Reeford P. Shea and Preco, Incorporated v. Blaw-Knox Company

388 F.2d 761
CourtCourt of Appeals for the Seventh Circuit
DecidedMarch 4, 1968
Docket16258_1
StatusPublished
Cited by5 cases

This text of 388 F.2d 761 (Reeford P. Shea and Preco, Incorporated v. Blaw-Knox Company) is published on Counsel Stack Legal Research, covering Court of Appeals for the Seventh Circuit primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Reeford P. Shea and Preco, Incorporated v. Blaw-Knox Company, 388 F.2d 761 (7th Cir. 1968).

Opinion

CASTLE, Circuit Judge.

Blaw-Knox Company, the defendant-appellant, prosecutes this appeal from the judgment order of the District Court adjudicating that Claims 1 and 3 of Shea U. S. Patent No. 3,029,716 are valid and have been infringed by the defendant, and granting injunctive relief against further infringement. The patent in suit is owned by the plaintiffs-appellees, Ree-ford P. Shea and Preco, Incorporated. It relates to a paving machine control system.

The record discloses that for many years mechanical paving machines of the “floating screed” type, exemplified by the long-expired Barber U. S. Patent No. 2,138,828, have been used for the surfacing of highways with bituminous material. Generally, the floating-screed type pavers employ a flat plate or “screed” which is towed behind a motivating means, such as a tractor, with the paving material being dumped from a hopper in advance of the plate. This screed functions to iron the dumped material to form the smooth upper surface of a paved road. The screed is supported solely by the material having already been deposited and operates at a slight positive angle of attack. The thickness of the mat of road material laid varies with the adjustment of the angle of the screed. As the angle of attack is changed, the screed will either gradually rise until an equilibrium is attained or gradually sink until an equilibrium angle of attack is restored. As the paving machine moves along the road, if high or low spots in the subsurface or grading are encountered the screed creates a corresponding rise or dip in the surface of the mat being laid unless the roughness is short enough to be bridged by the wheels or tracks of the towing vehicle or some form of correction of the angle of attack is made.

In the machine illustrated in the patent in suit, the machine of the Barber patent, and in defendant’s accused machines, the free-floating screed is connected to the tractor by “side” or “draft” arms, and provision is made for the adjustment of the angle of attack of the screed. The specification of the patent in suit recognizes that preexisting paving machines (such as the machine of the Barber patent) controlled the level of the mat surface produced by variation of the inclination of the screed in the direction of travel; that means were provided for the manual adjustment of each end of the screed to vary screed inclination; and that the screed is torsionally flexible about its longitudinal axis sufficiently to permit different settings at the two ends of the screed. The specification recites that “[i]n the normal operation of such machines, the operator varies those adjustments simultaneously in the same direction to control the general thickness of the mat [thereby achieving some measure of longitudinal slope or grade control], and varies them differentially to *763 control the lateral slope of the mat surface [to achieve transverse slope control]”. But, as the evidence herein discloses, merely changing the angle of attack of the screed does not instantaneously alter the thickness of the mat being laid to compensate for the variation in subsurface transverse slope encountered. The mat thickness will gradually change as the machine progresses from the point where the adjustment was made to alter the angle of attack, either increasing or decreasing in the shape of a wedge until a new state of equilibrium is effected. The problem of lateral or transverse slope control to which the patent in suit was addressed was the need to anticipate that the screed was going to make a mistake (lay a surface reproducing a subsurface irregularity) and to compensate for the same before any appreciable error occurred.

Claim 1 of the patent in suit defines a structure embracing a combination of eight elements. These components combine to produce a structure capable of anticipating the existence of a subsurface irregularity forward of the approaching screed, which condition would produce error in the desired transverse slope of the mat being laid, and signalling the correction in screed angle 1 required to prevent the occurrence of appreciable error. Claim 3 contains the further limitation that the correction is automatically made.

Illustrative of the claimed invention, but “not as a limitation” upon the scope of the claims, the specification and drawings describe and show a Barber patent type floating-screed paving machine in which, however, the draft arms are pivoted at their forward or tractor ends rather than at the screed. In Shea a crossbeam or gantry arm is placed on the machine forward of the screed and pivotally connected with arms extending from the side frames of the screed to the gantry arm. The gantry arm structure geometrically forms and represents a lineal extension or forward projection of the screed. A sensing pendulum is mounted on the gantry arm. When the tractor encounters an irregularity in subsurface slope the crossbeam of the gantry arm tips or tilts, and the gantry arm would be representative of the axis of the screed when it got to that position in the future. By means of electrical components and circuitry the pendulum is utilized to create an electrical impulse which indicates the degree and direction of pivoting of the gantry arm and hence the forward projection of the screed. This electrical impulse or signal is electrically compared with a predetermined signal representing the desired transverse inclination of the screed to create the desired transverse slope of the road. The resulting output of the two signals is either visually displayed on an indicator as a guide to the operator in making a corresponding correction in angle of the screed by use of the adjustment means so as to compensate for the anticipated irregularity, or it is utilized through a bridge circuit to drive an electric motor to vary the angle of attack of one pre-selected end of the screed to overcome the effect of the subsurface irregularity on the transverse slope of the mat. This automatic correction is substantially instantaneous and operates to anticipate and to make, without intervention by the operator, the needed change in screed angle so as to prevent the occurrence of appreciable error in the transverse slope of the material being laid.

The defendant asserts invalidity of the patent in suit on the ground of anticipation in the prior art; contends its accused machines do not infringe because they lack the element of a “forward projection of the screed”, and because the only things they have in common with the structure of the patent are elements in common with prior art; and claims that the patent is unenforceable because of its misuse by plaintiffs.

The defense of invalidity is primarily based on two prior art patents, Waldvogel British Patent No. 397,882, and Adams U. S. Patent No. 2,284,550, not cited by *764 the Patent Office examiner. On the basis of the disclosures of these patents, and of the cited Barber patent, the defendant argues that the Shea patent is but a congregation of elements old in the art which performs no new function and achieves no new result. Defendant asserts that Shea did no more than to put a plumb bob forward of the screed of an old and well-known paving machine to measure and visually indicate the transverse inclination of the screed — an obvious arrangement.

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Bluebook (online)
388 F.2d 761, Counsel Stack Legal Research, https://law.counselstack.com/opinion/reeford-p-shea-and-preco-incorporated-v-blaw-knox-company-ca7-1968.