L.J. Mueller Furnace Co. v. Groeschel

• Citation: 166 F. 917
• Parties: L. J. MUELLER FURNACE CO. v. GROESCHEL.
• Decision Date: 19 January 1909
• Court: U.S. District Court — Eastern District of Wisconsin

166 F. 917

L. J. MUELLER FURNACE CO. v. GROESCHEL.

United States Circuit Court, E.D. Wisconsin.

January 19, 1909

Winkler Flanders, Bottum & Fawcett, Sol., for complainant.

Erwin &amp Wheeler, Sol., for defendant.

SANBORN District Judge.

Suit in equity for injunction and account for infringement of letters patent No. 746,355, issued to L. J. Mueller December 8, 1903 for an improved wall register used in connection with hot-air furnaces. Defendant denies invention and novelty, denies infringement, alleges anticipation by 24 prior patents specifically referred to, also alleges prior public use and common general knowledge for two years before application.

The main question may be illustrated by supposing that an ordinary bound book represents the register. If the book is placed on a table with the back in a horizontal position, and the covers perpendicularly resting on the table, the covers will represent the movable damper or register lid, and the printed matter the fixed portion, frame, or grill of the register. If a cover is raised and lowered, and held in different positions, it will practically represent the movable damper of both devices, hinged to the book by the flexible binding. The aim of both parties in the construction of their several devices was to attach to the damper or movable lid near the top or angle with the frame a small fixture called an 'operating piece,' and bring it through the fixed portion, frame, or grill of the register so as to bind against or rest upon a part of the frame or grill serving as a bearing. The frictional resistance of the operating piece in plaintiff's device holds the damper in any desired place. In the defendant's the combined weight of the damper and operating piece, resting upon such bearing, secures the same result.

Plaintiff's first claim covers a combination of four things-- a frame, a bearing (part of the grill), a damper, and an operating piece. The second claim covers the same things, except that the last is a spring operating piece. The operating piece, about two inches in length, firmly attached to the damper, whether made rigid or elastic, binds against the perpendicular sides of a part of the openwork of the grill, and thus permits the damper to be opened, closed, or held at any angle, so as to regulate the admission of the hot-air current.

Defendant's device also consists of the combination of a frame, bearing, damper, and operating piece, but the latter, instead of pressing by friction against a perpendicular bearing in the grill, and this acting against the weight of the damper, rests by gravity alone upon a bearing consisting of a horizontal portion of the grill. One works against gravity by friction, due either to the rigidity of the operating piece, or to its elasticity or springiness; the other by weight. In some of the registers made by defendant under the Foster patent the operating piece is so attached to the damper that the resilience of the damper presses the piece against the grill or bearing, as well as the weight of itself and the damper. In the actual operation of the registers this difference does not appear to be of much importance. The mode of operation, therefore, of complainant's and defendant's devices is quite distinct, one working against gravity by friction, and the other by gravity alone, or gravity aided by a spring.

However, no matter how great the apparent difference in the mode of operation of these operating pieces, if they are only mechanical equivalents the latter may infringe. As so clearly and expressively stated by Mr. Caldwell, expert witness called by defendant:

'It is a well-accepted principle that in interpreting and applying claims mechanical equivalents are to be treated alike, and there is no clearer example of mechanical equivalency than that which exists between a part which operates by spring force and a part which operates by the force of gravity. In other words, a weight is to be considered the mechanical equivalent of a spring.'

This statement is fully supported by the decisions, and was made by the witness to illustrate his opinion that an operating piece found in the prior art, frictionally held in place by gravity, was mechanically the same as the Mueller device, held in place by a spring operating against gravity.

The doctrine of mechanical equivalents has been stated by the Supreme Court in many cases. In Kokomo Fence Mach. Co. v. Kitselman, 189 U.S. 8, 24, 23 Sup.Ct. 521, 527, 47 L.Ed. 689, 696, it is said:

'The machines lack that identity of means and identity of operation which must be combined with identity of result to constitute infringement.'

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