91 The Australian application of the Bakerdrill patent, entitled "Sampling Airhammer Apparatus" became open to public inspection in Australia on 24 November 1977, and its publication appears to be that which introduced face sampling reverse circulation percussive hammers on to the Australian scene.
92 The Bakerdrill specification is difficult to understand. Two of the respondents' witnesses, Messrs Stevens and Purcell, doubted that the drill, as described in the specification, would work. The specification contains mistakes in that descriptions relating to figures 6 and 7, and a section line through figure 1(d), are inaccurate. These mistakes were not detected by the respondents' witnesses Messrs Stevens and Schwann. Their failure to detect these mistakes, which were relevant to issues under consideration, in my opinion reflects adversely on the quality of their evidence. I accept the submission of counsel for the applicant that this omission indicates that they too readily allowed information given to them by the respondents to influence their opinions.
93 Read at its publication date, I do not consider a skilled addressee would understand the specification as disclosing the features of the sacrificial transmission sleeve of the SDS patent.
94 The invention described in the Bakerdrill specification is said to overcome those problems associated with hammers using a crossover sub to divert the airflow and samples from outside of the hammer to the inside of the dual pipe drill string. The claimed apparatus is said to operate with reverse circulation airflow and a static air seal. The static air seal of the invention includes what is called a "gauge sleeve" which is mounted on a housing structure a short distance above the lower end of the drill bit. The gauge sleeve does not extend below the drive sub. The gauge sleeve is of slightly less diameter than the outer diameter of the gauge row of the drill bit, and it is held in place by being clamped between the drive sub and the outer housing of the hammer. In those respects its features are similar to those of the DTA compensating ring patent, but the specification is silent as to whether the gauge sleeve is intended to wear at all, and if it is, there is no statement as to its wear characteristics. Rather, the specification describes a static (fluid) seal created around the gauge sleeve by exhaust air from the hammer being directed into the bore hole adjacent to the upper and lower ends of the gauge sleeve. The static seal is described as preventing drill cuttings or rock debris from passing upwards or downwards around the gauge sleeve.
95 It is clear from the body of the specification, although not so clear from the figures attached, that the operation of the Bakerdrill depends on two separate air circuits, one circuit being for high pressure or supply air, and the other being for exhaust air expelled after driving the piston of the hammer. In contrast, the SDS patent is concerned only with the transmission of exhaust air, and with a face sampling apparatus in which the cuttings are entrained solely in exhaust air.
96 The exhaust air from the Bakerdrill is expelled through exhaust ports or holes in the drive sub below the gauge sleeve. The gauge sleeve therefore has no function in directing exhaust air. In addition to the exhaust air, high pressure air also flows into the bore hole "to sweep the cuttings produced on the bottom of the hole around the bit drilling face and into the (central) passages through the anvil bit". High pressure air is constantly pumped through discharge ports of holes for this purpose. The discharge ports open into a shallow annular space at the lower edge of the gauge sleeve but at a point above the lower end of the drive sub. It is said by the respondents that this feature teaches that the gauge sleeve directs or transmits air and therefore acts as a "transmission sleeve". Although there is no reference to the gauge sleeve being sacrificial, or being intended to have a similar wear rate to the drill bit, the respondents contend that it would go without saying that the gauge sleeve was sacrificial and that standard drilling practice would dictate that so far as possible a skilled addressee would attempt to achieve a similar wear rate for the gauge sleeve and drill bit.
97 Insofar as the intended operation of the Bakerdrill can be deduced from the specification, the purpose of the gauge sleeve is quite different to the transmission sleeve of the SDS patent. Its stated purpose is to create a static seal in conjunction with airflow from ports above and below the gauge sleeve. In the absence of any reference to the potential of the gauge sleeve to wear, or to its wear characteristics, I am unable to accept that a skilled addressee would infer that the gauge sleeve was sacrificial or that standard drilling practice would dictate that the skilled addressee should attempt to achieve a similar wear rate for the gauge sleeve and a drill bit. Moreover, high pressure air flowing from the discharge ports at the lower end of the gauge seal is not described in the Bakerdrill patent as being directed to the cutting face of the bit. On the contrary, once the high pressure air is discharged, the specification says, only, that it "flows into the bore hole … to sweep the cuttings produced on the bottom of the hole around the drill bit face …". The specification does not teach that air, either exhaust or high pressure, should be transmitted by a sleeve extending towards the drill bit in the manner required by the SDS patent, nor does the Bakerdrill have a flange which encircles at least a portion of the length of the drill bit to form a continuous shroud to assist in the downward passage of exhaust air to the cutting face of the drill bit as required by claims 2 and 8 of the SDS patent.
(d) The Bulroc (Weaver and Hurt) patent
98 This patent entitled "Closed Fluid Circulation in Down Hole Drill" became open to public inspection in Australia on 11 December 1986. The patent discloses a reverse circulation face sampling percussive hammer, the object of which is to provide a rock drill where clearing of the chippings and debris from the bottom of the hole can be substantially guaranteed, thereby overcoming difficulties in the prior art where airways feeding exhaust air to the cutting face become blocked. The consistory clause reads (page 3):
"According to the present invention, a rock drill comprises an outer wear tube, an inner centre tube, a drill bit mounted on the end of the centre tube, a reciprocal piston slidably mounted on the centre tube…the arrangement being such that the piston, at the end of its down-stroke, strikes the inner end of the drill bit, and there being porting means…to direct exhaust air to an annular passageway between the end of the wear tube and the drill bit and whereby air is exhausted in its entirety around the periphery of the drill bit to the bottom of the hole, from where it enters a central bore through the drill bit and is exhausted through the centre tube carrying with it all chippings and debris gathered in the bottom of the hole. While the annular passageway can be formed between the end of the wear tube and the drill bit, it is preferred to provide a short extension tube connected to the end of the wear tube, the annular passageway being formed between the extension tube and the drill bit.
…
An inevitable result of producing a bore is the creation of a narrow annular gap between the outer face of the wear tube and the wall of the hole, and up which exhaust air can pass. It is therefore usual to seal the upper end of the bore at the surface, but this can have the possibly harmful effect of a gradual build-up of pressure in the annular gap. It is therefore a further advantageous feature of the invention that seal means are provided between the outer wear tube and the hole wall to limit the length of the annular gap over which pressurisation can occur. Thus, a sealing ring may be secured to the wear tube of a material that combines the two required properties of reasonable flexibility and wear resistance, and which will therefore not impede the passage of the drill down the hole or its withdrawal." (emphasis added)
99 A drawing depicting an embodiment of the invention is attached to the specification. In describing that embodiment the specification reads:
"In the drawing, a down-the hole rock drill as (sic-has) an outer wear sleeve 1 secured at one end to a back head 2 and at the opposite end to a chuck 3…"
100 It is plain from the drawing and the description that the wear sleeve 1 referred to in the specification is the outer casing of the hammer, and is separate and distinct from both the back head 2 and the chuck 3 (i.e. the drive sub).
101 There is no description in the specification of the seal means which is said to be a further advantageous feature. Nor is there any description of its placement on the "wear tube", or of its dimensions. However, as it is described as "secured to the wear tube", I conclude that the sealing ring must be above the drive sub.
102 The description of the drawing also instructs that:
"The outer surface of the drill bit and the inner surface of the chuck are correspondingly splined as indicated at 12, the splines being so dimensioned as to provide a number of gas passageways 13 around the drill bit 10…Thus, for so long as pressure air is provided the piston is caused to reciprocate at high speed, with pressure air in the chambers 32 and 33 being alternatively exhausted through the passageways 13 around the exterior of the drill bit. Consequently, all of the exhausted air passes around the exterior of the drill bit and into the bottom of the hole being drilled from where it escapes through the angled passageway 31 in the bit and up through the centre of the drill…"
103 In the drawing the drill bit is depicted as having a pronounced shoulder, giving the head of the drill bit, to use the applicant's description, a square profile at the point of contact of the drive sub with the shoulder of the bit. This shoulder would deflect the downward flow of exhaust air towards the sides of the bore hole.
104 The respondents contend that the "short extension tube" referred to in the specification teaches a reader of the Bulroc patent of a transmission sleeve with all the features of the SDS patent. This view was supported by the evidence in chief of Messrs Stevens and Schwann who deposed to diagrams, prepared by Mr Joseph Purcell for the purposes of these proceedings, as representing their interpretation of the "extension tube" (see Exhibits RS45 and PS27 to their respective affidavits). These diagrams depict a length of tubing slid over the external circumference of the drive sub and affixed so that portion of the tube extends from the bottom of the drive sub towards the cutting face of the bit in a manner that encircles the portion of the bit below the square shoulder. The "short extension tube", so placed by these diagrams, is said to constitute a transmission sleeve with all the features of the SDS patent.
105 The effect of sliding a tube over the drive sub in this manner, is to create a flange with an outer diameter substantially the same as that of the drill bit. This is not a feature of the drawing accompanying the Bulroc specification. The extension tube in this position also gives it the appearance of being a sacrificial sleeve which would wear in use in preference to the drive sub and the outer housing of the hammer (i.e. the "wear tube"). The specification does not state that the short extension tube is intended to be a sacrificial component.
106 I found the evidence led by the respondents in support of their interpretation of the Bulroc patent depicted in these diagrams unconvincing. Doubts about their correctness were heightened when in cross examination it was revealed by Mr Stevens that in his attempts to understand the Bulroc patent he had created his own "independent" diagram which he had given to the respondents' solicitors. This diagram was not referred to in his witness statements. That diagram (Exhibit A9) showed the extension tube as being of equal diameter to the outer circumference of the drive sub, and extending from its lower edge.
107 The features and configuration of the "short extension tube" referred to in the Bulroc specification are not clearly described, nor is its location. Neither the diagrams deposed to by Messrs Stevens and Schwann, nor Mr Stevens own diagram depict an extension tube "connected to the end of the wear tube", that is, to the end of the outer casing of the hammer. On the contrary, they show an extension tube affixed to the drive sub, an interpretation which finds no support in the wording of the specification.
108 Moreover, the diagrams deposed to by Messrs Stevens and Schwann are not a fair representation of the Bulroc assembly as it appears in the drawing accompanying the specification. The diagrams give a different representation to the drive sub, they disregard or span the spanner flats depicted in the drawing, and they show a different configuration of the splines on the inside of the drive sub and on the shaft of the drill bit. The collection ports and grooves on the face of the bit are different, and, importantly, the grooves in the side of the bit are more sharply angled in the drawing accompanying the specification plan than in the diagrams. This last mentioned feature of the diagrams suggests that exhaust air would encounter less obstruction from the curves in the grooves in the side of the bit than would occur in the preferred embodiment of the Bulroc patent.
109 Mr McGoggin, whose evidence I accept on this topic as I do on others in preference to that of Messrs Stevens and Schwann, was not able to put any clear meaning or definition to the reference in the Bulroc specification to the "short extension tube". However, in cross examination he indicated how it would be possible to attach a short extension tube to the end of the wear tube in a manner that accorded with the teaching of the specification (see his drawing, Exhibit R5). In particular, a short extension tube in the position shown, would result in an annular passageway being formed between the extension tube and the drill bit in accordance with the description of the preferment of a short extension tube. The specification does not teach that air is exhausted through an annular passage formed between the drill bit and the drive sub. In my opinion the respondents' construction, which treats the annular passageway as being formed between the drive sub, or an extension to it, and the drill bit is incorrect.
110 The respondents say that Mr McGoggin's interpretation of the specification should be rejected, as an extension tube so positioned would perform no function. Mr McGoggin disagreed with this proposition, offering the opinion that it would serve to protect the bottom edge of the hammer housing (the "wear tube") from abrasion. This is not a function described in the specification but Mr McGoggin's evidence reflects the best interpretation which a skilled addressee reasonably and intelligibly could place on the otherwise vague and imprecise instruction offered by the specification.
111 In my opinion the Bulroc patent does not anticipate the SDS patent.
The Giehl patent - novelty
112 It is convenient now to deal with the eight prior patent specification publications relied on by the respondents as anticipating the Giehl patent.
(a) The 1987 Giehl patent
113 This patent became open to public inspection on 28 April 1988. It is entitled "Rotary‑Percussive Drill with Reversed Air Circulation" and relates to a drilling arrangement for rotary percussive drilling. Prior percussive hammers relied on normal circulation, and the specification describes important factors for drilling arising from reverse circulation. The invention uses air pressure to drive a hammer which is characterised by the fact that there are two air passages in the drill stem, and that it is a face sampling reverse circulation hammer:
"The air passageways being arranged with respect to the drill bit such that air at pressure is directed from above and outside of the drill bit so as to pass around the side of the drill bit and below and into an aperture passing upwardly through the body of the drill bit, whereafter connecting with one of the said two passageways extending to an above surface outlet.
A significant advantage of this arrangement is that the drill bit has then only to be designed to allow for air only to pass around its outer perimeter rather than to include both air and chips so that accordingly, any channels or scallop shape (sic) passageways that must be cut from the external side of the drill bit, can be significantly smaller than hitherto.
…
The invention can also be said to reside in the method of effecting percussion drilling which includes the steps of directing air such that it will pass from above and then around the outside of the drill bit and then pass across the bottom of the drill bit whereby to carry cut chips into an inner located upwardly extending conduit.
One of the significant further advantages of having air travel in the direction stated, is that the air can be caused to flow prior to collecting chips, across most of an external surface of the drill bit.
…
One problem that has been further discovered relates to maintaining that a majority of air directed into the location immediately above the drill head will indeed travel through the channels and across the drill bit face and into an outer conduit.
Conventionally, the drill bit is supported by a backing cylinder housing which has a diameter approximately equal to the diameter of the hole cut.
It has been found that, however, in some situations with the ground, particularly where the surface that is being cut is relatively soft, some bleed out from the housing at the outside of the drill stem will occur.
This is considered an advantage with soft material but if the cutting surface is hard, there is found to be more advantage in providing that with air being introduced into a channel, that the channel be only open downward towards the drill bit face and that the housing will provide a more effective seal against air loss up the side of the drill stem.
It is presumed nonetheless that such channels as would be provided, would open onto the bit face and in a preferred instance would have an axis which is parallel to the axes of other of the channels so that there might be four or five or more such channels around the peripheral side wall of the drill bit and support housing and further that these axes are parallel to the axis of the drill bit head.
According to a preferred arrangement then, there are provided distinct channels connecting the bottom of each channel extending up the side of the support housing, to an inlet conduit within the drill bit adapted to collect the cuttings."
114 The attached drawings illustrating the preferred embodiments depict a drill bit with a prominent square shoulder, or weight bearing surface, and with grooves positioned in the head of the bit such that air from the hammer exhausting through the drive sub would be substantially deflected by curves in channels as they pass around the shoulder of the bit.
115 The respondents contend that the 1987 Giehl patent discloses all the features of the Giehl patent. Although it is acknowledged that the language is different, they contend that there is nothing of substance new in the Giehl patent. The respondents argue that the only apparent difference between the assemblies of the two patents is the presence of a shroud on the head of the bit in the case of the Giehl patent, yet (contrary to an argument put in their defence to the infringement claim) they say there is nothing in the Giehl patent that makes it clear that the shroud must extend around the head of the bit rather than the shank. Through their witness Mr Stevens, the respondents argue that if the words "drill bit" in the Giehl patent include the shank, then a drive sub shrouding the shank (as in the 1987 Giehl patent) would fall within and therefore anticipate the claims of the Giehl patent.
116 It follows from what I have said above regarding the infringement of the Giehl patent, that I construe the words "drill bit" in the Giehl patent as meaning the whole drill bit component, and that the invention claimed does not require that the shroud extend around or cover part of the head of the bit. Nevertheless, I do not consider that the 1987 Giehl patent anticipates the Giehl patent.
117 The Giehl patent expressly refers to the 1987 Giehl patent application, and refers to problems with the hammer described in the 1987 Giehl patent in that it returns only about 70 per cent of chips to the surface. The 1987 patent does not describe or illustrate an "outermost cover acting as a shroud to direct the air directly at the periphery of the cutting face of the bit" as required by the Giehl patent, and the 1987 Giehl patent does not show a flange that extends towards the drill bit that directs air that is exhausted from the hammer in the manner described and claimed in the Giehl patent.
(b) The Samplex (Ennis) patent
118 The respondents particulars of prior publication plead two Samplex patents, the first being the publication of the Australian patent number 15048/88 which became open to public inspection on 27 October 1988, and the United States patent specification number 4765418 which became available for inspection in the Patent Office Library, Canberra, on 19 September 1988. The two specifications are in material respects identical, and there does not appear to have been any evidence adduced by the respondents directed specifically to the United States patent. It is convenient to deal with the two together as the Samplex patent.
119 The Samplex patent describes a "Valveless Down-the-Hole Hammer". The assembly disclosed in the patent is directed to a valveless hammer with a less complex piston design than those in the prior art. The object of the assembly is to provide a valveless type hammer drill in which damage to the piston is avoided by not having a complex piston design incorporating complicated port and or passage configurations formed in the hammer piston. The valveless hammer described comprises a body tube, a chuck mounted on the body tube with exhaust ports and three axially projecting dogs which fit into corresponding recesses in the exterior of the cutter bit so as to provide a driving connection between the body tube and the cutter bit which is retained within it. The hammer comprises an inner tube, surrounding a sample tube and an annular section piston with the ports controlling the airflow. Face sampling from the hammer is achieved by a sample tube and annular nozzle within the central passageway in the cutter bit to inject a portion of high pressure air upwardly into the lower end of the sample tube. In the operation of the hammer, high pressure air, which bypasses the hammer, is redirected upwardly into the sample tube by "an airflow reversing device". This arrangement, according to the specification, "ensures a strong upward flow of high pressure air into the sample tube which can entrain the chippings or other material and carry it away up the sample tube". This arrangement creates a venturi effect. The invention intends that a suction effect at the cutting face will entrain cuttings from the bit face and carry them into the sample tube and thence to the surface. The intended operation of the invention is more fully described in a brochure published in 1988 by Entech Industries Limited, a Northern Ireland company promoting the sale of the preferred embodiment of the invention of the Samplex patent.
120 The bit shank of the hammer does not have any splines to facilitate the rotation of the bit, as the rotational force is applied through the dogs projecting from the chuck (the drive sub).
121 The respondents contend that the projecting dogs form a shroud that directs exhaust air to the periphery of the cutting face of the drill bit, as is done in the Giehl patent.
122 I do not agree that the Samplex patent anticipates the Giehl patent. The Samplex patent is concerned with a valveless hammer that recovers chips from the cutting face by suction, whereas the invention disclosed in the Giehl patent does not rely to any extent on a suction effect. The projecting dogs of the Samplex hammer do not act as a continuous shroud which "extends around the side of the drill bit".
123 Exhaust air from the operation of the Samplex hammer passes through the inner portion of the chuck, or drive sub, and exhausts mainly at the lower end of the drive dogs. The respondents contend that the venturi effect cannot and is not expected to work on its own and is dependent on the exhaust air directed by the dogs to the cutting face. Whilst it is clear from the description of the invention that exhaust air passes between the drive dogs and the body of the bit, the specification does not describe that the passage of exhaust air past the drive dogs is designed to contribute to the flushing of chips produced at the bit face, nor does the specification teach that the dogs direct air to assist with the recovery of cuttings from the drill face.
(c) DTA compensating ring patent
124 This patent has already been discussed in relation to the allegation of want of novelty in the SDS patent. It did not become open to public inspection until seven days after the priority date of the Giehl patent which was 19 April 1990. The DTA compensating ring patent is therefore not available as an anticipation of the Giehl patent. In addition, the respondents' witnesses did not assert that the invention of the DTA compensating ring patent disclosed all the features of the Giehl patent. In particular, the compensating ring does not operate to constrain exhaust air or direct it to the periphery of the face of the bit, nor does the compensating ring locate or engage against, and extend around, the drill bit.
(d) The Lister patent
125 This patent became open to public inspection on 18 April 1990, the day before the Giehl patent. It is entitled "Improvements in Pneumatic Percussion Hammers". The patent describes a face sampling reverse circulation hammer. An important feature of the hammer is that exhaust air is directed by internal ducts within the drill bit itself to flutes in the side of the drill bit, where it is released into the bore hole significantly below the drive sub. The exhaust air is then intended to flow through the flutes or channels in the face of the bit into and up the central bore of the hammer.
126 The respondents, through Mr Schwann, sought to support the pleading that the Lister patent anticipated the Giehl patent, and has the features of the invention of the Giehl patent. Mr Schwann gave evidence about the introduction in the late 1980's of the Halco-Lister hammer, which appears to be the commercial embodiment of the Lister patent. Mr Schwann noted that the features of the Halco-Lister hammer include an "oversized" drive sub, the outside diameter of which is greater than that of the hammer casing and nearly the same as the outside diameter of the drill bit itself, that air is directed through passageways in the drill bit towards the cutting face of the drill bit, and that air also passes between the drive sub and the drill bit towards the cutting face of the bit. In his evidence, however, Mr Schwann acknowledged that this airflow was for lubrication purposes. Mr Schwann's evidence seems not clearly based upon the specification itself, but rather to be based partly on promotional leaflets published in connection with the Halco-Lister hammer.
127 Again, I do not think that the Lister patent anticipates the Giehl patent. There is no disclosure in the Lister patent of "an outermost cover acting as a shroud to direct air to the periphery of the cutting face of the bit". Whilst the Lister drive sub is connected to the outer casing of the hammer, there is no space between the drive sub and the drill bit to direct any relevant airflow to the face of the bit. There is no skirt or shroud to form channels to direct the air to the face of the bit. Rather, the flow of air exhausted from the hammer is transmitted to the face of the bit through oblique air ducts and flutes in the body of the drill bit itself, and, as already mentioned, the air exhausts below the drive sub.
(e) The Klemm (Hydroc) patent
128 This patent became open to public inspection in Australia in about May 1982. The invention describes an "Annular Drilling Hammer". The patent is relied upon by the respondents primarily in support of its plea of obviousness in the case of the SDS patent, but it is also pleaded as an anticipation of the Giehl patent. The Klemm patent discloses a reverse circulation face sampling hammer. The hammer includes an annular bore crown (drill bit) with flow channels leading from the rear shoulder through to both the cutting face and to the central aperture in the bore crown. Air exhausted from the hammer flows through these channels and aids the entrapment of bored material (cuttings) which are then carried out through the inner tube with the aid of a venturi opening. The clearing mechanism disclosed in the patent depends primarily upon the venturi effect created by the flow of exhaust air through the channels leading into the central aperture of the bore crown. The specification describes longitudinal grooves or splines within the drive sub through which exhaust air flows. The lower end of the drive sub is:
"…conically enlarged and in this region the driving medium (exhaust air) flows against the bore crown… To ensure that as high a percentage as possible of working fluid flows back through the inside of the annular bore crown…rather than through the gap between the outer tube (drive sub) … and the bore hole wall, a set of bore holes 65 and 66 are provided in the bore crown. … The bores 65 extend from the rear shoulder of the bore crown to the front end, whilst the bores 66 lead directly from the rear shoulder to the interior of the bore crown.
A part of the working fluid is conducted directly through the bores 65 and 66 into the interior of the bore crown…and thence to the inner tube. This direct flow creates a suction at the bore crown by which the working fluid which leaks out laterally between the outer tube (drive sub) … and the bore crown…is entrained and urged into the inside of the bore crown…"
129 It is apparent from this description that in the intended working of the invention a high percentage of the exhaust air will flow through the flow channels, or bores 65 and 66, and that only a low percentage of exhaust air will "leak out laterally" between the conically enlarged end of the drive sub and the outer surface of the drill bit.
130 The respondents assert that the Klemm patent discloses an outermost cover acting as a shroud, namely, the conically enlarged drive sub. Mr Stevens expressed the opinion in his evidence in chief that the Klemm patent discloses all the features of the invention claimed in the Giehl patent. It appeared in his cross examination that this opinion was based on the assumption that most of the exhaust air would pass through an annular space between the conically enlarged end of the drive sub and the drill bit. This assumption is inconsistent with the teaching of the patent. Both Mr Stevens and Mr Schwann based their evidence on the assumption that there are "scallops" which convey airflow across the back of the bit and towards the periphery of the hole. This interpretation of the specification is not supported by the description in the body of the specification, or by the drawings (which do not show a cross section or representation at any point above the bit face).
131 In my opinion, the Klemm patent does not disclose a cover acting as a shroud in the manner of the invention of the Giehl patent. The mechanism for clearing cuttings from the bottom of the hole is by a suction effect. Whilst the specification of the Klemm patent describes a conically enlarged drive sub acting to constrain and direct air, it is directing air not through conduits external to the periphery of the bit for passage across the face of the bit into the inner tube, but through the internal flow channels in the drill bit described as the bores 65 and 66.
132 In my opinion the Klemm patent does not anticipate the Giehl patent.
(f) The Bakerdrill patent
133 This patent has already been discussed in relation to the SDS patent. It is pleaded that the Bakerdrill patent discloses an assembly that has all the features of the Giehl patent, but this allegation does not appear to have been taken up by the witnesses called for the respondents, or by the respondents in final submissions. The Bakerdrill patent does not have all the features of the Giehl patent. In particular, it does not have an outermost cover acting as a shroud, to direct exhaust air.
(g) The Bulroc (Weaver and Hurt) patent
134 This patent has also been discussed in relation to the SDS patent, and the respondents' assertions in relation to the Bulroc patent, as against the novelty of the Giehl patent, are essentially the same as those made against the SDS patent. It is contended that the short extension tube described in the Bulroc patent performs precisely the same function as the shroud referred to in the Giehl patent. Again, this submission depends upon the interpretation of the Bulroc patent represented in the diagrams deposed to by Messrs Stevens and Schwann as Exhibits RS45 and PS27 respectively. I have rejected that interpretation. In my opinion the Bulroc patent does not disclose an "extension tube" which acts as an outermost cover acting as a shroud to direct air to the periphery of the cutting face of the bit, nor does it disclose a skirt or a shroud to form channels to direct air to the face of the bit as in the invention of the Giehl patent.
(h) The Minroc patent
135 This patent became open to public inspection in Australia in approximately April or May 1989. The patent claims a reverse circulation down-the-hole face sampling hammer drill apparatus. In final submissions counsel for the respondents indicated that this patent was no longer relied on as an anticipation of the Giehl patent, and whilst it lay "at the edge of the respondents' case" it was said to be relevant in showing the general common knowledge in the relevant field of expertise at the priority dates of the patents in suit.
136 Within the drill bit of the Minroc patent there are exhaust air ducts leading from an expansion chamber into which exhaust air from the hammer flows. The ducts through the body of the bit emerge on the cutting face near its periphery. There are also angled passageways in the bit face which act as collection ducts. The stem (or shank) of the bit also has venturi orifices leading to the central bore of the bit.
137 The Minroc patent does not anticipate the Giehl patent. It does not disclose an outermost cover acting as a shroud to engage against and extend around the outer side of the drill to form conduits. Such a feature would be pointless as the exhaust air in the Minroc patent flows to the periphery of the cutting face through the air ducts situated within the body of the drill bit.
Novelty - prior uses
138 Against both the SDS patent and the Giehl patent a number of prior uses are alleged. In many instances the allegations of prior use are common to both patents. It is convenient first to deal with those which are not common.
(a) SDS patent - use of DTA patent compensating rings
139 There is evidence that prior to April 1990 about forty compensating rings were sold and thereafter presumably used in the field. However, it follows from the conclusion that the DTA patent did not anticipate the SDS patent, that the use of articles in the form of the preferred embodiment of the patent did not constitute prior use.
(b) Giehl patent - use of the Halco-Lister hammer
140 There is scant evidence about the use in Australia of any Halco-Lister reverse circulation face sampling percussive hammers prior to April 1990. The manufacturer in Australia of Halco-Lister hammers, Mr Bourne, gave evidence for the respondents. He said that some twelve to eighteen hammers were made in Australia prior to April 1990, which were exported to the United Kingdom. In cross examination, he said that the hammers were manufactured in accordance with the Lister patent. It appears that other hammers known as Halco-Lister hammers may have been imported into Australia, as there is evidence from Mr Cocking that he saw one at some stage in Kalgoorlie, and Mr McElroy was aware of brochures promoting such a hammer in Australia. Mr Schwann identified a brochure published by the Halifax Tool Co of England for a Halco-Lister hammer and an article in a mining journal "World Mining Equipment", April 1990, relating to reverse circulation sampling systems promoted by Halco-Lister, which incorporated a hammer. It seems these documents came into Mr Schwann's possession well after April 1990. The evidence falls short of establishing that Halco-Lister hammers imported into Australia were used in Australia before April 1990. Moreover, there is no suggestion in the evidence of Mr Cocking, or in the brochures, that the Halco-Lister hammer referred to departed in any material respect from the preferred embodiment of the Lister hammer described in the Lister patent.
141 It follows from the description of the Lister patent already given, that it operated in an entirely different manner to the invention of the Giehl patent, and that the use of a commercial embodiment of the invention of the Lister patent did not anticipate the Giehl patent.
(c) Giehl patent - use, publication and sales of the Samplex hammer
142 The evidence shows that there was minimal use of Samplex reverse circulation face sampling percussive hammers in Australia prior to April 1990. In November 1989 the second respondent entered into negotiations with Entech Industries Limited of Northern Ireland with a view to securing Australian distribution rights for the Samplex product. Two Samplex hammers were imported into Australia by the second respondent from Entech for trial purposes, arriving in about December 1989. The hammers were of the Samplex 501 model, the precise configuration of which is not disclosed in the evidence. Trials of the hammers were conducted by Davies Drilling and Drillcorp in Western Australia, and by Kelly Drilling in Queensland. The testing was completed in about February 1990, and in May 1990, orders for the commercial supply of these hammers were placed by the second respondent with Entech. With the delivery of the two hammers imported for trial purposes in December 1989, a number of brochures relating to the hammers were received by the second respondent. Although use of the Samplex hammers in Australia prior to April 1990 was for trial purposes only, it is not suggested that the trials were in any sense secret. It is not suggested that the Samplex hammers differed in any material respect from the preferred embodiment described in the Samplex patent. It follows from my conclusion that the Samplex patent did not anticipate the Giehl patent, that the use of the commercial embodiment of the Samplex patent also did not do so.
(d) Giehl patent - use of the Bakerdrill hammer
143 By late amendment to the Particulars of Objection filed by the respondents a prior use of the Bakerdrill hammer is alleged to anticipate the Giehl patent. This amendment was made following evidence from Mr George Bourne (Snr), given in the course of the trial that he had seen an experimental Bakerdrill hammer in Brisbane (of unknown operation and unknown configuration) on dates unknown (but probably in the late 1980's). Mr Bourne's evidence does not establish that the experimental Bakerdrill hammer observed by him was a reverse circulation face sampling hammer, being a commercial embodiment of the Bakerdrill patent. However, even accepting that it was, it follows from the finding that the Bakerdrill patent did not anticipate the Giehl patent, that the use of a commercial embodiment of the Bakerdrill patent would not do so.
(e) Both patents in suit - sale by Mincon Limited and use by Pontil Pty Ltd of a wear sleeve.
144 The respondents led evidence that a wear sleeve for use on the drive sub of a reverse circulation hammer, as described in the preferred embodiment of the Mincon patent, was sold by Mincon Limited and used by Pontil Pty Ltd in about February 1990. As I understand the final submissions of the respondent, this prior use is no longer relied upon. In any event, the features of the wear sleeve were similar to the DTA compensating ring patent, and it did not contain features which anticipated the invention of the SDS patent or the Giehl patent.
(f) Both patents in suit - prior use of tri-cone bits
145 The widespread use of tri-cone bits fitted with shrouds or skirts in rotary reverse cycle drilling is pleaded as an anticipatory use of the invention of both the patents in suit. As I understood the final submissions of the respondents, the respondents now rely on this use primarily as evidence showing the obviousness of the inventions of the patents in suit, rather than as an anticipatory use. Nevertheless, the pleadings require that the alleged anticipatory use be considered. In paras 12 and 13 of these reasons, a brief description is given of the process of rotary drilling with tri-cone bits. When coaxial drilling rods became available, it became common practice to place a shroud between the end of the drill string and the tri-cone bits. The process of drilling and the recovery of cuttings in the rotary drilling systems is fundamentally different to that employed in a reverse circulation percussive hammer which incorporates a face sampling drill bit. In reverse circulation rotary drilling, high pressure or supply air is delivered down the external annulus of the dual wall drill string with the sole function of entraining cuttings and carrying them to the surface. There is no hammer in the system and no reciprocating piston driven by the supply air. By contrast, the exhaust air has already worked the piston with reverse circulation percussive hammers.
146 Whilst evidence was given by the manufacturers of tri-cone bits about the probable directions of airflows within the bottom of the hole in the drilling process, there was no scientific evidence put forward to support any of the theories advanced. The evidence, however, reveals that the cuttings produced by the rotating tri-cone bits were cleared in consequence of high pressure air entering through restricted ports the cavity at the bottom of the hole in which the tri-cone bits operated, such ports acting as jets or nozzles to increase the velocity of the air released directly above the part of the bottom of the hole just cut by each rotating cone. Thus the air was expelled with force directly at the cuttings on the bottom of the hole without intermediate obstruction from the working part of a drill bit. In contrast, in a reverse circulation percussive hammer incorporating a face sampling drill bit, the bottom of the hole being drilled is always covered by the bit which necessarily impedes the collection of the cuttings. The shroud commonly used in reverse circulation tri-cone bit assemblies was an extension and continuation of the drill string fitted to better confine the high pressure air to ensure that it was vented through jets directed to the bottom of the hole, and between the rotating tri-cones. As I understand the evidence, the shroud also served a sealing function. However, as the nature of the reverse circulation tri-cone drilling process is fundamentally different to that involved in a reverse circulation percussive hammer incorporating a face sampling bit, I agree with counsel for the applicant that there is no relevant comparison at all to be made between the two drilling assemblies. I do not consider that the use of shrouds with reverse circulation tri-cone bits anticipates either of the patents in suit. Moreover, the dissimilarity of the nature of the two drilling processes means that the shroud on a tri-cone assembly is not relevantly sacrificial and is not intended to and does not wear at a similar rate to the drill bit.
(f) Both patents in suit - use of the Bulroc patent
147 Mr Schwann described the demonstration of a Bulroc hammer he witnessed in 1988. He said that it was fitted with a bit which had a similar configuration to the drawing appended to the Bulroc patent, and was not like the bit shown in the brochure. Insofar as the design followed the drawing of the patent, it did not anticipate the inventions of the patents in suit, for the reasons already given: see par 98-111, 134.
148 There is also evidence of the sale and use of a Bulroc reverse circulation hammer in Australia during the late 1980's which was of a slightly different design to that disclosed in the drawing appended to the Bulroc patent. The finding that the Bulroc patent did not anticipate the inventions of the patents in suit, therefore, does not necessarily dispose of the respondents' plea that the use and sale of Bulroc hammers before the relevant priority dates constituted anticipatory uses of the invention.
149 The design of the commercial production of the Bulroc hammers sold and used in Australia is depicted in a brochure tendered through the evidence of Mr Stevens, Exhibit RS26. The hammer did not incorporate a "short extension tube" and in this respect did not differ materially from the drawing of the Bulroc patent. Whilst the head of the bit as depicted in the brochure is of a slightly different configuration to that shown in the drawing appended to the patent, the passage of exhaust air through the internal mechanism of the hammer and the sub assembly is apparently the same. The exhaust air flows generally through the interlocking splines on the drill bit and the inner surface of the drive sub, and is expelled at the shoulder of the head of the bit. The air is exhausted much further from the face of the bit than is taught by the specifications of the patents in suit, a fact further illustrated by the drill bit and drive sub of a Bulroc hammer, which are Exhibit R9. The design philosophy of the Bulroc hammer appears to accept the then current belief that the outer housing of the hammer would act as a sufficient seal thereby causing exhaust air to travel to the bottom of the hole and across the face of the bit to the inlet ports on the face of the bit. To use Mr McGoggin's expression, it was generally understood in the drilling industry at that time that air could be "delivered" to the face of the bit in this way, but air so delivered did not sufficiently entrain the cuttings being produced by the hammer.
150 In my opinion, for present purposes, the Bulroc hammer depicted in the brochure does not materially differ from the preferred embodiment of the invention described in the Bulroc patent, and the sale and use of the Bulroc hammer did not anticipate the inventions in either of the patents in suit.