perhaps inconvenient in practice, would avoid having fines pack into the opening and jam the lock and other problems of wear and tear. 40 The respondents, on the other hand, submit that the language in dispute has a clear, simple and ordinary meaning. The respondents submit that the word "therethrough" requires the opening to extend all the way through the leg, and not merely to extend "into" or "substantially through" the leg. This argument, it is said, is supported by the definitions of the word "through" in the Macquarie Dictionary and the Shorter Oxford English Dictionary, both of which emphasise that the word connotes an entry on one side and an exit on the other side, with a tunnel-like passage between these two points. The respondents say that it would have been a simple matter to refer to an opening which extends "into" the leg, if it was the intention of the specifications not to require an opening which extended all the way through the leg. The respondents' construction is also said to gain support from the fact that every depiction of the preferred embodiment in Jones II and Jones III contains an opening that extends all the way through the leg, a matter which Mr Alden accepted in cross-examination. 41 Professor Wightley, whose evidence I accept on this point, was asked during cross-examination: 'Why does it follow that [the opening] has to extend right through the leg axially?' Professor Wightley replied: '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.) 42 This explanation, which I accept is consistent with the geometric logic of the claims in suit, is attractive not only in its simplicity but also because of its adherence to the ordinary meaning of the specifications of the patents. In contrast, Mr Alden's attempt to define the term "opening extending therethrough" was more complicated, and he was unable to give any example of an opening extending all the way through the boss other than axially. 43 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. "Digging Edge" 44 On this second point of construction, the respondents submit that their products do not have a "boss … adapted to be fixed to the digging edge of an excavator", and that any digging edge on their products is confined in a way that places them outside the claims in suit. 45 The requirement of the claims (although differently expressed in each of claim 1 of Jones II, claim 51 of Jones II and claim 1 of Jones III) is that the boss of the wear assembly should have one surface adapted to be fixed to the digging edge, and a second surface adapted to be positioned remote from the digging edge and having a T-shape structure. The digging edge is that portion of an excavator bucket to which the wear assembly is fixed. 46 The respondents submit that the digging edge is the leading edge of the bucket that separates the material being excavated by shear force. In simpler terms, the digging edge is the edge that does the digging. It removes the top layer of the earth or material which is then scooped up by the excavator bucket. If the leading edge is bevelled, the respondents argue that the digging edge will not extend beyond the point at which the bevel ends. Where there is no bevelled leading edge, it is the blunt or rounded edge to which the attachment is made. As a matter of practical or engineering necessity, the boss could not be fixed only at the digging edge; rather, as Professor Wightley acknowledged, the boss would also need to be fixed "back on the lip" to provide the necessary force to prevent uplift at the rear of the leg. This evidence of Professor Wightley, the respondents submit, is consistent with the diagrams attached to the specifications of the patent, particularly those which show the weld beads located on the bevelled ramp (that is, the digging edge) and further back on the lip. In light of this evidence, the respondents say that none of their products has a boss that is adapted to be fixed to the digging edge of an excavating bucket. In contrast, the boss in the respondents' products is said to be welded to the inside lip of the excavator bucket, and is situated rearward of the digging edge of the excavator. 47 Contrary to these submissions, the applicants say that it would be impractical for the boss to be attached only to the front face, bevelled ramp or semicircular end of a lip. Indeed, it is said that attachment of the boss further back on the lip is necessary if the equipment is going to perform its specified tasks. Without such characteristics, a practical piece of machinery will not exist. For this reason alone, the applicants argue, the respondents' construction of the claim cannot be supported. It does not properly reflect the claims in suit, and excludes the preferred embodiment of the claims. In addition, the applicants rely on claim 5 of Jones II (which refers to a "deflector" which is to be "fixed to the digging edge rearward of said boss") to support its contention that the digging edge described in the patents in suit must extend rearwards of the boss. Finally, when describing the background to the invention, the specification of Jones II refers to three examples where wear members described in earlier patents were attached to an excavator bucket behind the line of any bevelled ramp. This, it is said, is a further reason why the construction of the claims advanced by the respondents cannot be accepted. 48 Having regard to the terms of the claims in suit and to the principles of construction set out in the authorities (see Kimberly-Clark Australia Pty Ltd v Arico Trading International Pty Ltd (2001) 201 CLR 1 at 16; Populin v HB Nominees Pty Ltd (1982) 41 ALR 471 at 475-476; Stena Rederi Aktiebolag v Austral Ship Sales Pty Ltd (2007) 73 IPR 257 at 263-264), 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. 49 Accordingly, on this point of construction, the arguments advanced by the applicants are accepted. "Rigid Lock" 50 The final issue of construction is what is meant by "a rigid lock received into said opening" (as in claim 1 and 51 of Jones II) or "a lock received into the opening" (as in claim 1 of Jones III). 51 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. 52 The purpose of the lock in a wear assembly is to act as a jamming device. As such, the lock is subject to compression between the boss and the wear member, and must therefore be capable of withstanding forces which are brought to bear during operation. Mr Alden gave evidence that the lock must be positioned between these two surfaces and be strong enough to take the relevant load. Professor Wightley gave evidence to similar effect. On the basis of this evidence and by reference to the patents' specifications, the respondents submit that the lock must be "rigid" before it is received into the opening. It is not sufficient, it is said, for the lock to become rigid only after a variety of parts (including a nut, bolt, keeper plate, spring washer and nut washer assembly) have been assembled and tightened. Mr Alden's evidence to the contrary does not accord with the requirements of the language used in the specifications, especially in respect of its inability to identify among the variety of parts what the specifications refer to as the "body" of the lock. The respondents say that, until assembled and tightened, the parts of the lock cannot be described as a single or "rigid" lock; rather, they can at most be described as a combination of component parts. 53 In addition, the respondents submit that the nut and bolt assembly which constitutes the lock in its products use a tension member to fasten the wear member to the bucket by tensile forces rather than shear forces. Both Mr Alden and Professor Wightley agreed that the nut and bolt assembly used in the respondents' products is, when tightened, in tension, not in shear. Given that the specifications call for a "shear" member (and do not mention a tension member), the respondents' product cannot be said to fall within those specifications, properly construed. 54 Finally, the respondents submit that the evidence given by Mr Alden in relation to the lock being "received into the opening" was inconsistent and therefore unreliable. The preferable conclusion on the evidence, it is said, is that the respondents' products have a lock which is not wholly received into the opening (as identified by Mr Alden), is not rigid when received into the opening, and does not sit between the bearing face of the boss and the rear wall of the wear member. 55 The applicants start from the premise that, on its ordinary meaning, "lock" includes an assembly of parts which secure two things together. The word does not connote that any particular force, such as a shear force instead of a tensile force, is dominant, particularly since multiple forces are at play in the operation of a wear assembly. The expression "lock" is said to be broad enough to encompass all of the locking assemblies in the respondents' products. In the present case, the lock the subject of the patents must have as a component an adjustment assembly which is selectively moveable to eliminate looseness in the manner defined. The preferred embodiment of the lock, it is said, involves a number of components, including the adjustment assembly. In other words, the adjustment assembly is part of the lock and is the means by which it is made rigid. 56 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. 57 As referred to above, the respondents further contend that the claims contemplate that the whole of the lock must be located within the part of the opening defined by the bearing surfaces established by the boss and the opening (also known as the first and second bearing surfaces). The respondents rely on evidence given by Professor Wightley to support this contention. Further and in the alternative, the respondents submit that, even if claim 1 of Jones III does not require the whole of the lock to be received within the first and second bearing surfaces, then at least the essential parts of the lock must be received between those two surfaces. In relation to this alternative construction of the claim, the respondents refer to Mr Alden's acceptance of the proposition that important components of the lock in the respondents' product (the nut, bolt, keeper plates, spring washer and nut washer) are not received between the two relevant bearing surfaces. Finally, the respondents also submit that, on a proper construction of the claims in suit, the operation of a further included adjustment assembly in the rigid lock is not an essential requirement (although its presence is mandatory and its operation may be a desirable option). The language of the claims, it is said, together with a practical understanding of the function of the invention, demonstrates that the inclusion of an operative adjustment assembly is an additional and optional component of the wear assembly described in the claim, rather than an integral part of the rigid lock. 58 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. 59 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. 60 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. 61 Accordingly, for these reasons I accept the submissions of the applicants on this question of construction. Validity Novelty 62 The issue of novelty which arises in this case is whether claim 1 of Jones III lacks novelty in light of Hahn (United States Patent number 3,919,792). The answer to this question turns largely on the meaning of the expression "shoulder" which is repeated several times in claim 1 of Jones III (set out in full at [19] above). Professor Wightley gave evidence that he could identify "shoulders", as that term is used in claim 1 of Jones III, in the wear member the subject of Hahn. If the Court agrees with Professor Wightley's conclusion, then it is clear that the patent is invalid for lack of novelty. 63 For the reasons set out below, I am not of the view that Hahn anticipates claim 1 of Jones III, and as a consequence I find that Jones III is not invalid for lack of novelty. 64 Professor Wightley for the respondents gave evidence that the "shoulders" which he identified on the Hahn specification existed at the contoured surfaces on the mount (that is, the socket member) and the wear member (that is, the shank). Professor Wightley stated that the function of these contoured surfaces is to prevent uplift and rotation by supporting or "shouldering" the load. This, it is said by the respondents, is consistent with the ordinary meaning of the term "shoulder". The respondents also submit that examination of these contoured surfaces discloses shoulder-like protrusions on either side, in much the same way as a human torso is shaped. Finally, the respondents also reject as too narrow the applicants' construction of the word "shoulder" as requiring a stepped flange, particularly in the context of describing a mechanical assembly. 65 Mr Alden for the applicants disagrees with Professor Wightley. He says that nothing which could properly be described as "shoulders" can be identified in the specification of Hahn because no stepped profile or projection is therein disclosed. The applicants submit that the reason Mr Alden must reach this conclusion is because, in Hahn, there is no need for shoulders because the wear member is located inside the socket rather than on top of it. 66 In my view, the ordinary meaning of the term "shoulder" connotes the existence of a stepped profile or a projection which serves as a support for something. This definition is supported by the definition in the Oxford English Dictionary. Accordingly, in light of this definition and given that I accept the applicants' submission that the "shoulders" in claim 1 of Jones III function by engaging with each other to secure the wear member to the mount (and thereby prevent any release perpendicular to the lip), I find that such a configuration is not present in the contoured surfaces on the socket member and the shank in Hahn, and that as a consequence Hahn cannot be said to anticipate Jones III. Jones III therefore is novel as required by s 7(1) of the Patents Act 1990 (Cth) ("the Act"). 67 The respondents' claim based on an asserted lack of novelty in Jones III must therefore be dismissed. Obviousness 68 The issue of obviousness which arises in this case is whether a hypothetical person skilled in the relevant art in light of the common general knowledge as at 6 November 1995 would have regarded it as obvious, in the production of an improved wear assembly, to utilise a screw as a means of eliminating looseness in the wear assembly and thereby arrive at the claimed invention in Jones III: see s 7(2) of the Act; Lockwood Security Products Pty Limited v Doric Products Pty Limited (No. 2) (2007) 235 ALR 202 at 231. When addressing this question, the Court must be careful not to substitute its own deduction or perception for that of the hypothetical person. Furthermore, as the High Court has stated on several occasions, "[a] scintilla of invention remains sufficient in Australian law to support the validity of a patent": see Lockwood 235 ALR at 217 and cases cited therein. 69 The applicants contend that the person skilled in the relevant art in this case is someone who works in the earthmoving industries who would be involved in the design and manufacture of wear assemblies and therefore would be familiar with factors relevant to their design and development. It is said by the applicants that Professor Wightley is not a person skilled in the relevant art because he had no experience in the design, operation or manufacture of wear assemblies attached specifically to excavators. 70 The respondents' contention is that only Professor Wightley and Messrs Meyers, Ashworth and McClanahan are persons skilled in the relevant art. It is said that Professor Wightley is a mechanical engineer with extensive experience in design and manufacture of replacement wear parts for use in the mining industry generally; Mr Meyers is a mechanical engineer with experience in the design, manufacture, sale and maintenance of replaceable wear parts for excavators; and Messrs Ashworth and McClanahan are relevantly skilled mechanical engineers. On the other hand, say the respondents, Mr Alden, the expert called by the applicants, is a structural engineer, which means he is not skilled in the relevant art. In addition, the respondents argue that the only witness called by the applicants on the issue of obviousness was Mr McClanahan (the co-inventor of the patents), and that the evidence called by the respondents in relation to this point was therefore not directly challenged by any qualified expert. 71 In my opinion, Professor Wightley and the other mechanical engineers whose evidence was adduced by the respondents have sufficient expertise to express the opinions as persons skilled in the art. However, for reasons given below, I do not accept Professor Wightley's evidence and the respondents' submission that the solution provided by the invention in Jones II and Jones III was obvious. 72 The applicants say that the invention in this case is an improved wear assembly which is constituted by the combination of elements set out in claims 1 and 51 of Jones II and claim 1 of Jones III. Each of these claims in suit, it is said, involves a combination of elements in a way that constitutes a new inventive thing, despite the fact that each of the elements (other than the lock adjustment assembly) was contained in the Toplok shroud, which the applicants' properly acknowledged formed part of the common general knowledge. In simpler terms, the new combination achieved by the patents in this case provided a new benefit beyond what had previously been provided, and was therefore inventive. 73 The applicants submit that the invention the subject of Jones II and Jones III was based on perceptions that: · the Toplok shroud provided a good foundation upon which to develop an improved wear assembly that could serve not only as a shroud but also as an adapter; · the forces to which an adapter may be exposed could produce looseness in mounting of the wear assembly to a Toplok style of mounting; and · this looseness could be overcome by an adjustment assembly that moved the relative positions of the bearing surfaces of the Toplok style lock so as to pull the wear assembly over the mount. 74 The applicants' argument is that the use of this type of adapter with a Toplok style of mounting was not part of the common general knowledge at the relevant date. Furthermore, the applicants say that, since there were at the relevant date many wear assemblies available to be used as the starting point to develop an improved assembly which overcame looseness between the wear member and the boss, the use of Toplok as the starting point was not required by any design principle, and was therefore not obvious. Indeed, as Professor Wightley acknowledged in cross-examination, even if an inventor were confined to the Toplok shroud as a starting point, there were several other locking methods known which may have been used instead of the method ultimately used in the invention. One such alternative method was the use of two piece pins, wedges and spools to take up any looseness in the wear assembly. 75 The applicants argue that the common general knowledge as at the priority date included not only a significant number of wear assemblies and wear parts used in the mining industries, but also a specific awareness of the use of the Toplok shroud and its locking mechanism. This awareness, it is said, extended to the way in which the Toplok shroud had a tendency to looseness and slippage, which was a consequence of its usage of cast parts, general wear and tear and the absence of any tightening mechanism. The applicants submit that the evidence of Professor Wightley on this point should not be accepted because (i) he was presented at the outset with both the details of the problem encountered by the Toplok design as well as the specifications for the patents in suit which solved the problem, meaning that his evidence is weakened by hindsight reasoning; and (ii) his conclusion that Toplok suffered from a "design flaw" referable to inherent looseness is erroneous. The applicants also argue that the alleged problems in relation to looseness, while known to a limited extent, were not part of the common general knowledge, a conclusion which is supported by the evidence of Messrs Ashworth and Meyers who said that they were unable to confirm whether they were aware of this problem at the relevant date. In addition, the applicants say that the weight of the evidence demonstrates that there is no reason to suppose that a hypothetical addressee, confronted with this problem of looseness, would come up with the invention the subject of Jones II and Jones III. 76 In relation to the criticism of the hindsight reasoning involved in Professor Wightley's evidence, the applicants say that a person skilled in the art would have attempted to understand the nature of the problem before attempting to formulate a solution. To do otherwise would risk confusing the exact nature of the problem to which the solution is sought. By engaging in hindsight reasoning, it is said, one cannot conclusively determine whether the solution is a response to a so-called "design flaw" in the existing art or as a response to, say, the excessively large forces which arise specifically in the case of large excavator buckets. In short, the applicants say, all other problems which may have given rise to the difficulty encountered by the Jones I design would need to be explored before ascertaining the cause of that difficulty and positing a solution. Professor Wightley, it is said, did not identify the precise cause and nature of the problem; rather, he was asked to assume that it existed, and as a consequence he did not consider solutions alternative to the one used by the inventors of Jones II and Jones III (such as the possibility that looseness could be overcome by adjusting tolerances or using shins or rails as temporary fixes). Accordingly, the applicants conclude, Professor Wightley's evidence is affected by hindsight reasoning and should not be accepted. 77 In answer, the respondents contend that detailed knowledge of Toplok, including knowledge of how it was assembled in the field and the problems of looseness from which it suffered, was common general knowledge as at the priority date. They directly dispute the perceptions on which the applicants say the invention in Jones II and Jones III was based. The respondents say that each of claims 1 and 51 of Jones II and claim 1 of Jones III was an obvious solution to a recognised problem in Toplok, and that if a person skilled in the art wished to provide a means for tightening the Toplok assembly, then such a person would be led directly as a matter of course to try a screw adjustment mechanism. The screw adjustment is said to have been a basic and practical measure which was well known to mechanical engineers as a way to tighten assemblies that needed to be made rigid. It was also, the respondents say, clear that the only practical way of introducing such an adjustment to Toplok was by providing a threaded aperture through the rigid lock, with a gap in the rear wall of the opening provided to allow the adjusting screw to pass through the wear member, thereby protecting it from abrasive material while still making it reasonably accessible. 78 The respondents rely largely on the opinion of Professor Wightley in relation to the issue of obviousness. His opinion was that, as at the priority date, it was common general knowledge amongst mechanical engineers that the Toplok shrouds experienced problems of looseness in the assembly due to problems arising from the design and dimensions of the assembly and abrasive wear. Professor Wightley also stated that the common general knowledge included knowledge of basic mechanical engineering principles and techniques relevant to the reduction of looseness in wear assemblies (by, for example, the use of take-up mechanisms such as a screw adjustment). Professor Wightley also described the inability to tighten the wear assembly in Toplok as a "design flaw", an opinion which (among others) the respondents deny is affected by any hindsight reasoning. Professor Wightley suggested that a mechanical engineer who wanted to overcome the looseness problem in Jones I, would readily appreciate that some mechanism to tighten the assembly was required and that one measure which would immediately come to mind would be the use of a screw adjustment to remove the looseness. He said that this was a simple and practical measure, routinely used by mechanical engineers to eliminate looseness where rigid assemblies are required, which was beneficial because it could be located towards the rear of the wear member away from abrasive material, was self locking, would not rattle loose, was inexpensive and was adjustable over its effective length. 79 Finally, the respondents also contend that, having regard to the dates of application and filing for United States Patent number 5,713,125 ("Hensley") and Jones II, which were in close proximity, the fact that Hensley independently arrived at the same invention at around the same time supports the respondents' argument on obviousness. This, it is said, is because such circumstances suggest that the very similar designs which are the subject of these two patents were not beyond the ordinary skills of the art at the relevant time. 80 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. 81 The dangers inherent in drawing conclusions with the benefit of hindsight have been emphasised in the authorities. As Aickin J pointed out in Meyers Taylor Pty Ltd v Vicarr Industries Ltd (1977) 137 CLR 228 at 242: '… subsequent analysis of an invention – "the dissection of the invention" – is not often helpful in resolving the question of obviousness. It has been criticized as being a mistaken approach, see Blanco White, Patents for Inventions, 4th ed. (1974), at par.4-214. This matter was also discussed by Menzies J in Commonwealth Industrial Gases Ltd. v M.W.A. Holdings Pty. Ltd. where he commented on the undesirability of analysis by hindsight because once one sees an invention it may very often appear very simple and one may then wonder why no one previously had thought of so simple an improvement device.' 82 The danger of hindsight was also referred to by Lord Diplock in Technograph Printed Circuits Ltd v Mills-Rockley (Electronics) Ltd [1972] RPC 346 at 362 (and approved by the High Court in Aktiebolaget Hässle v Alphapharm Pty Ltd (2002) 194 ALR 485 at 491) in these terms: 'Once an invention has been made it is generally possible to postulate a combination of steps by which the inventor might have arrived at the invention that he claims in his specification if he started from something that was already known. But it is only because the invention has been made and has proved successful that it is possible to postulate from what starting point and by what particular combination of steps the inventor could have arrived at his invention. It may be that taken in isolation none of the steps which it is now possible to postulate, if taken in isolation, appears to call for any inventive ingenuity. It is improbable that this reconstruction a posteriori represents the mental process by which the inventor in fact arrived at his invention, but, even if it were, inventive ingenuity lay in perceiving that the final result which it was the object of the inventor to achieve was attainable from the particular starting point and in his selection of the particular combination of steps which would lead to that result. 83 As can be understood from these comments, a posteriori reasoning, which starts with an understanding of the solution to a given problem and then seeks to draw a conclusion as to how obvious it was to reach that solution, has been correctly criticised by the Courts. Where both the problem and the solution are put before a person from the outset, it becomes a simpler task to reason backwards from solution to problem, which may lead that person to draw an incorrect or flawed conclusion as to obviousness of the solution. 84 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. 85 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. 86 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. 87 On balance, I find that the evidence given on behalf of the respondents by Professor Wightley in relation to obviousness is reduced in weight by hindsight assumptions relating to the nature of the problem, the need for a new design and the solution ultimately developed. I do 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. In my view, the identification of the problem encountered by Jones I and the solutions proposed by Jones II and Jones III involved considerable inventive thought. Accordingly, I find that the respondents have not established that the move to the wear assembly locking device in Jones II and Jones III was an obvious solution to a person skilled in the art having regard to the common general knowledge at 6 November 1995. Fair basis 88 The respondents say there was a lack of fair basis in the present case because the specifications of the patents in suit do not provide real and reasonably clear disclosure of the invention. The relevant principles as to fair basis were set out in Lockwood Security Products Pty Limited v Doric Products Pty Limited (2004) 217 CLR 274 at 294ff. 89 I do not accept this submission of the respondents. 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. CONCLUSION 90 I direct the parties to consult with a view to agreeing upon and sending to my Associate in chambers Short Minutes of Order giving effect to the above reasons. If the parties are unable to agree, they are to send to my Associate in chambers competing Short Minutes of Order with brief reasons. 91 I will hear the parties on costs at a date to be arranged, or on the papers if appropriate. I certify that the preceding ninety-one (91) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Tamberlin. Associate: Dated: 12 May 2008 Mr R. Macaw QC and Mr S. Burley SC Counsel for the Applicants: Solicitor for the Applicants: Mallesons Stephen Jaques Counsel for the Respondents: Mr J. Nicholas SC and Mr H. Bevan Solicitor for the Respondents: DLA Phillips Fox Dates of Hearing: 5, 6, 7, 10, 11, 13 and 14 December 2007 Date of Judgment: 12 May 2008