Full opinion text
MEMORANDUM AND ORDER LUNGSTRUM, District Judge. This patent case was tried to the court in Kansas City, Kansas over twelve days from September 29, 1998 to October 15, 1998. Plaintiffs Hay & Forage Industries, Case Corporation, HFI Holdings, Inc., AGCO Corporation, and Hesston Ventures Corporation sued defendant New Holland North America, Inc. for infringement of United States Patent No. 5,272,859 (“ ’859 patent”), which is owned by plaintiff Hay & Forage Industries. Plaintiffs allege that certain hay harvesting machines sold in the United States by the defendant infringe the ’859 patent. The court held a Markman hearing on the matter on June 1, 1998, and subsequently issued an order construing certain disputed claims of the ’859 patent. Hay & Forage Indus. v. New Holland North America, Inc., 25 F.Supp.2d 1170 (D.Kan.1998), (“Hay & Forage I ”). Later, the court concluded on summary judgment that the defendant’s accused machine literally infringes claims 1, 2, 8, and 9 of the ’859 patent. The parties tried to the court the issues of infringement of claims 10 and 11 under the doctrine of equivalents and invalidity of the patent for anticipation, derivation, omission of a coinventor, and obviousness. The court ultimately concludes that judgment must be for the defendant. First, the court concludes that the defendant’s machine does not infringe claims 10 and 11 under the doctrine of equivalents. Next, the court concludes that the ’859 patent is not invalid pursuant to defendant’s anticipation, derivation, or omission of a coinventor theories. Finally, the court concludes that claims 1, 2, 8, and 9 of the patent are invalid because they would have been obvious to a person of ordinary skill in the art. Claims 10 and 11 are not invalid for obviousness. The following findings of fact and conclusions of law are made pursuant to Fed. R.Civ.P. 52(a). TABLE OF CONTENTS I. Background. .1104 A. The Parties. .1104 1. Plaintiffs.'. .1104 2.Defendant. .1104 B. General Characteristics of Mower Conditioners. .1104 C. The’859 Patent .. .1105 D. The Accused Machine. .1107 E. Development Work by Marc Berlivet in Coex, France .1108 1. PT-8D. .1108 2. X56-1 . .1109 3. X56-2. .1109 4. X56-3 . .1109 5. Alleged Mockups in Winter 1976-77 . .1109 6. X56-4 . .1109 7. X56-5 1110 F. Prior Art 1. Niemeyer 1570.•.1110 2. ’418 Patent.1110 3. Australian Patent.1111 4. New Holland 601-611 Forage Harvesters .1111 5. Dickensheid Patent.1112 6. Eberly Patents .1112 7. Dutch Patent.1112 8. Deere Patents.1112 9. Kuhn Patent.1113 10. Other Patents.1113 G. Defendant’s Design Efforts.1113 1. Creation of the 1431.1113 2. Ken McLean .1114 II.Infringement of Claims 10 and 11.1114 A. Legal Framework.1114 B. Analysis.1115 1. Inclusion of Bracket and Slide Plates in 1431 Steering Structure .1115 2. Claim 10 and the All Elements Rule.1116 a. Pivotal Connection with the Tongue at a Point.1116 b. Approximately Equidistant.1116 c. Telescoping Linkage.1118 3. Claim 11.1118 IV. Invalidity Generally.1119 V. Invalidity Pursuant to 35 U.S.C. § 102(b) .1119 A. Legal Framework.1119 B. Analysis: Claim 1.1120 1. Horizontally Spaced Pivot Axes.1120 2. Steering Structure.1121 3. Header Supported by the Frame.1123 D. Analysis: Claims 2, 8, and 9.1124 VI. Invalidity Pursuant to 35 U.S.C. § 102(f); Related Theories.’..1125 A. Legal Framework.1125 1. Derivation.1125 2. Coinventorship .1126 B. Analysis.1126 1. Prior Complete Conception.1126 a. Lack of Contemporaneous Documents or Photographs.1127 b. Unclear Memories.1128 c. Rule of Reason.1128 2. Contribution to Conception.1130 VII. Invalidity Pursuant to 35 U.S.C. § 103 1131 A. Legal Framework .1131 B. Claims 10 and 11 Not Invalid for Obviousness.1132 1. Scope and Content of Prior Art.1132 2. Level of Ordinary Skill in the Art.1133 3. Differences Between the Claimed Invention and the Prior Art.1133 4. Objective Considerations.1135 a. Praise in the Industry.1135 b. Commercial Success .1135 c. Long-felt Need.1136 d. Synergy.1136 e. Independent Development.1136 5. Summary.1137 C. Claims 1, 2, 8, and 9 Invalid for Obviousness .1137 1. Scope and Content of Prior Art.1137 2. Level of Ordinary Skill in the Art.1137 3. Differences Between the Claimed Invention and the Prior Art.1137 4. Objective Considerations.1142 a. Independent Development.1142 b. Copying; Praise in the Industry.1142 c. Commercial Success.1143 d. Long-felt Need.1143 5. Summary.1144 VIII. Conclusion...1144 I. Background A. The Parties 1. Plaintiffs The parties plaintiff in this lawsuit are generically controlled by two entities: plaintiff Case Corporation (“Case”) and plaintiff AGCO Corporation (“AGCO”). Case is a Delaware Corporation and has its principal place of business in Racine, Wisconsin. AGCO is a Delaware corporation and has its principal place of business in Duluth, Georgia. Plaintiff Hay & Forage Industries (“HFI”) is a Kansas general partnership and has its principal office in Hesston, Kansas. HFI consists solely of two partners: plaintiff HFI Holdings, Inc., which is a wholly owned subsidiary of Case, and plaintiff Hesston Ventures Corporation, which is a wholly owned subsidiary of AGCO. HFI is an engineering center and a factory that designs and manufactures “hay tools” for Case and AGCO, such as square balers, round balers, pull-type mower conditioners, and self propelled windrowers. Case markets these products under the “Case IH” brand name, and AGCO markets them under the “Hesston” brand name. Except for labeling and paint color, the products HFI manufactures for Case and AGCO are identical. 2. Defendant Defendant New Holland North America, Inc. (“New Holland”) is a Delaware corporation and has its principal place of business in New Holland, Pennsylvania. New Holland engineers and manufactures a full line of farm equipment: large four-wheel drive articulated tractors, compact tractors, combines, round balers, square balers, skid steer loaders, seeding equipment, grape harvesters, and others. Most importantly for purposes of this lawsuit, New Holland also manufactures a full line of hay handling equipment, including pull-type mower conditioners. The engineering work for New Holland’s product line is done all over the world. B. General Characteristics of Mower Conditioners The ’859 patent generally describes a “mechanical drive center pivot mower conditioner.” When a hay crop is ready to be harvested, the field must be cut or “mowed” to sever the standing crop materials from the ground. Mowing is typically done with either disc or sickle bar cutters. Disc cutters use rapid rotary motion, similar to a lawnmower, to sever the crop. Sickle bar mowers use back and forth motion, similar to a series of large scissors, to sever the crop. As crop is mowed, it is deposited back onto the ground in a “windrow” or “swath” to dry down the materials to a certain moisture level before baling them into a compressed package by other machines such as round or square balers. To speed up drying, it is conventional to “condition” the cut crop before it is deposited back on the ground. Conditioning is usually carried out by passing the materials between a pair of conditioning rollers that crimp and abrade the crop stems to remove a waxy substance and facilitate the escape of moisture. Pull-type machines that both mow and condition the crop are typically referred to in the industry as “mower conditioners,” while self-propelled machines are more commonly known as “windrowers,” although these terms are frequently used interchangeably by those skilled in the art. Mower conditioners are designed to operate with their harvesting headers off to one side of the pulling tractor rather than directly behind the tractor. This allows the tractor to travel on previously mowed ground while the header is pulled through the standing crop. A “side pull” mower conditioner is designed to operate only on one side of the pulling tractor. Thus, a farmer using a side pull machine is not able to cut swaths going back and forth in a field without running over standing crop with the tractor. A “center pivot” mower conditioner is designed to operate on either side of the pulling tractor. A farmer using a center pivot mower conditioner is able to mow a swath in one direction and then turn the tractor around, position the mower conditioner on the other side of the tractor, and mow back in the direction opposite of the original swath without drivT ing the tractor over uncut crop. Center pivot mower conditioners have the added benefit of greater maneuverability around obstacles in the field. Driving power for a mover conditioner’s cutting components is typically supplied in one of two ways. Hydraulic power is sometimes used, although hydraulic power can be complicated and requires extensive maintenance. The machine disclosed in the ’859 patent and the defendant’s accused machine both use a mechanical drive system. In these machines, mechanical power is supplied to the mower conditioner via a rotating drive line attached to the power take off mechanism, or PTO, of the pulling tractor. Mechanical drive systems generally require far less maintenance and are far less complicated than hydraulic systems. C. The ’859 Patent The ’859 patent issued on December 28, 1993, naming Martin E. Pruitt, Cecil L. Case, and H. Keith Garrison as inventors. The application had been filed on April 14, 1992. The inventors subsequently assigned the patent to HFI. Claim limitations central to the dispute between the parties include the “steering structure” clause of claim 1, the limitation in claim 1 requiring that the junction (gear) box pivot axis be “spaced horizontally” from the tongue pivot axis, and the entirety of claim 10. As explained in detail below, the court construed all of these limitations except the “spaced horizontally” limitation in connection with the Mark-man proceeding in Hay & Forage 1 Also playing a role in the dispute, albeit minor, is claim 11. Claim 1 of the ’859 patent is as follows: [We claim,] [i]n a pull-type crop harvesting machine, the improvement comprising: a mobile frame; a pull-tongue pivotally coupled with the frame for horizontal adjusting movement about a first upright axis between a number of angular positions relative to the path of travel of the machine for varying the lateral position of the machine relative to a towing vehicle; a harvesting header supported by the frame in a position for performing harvesting operations on a crop as the machine is towed across a field, said header having drivable operating components associated therewith; a mechanical drive line extending along and rotatably supported by the tongue for supplying driving power to said operating components in said angular positions of the tongue; a junction box on the header having an input shaft and an output shaft rotatably supported by the box and operably intercoupled in fixed angular relation to one another within the box, said input shaft being operably connected with said drive line for receiving driving power therefrom and said output shaft being oper-ably connected to said operating components for driving the same, said box being pivotally mounted on the header for swinging movement about a second upright axis spaced horizontally from the first axis; and steering structure connected between the junction box and the tongue for causing the junction box to swing responsively when the latter is pivoted about said first axis between its various angular positions. Claim 10 of the ’859 patent is as follows: In a pull type harvesting machine as claimed in [claims 1, 8, and 9], said steering structure including telescoping linkage having a front pivotal connection with the tongue at a point which is at least approximately equidistant from said opposite ends of the telescopic section. Claim 11 of the ’859 patent is as follows: In a pull type harvesting machine as claimed in [claims 1, 8, 9, and 10], said telescoping linkage having a rear connection with the junction box tht [sic] includes horizontal pivot means for up-and-down swinging of the linkage relative to the junction box. In the prior Markman proceeding, the court construed the steering structure clause of claim 1 and the entirety of claim 10. See Hay & Forage I, 25 F.Supp.2d at 1176, 1179-80. The court construed the “steering structure” clause of claim 1 to mean “a steering structure separate from the drive line that operatively interacts with the tongue at one end and operatively interacts with the junction box at the other end and that transmits the swinging motion of the tongue to the junction box during swinging of the tongue.” Id. at 1176. The court construed the “telescoping linkage” element of claim 10 to require a linkage having “overlapping sections, as if in overlapping cylindrical sections.” Id. at 1179. The court construed the “front pivotal connection with the tongue at a point” element of claim 10 to require that the steering structure be “connected to the tongue at a spot which allows for pivotal movement.” Id. at 1180. The court construed the “at least approximately equidistant” element of claim 10 to require a placement of the front pivotal connection “at least reasonably close to” the exact point on the tongue that is equidistant from the opposite ends of the telescoping drive line. Id. at 1180. The following diagram, taken directly from the first page of the ’859 patent, shows the preferred embodiment, but by no means the only conceivable embodiment, of the pertinent elements described in claims 1 and 10: [T]he steering structure 138 comprises a tubular, telescoping linkage consisting of an inner section 140 and a concentrically disposed outer section 142. The inner tube 140 has at its forward end a ball and socket swivel connection 144 with a bracket 146 on the underside of the tongue 30. The opposite end of the inner tube 140 is slidingly received within the outer tube 142.... ’859 patent, col. 6, lines 17-24. D. The Accused Machine New Holland entered the market with the New Holland Model 1431 mower conditioner (“1431”) in the Fall of 1996, just under three years after the ’859 patent issued and approximately three and a half years after the plaintiffs introduced their commercial embodiments of the ’859 patent. The 1431 is similar in many respects to the machine described in the ’859 patent. It is a mechanical drive center pivot disc mower conditioner. Like the device described in the ’859 patent, the 1431 has a steering structure interposed between the junction box and the tongue for causing the junction box to swing responsively about an axis that is horizontally spaced from the tongue pivot axis. Plaintiffs sought summary judgment that the 1431 literally infringes claims 1, 2, 8, and 9 of the ’859 patent, and the court granted the plaintiffs’ motion. Hay & Forage III, 25 F.Supp.2d at 1196. Accordingly, the 1431 has all the features disclosed in claims 1, 2, 8, and 9 of the ’859 patent. The parties agree, however, that under the court’s Markman construction the 1431 does not literally infringe claims 10 and 11 of the '859 patent because the steering structure of the 1431 is constructed somewhat differently than the steering structure described in claims 10 and 11 and in the specification of the ’859 patent. Instead of a telescoping linkage having a stationary front pivotal connection with the tongue, the 1431 steering structure has a fixed length arm connected to a slide plate housed in a U-shaped bracket attached to the underside of the tongue which allows the pivotal connection to slide relative to the tongue. Instead of having the pivotal connection at a spot very nearly equidistant between the opposite ends of the telescopic section of the drive line, the 1431 steering structure has a pivotal connection that slides within a range that is more to one side of the telescopic section. The following diagram depicts what the court has determined to be some of the parts that constitute the steering structure of the 1431, including the slide plate, the pivotal connection, and the fixed length arm. Also associated with the steering structure, although not depicted above, is the bracket attached to the underside of the tongue and the opposing slide plate guides housed in the bracket in which the slide plate slides relative to the tongue. The slide plate guides effectively form a channel in which the slide plate may slide along the underside of the tongue where the bracket is attached. E. Development Work by Marc Berli-vet in Coex, France Mr. Marc Berlivet, a French citizen, studied engineering in France and then went to work for a company in Coex, France known as Rochland S.A. in the early 1970s. Rochland S.A. manufactured and sold agricultural equipment. In the mid-1970s, Hesston Corporation (“Hesston USA”) acquired Rochland S.A. and renamed it Hesston, S.A. The Hesston, S.A. facility in Coex included an engineering department, a prototype shop, and a field test department. In effect, Mr. Berlivet worked for the plaintiffs in this lawsuit during the mid- to late-1970s. Through a series of transactions, he now, in effect, works for the defendant. Defendant claims the ’859 patent is invalid because the named inventors either derived their work from Mr. Berlivet or improperly omitted Mr. Berlivet as a coinventor. 1. PT-8D In 1975, Mr. Berlivet started engineering and development work in Coex on a pull-type, mechanically driven, center pivot tongue, rotary mower conditioner that became identified as the X56 project. The prototype that essentially began the X56 project was referred to as the PT-8D. The PT-8D machine had some of the features of the ’859 patent, but, importantly, did not have horizontally spaced tongue and gearbox pivot axes, did not have (or require) a separate steering structure, and did not have a gearbox mounted on a header. The gearbox on the PT-8D was pivotal, but it was mounted inside the tongue such that the gearbox and tongue pivot axes were aligned. The parties produced numerous contemporaneous documents, including photographs, showing the pertinent features of the PT-8D. 2. X56-1 The X56-1 was the first prototype formally built under the X56 program. Contrary to the PT-8D machine, the X56-1 machine did not have a gearbox drive. Instead, the X56-1 machine included a belt and sheave drive located at the rear of the center pivot tongue and connected to a drive line that extended through the tongue. The X56-1 had some features of the ’859 patent, but lacked at least a gearbox mounted on a header and steering structure connected between the junction box and the tongue. The X56-1 experienced drive line problems in field testing associated with U-joints. The parties have produced numerous contemporaneous documents, including photographs, showing the pertinent features of the X56-1. 3. X56-2 The X56-2 machine, also part of the X56 project, originally had the same belt and sheave drive located at the rear of the tongue as the X56-1 machine. As soon as Hesston, S.A. experienced drive line problems during field testing of the X56-1 machine, Mr. Berlivet directed the modification of the X56-2 machine. As modified, the X56-2 machine included a drive line supported underneath the tongue. The drive line was attached through a constant velocity joint to a- large belt and sheave assembly located in front of the tongue axis. The X56-2 machine, however, continued to use the belt and sheave drive system and not a gearbox drive system on the header. In field testing, the X56-2 experienced significant drive line problems associated with failed U-joints. The parties have produced numerous contemporaneous documents, including photographs, showing the pertinent features of the X56-2. 4. X56-3 The Coex facility developed the X56-3 prototype in late 1976. It also had a belt and sheave design. The drive assembly of the X56-3 machine was similar to the drive assembly of the X56-2 machine, except that the large belt and sheave assembly was moved rearwardly relative to its placement in the X56-2 machine in an attempt to reduce the drive line angles. The X56-3 performed better than its predecessors, but still experienced drive line problems. The parties have produced numerous contemporaneous documents, including photographs, showing the pertinent features of the X56-3. 5.Alleged Mockups in Winter 1976-77 Mr. Berlivet testified that in late 1976 or early 1977, between the fabrication of the X56-3 machine and the X56-4 machine, he directed the preparation of three experimental mockups using the X56-2 machine as a “mule.” According to Mr. Berlivet, each of these mockups involved the use of a pivoting central gearbox located on the header and a means to steer or pivot the gearbox in response to swinging movement of the tongue. There are no contemporaneous documents or photographs that show the pertinent features of these mockups. The court will discuss the alleged mockups in greater detail in connection with its findings and analysis on the derivation and coinventorship issues. 6.X56^4 Unlike the X56-1, -2, and -3 machines, the X56-4 machine had a stationary (non-pivoting) gearbox affixed to the header. The drive line of the X56-4 machine included a telescopic section connected between the fixed gearbox and the primary shaft supported underneath the tongue. A double yoke support assembly mounted to the underside of the tongue and a second double yoke support assembly mounted to the header in front of the fixed gearbox cooperatively supported the telescopic portion and accommodated drive line angles between the primary shaft and the fixed gearbox. The X56At did not include a junction box pivotally mounted on the header for swinging movement about an axis horizontally spaced from the tongue pivot axis. It also did not include steering structure. The parties have produced numerous contemporaneous documents, in-eluding photographs, showing the pertinent features of the X56-4. 7. X56-5 Mr. Berlivet testified that he directed the preparation of the X56-5 machine around the same time the X56-4 machine was being produced. Around the same time, however, Hesston USA and Hesston S.A. decided to move away from the center pivot concept and focus on developing a side pull mower conditioner. According to the testimony of Mr. Berlivet concerning the X56-5, the X56-5 had every limitation of claim 1 of the ’859 patent. There are no contemporaneous documents or photographs that show the pertinent features of the X56-5. The court will discuss the X56-5 in greater detail in connection with its findings and analysis on the derivation and coinventorship issues. F. Prior Art 1. Niemeyer 1570 Defendant contends that independent claim 1 and dependent claims 2, 8, and 9 of the ’859 patent are invalid because they were anticipated by a hay harvesting machine manufactured by H. Niemeyer Sohne GmbH & Co. KG, a German concern. Specifically, defendant contends that the Niemeyer RO 301-GK machine, serial number 1570 (“Niemeyer machine”), anticipates claim 1 of the ’859 patent and the claims dependent thereon. Like the device described in the ’859 patent, the Niemeyer machine is a mechanical drive center pivot mower conditioner. The parties have agreed that the machine was on sale or in public use prior to April 14, 1991, one year before the application for the ’859 patent was filed, but they have not agreed that the machine as it exists today is in substantially the same condition as it was on April 14, 1991. 2. ’418 Patent On its face, the ’859 patent cites United States Patent No. 4,858,418 (“ ’418 patent”), issued August 22, 1989. The parties agree that the ’418 patent is pertinent prior art. Plaintiffs concede that the ’418 patent discloses each and every element of claims 1, 2, 8, and 9 of the ’859 patent except the steering structure element of claim 1. Figures 1, 2, and 3 of the ’418 patent appear below: As the figures show, the ’418 machine has a pivoting gearbox, horizontally spaced tongue and gearbox pivot axes, and a telescoping drive line, but lacks a steering structure for the gearbox that is connected to the tongue and separate from the drive line. Instead of having a separate steering structure as disclosed in the ’859 patent, the mechanical drive line (5, 5a), along with a forked support joint (14) steer the gearbox as the tongue swings. In effect, the forked support joint mechanism allows for vertical movement of the gearbox while resisting horizontal movement. The support joint also helps the machine resist torque that tends to rotate the gearbox during operation. To serve these functions, the rear part of the forked support joint is rigidly secured to the gearbox. The front portion (24) o,f the forked support joint includes a bearing rotatably supporting the drive line section (5a). The front portion of the forked support joint is connected to the rear portion through pivot pins (15') which allow for vertical movement. A person of ordinary skill in the art would understand the ’418 patent to have certain undesirable features. Using the drive line to steer the gearbox introduces detrimental bending loads into the drive line and the bearings that support it. Moreover, using the drive line to resist torque from the operating components subjects the drive line and bearings to harmful loads. 3. Australian Patent The parties agree that Australian Patent No. 108,592 (“Australian patent”), issued in 1939, is pertinent prior art. The Australian patent discloses a harvester machine and an improved power take off for connecting the drive line to a tractor. As shown in the figure below, the patent discloses a gearbox with a fixed lower portion 9 and a rotating or pivoting upper portion 17. The patent also discloses a torque rod 33 which is pivotally attached to the upper housing 17 at one end and slidably disposed through a bracket 37 at the other end. As described in the specification, the purpose of the torque rod 33 is to rotate the upper half of the gearbox housing when the tractor turns, to keep the output shaft of the gearbox in its housing when the tractor turns, and to resist torque in the rotatable housing. 4. New Holland 601-611 Forage Harvesters The parties agree that 1950s publications describing the defendant’s Model 601-611 Forage Harvesters (“New Holland forage harvesters”) disclose pertinent pri- or art. The New Holland forage harvesters are pull-type harvesters with driving power supplied through the tractor PTO. The harvesters are designed to cut crops such as hay and corn. A cutting mechanism severs the crop which feeds up through an elongated upright spout and blows into a wagon trailing behind the harvester. A draw bar or tongue connects the wagon to the harvester. The upright spout on the New Holland forage harvester pivots in order to keep the spout generally aligned with the wagon when the tractor pulling the harvester and wagon turns a corner or otherwise follows field contours. A telescoping steering linkage called a deflector guide allows the spout to pivot in the proper direction. The deflector guide has a pivotal connection to the wagon tongue at one end and a horizontal pivotal connection to the rotating spout at the other end. 5.Dickensheid Patent The parties agree that United States Patent No. 2,864,517 to Dickensheid (“Dickensheid patent”), issued in 1958, is pertinent prior art. The Dickensheid patent is similar to the New Holland forage harvesters in that it discloses a “spout locator” for a pull type harvester designed to be used with a trailing wagon. The spout locator is an arm or lever that is connected by a horizontal pivot to a bracket attached to a pivoting discharge chute at one end and slidingly engaged to the wagon tongue at the other end. As explained in the patent, as the harvester turns during field operation, the lever responsively turns the spout for correct positioning over the wagon. 6.Eberly Patents The parties agree that United States Patent 2,789,705 to Eberly (“Eberly ’705 patent”), issued in 1957, and United States Patent 2,762,517 to Eberly (“Eberly ’517 patent”), issued in 1956, are pertinent pri- or art. Like the New Holland forage harvesters and the Dickensheid patent, the Eberly patents disclose steering structures for pivoting the spouts on pull type forage harvesters with trailing wagons. 7. Dutch Patent The parties agree that Dutch Patent NL 8700863-A (“Dutch patent”) published in November, 1988, is pertinent prior art. The Dutch patent discloses a side pull rotary mower conditioner. A pivoting gearbox is located on top of the tongue near the pulling tractor. The pivoting gearbox receives driving power from the tractor PTO through a short telescoping drive line. The gearbox directs driving power down vertically into the tongue, where a belt and pulley system convey power to the cutting components of the machine. A steering linkage steers the pivoting gearbox so that the gearbox input shaft stays generally aligned with the drive line during turning or swinging of the tongue. The steering linkage is pivot-ally attached to the gearbox housing at one end and slidingly engages in a hole at the other end. The hole is associated with the tractor/implement hitch, so that force is applied to the steering linkage when the tractor turns. 8. Deere Patents The parties agree that Untied States Patent Nos. 3,557,892, 4,008,905, and 4,195,704, issued in 1971, 1977, and 1979, respectively, and all assigned to John Deere (“Deere patents”), are pertinent pri- or art. These patents disclose an adapter for a tractor to implement hitch whereby a vertical pivot axis is placed at the midpoint of two universal joints at opposite ends of a telescoping drive line. In the Deere ’892 patent, for example, an adapter is provided for connecting the implement tongue to the tractor drawbar, whereby the axis of articulation is provided equidistantly between the end of the PTO shaft and the implement input drive shaft, providing equiangular articulation at the front and rear universal joints in the drive line connecting assembly and thereby providing constant speed in the implement drive line regardless of the angle of articulation between the tractor and implement. Deere ’892 patent, col. 2, Ins. 19-27. A figure from the ’892 patent is shown below: 9. Kuhn Patent The face of the ’859 patent discloses United States Patent No. 5,060,462, assigned to Kuhn, S.A. of Saverne, France (“Kuhn Patent”). The Kuhn patent discloses a center pivot mower conditioner with generally aligned tongue and gearbox pivot axes. Kuhn, S.A. created a commercial embodiment of this patent — the Kuhn Alterna 500. 10. Other Patents The parties apparently agree that the other patents cited on the face of the ’859 patent are prior art. Because the parties do not address their arguments to any of these patents, the court simply acknowledges them as prior art in the record without further exposition. G. Defendant’s Design Efforts 1. Creation of the 1431 The plaintiffs’ commercial embodiments of the ’859 patent were a huge commercial success. The plaintiffs went from a very small market share to approximately a fifty percent market share in only four years. Defendant had not been heavily focusing on the center pivot design at the time of the ’859 patent because its long term marketing and design plans led it to focus on what it termed the “modular cutterbar” system. In lay terms, the modular cutter-bar system was a way to drive individual elliptical-shaped rotary cutters independently of the other rotary cutters, while still timing the rotation of the cutters so that the ellipses would overlap to avoid missing crop. The benefits of the modular cutterbar system included less down time for farmers because problems with individual cutterbars could be isolated and would thus not cause catastrophic failure to the entire gear system. When defendant learned of the plaintiffs’ machines and began to realize how successful they were, the defendant began attempts to design a center pivot mechanical drive machine. The defendant’s first attempt at a center pivot machine was essentially a copy of the plaintiffs’ machines. The defendant’s first attempt featured a horizontally spaced pivoting gearbox and a telescoping steering structure connected between the gearbox and the tongue at a point approximately equidistant from the opposite ends of a telescoping drive line. When the defendant became aware of the ’859 patent, it went back to the drawing board and attempted to design a center pivot machine with a hydraulic drive system instead of a mechanical drive system. These attempts were wholly unsuccessful. The defendant finally arrived at the design reflected in the New Holland 1431, the accused machine, after scrapping the hydraulic drive idea. The defendant apparently took great pains to try to design around the ’859 patent when it designed the 1431 because there were a flurry of communications between the defendant’s, engineering department and its patent counsel around the time the 1431 was conceived. 2. Ken McLean In 1987, Ken McLean of New Holland’s engineering department conceived of a pivot tongue rotary mower conditioner, having a pivoting gearbox and a telescoping steering linkage connected to the tongue. Mr. McLean’s concept is largely identical to the steering structure disclosed in the ’859 patent. The only pertinent conceptual difference between Mr. McLean’s idea and the ’859 patent is the limitation in claim 10 of the patent that the front pivotal connection of the steering structure at the tongue be at a point approximately equidistant between the opposite ends of the telescoping drive line. Mr. McLean’s idea shows the connection much closer to one end of the drive line, away from any point of approximate equidistance. Although Mr. McLean envisioned his concept as an improvement to a side pull machine rather than a center pivot machine, there is no dispute that his concept would have worked on a center pivot machine as well. Mr. McLean submitted an invention disclosure form to the New Holland patent department. New Holland retained the concept under consideration for possible pursuit of a patent for a period of time, but ultimately rejected it in early 1990. The parties dispute the precise reason for the rejection, but there is no dispute that both Mr. McLean and the New Holland patent department had at least considered the ramifications of the Australian patent on the patentability of Mr. McLean’s idea. II. Infringement of Claims 10 and 11 Plaintiffs claim that the New Holland Model 1431 infringes claims 10 and 11 of the ’859 patent under the doctrine of equivalents. The court concludes that the 1431 does not infringe claims 10 and 11 because it does not have the substantial equivalent of the “telescoping linkage” limitation. A. Legal Framework “A determination of infringement requires a two step analysis. First, the claim must be properly construed to determine its scope and meaning. Second, the claim as properly construed must be compared to the accused device or process.” Ethicon Endo-Surgery, Inc. v. United States Surgical Corp., 149 F.3d 1309, 1315 (Fed.Cir.1998). As noted above, the court has already performed the first step. See Hay & Forage, 25 F.Supp.2d at 1172-80. “The second step of the infringement analysis, determining whether a particular device infringes a properly construed claim, is a question of fact.” Ethicon Endo-Surgery, Inc., 149 F.3d at 1315. A product that does not literally infringe the express terms of a patent claim may nonetheless be found to infringe if there is “equivalence” between the elements of the accused product and the elements of the claim. Id. (citing Warner-Jenkinson, 117 S.Ct. at 1045). Infringement may be found under the doctrine of equivalents if every limitation of the asserted claim, or its “equivalent,” is found in the accused subject matter, where an “equivalent” differs from the claimed limitation only insubstantially. Whether a component in the accused subject matter performs substantially the same function as the claimed limitation in substantially the same way to achieve substantially the same result may be relevant to this determination. Ethicon, 149 F.3d at 1315. The former of these analyses is often referred to as the “insubstantial differences” approach. Warner-Jenkinson, 117 S.Ct. at 1054. The latter is often referred to as the “triple identity” or the “ function/way/result” approach. Id. The triple identity approach is thought to be particularly suitable for analyzing mechanical devices, such as the device disclosed in the ’859 patent. The Supreme Court recently rejected a direct challenge to the doctrine of equivalents. See id. at 1045 (“Petitioner ... invites us to speak the death knell of [the] doctrine [of equivalents]. We decline that invitation.”). The Court recognized that “[t]he doctrine of equivalents, when applied broadly, conflicts with the definitional and public notice functions of the statutory claiming requirement.” Id. at 1048. The Court upheld the doctrine, however, teaching that courts must remain vigilant in their application of, inter alia, the “All Elements” rule to avoid the potential conflict. See Ethicon, 149 F.3d at 1315 (quoting Warner-Jenkinson, 117 S.Ct. at 1054 (“The determination of equivalence should be applied as an objective inquiry on an element-by-element basis.”)). One of the purposes of the doctrine of equivalents is to protect inventors from unscrupulous copying or from making insubstantial changes between the claimed and accused products or processes. Hilton Davis Chemical Co. v. Warner-Jenkinson Co., 62 F.3d 1512, 1519 (Fed.Cir.1995), rev’d on other grounds, 520 U.S. 17, 117 S.Ct. 1040, 137 L.Ed.2d 146 (1997); Kinzenbaw v. Deere & Co., 741 F.2d 383, 389 (Fed.Cir.1984). B. Analysis 1. Inclusion of Bracket and Slide Plates in 1431 Steering Structure The parties hotly contest whether the bracket attached to the tongue and the slide plate guides housed in the bracket that receive the slide plate are part of the 1431 steering structure. Defendant argues that the steering structure consists only of the components shown in the figure supra at page 1108; that is, defendant argues that the steering structure does not include the bracket and slide plate guides. Plaintiffs argue that the steering structure includes the bracket and slide plate guides. Defendant’s expert, Mr. Willis Campbell, testified that the bracket and slide plate guides are part of the tongue and not part of the steering structure. Plaintiffs’ expert, Mr. James Pope, testified that the bracket and slide plate guides are part of the steering structure. Defendant impeached Mr. Pope’s opinion at trial by noting Mr. Pope had given an expert report earlier in this case stating that the bracket is part of the tongue. Moreover, j there was some evidence that defendant distributes the tongue and bracket arid slide plate guide assembly as one part. The court concludes that the bracket and slide plate guides are part of the steering structure. The court finds Mr. Pope’s opinion at trial more persuasive than Mr. Campbell’s opinion on this issue because Mr. Campbell did not articulate any reason why the 1431 would require a bracket and slide plates on the underside of the 1431 tongue other than to accommodate steering. The court discounts the evidence of how defendant distributes the part assembly because the evidence simply has nothing to do with the function of the parts. Accordingly, the court will evaluate the parties’ factual arguments concerning the doctrine of equivalents with the premise that the bracket, the slide plate guides, the slide plate, the pivotal connection with a ball joint, and the fixed length arm are all part of the steering structure of the 1431 machine. 2. Claim 10 and the All Elements Rule Evaluating the limitations found in claim 10 under the all elements rule, the court concludes that the 1431 machine does not infringe claim 10 under the doctrine of equivalents. The three disputed limitations in claim 10 are the “telescoping linkage” limitation, the “pivotal connection with the tongue at a point” limitation, and the “at least approximately equidistant” limitation. Although the court concludes that the pivotal connection at a point limitation and the approximately equidistant limitation are equivalently present in the 1431 steering structure, the court concludes that there are substantial differences between the telescoping linkage limitation in the patent and the sliding plate mechanism used in the 1431. Moreover, the court concludes that although the sliding plate mechanism used in the 1431 has the same function and the same result as the telescoping linkage limitation, it does not operate in the same way as the telescoping linkage limitation. a. Pivotal Connection with the Tongue at a Point First, the court concludes that the 1431 steering structure’s connection to the tongue is substantially equivalent to the pivotal connection with the tongue limitation of claim 10. The court interpreted claim 10 to require the steering structure to be connected to the tongue “at a spot which allows for pivotal movement.” Hay & Forage I, 25 F.Supp.2d at 1180. The steering structure on the 1431 is connected to the tongue through the bracket which houses the slide plate guides and, in turn, the slide plate. A ball joint connected to the slide plate allows for pivotal movement of the fixed-length steering arm. The slide plate mechanism allows the pivot point to vary relative to the tongue as the angle of the tongue and gearbox changes. Although the pivot point on the 1431 is at a different “spot” relative to the tongue at any given tongue angle, the court believes the differences between the 1431 configuration and the pivotal connection at a point limitation in the ’859 patent are insubstantial because the pivot point on the 1431 is at only one spot relative to the tongue at any given tongue angle. That is, even though the spot on the 1431 moves relative to the tongue, it is still a spot that allows for pivotal motion. Moreover, the configurations perform substantially the same function in the substantially the same way to achieve substantially the same result. The function of both configurations is to connect the steering linkage to the tongue and at the same time allow pivotal movement of the steering linkage relative to the tongue. The way this is done in both configurations is through a pivot point that allows for the steering structure to rotate. The result obtained is to allow the steering linkage to swing in different arcs while still transmitting the tongue motion to the gearbox. b. Approximately Equidistant Next, the court concludes that the location of the 1431 steering structure’s connection point is substantially equivalent to the approximately equidistant limitation of claim 10. The court interpreted the approximately equidistant limitation of claim 10 to require a connection point that is “at least reasonably close to the exact point on the tongue that is equidistant from the opposite ends of the telescoping driveline.” Hay & Forage I, 25 F.Supp.2d at 1180. Also, a person of ordinary skill in the art, by looking at the drawings and specification of the ’859 patent, would recognize that the geometry by which the exact center point is measured changes as the drive line telescopes. As the tongue swings [in the figure shown below], the distance between the connection point 144 and the U-joint 110 changes (in conjunction with the telescoping of the steering structure), but the distance between the connection point 144 and the U-joint 104 stays the same. Consequently, the imaginary exact point of equidistance moves a short distance away from the connection point 144. Hay & Forage II, 25 F.Supp.2d at 1175. ’859 patent, figure 6. Accordingly, the exact point of equidistance is a moving target due to the telescoping characteristic of the drive line. The court concludes that the location of the 1431 steering structure’s connection point is substantially equivalent to the approximately equidistant limitation of claim 10 because it believes there are only insubstantial differences between the location of the 1431 pivot point at any given positioning of the tongue and the limitation set forth in the patent. Defendant exerted great effort at trial to show that the 1431 pivot point never reaches the exact midpoint of the 1431 telescoping drive line. Although the court finds that the 1431 pivot point always is some distance from the imaginary exact midpoint, and the court further finds that the 1431 pivot point always is a greater distance from the imaginary exact midpoint than plaintiffs commercial embodiments of the ’859 patent, the court believes the differences between the 1431 and the pertinent limitation in claim 10 to be insubstantial because the location of the pivot point relative to the tongue on the 1431 achieves substantially the same function in substantially the same way to achieve substantially the same result. The location of the pivot point in both configurations achieves the function of substantially equalizing U-joint angles at opposite ends of the telescoping drive line when the tongue and drive line are swung fully to their normal operating positions. The way this is done in both configurations is by locating the pivotal connection relative to the tongue at a spot that is sufficiently close to a point equidistant from opposite ends of the drive line to take advantage of the resultant geometric relationship between the tongue, drive line, and steering structure. The result achieved by both configurations is the avoidance of untoward torsional forces on the drive line. c. Telescoping Linkage Notwithstanding the court’s findings concerning the pivotal connection at a point and the approximately equidistant limitations, the court concludes that the 1431 steering linkage is not substantially equivalent to the telescoping linkage limitation of claim 10. The court construed the telescoping linkage limitation of claim 10 to require “a linkage having overlapping cylindrical sections.” Plaintiffs assert, and Mr. Pope testified, that the slide plate and the opposing slide plate guides housed within the U-shaped bracket under the tongue are substantially equivalent to a linkage having overlapping cylindrical sections. The court disagrees because no aspect of the sliding linkage approximates overlapping cylinders. The slide plate guides, as previously stated, create a channel in which the slide plate moves. This channel is not cylindrical, nor is it entirely enclosed in the way overlapping cylinders would enclose one cylinder within another. Moreover, although the 1431 sliding mechanism has substantially the same function and achieves substantially the same result as the telescoping linkage limitation in the ’859 patent, it does not operate in substantially the same way. The sliding linkage in the 1431 slides in a plane parallel to the plane defined by the underside of the tongue, whereas the telescoping linkage of claim 10 slides along an axis defined by the stationary connection point on the tongue and the junction box. In the triangle defined by the following three points, (1) the pivot point, (2) the end of the telescoping drive line closest to the tractor (“U-joint 3”), and (3) the end of the telescoping drive line closest to the gearbox (“U-joint 4”), the sliding linkage in the 1431 and the telescoping linkage in claim 10 operate in a substantially different way. The sliding linkage in the 1431 allows the distance between the pivot point and U-joint 3 to vary while keeping the distance between the pivot point and U-joint 4 fixed, whereas the telescoping linkage in claim 10 allows the distance between the pivot point and U-joint 4 to vary while keeping the distance between the pivot point and U-joint 3 fixed. In effect, the triangle in the 1431 has been “flipped” relative to the comparable triangle in claim 10. The court believes this distinction supports its conclusion that the two configurations operate in a substantially different way. 3. Claim 11 The court’s conclusion that the 1431 does not infringe claim 10 under the doctrine of equivalents compels a similar conclusion with respect to claim 11, because claim 11 is dependent upon claim 10. One who does not infringe a claim cannot infringe a claim dependent on (and thus containing all the limitations of) that claim. See, e.g., Wolverine World Wide, Inc. v. Nike, Inc., 38 F.3d 1192, 1199 (Fed.Cir.1994) (citing Wahpeton Canvas Co. v. Frontier, Inc., 870 F.2d 1546, 1553 (Fed.Cir.1989) (“It is axiomatic that dependent claims cannot be found infringed unless the claims from which they depend have been found to be infringed.”)). IV. Invalidity Generally The court presumes the ’859 patent to be valid: A patent shall be presumed valid. Each claim of a patent (whether in independent or dependent form) shall be presumed valid independently of the validity of other claims; dependent claims shall be presumed valid even though dependent upon an invalid claim. The burden of establishing invalidity of a patent or any claim thereof shall rest on the party asserting it. 35 U.S.C. § 282. The purpose of the statutory presumption is to “contribute stability to the grant of patent rights.” Magnivision, Inc. v. Bonneau Co., 115 F.3d 956, 958 (Fed.Cir.1997). The presumption of validity places the burden of proof of facts and the ultimate burden of persuasion to establish invalidity on the party asserting that a claim is invalid. SmithKline Diagnostics, Inc. v. Helena Lab. Corp., 859 F.2d 878, 885 (Fed.Cir.1988). A party challenging a patent’s validity has the burden to show invalidity by clear and convincing evidence. National Presto Indus. v. West Bend Co., 76 F.3d 1185, 1189 (Fed.Cir.1996). Clear and convincing evidence involves a greater degree of persuasion than that which will satisfy a preponderance of the evidence standard, albeit a lesser standard than beyond a reasonable doubt. Clear and convincing evidence is evidence that creates in the fact finder’s mind an abiding conviction that the truth of a factual contention is highly probable. Colorado v. New Mexico, 467 U.S. 310, 316, 104 S.Ct. 2433, 81 L.Ed.2d 247 (1984). If the evidence requires the fact finder to draw extensive inferences, the evidence does not satisfy the clear and convincing proof requirement. Intel Corp. v. U.S. Int’l Trade Comm’n, 946 F.2d 821, 830 (Fed.Cir.1991). V. Invalidity Pursuant to 35 U.S.C. § 102(b) Defendant contends that the Niemeyer machine anticipates claims 1, 2, 8, and 9 of the ’859 patent. Plaintiffs concede that the Niemeyer machine meets the on sale or public use requirements of section 102(b). Plaintiffs argue, however, that defendant has not met its burden to show by clear and convincing evidence that the Niemeyer machine anticipates the following three claim 1 limitations: (1) a header supported by the frame as claimed in claim 1, (2) a steering structure “separate from the drive line” as claim 1 has been construed by the court, and (3) a gearbox axis “spaced horizontally” from the tongue pivot axis as required by claim 1. Plaintiffs also claim that, even if the Niemeyer machine now has horizontally spaced axes, the defendant has not met its burden to prove by clear and convincing evidence that the Niemeyer machine had horizontally spaced axes on or before the critical date of April 14,1991. The court concludes that the Niemeyer machine does not anticipate any claims of the ’859 patent. Although the Niemeyer machine anticipates the header supported by the frame limitation and the steering structure separate from the drive line limitation, the Niemeyer machine does not anticipate the limitation requiring the gearbox pivot axis to be spaced horizontally from the tongue pivot axis. Because it does not anticipate independent claim 1, the Niemeyer machine also does not anticipate dependent claims 2, 8, and 9. A. Legal Framework Anticipation is a question of fact. Id. A patent is invalid because of anticipation when the patent challenger can show by clear and convincing evidence that “the invention was ... in public use or on sale in this country, more than one year prior to the date of the application for patent. ...” 35 U.S.C. § 102(b); Electro Med. Sys. S.A v. Cooper Life Sciences, Inc., 34 F.3d 1048, 1052 (Fed.Cir.1994). Anticipation requires the presence of each and every element of a claimed invention within a single prior art disclosure. Id. Put another way, “[tjhat which would literally infringe if later in time anticipates if earlier than the date of the invention.” Lewmar Marine, Inc. v. Barient, Inc., 827 F.2d 744, 747 (Fed.Cir.1987) (emphasis omitted). B. Analysis: Claim 1 1. Horizontally Spaced Pivot Axes The court concludes that the Niemeyer machine does not anticipate the horizontally spaced pivot axes limitation of claim 1 because the alleged horizontal spacing was entirely accidental, not intended, and not appreciated. The Niemeyer machine, as it exists today, unquestionably has gearbox and tongue pivot axes that are spaced a tiny distance apart. Moreover, the defendant has proven by clear and convincing evidence that the Niemeyer machine as it existed on the critical date likely had similarly spaced axes. Nonetheless, the court finds that the evidence is overwhelming that the designers of the Niemeyer machine intended the gearbox pivot axis and tongue pivot axis to coincide and did not appreciate the significance of horizontal spacing. Defendant has proven by clear and convincing evidence that the tongue and gearbox pivot axes on the Niemeyer machine likely had some small and unintentional amount of horizontal spacing on or before the critical date. The Niemeyer machine, which defendant produced at trial, today clearly has some minute spacing between the gearbox pivot axis and the tongue pivot axis. The spacing amounts to no more than a few millimeters. Although some of this spacing might have been caused by wear and tear on the machine, Mr. Un-gruh, the designer of the Niemeyer machine, testified that every RO 301-GK machine built by Niemeyer, including the Niemeyer 1570 machine produced at trial, had a tongue pivot axis that was marginally spaced apart from the gearbox pivot axis. Mr. Ungruh testified, and the parties agreed, that Niemeyer manufactured its machine using a cut and weld technique, which would not have allowed for precise alignment between the axes except by fortuitous accident. Mr. Ungruh’s testimony is corroborated by the existence in the Niemeyer machine of a telescoping drive line — a feature apparently only necessary in the Niemeyer machine to accommodate for relative movement between the tongue and the gearbox. Despite the minute horizontal spacing, the court concludes that the Niemeyer machine does not anticipate claim 1. “[A]ccidental results, not intended and not appreciated, do not constitute anticipation.” Eibel Process Co. v. Minnesota & Ontario Paper Co., 261 U.S. 45, 66, 43 S.Ct. 322, 67 L.Ed. 523 (1923), cited in Scaltech, Inc. v. Retec/Tetra, L.L.C., 156 F.3d 1193, 1198 (Fed.Cir.1998) (“[A]n accidental or unwitting duplication of an invention cannot constitute an anticipation”). The court is convinced that even if the Niemeyer machine has horizontally spaced axes as contemplated by claim 1 of the ’859 patent, these results were accidental. Mr. Un-gruh clearly testified that the horizontal spacing was not intentional but, rather, was accepted as practical reality in light of the necessity to allow for manufacturing tolerances with the imprecise cut and weld technique. Moreover, Mr. Ungruh and others associated with the Niemeyer machine clearly did not appreciate the significance of horizontally spaced axes because the tiny spacing simply did not produce a significant result. Figure 9 of the German patent application associated with the Niemeyer machine shows these axes in precise alignment. Mr. Ungruh testified that he designed the gearbox and tongue pivot axes to be identical. 2. Steering Structure Claim 1 of the ’859 patent calls for a steering structure “connected between the junction box and the tongue for causing the junction box to swing responsively about said [junction box] axis with the tongue when the latter is pivoted about said [tongue] axis between its various angular positions.” The court has construed this limitation to mean “a steering structure separate from the drive line that op-eratively interacts with the tongue at one end and operatively interacts with the junction box at the other end and that transmits the swinging motion of the tongue to the junction box during swinging of the tongue.” Hay & Forage I, 25 F.Supp.2d at 1176. The court concludes that defendant has met its burden to show by clear and convincing evidence that the Niemeyer machine anticipates the steering structure separate from the drive line limitation as that limitation has been construed by the court. The gearbox on the Niemeyer machine has a specially designed cover with a long nose that interacts with the tongue. As Mr. Ungruh testified, the long nose serves the function of steering the gearbox in response to the swinging motion of the tongue. Mr. Ungruh also testified that the gearbox cover on the Niemeyer machine was specially designed to steer the gearbox and was not a standard gearbox part. The following diagram shows a conceptual comparison between a standard gearbox cover and a gearbox cover with a long nose for steering. The gearbox cover in the top drawing approximates the design of the gearbox cover on the plaintiffs’ commercial embodiment, of the ’859 patent, and the gearbox cover in the bottom drawing approximates the design of the gearbox cover on the Niemeyer machine. The long nose fits inside the tongue and serves to swivel the gearbox as the tongue swings about the tongue pivot axis. Accordingly, the gearbox cover “operatively interacts with the tongue at one end and operatively interacts with the junction box at the other end and ... transmits the swinging motion of the tongue to the junction box during swinging of the tongue.” Plaintiffs’ arguments against recognizing the gearbox cover as a steering structure within the meaning of claim 1 are essentially twofold. First, plaintiffs argue that the gearbox cover is part of the gearbox and thus cannot operatively interact with the gearbox. Second, plaintiffs argue that the part’s designation as a gearbox cover precludes it from serving as a steering structure. The court rejects both arguments. As Mr. Campbell testified, the gearbox cover serves multiple purposes, one of which is to steer the gearbox. Nothing about this multiple functionality precludes the gearbox cover from being a steering structure. Moreover, the court affords little weight to the name given the part in the parts manual. The gearbox cover is clearly a gearbox cover as indicated in the Niemeyer parts manual, but it also serves to steer the gearbox. The court concludes that the Niemeyer machine anticipates the steering structure limitation disclosed in claim 1 of the ’859 patent. 3. Header Supported by the Frame Claim 1 of the ’859 patent calls for.“a harvesting header supported by the [mobile] frame in a position for performing harvesting operations on a crop as the machine is towed across a field.” The harvesting header claim language is straightforward, and basically describes the crop harvesting portion of the machine, which includes at least a frame and parts for cutting or severing the crop. The patent specification defines the header in broad, functional terms: Supported by the frame 12 beneath the swing tongue 30 is a harvesting header broadly denoted by the numeral 50. [See supra, the figure at page 13.] In accordance with the principles of the present invention, the header 50 may be constructed in a number of different ways to perform a number of