ESCO CORPORATION v. Tru-Rol Company, Inc.
| Decision Date | 21 December 1972 |
| Docket Number | Civ. No. 71-912-M |
| Citation | 352 F. Supp. 416 |
| Parties | ESCO CORPORATION v. TRU-ROL COMPANY, INC. |
| Court | U.S. District Court — District of Maryland |
COPYRIGHT MATERIAL OMITTED
Jerome F. Fallon and Dawson, Tilton, Fallon & Lungmus, Chicago, Ill., and Benjamin C. Howard and Miles & Stockbridge, Baltimore, Md., for plaintiff.
Patrick J. B. Donnelly and Niles, Barton & Wilmer, Baltimore, Md., and George H. Spencer and Spencer & Kaye, Washington, D. C., for defendant.
This is an action for infringement of U. S. Patent No. 2,919,506, which was issued on January 5, 1960, and is owned by the plaintiff, Esco Corporation.1 The patent in suit relates to excavating teeth and base supports therefor of the type used on power-driven equipment such as excavating and loading buckets, dippers, scoops and scarifiers. The base supports, known in the trade as adapters, are bolted to the power-driven equipment, and the teeth, also known in the trade as points, are detachably connected to the adapters.2 The defendant, the Tru-Rol Company, Inc., is charged with infringement by sales of tooth points, adapters and combinations thereof covered by the patent in suit. Defendant denies that the points and adapters it sells are covered by the patent in suit.
Jurisdiction exists under 35 U.S.C. § 281 and 28 U.S.C. § 1338. Venue has been admitted.3
The plaintiff is a corporation organized and existing under the laws of the State of Oregon and has its principal place of business in Portland, Oregon. The defendant is a corporation organized and existing under the laws of Maryland and has its principal place of business in Baltimore, Maryland.
In the most common application of the use of excavating teeth, the adapter is secured to the leading edge of a powerdriven bucket and a replaceable point secured to the adapter by means of a removable locking pin. Without these penetrating teeth, generally wedgeshaped, the leading edge of the bucket would have to withstand the shock of encountering rocks and other hard substances. The digging action is performed by the tooth assembly while at the same time the leading edge of the bucket is spared the shock of initial contact with the rocks or other materials with which the equipment is working. Expensive and time-consuming repairs to the bucket are thereby eliminated and instead the problem becomes one of merely replacing or renewing the digging projections themselves. Through the use of two-part excavating teeth, it is possible to renew the digging projection by the introduction of a new point as contrasted to the entire tooth, thereby saving substantial time and metal.
In the type of adapter and point commonly used prior to the invention of the patent in suit, the adapter and point had angularly related flat surfaces. More particularly, most two-piece excavating teeth had a wedge-shaped projection or nose on the adapter with a correspondingly-shaped socket in the rear of the wear point. The flat surfaces of the wedge-shaped adapter and point were the bearing surfaces at which the two parts came in contact. Under some operating conditions, lateral pressure on the tooth caused sideways movement producing a pivoting or swinging action between the adapter and point. This reduced the fitting contact or bearing between the two parts to a small limited area, resulting in localized and greatly increased stress on the point and nose in that area. Under these conditions the nose and point were subject to rapid distortion and wear and often broke under the concentrated pressure. In order to prevent this phenomenon, there was need for the nose and point members to have surfaces which maintained the bearing contact constant during lateral movement of one of the members with respect to the other.
The invention of the patent in suit departs from the flat angular contacting nose and point socket surfaces and uses instead convergent surfaces of revolution having a common vertical axis near the rear of the point. The surfaces of the invention of the patent in suit, colloquially called "conical," enable the parts to move relative to each other with the bearing surfaces of the two members maintaining substantially constant the bearing realized before the application of lateral stress. The main feature of all the claims of the patent in suit is that the upper and lower bearing surfaces of the point or adapter, or both, have surfaces of revolution generated about a vertically-extending axis.
The specification of the patent describes that it is an object of the invention to provide a nose support and socket element in the nature of a point or cap or sleeve mounted on said nose whereby under impact the element may swing to a limited extent laterally while providing full bearing or surface contact between the parts throughout such lateral movement. Another object is to provide an excavating device in which cooperating nose and socket elements have surfaces which remain in contact during lateral movement of one of the members with respect to the other, while at the same time providing a sturdy interlock between the members. A still further object is to provide a combination of nose and socket elements united by keys or other means whereby the parts may swing relative to each other to a limited extent while at the same time providing wide areas of contact between the members during each portion of such travel so that a large bearing surface is provided between the members under heavy load and irrespective of the relative position of the two members. Yet another object is to provide in excavating devices, nose and socket elements wherein the nose is provided with a cone surface or other surface of revolution contacting a corresponding surface of the socket element, thus enabling the parts to move in an arc relative to each other with the bearing surfaces of the two members substantially in full contact. It is a purpose of the cooperating nose and socket structure shown herein to support fully the point upon the nose in such lateral swinging movements so that point contact or point wear is substantially obviated. This structure avoids point contact and wear, and by maintaining the bearing surfaces in contact over wide areas during the movements of the parts, a long-wearing point or socket element is provided.
Esco Corporation manufactures and sells excavating teeth with surfaces of revolution as provided by the invention of the patent in suit and has enjoyed substantial commercial success with such teeth. Such teeth have resulted in longer life, smaller size for equivalent work and less breakage. Caterpillar Tractor Company, Clark Equipment Company and International Harvester Company, well known manufacturers of excavating equipment, utilize the patented teeth. Esco in connection with the patented teeth received the 1962 Mining World Award for "Achievement in equipment development aiding the technological advancement of the mining industry." Esco markets teeth made with "conical" bearing surfaces according to the invention of the patent in suit. These surfaces of revolution are those resulting from revolving a broken or bent line about an axis of revolution.
Although the defense of invalidity of the patent was interposed in the Answer and First Counterclaim, this defense was abandoned when two weeks prior to the trial the defendant moved to amend its Answer and First Counterclaim and the court subsequently allowed the amendment. The patent in suit has previously been litigated and found valid. See Hensley Equipment Company v. Esco Corporation, 383 F.2d 252 (5th Cir. 1967), modified on rehearing, 386 F.2d 442 (5th Cir. 1967).
The claims of the patent in suit asserted to be infringed are Claims 1, 3, 8, 15, 20, 21 and 28. Claims 1 and 3 are directed to the combination of the point and adapter while claims 8, 20 and 28 are directed to the point per se. Claims 15 and 21 are directed to the adapter per se.
Of the claims directed to the combination, claim 3 can be taken as representative. Claim 3 reads, when separated into its various mechanical elements, as follows:
Of the claims directed to the point per se, claim 8 can be considered representative and, when separated into its various mechanical elements, reads as follows:
Of the claims directed to the adapter per se, claim 15 can be taken as representative. Claim 15 when separated into its various mechanical elements, reads as follows:
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