Hensley Equipment Company, Inc. v. Esco Corporation

Esco Corporation (Esco), owner of Baer Patent No. 2,483,032 (Baer), brought this patent infringement suit against Hensley Equipment Company, Inc. (Hensley), manufacturer and seller of the accused apparatus. The Baer patent is a combination patent describing a mechanical device known in the heavy construction industry as a two-part excavating tooth.

Esco alleged that Hensley had infringed claims 5, 8 and 9 of Baer. Claim 5 describes the overall combination of the two parts of an excavating tooth. One part is an “adapter,” which is secured to the lip of a piece of excavating •equipment. The other part is a replaceable “wear point” which fits on the adapter and provides the actual cutting edge of the overall tooth. Claims 8 and 9 pertain only to the replaceable wear point. In addition to denying infringement, Hensley defended on the grounds that claims 5, 8 and 9 of Baer are invalid and that, by reason of misuse, Esco is estopped from claiming infringement.

The trial court found and concluded that claim 5 of Baer was not infringed. Therefore, without determining the validity of claim 5, the court denied Esco any relief as to that claim. The trial court further found and concluded…