On Petition for Rehearing.
The plaintiff-appellant, in its petition for rehearing, complains of four errors which it says we made in our opinion, indicating error in the decree of non-infringement. The first is our statement that, "In practice the plaintiff found that a tread chain which conforms precisely to these defined claims is impracticable. It extends too far in front, prevents easy turning of the vehicle and presents other difficulties arising from too much slack." This, the appellant asserts, has no foundation in the record. That may be true; we shall assume it is true; though the point was made somewhere, probably in the argument. However that may be, the fact is the plaintiff in its commercial device departs for some reason from the slack of the claims which were allowed and uses the lesser slack of claims which were rejected.
The plaintiff next complains that we unduly limited the claims of the patent. We were not conscious of placing any limitations upon them. We took the claims as they are written and applied them as they are limited by their own terms after long travail in the Patent Office. Nor were we conscious of reading into them a meaning different from that disclosed by their words. The plaintiff asks us to construe the claims not by their express terms but by the patent and the original application and particularly by a broad expression in the specification "that the chain 39 is made somewhat greater in length than is necessary for it to pass around the bridge wheels."
In view of the history of the patent application and of the condition as to slack on which the claims were in part ultimately allowed, we were compelled to find that the claims are subject to their own limitations and that the invention is no broader than that which they disclose.
The next error into which, it is alleged, we fell was in speaking of the slack in the mechanism of the patent as the slack generally of the prior art, against the plaintiff's contention that the slack here is novel in location, kind and utility. We think it is the same kind of slack, with a different location, because of the difference in position of the moving instrumentalities, the wheels, yet we cannot find patentable novelty or utility in using common art slack for slack purposes even in a new mechanism.
The plaintiff next complains that we "failed to give to the slack defining expressions of the claims in suit * * * the range of equivalency to which the disclosure of the patent, the merit and novelty of Athey's contribution to the art and the proceedings in the Patent Office on Athey's application clearly entitle them." It was because of the action of the Patent Office in rejecting broad claims as to the dimensions of the slack and allowing narrow claims definitely limiting them and because of Athey's acquiescence in its action (which amounted to a disclaimer) that we felt unable to give the claims allowed an equivalency equal to the claims rejected. We were, under the law, forced to hold that Athey was estopped to assert for the allowed claims of his patent an equivalency or scope commensurate with that of his rejected claims. Weber Electric Company v. Freeman Electric Company, 256 U.S. 668, 41 S. Ct. 600, 65 L. Ed. 1162; I.T.S. Rubber Company v. Essex Rubber Company, 272 U.S. 429, 47 S. Ct. 136, 71 L. Ed. 335.
And, finally, the plaintiff emphasizes the whole mechanism as a patentable combination and minimizes the element of slack.It is a combination; and for such a combination, within the claims, the patent may be valid; yet it is not an invention without the slack of the claims. So, however approached and however discussed, the question of infringement turns on the slack defined by the claims.
The decree holding noninfringement remains affirmed.