## Facts

- Westinghouse owned U.S. Patent No. 360,070 (issued Mar. 29, 1887) covering a fluid-pressure automatic brake mechanism for trains.
- The patent described a specific combination of components—brake pipe, auxiliary reservoir, brake cylinder, and a triple-valve device—arranged so the triple valve governed communications between the reservoir, brake pipe, and brake cylinder.
- The invention aimed to apply brakes more rapidly and effectively on long trains and to conserve compressed air by using air in the brake cylinders that had previously been discharged to the atmosphere.
- Boyden manufactured and used a fluid-pressure brake system intended to address similar operational goals in train braking.
- Westinghouse sued Boyden in equity for patent infringement; the district court found partial validity and infringement, but the court of appeals reversed and found no infringement.
- The Supreme Court reviewed the case and addressed whether Boyden’s system embodied the patented combination or an equivalent.

## Issues

1. Whether Westinghouse’s Patent No. 360,070, properly construed as a combination patent, covered Boyden’s brake system.
2. Whether Boyden’s system contained each element of the claimed combination or a legally equivalent substitute.
3. Whether achieving similar braking results establishes infringement when the accused device operates through a materially different mechanism or mode of operation.

## Decision

- The Supreme Court affirmed the court of appeals.
- The Court held that Boyden’s device did not infringe Patent No. 360,070.
- The Court treated the asserted claims as directed to a specific combination and cooperation of elements, not to the general goal of improved fluid-pressure braking.
- The Court concluded Boyden did not appropriate the same combination or its equivalents because the accused mechanism differed in essential operation and structure.

## Legal Principles

- A combination patent is infringed only if the accused device includes all claimed elements or substitutes an element with a true equivalent; omission or non-equivalent substitution avoids infringement.
- Equivalence generally requires that the accused element perform substantially the same function, in substantially the same way, to achieve the same result; similarity of result alone is insufficient.
- Patent protection extends to the claimed means (and genuine equivalents), not to the underlying principle, function, or result; courts should not construe claims to cover every mechanism that achieves the same outcome.
- An accused device may be a noninfringing improvement where it attains comparable benefits through a different mode of operation and does not take the patented combination.

## Conclusion

The Court held that Westinghouse’s patent protected a particular combination and cooperative arrangement of brake components, and Boyden’s fluid-pressure brake, though aimed at similar benefits, did not use the same combination or equivalent means; therefore, there was no infringement.


Westinghouse v. Boyden Power Brake Co., 170 U.S. 537 (1898)