Source: https://openjurist.org/170/us/537
Timestamp: 2019-04-22 14:20:04+00:00

Document:
BOYDEN POWER-BRAKE CO. et al.
WESTINGHOUSE et al. WESTINGHOUSE et al. v. BOYDEN POWER-BRAKE CO. et al.
The patent in suit, which was issued March 29, 1887, to George Westinghouse, Jr., is for a fluid-pressure automatic brake mechanism, the object of which is said in the specification to be 'to enable the application of brake shoes to car wheels by fluid pressure, to be effected with greater rapidity and effectiveness than heretofore, more particularly in trains of considerable length, as well as to economize compressed air in the operation of braking, by utilizing in the brake cylinders the greater portion of the volume of air which in former practice was directly discharged into the atmosphere.
'In the application of the Westinghouse automatic brake, as heretofore and at present commonly in use, each car is provided with a main air pipe, an auxiliary reservoir, a brake cylinder, and a triple valve; the triple valve having three connections, to wit, one to the main air-brake pipe, one to the auxiliary reservoir, and one to the brake cylinder. The main air pipe has a stopcock at or near each of its ends, to be opened or closed as required, and is fitted with flexible connections and couplings for connecting the pipes from car to car of a train, so as to form a continuous line for the transmission of compressed air from a main reservoir supplied by an air pump on the engine. When the brakes are off or released, but in readiness for action upon the wheels of the train, the air which fills the main reservoir and main air pipes has a pressure of from sixty-five to seventy-five pounds to the square inch, and by reason of the connections referred to the same pressure is exerted in the casings of the triple valves on both sides of their pistons, and in the auxiliary reservoirs connected therewith. At the same time passages called 'release ports' are opne from the brake cylinders to the atmosphere. When it is desired to appy the brakes, air is allowed to escape from the main air pipes through the engineer's valve, thereby reducing the pressure in the main air pipes, whereupon the then higher pressure in the auxiliary reservoirs moves the pistons of the triple valves, so as to first close the passages from the triple valves to the brake pipe, and at the same time close the release ports of all the brake cylinders, and then open the passages from h e auxiliary reservoirs to the brake cylinders, the pistons of which are forced out by the compressed air thereby admitted to the brake cylinders, applying the brakes by means of suitable levers and connections, all of which mechanism is fully shown in various letters patent granted to me.
After a further reference to the drawings, he again states that, 'so far as hereinbefore described, the triple valve accords in all substantial particulars with, and is adapted to operate similarly to, those of my letters patent Nos. 168,359, 172,064, and 220,556; and, in order that it may perform the further functions requisite in the practice of my present invention, it is provided with certain additional members, which will now be described.' These additional members, which are said to be for the purpose of effecting the admission of air directly from the main air pipe to the brake cylinder when it is desired to apply the brakes with great rapidity and full force, consist of (1) a passageway through which air can be admitted directly from the main air (or train) pipe to the brake cylinder without passing through the auxiliary reservoir; and (2) an auxiliary valve in connection with such passage, that, when the triple-valve piston makes a short or preliminary movement, the passageway direct from the train pipe to brake cylinder, controlled by said valve, will not be opened, while in the event of a long or full movement of the piston, or 'further traverse,' as it is called, such direct passageway will be thrown wide open to the admission of trainpipe air, and the brake cylinder will be rapidly filled thereby.
'In the event, however, of its becoming necessary to apply the brakes with great rapidity and with their greatest available force, the engineer, by means of the valve at his command, instantly discharges sufficient air from the front end of the main air pipe to effect a sudden reduction of pressure of about twenty pounds per square inch therein, whereupon the piston, 12, of the triple valve, is forced to the extreme limit of its stroke in the direction of the drain cup, 19, carrying with it the stem, 36, and auxiliary slide valve, 41, which instantly uncovers the port, 42, and discharges air from the main air pipe through the opening of the check valve, 49, and the passages, 46 and 48, to the brake cylinder; and, each car being provided with one of these devices, it will be seen that they are successively moved with great rapidity,—there being, practically, on a train of fifty cars, fifty openings for discharging compressed air from the main pipe, instead of the single opening heretofore commonly used. Not only is there a passage of considerable size opened from the brake pipe on each car, whereby the pressure is more quickly reduced, but the air so discharged is utilized in the performance of preliminary work; it being found, in practice, that the air so taken from the pipe will exert a pressure of about twenty-five pounds in the brake cylinders. When the piston, 12, arrives at the extremity of its stroke as above specified, the supplemental port, 35, of the slide valve, 14, is brought into communication with the port, 33, and passages, 22 and 16, which serves to discharge the reservoir pressure into the brake cylinder, thereby augmenting the pressure already exerted in the brake cylinder by the air admitted from the main air pipe. Upon the reduction of the pressure in the main air pipe below that in the brake cylinders, as by the breaking in two of the train, the check valve, 49, closes communication between the passages, 46 and 18, thereby preventing the return of the air from the brake cylinder to the main air pipe. The feed opening for the admission of air from the auxiliary reservoir to the brake cylinder is purposely made of comparatively small diameter, it having been determined by experiment that the initial application of the brakes should not be made with maximum force, and this opening may be made of such size as to apply the brakes exactly in accord with the requirements of the most efficient work.
'In using the terms 'triple valve' and 'triple-valve device,' I refer to a valve devide, however specifically constructed, having a connection with the main air or brake pipe, another with an auxiliary reservoir or chamber for the storage of power, and another with a brake cylinder, or its equivalent, for the utilization of the stored power, and with a release or discharge passage for releasing the operative power from the brake cylinder, whether the valves governing these passages or connections are arranged in one or more cases, and are moved by a piston, or its equivalent, or by a series of pistons, or their equivalents; there being numerous examples in the art of constructions varying materially in appearance, whereby these functions are performed, both in plenum and vacuum brake mechanisms.
The above drawings are somewhat clearer than those annexed to the patent, and exhibit the triple valve and its connections in three positions, viz.: No. 13, released, or 'brakes off'; No. 14, ordinary service application; and No. 16, 'quick-action' position.
'(1) In a brake mechanism, the combination of a main air' pipe, an auxiliary reservoir, a brake cylinder, a triple a lve, and an auxiliary valve device, actuated by the piston of the triple valve, and independent of the main valve thereof, for admitting air in the application of the brake directly from the main air pipe to the brake cylinder, substantially as set forth.
The joint and several answer of the Boyden Brake Company and the individual defendants admitted that such company was engaged in manufacturing and selling a fluid-pressure brake, but denied that the same was an infringement upon complainants' patent, and also denied that Westinghouse was the original inventor of the mechanism covered by the patent, and alleged that an apparatus substantially identical in character had been previously granted Westinghouse, March 5, 1872 (No. 124,404), and that a like apparatus was previously described in the following patents issued to Westinghouse, viz.: No. 138,827, May 13, 1873; No. 144,006, October 28, 1873; No. 168,359, October 5, 1875; No. 172,064, January 11, 1876; No. 220,556, October 14, 1879,—and also in three patents to other parties, not necessary here to be specifically mentioned.
The answer further denied any infringement of the first, fourth, and fifth claims of the patent sued upon (No. 360,070), and, with respect to the second claim, averred the same to be invalid because the combination of parts therein named is inoperative to perform, and incapable of performing, the function set forth in said claim, and that, if the said claim be considered merely as the combination of parts therein set forth, and without reference to the function described as performed by it, it is invalid for the reason that the same combination of parts is shown in most of the prior patents above cited, and has been publicly used by the complainants for a long time prior to the date of the said letters patent No. 360,370.
Upon a hearing in the circuit court upon the pleadings and proofs, that court was of opinion that the second claim was valid, and had been infringed, but that defendants had not infringed claims 1 and 4, and as to those the bill was dismissed. 66 Fed. 997. From the decree entered in pursuance of this opinion both parties appealed to the court of appeals for the Fourth circuit, which affirmed the action of the circuit court with respect to the first and fourth claims, but reversed it with respect to the second claim, and dismissed the bill. 25 U. S. App. 475, 17 C. C. A. 430, and 70 Fed. 816. Whereupon complainants applied for, and were granted, a writ of certiorari.
Full copies the prini pal Westinghouse patents are printed in Westinghouse Air-Brake Co v. New York Air-Brake Co., 26 U. S. App. 248, 11 C. C. A. 528, and 63 Fed. 962, and of the Boyden patents in the report of this case in 25 U. S. App. 475, 17 C. C. A. 430, and 73 Fed. 816.
George H. Christy and F. H. Betts, for Westinghouse.
Lysander Hill, Hector T. Fenton, Philip Manro, and Melville Church, for Boyden Co.
The original substitution of the air brake for the old hand brake was itself almost a revolution; but the main difficulty seems to have arisen in the subsequent extension of that system to long trains of freight cars, in securing a simultaneous application of brakes to each of perhaps 40 or 50 cars in such a train, and finally in bringing about the instantaneous as well as simultaneous application of such brakes in cases of emergency, when the speediest possible stoppage of the train is desired to avoid a catastrophe.
Patent No. 88,929, issued April 13, 1869, appears to have been the earliest of the Westinghouse series. This brake, known as the 'straight air brake,' consisted of an aircompressing pump, operated by steam from the locomotive boiler, by which air was compressed into a reservoir, located under the locomotive, to a pressure of about 80 pounds to the square inch. This reservoir, being still in sue, is now known as the 'main reservoir.' From this reservoir an air pipe, usually called the 'train pipe,' led into the cab, where the supply of air was regulated by an 'engineer's valve,' and thence down and back under the tender and cars; being united between the cars by a flexible hose with metal couplings, rendering the train pipe continuous. These couplings were automatically detachable; that is, while they kept their grip upon each other under the ordinary strains incident to the running of the train, they would readily pull apart under unusual strains, as when the car coupling broke, and the train pulled in two.
From the train pipe of each car a branch pipe connected with the forward end of a cylinder called the 'brake cylinder,' which contained a piston, the stem of which was connected with the brake levers of the car. This piston was moved and the brakes applied by means of compressed air admitted, through the train pipe and its branches, into the forward end of the brake cylinder. When the brakes were to be applied, the engineer opened his valve, and admitted the compressed air into the train pipes and brake cylinders, whereby the levers were operated and the brakes applied. To release the brakes, he reversed the valve, whereby the compressed air escaped from the brake cylinders, and flowed forward along the train pipe to the escape port of the engineer's valve, and thence into the atmosphere. Upon the release of the compressed air, the pistons of the brake cylinders were forced forward again by means of springs, and the brake shoes removed from the wheels. By means of this apparatus the train might be wholly stopped or slowed down by a full or partial application of the brakes. As between a full stop and a partial stop, or slow speed, there was only a question of the amount of air to be released from the main reservoir. The validity of this patent was sustained by the circuit court for the Northern district of Ohio (Mr. Justice Swayne and Judge Welker sitting) in Westinghouse v. Air-Brake Co., 9 O. G. 538, Fd . Cas. No. 17,450. The court said, in its opinion, that, while Westinghouse was not the first to conceive the idea of operating railway brakes by air pressure, such fact did not detract at all from his merits or rights as a successful inventor; that the new elements introduced by him 'fully substantiated his pretensions as an original and meritorious inventor, and entitled him, as such, to the amplest protection of the law'; and that it appeared from the record and briefs that he was the first to put an air brake into successful, actual use.
While the application of this brake to short trains was reasonably successful, the time required for the air to pass from the locomotive to the rear cars of a long train (about one second per car) rendered it impossible to stop the train which the requisite celerity, since in a train of 10 cars it would be 10 seconds before the brakes could be applied to the rear car, and, to a freight train of 50 cars, nearly a minute. While the speed of the foremost car would be checked at once, those in the rear would proceed at unabated speed, and, in their sudden contact with the forward cars, would produce such shocks as to often cause damage. As a train moving at the rate of 50 miles an hour makes over 70 feet per second, a train of 50 cars would run half a mile before the brakes could be applied to the rear car. So, too, if the rear end of the train became detached from the forward end by the rupture of the train pipe or couplings, the brakes could not be applied at all, since the compressed air admitted to the train pipe by opening the engineer's valve would escape into the atmosphere without operating the brakes, or, if the brakes were already applied, they would be instantly released when such rupture occurred.
The first step taken towards the removal of these defects resulted in what is known as the 'automatic brake,' described first in patent No. 124,404 in a crude form, and, after several improvements, finally culminating in patent No. 220,556 of 1880. The salient features of this brake were an auxiliary reservoir beneath each are for the reception and storage of compressed air from the main reservoir, and a triple valve, so called, automatically controlling the flow of compressed air in three directions, by opening and closing, at the proper times, three ports or valve openings, viz.: (1) A port or valve, known as the 'feeding-in valve,' from the train pipe to the auxiliary reservoir, allowing the auxiliary reservoir to fill so as to be ready when the brakes were applied; (2) a port or valve from the auxiliary reservoir to the brake cylinder, which allowed a flow of compressed air to apply the brakes, and was called the 'main valve'; (3) a port or valve from the brake cylinder to the open air, denominated the 'release valve,' to be opened when it was desired to release the brakes.
The operation of these valves was as follows: Before the train starts, compressed air from the main reservoir is permitted to flow back through the train pipe, and through valve No. 1, for the purpose of charging the auxiliary reservoir beneath each car with a full working pressure of air. When it is desired to apply the brakes, the engineer's valve is shifted, and the air in the train pipe is allowed to escape into the atmosphere at the engine. Thereupon the compressed air in the auxiliary reservoir closes valve No. 1, leading to the train pipe, and opens the main valve, No. 2, from the auxiliary reservoir to the brake cylinder, whereby the piston of that cylinder operates upon the brake levers and applies the brakes. By this use of the auxiliary reservoirs a practically simultaneous application of the brakes is secured for each car. This application of the brakes is secured, not by direct application of compressed air from the engine through the train pipe, but by a reverse action, whereby the air is allowed to escape from the train pipe towards the engine; the pressure being applied by the air escaping from the auxiliary reservoirs. It also results h at, if a train should pull in two, or a car become detached, the same escape of air occurs, the same action takes place automatically at the broken part, and the same result follows by the escape of the compressed air through the separated couplings. When it is desired to release the brakes, the engineer's valve is again shifted, and the compressed air not only opens valve No. 1, from the train pipe to the auxiliary reser, voir, but valve No. 3, from the brake cylinder to the open air, which allows the air from the brake cylinder to escape, and thus release the brake.
While the automatic brake had thus obviated the most important defects of the old or straight air brake, and came into general use upon passenger trains throughout the country, it was found, in practice, upon long freight trains, that the air from the auxiliary reservoirs did not act with sufficient promptness upon the brakes of the rear cars, whee a particularly speedy action was required, and that it would be necessary to devise some other means for cases of special emergency. In the business of transporting freight over long distances, the tendency has been in the direction of increasing the load by using stronger and heavier cars and larger locomotives. Upon a long train of this kind, composed of 30 to 50 cars, a demand was made for quicker action in cases of emergency than had yet been contemplated, although, for ordinary work, such as checking the speed of a train while running, holding it at a slow speed on a down grade, and also for making the ordinary station stops, the automatic brake was still sufficient, and produced satisfactory results, even in the equipment of long and heavy trains. But, however effective for ordinary purposes, the automatic brake did not sufficiently provide for certain emergencies, requiring prompt action, and therefore failed in a single important particular.
Upon examination of these defects, it was found that they could only be remedied by securing (1), in cases of emergency, a more abundant discharge of compressed air into the brake cylinder; and (2) an escape of air near to each triple valve without requiring the escaping air to travel all the way back to the engine. The latter device having been already embodied in patent No. 217,838, these features Mr. Westinghouse introduced into the patent in suit, by which a passage was opened directly from the train pipe, filled from the main reservoir on the engine, to the brake cylinder, through which, in cases of emergency, the train-pipe air, instead of being discharged into the atmosphere, could pur directly from the train pipe into the brake cylinder. This operation resulted in charging the brake cylinder and applying the brakes more quickly than before; and also, by reason of the fact that the filling of the brake cylinder from the train pipe on one car made what was, in effect, a local vent for the release of pressure sufficient to operate the valve on the next car behind, each successive valve operated more quickly than when a diminution of pressure was caused by an escape of air only at the locomotive. The direct passage of the air from the train pipe to the brake cylinder was effected by a valve, 41, colored red in the above diagrams, which is never opened except in cases of emergency. In ordinary cases, when the brakes are desired to be applied, sufficient air is released from the train pipe to open the passage from the auxiliary reservoir to the brake cylinder by what is called a 'preliminary traverse' of the piston, 12; but, when a quick action is required, sufficient air is drawn from the train pipe, not only to open this passage, but, by a further traverse of the piston, to shove valve 41 off its port, and introduced air directly from the train pipe to the brake cylinder, as shown in the third drawing above set forth.
In the foregoing skeleton drawings, from which all details of construction and all figures of reference not necessary for a clear understanding of the structure are omitted, the essential parts are colored, so that their changes of position in the different stages of action can be easily followed.
The access of train-pipe air is shown located at the right end of the structure, instead of the left, as in the patent drawings, simply for greater clearness. Its course from the train pipe to the auxiliary cylinder is through the small port above the upper arm of the piston, 12.
The quick-action valve is colored red. Its office is to admit train-pipe air to brake cylinder.
There is also shown, in yellow, what is known as the 'graduating valve,' the function of which will be hereafter explained. As at present used, the triple valve is in rel ity a quadruple valve.
Air flowing from auxiliary reservoir to brake cylinder, in 'service' application of the brakes, by red line; and air flowing from train pipe to brake cylinder in 'quick-action' application, by blue line.
We are now in position to take up the several claims of the patent in suit, and their defenses thereto. It may be stated generally that the position of complainants in this connection is that the novel feature of this patent, in respect to which they are entitled to be protected, is the opening of a passage directly from the train pipe to the brake cylinder, without passing through the auxiliary reservoir, and without reference to the means by which such passageway is controlled. Defendants' theory is that they are limited to such passageway when governed by the auxiliary valve, 40,—a device which, although of no utility as arranged in the patent in suit, became afterwards exceedingly useful, when further combined with the supplementary piston shown in patent No. 376,837. The further inference is that, as they do not use the auxiliary valve of this patent, they cannot be held liable as infringers.
Complainants' case must rest either upon the theory that the admission of compressed air directly from the train pipe to the brake cylinder is patentable as a function, or that the means employed by the defendants for that purpose are a mechanical equivalent for the auxiliary valve, 41, described in the patent.
In the construction of this claim, the district judge was of opinion that it was broad enough to cover other devices in which air was admitted directly from the train pipe to the brake cylinder by the further traverse of the piston actuating a valve admitting such air, and that the defendants could not exculpate themselves from the charge of infringement, from the fact that in their device the train-pipe air was admitted through the triple-valve chamber, and not through a by-passage, nor by the fact that in their device the further traverse of the piston opens the main valve in a special manner, which produces the same result, but does not make use of a separate auxiliary valve.
The claim in question is, to a certain extent, for a function, viz. the admission of air directly from the train pipe to the brake cylinder, and is only limited to such function when performed by the further traverse of the piston of the triple valve. This limitation, however, does not obviate the objection that the means are not fully and specifically set forth for the performance of the function in question.
The difficulty we have found with this claim is this: That, if it be interpreted simply as a claim for the function of admitting air to the brake cylinder directly from the train pipe, it is open to the objection (held in several cases to be fatal) that the mere function of a machine cannot be patented.
'It is for the discovery or invention of some practicable method or means of producing a beneficial result or effect that a patent is granted, and not for the result or effect itself. It is when the term 'process' is used to represent the means or method of producing a result that it is patentable, and it will include all methods or means which are not effected by mechanism or mechanical combinations.
'But the term 'process' is often used in a more vague sense, in which it cannot be the subject of a patent. Thus, we say that a board is undergoing the process of being planed; grain, of being ground; iron, of being hammered or rolled. Here the term is used subjectively or passively, as applied to the material operated on, and not to the method or mode of producing that operation, which is by mechanical means, or the use of a machine, as distinguished from a process.
Most or the prior authorities upon this subject are reviewed in the recent case of Locomotive Works v. Medart, 158 U. S. 68, 15 Sup. Ct. 745, in which it was also held that a valid patent could not be obtained for a process which involved nothing more than the operation of a piece of mechanism, or the function of a machine. See, also, to the same effect, Wicke v. Ostrum, 103 U. S. 461, 469. These cases assume, although they do not expressly decide, that a process, to be patentable, must involve a chemical or other similar elemental action; and it may be still regarded as an open question whether the patentability of processes extends beyond this class of inventions. Where the process is simply the function or operative effect of a machine, the above cases are conclusive against its patentability; but where it is one which, though ordinarily and most successfully performed by machinery, may also be performed by simple manipulation,—such, for instance, as the folding of a paper in a peculiar way for the manufacture of paper bags, or a new method of weaving a hammock,—there are cases to the effect that such a process is patentable, though none of the powers of nature be invoked to aid in producing the result. Eastern Paper-Bag Co. v. Standard Paper-Bag Co., 30 Fed. 63; Machine Co. v. Waterbury, 39 Fed. 389; Travers v. Cordage Co., 64 Fed. 771. This case, however, does not call for an expression of our opinion upon this point, nor even upon the question whether the function of admitting air directly from the train pipe to the brake cylinder be patentable or not, since there is no claim made for an independent process in this patent, and the whole theory of the specification and claims is based upon the novelty of the mechanism.
But, if the second claim be not susceptible of the interpretation that it is simply for a function, then the performance of that function must be limited to the particular means described in the specification for the admission of air from the train pipe to the brake cylinder. This we understand to be the theory of the defendants, and this raises the same question which is raised under the first and fourth claims,—whether defendants' device contains the auxiliary valve of the Westinghouse patent, or its mechanical equivalent.
In this view, it becomes unnecessary to express an opinion whether the second claim be valid or not, since, in the aspect of the case most favorable to the complainants, it is necessary to read into it something which is not found there, or, in the language of complainants' brief, 'to refer back to the specification,—not, it is true, for a slavish adoption of the identical instrumentalities therein described, but for the understanding of the essential and substantial features of the means therein illustrated.' In thus reading the specification into the claim, we can adopt no other construction than to consider it as if the auxiliary valve were inserted in the claim in so many words, and then to inquire whether the defendants make use of such valve, or its mechanical equivalent.
There are two other facts which have a strong bearing in the same connection, and preclude the idea that this can be interpreted as a claim for a function, without reading into it the particular device described in the specification.
One of these is that the claim is for a triple-valve device, etc., for admitting air from the main air pipe to the brake cylinder, 'substantially as set forth.' These words have been uniformly held by us to import into the claim the particulars of the specification, or, as was said in Seymour v. Osborne, 11 Wall. 516, 547: 'Where the claim immediately follows the description of the invention, it may be construed in connection with the explanations contained in the specifications; and, where it contains words referring back to the specifications, it cannot be properly construed in any other way.' In that case it was held that a claim which might otherwise be bad, as covering a function or result, when containing the words 'substantially as described,' should be construed in connection with the specification, and, when so construed, was held to be valid. To the same effect is the Corn-Planter Patent, 23 Wall. 181, 218.
While it is true that no claim is formally made for the admission of train-pipe air directly to the brake cylinder, as a method or process, a construction is given by the complainants and the circuit court to the second claim, which eliminates the mechanical features described, and one which could only be supported upon the theory that the claim was for a method or process. If the mechanism described by Westinghouse, and partieularly the auxiliary valve, be not essential to the validity of the second claim, then it could only be supported upon the theory that it was for the process of admitting train-pipe air directly to the brake cylinder.
These two claims are practically little more than different expressions of one and the same invention. In both of them there is a main air pipe, an auxiliary reservoir, a brake cylinder, a triple valve and piston, described in the fourth claim as 'fixed upon a stem and working in a chamber' in a case or chest, and an auxiliary valve; and in the fourth claim, also, a case or chest, which contains the whole device, and is immaterial.
To what liberality of construction these claims are entitled depends, to a certain extent, upon the character of the invention, and whether it is what is termed, in ordinary parlance, a 'pioneer.' This word, although used somewhat loosely, is commonly understood to denote a patent covering a function never before performed, a wholly novel device, or one of such novelty and importance as to mark a distinct step in the progress of the art, as distinguished from a mere improvement or perfection of what had gone before. Most conspicuous examples of such patents are the one to Howe, of the sewing machine; to Morse, of the electrical telegraph; and to Bell, of the telephone. The record in this case would indicate that the same honorable appellation might be safely bestowed upon the original air brake of Westinghouse, and perhaps, also, upon his automatic brake. In view of the fact that the invention in this case was never put into successful operation, and was to a limited extent anticipated by the Boyden patent of 1883, it is perhaps an unwarrantable extension of the term to speak of it as a 'pioneer,' although the principle involved subsequently, and through improvements upon this invention, became one of great value to the public. The fact that this invention was first in the line of those which resulted in placing it within the power of an engineer, running a long train, to stop in about half the time and half the distance within which any similar train had stopped, is certainly deserving of recognition, and entitles the patent to a liberality of construction which would not be accorded to an ordinary improvement upon prior devices. At the same time, as hereinafter observed, this liberality must be exercised in subordination to the general principle above stated,—that the function of a machine cannot be patented, and hence that the fact that the defendants' machine performs the same function is not conclusive that it is an infringement.
The device made use of by the defendants is exhibited in patents No. 481,134 and No. 481,135, both dated August 16, 1892, and both of which were granted after the commencement of this suit. There are two forms of this patent, one of which, illustrated in patent No. 481,135, is here given in its three positions,—of release (20), service application (21), and quick action (22).
of air from the train pipe to the brake cylinder through the feeding-in valve, 26; second, for the passage of air from the auxiliary reservoir to the brake cylinder through the apertures, i, j, k, in the stem slide valve, 18; and, third, for the release of air from the brake cylinder to the exhaust port by means of valve, 17, colored green. Whether this device has an auxiliary valve, or not, is one of the main questions in the case; complainants' theory being that poppet valve, 22, is an auxiliary valve, while defendants' claim is that it is in reality the main valve.
D The operation of this device is best shown by the foregoing skeleton drawings.
The auxiliary reservoirs are charged by air under pressure, entering from the train pipe, raising and passing through the feeding-in value piston, 26, and flowing slowly into and through the passage, A, to the auxiliary reservoir, until such reservoir is filled. In this condition the brake cylinder is empited and opened to the atmosphere through the exhaust passage. G.
In order to apply the brakes gradually, so as to slacken speed or made an ordinary stop, air pressure in the train pipe is reduced slightly (say from 3 to 5 pounds) by action of the engineer's value, and the reduction of pressure on the right side of the piston, 29, causes in piston to make what is termed a 'preliminary traverse' to the position shown in diagram 'Service Application.' Such preliminary traverse pulls the stem slide valve, 18, to the right, and opens the apertures, i, j, and k (one of these apertures being to the right, and the other to the left, of valve 22), and through these apertures air rushes from the auxiliary reservoir to the brake cylinder; but the poppet valve, 22, still remains upon its seat.
If quick action be required, the pressure in the train pipe is suddenly lowered to the extent of 15 or 20 pounds, and the traveling piston, 29, instead of making a preliminary traverse to the intermediate position shown in the 'Service Application,' makes a full traverse to the extreme right, the effect of which is that the valve, 22, is pulled off its seat by the collar, M, and a large passage is opened to the brake cylinder under the valve, 22, and around the stem, 18. The result is, as shown in the last diagram, that not only does the air in the auxiliary reservoir escape in full volume to the brake cylinder, but air from the train pipe rushes directly to the brake cylinder through the large passage, F, into the chamber, C, and under valve, 22.
The argument of the defendants in this connection is that in this device there is no auxiliary valve or by-passage, but the quick-action result is effected simply by proportioning the ports and passages of the old triple valve, and using a fixed partition, 9, to divide the piston chamber, D, from the main-valve chamber, C; that it is this partition which produces the quick action, and that such partition is not a valve, nor the mechanical equivalent of a valve, but merely a metal ring screwed immovably into the triple-valve casing, and serving to divide the piston chamber from the main-valve chamber; that this partition was a new element, never before found in triple valves, and introduced a new principle and mode of operation, totally different from anything ever invented by Mr. Westinghouse or any other inventor; and that its effect is to make valve, 22, termed by them the 'main valve,' admit the train-pipe air to the brake cylinder at the same time that it admits the auxiliary air thereto.
It is claimed that, in embodying this new principle, Mr. Boyden adopted the form of triple valve shown in the expired Westinghouse patent, No. 141,685 (1873), in which the main valve, 22, is of the poppet form, and the separate valve, 17, controlled by a rod sliding through the main valve, is employed for releasing the brakes. For charging the auxiliary reservoir, he adopted, from the expired Westinghouse patent, No. 144,006 (1873), a check-valved feed passage through the triple-valve piston, but arranged the feed passage and its check valve, 26, in a tubular extension, F, of the piston, and substantially in the form shown in Boyden patent, No. 280,285 (1883). He also provided a sensitive graduating valve, similar in results to the graduating valve, e, of the Westinghouse patent No. 220,556 (1879), by so arranging a small passage, 40, in the sliding stem, which actuates the release valve, that such passage will be opened and closed by the sliding of such stem through the main valve, 22. As thus constructed, the triple value operates much the same § that of patent No. 220,556, and, like the latter, is incapable of quick action.
In both the complainants' and defendants' devices there is (1) a feeding-in valve to charge the auxiliary reservoir; (2) a valve, which complainants call their main value,' and which the defendants denominate a 'graduating valve,' which is opened by the preliminary traverse of the piston to admit reservoir air to the brake cylinder; (3) a release valve which discharges air from the brake cylinder to the atmosphere; and (4) a quick-action valve,—41 in the complainants' patent, and 22 in the defendants',—which is opened by the further traverse of the piston to admit train-pipe air to the brake cylinder. In defendants' patent it may also be used to admit auxiliary reservoir air to the brake cylinder.
One of the main controversies in the case turns upon the construction and operation of the poppet valve, 22, called by the defendants their 'main valve.' Complainants insist that the office of their main valve is performed by the stem slide valve, 18, of defendants' patent, and by its apertures, i, j, and k, through which air passes from the auxiliary reservoir to the brake cylinder, and that the poppet valve, 22, is only called into action in emergency cases, when a large quantity of air is suddenly withdrawn from the train pipe, and the valve is unseated by the traverse of the piston to the extreme right.
There is no doubt that the function of admitting air from the auxiliary reservoir to the brake cylinder, which is performed in the Westinghouse patent by what the complainants term the 'main valve' (aided, however, by the graduating value) is, in ordinary cases, performed principally, if not altogether, by the stem slide valve, 18, and its three ports, i, j, k, of the Boyden patent, which defendants term their 'graduating valve.' It is equally clear that in emergencies, where quick action is required, air, which in the Westinghouse patent passes through auxiliary valve, 41 (opened by the further traverse of the piston), in the Boyden patent finds its way through the poppet value,22, which has also been lifted from its seat by the further traverse of the piston.
One of the main differences between the two devices is this: That in the preliminary traverse of the piston of the Westinghouse patent there is a movement first of the graduating valve to open its port from the auxiliary reservoir, and then of the main valve, carrying the graduating valve, also, with it, to open a passage to the brake cylinder, while in the Boyden patent it is only the graduating valve which is opened by the preliminary traverse of the piston. In doing this, the graduating valve moves through the poppet valve, but does not lift it from its seat. In emergency cases not only do the graduating valve and the main valve of the Westinghouse patent move as before, but by the extreme traverse of the piston the auxiliary valve, 41, is shoved from its seat, and a separate passage is opened for the air from the train pipe to the brake cylinder. In the Boyden patent, however, the extreme traverse of the piston lifts the poppet valve from its seat, and opens a wide passage to the brake cylinder, not only for the air from the auxiliary reservoir, but, through the peculiar operation of the partition, 9, and its aperture, B, directly from the train pipe. As the graduating valve of the Boyden patent practically does all the work in ordinary cases, and the poppet valve is only called into action in emergency cases, the latter is practically an auxiliary valve, by which we understand, not necessarily an independent valve, nor one of a particular construction, but simply a valve which in emergency cases is called into the assistance of the graduating valve. In this particular the poppet valve of the Boyden device performs practically the same function as the slide valve, 41, of the Westinghouse. It is not material in this connection that it is a poppet valve, while the other is a slide valve, since there is n invention in substituting one valve or spring of familiar shape for another (Imhaeuser v. Buerk, 101 U. S. 647, 656); nor that in one case the piston pushes the valve off its seat, and in the other pulls it off; nor is it material that this poppet valve may have been used in prior patents to perform the function of a main valve, so long as it is used for a different purpose here. Indeed, this valve seems to have been taken bodily from Westinghouse patent No. 141,685, where it was used as a main valve, and the stem valve, 18, with its ports, i, j, k, added for ordinary uses, and the poppet valve thus converted from a main valve to an auxiliary valve.
We have not overlooked in this connection the argument that the poppet valve, 22, is also sometimes used for graduating purposes; but it is not commonly so used, and appears to be entirely unnecessary for that purpose. It seems to be possible to move the piston, 29, to its extreme traverse so slowly, and hence to open valve, 22, so gradually, that the pressure in the chamber, C, will be reduced so slightly that the train-pipe air will not have sufficient force to throw open the check valve, 26; and hence in such case no train-pipe air will be admitted directly to the brake cylinder, which will be filled with auxiliary reservoir air only. But, as a matter of fact, this seldom or never takes place in the practical operation of the device, and is an unnecessary and wholly unimportant incident, and for all practical purposes valve, 22, is solely a quick-action valve. As this valve is actuated by the piston of the triple valve, and in such action is independent of the main valve, it meets the demand of the first claim of the patent; and as it is actuated by the piston-stem, and controls communication between passages leading to connections with the main air pipe and with the brake cylinder, it seems also to be covered by the fourth claim.
But, even if it be conceded that the Boyden device corresponds with the letter of the Westinghouse claims, that does not settle conclusively the question of infringement. We have repeatedly held that a charge of infringement is sometimes made out, though the letter of the claims be avoided. Machine Co. v. Murphy, 97 U. S. 120; Ives v. Hamilton, 92 U. S. 431; Mory v. Lockwood, 8 Wall. 230; Elizabeth v. Pavement Co., 97 U. S. 137; Sessions v. Romadka, 145 U. S. 29, 12 Sup. Ct. 799; Hoyt v. Horne, 145 U. S. 302, 12 Sup. Ct. 922. The converse is equally true. The patentee may bring the defendant within the letter of his claims, but if the latter has so far changed the principle of the device that the claims of the patent, literally construed, have ceased to represent his actual invention, he is as little subject to be adjudged an infringer as one who has violated the letter of a statute has to be convicted, when he has done nothing in conflict with its spirit and intent. 'An infringement,' says Mr. Justice Grier in Burr v. Duryee, 1 Wall. 531, 572, 'involves substantial identity, whether that identity be described by the terms, 'same principle,' same 'modus operandi,' or any other. * * * The argument used to show infringement assumes that every combination of devices in a machine which is used to produce the same effect is necessarily an equivalent for any other combination used for the same purpose. This is a flagrant abuse of the term 'equivalent."
Not only is this sound as a general principle of law, but it is peculiarly appropriate to this case. Under the very terms of the first and fourth claims of the Westinghouse patent, the infringing device must not only contain an auxiliary valve, or its mechanical equivalent, but it must contain the elements of the combination, 'substantially as set forth.' In other words, there must not only be an auxiliary valve, but substantially such a one as is described in the patent, i. e. independent of the triple valve. Not only has the Boyden patent a poppet instead of a slide valve,—a matter of minor importance,—but it performs a somewhat different function. In the Westinghouse patent the valve is not in the line of travel between the auxiliary reservoir and the brake cylinder, and admits train-pipe air only. In the Boyden patent it is in the line of travel, both from the auxiliary reservoir and from the train pipe, and admits both currents of air to the brake cylinder. The by-passage, to which the auxiliary reservoir is merely an adit, is wholly wanting in the Boyden device; both currents of air uniting in chamber, C, and passing to the brake cylinder together, through the poppet valve.
Conceding that the functions of the two devices are practically the same, the means used in accomplishing this function are so different that we find it impossible to say, even in favor of a primary patent, that they are mechanical equivalents. While the poppet valve, which, for the purposes of this case, we may term the auxiliary valve, is, in its operation, independent of the main valve, the word 'independent' in the claims of the Westinghouse patent evidently refers to a valve auxiliary to the triple valve, and independently located as well as operated. The difference is that in one case the air from the train pipe is introduced into the brake cylinder separately and independently from the air from the auxiliary reservoir, while in the other case they unite in the chamber, C, and pass through the same valve to the brake cylinder. In the Westinghouse patent there is one valve operated by the direct thrust of the piston, opening a bypassage; in the other, there is a poppet valve also opened by the piston, and another valve, 26, opened by the pressure maintained upon the outside of the partition, 9.
It is claimed, however, by the complainants, that Boyden was not the inventor of the differential pressure theory; that there is such a differential pressure in their own patent, caused by the fact that the air from the auxiliary reservoir in passing to the brake cylinder travels through a restricted port, 35, and, as the entrance to the brake cylinder is through a much larger port, the air is taken up by it much more rapidly than it is supplied by the restricted port, which reduces the pressure in the by-passage so much that when the quick-action valve, 41, is opened, the pressure from the trainpipe air is sufficient to open the valve, 49, and admit a full volume of train-pipe air, at a pressure of 55 pounds, to the brake cylinder. The fact, however, that no suggestion is made in the patent of such a function of the restricted port, 35, indicates either that none such had been discovered, or that it was not considered of sufficient importance to mention it. Indeed, it seems to have been an afterthought, suggested by the necessity of an answer to defendants' argument, based upon their partition, 9. That, when the auxiliary valve is opened, there must be a difference in pressure above and below the check valve, 49, in order to open it, is manifest; yet this is rather an incident to the Westinghouse device, than the controlling feature that it is made in the Boyden patent. There is no partition, in the proper sense of the word,—certainly none located as in the Boyden device,—between the chambers, D and C, and no aperture in such partition opened for the express purpose of maintaining this differential pressure. If such differential pressure existed to the extent claimed in the Westinghouse patent, it certainly was not productive of the results flowing from the same device in the Boyden patent.
We are induced to look with more favor upon this device, not only because it is a novel one, and a manifest departure from the principle of the Westinghouse patent, but because it solved at once, in the simplest manner, the r oblem of quick action, whereas the Westinghouse patent did not prove to be a success until certain additional members had been incorporated into it. The underlying distinction between the two devices is that in one a separate valve and separate by-passage are provided for the train-pipe air, while in the other the patentee has taken the old triple (or quadruple) valve, and by a slight change in the functions of two of its valves, and the incorporation of a new element (partition 9), has made a more perfect brake than the one described in the Westinghouse patent. If credit be due to Mr. Westinghouse for having invented the function, Mr. Boyden has certainly exhibited great ingenuity in the discovery of a new and more perfect method of performing such function. If his patent be compared with the later Westinghouse patent, No. 376,837, which appears to have been the first completely successful one, the difference between the two, both in form and principle, becomes still more apparent, and the greater simplicity of the Boyden patent certainly entitles it to a favorable consideration. If the method pursued by the patentee for the performance of the function discovered by him would naturally have suggested the device adopted by the defendants, that is in itself evidence of an intended infringement; but, although Mr. Boyden may have intended to accomplish the same results, the Westinghouse patent, if he had had it before him, would scarcely have suggested the method he adopted to accomplish these results. Under such circumstances, the law entitles him to the rights of an independent inventor.
Upon a careful consideration of the testimony, we have come to the conclusion that the Boyden device is not an infringement of the complainants' patent, and the decree of the circuit court of appeals is therefore affirmed.
The history of the art discloses that the patent in suit was what is called a 'pioneer invention.' In it for the first time was brought to light a method or process which, by the co-operation of the air from the train pipe with that from the car reservoir, created the 'quick-action' brake. The patent, in its specification and claims, clearly described a machine or mechanical combination whereby the invention was exemplified or rendered operative.
It is not an unwarrantable extension of the term to speak of this invention in suit as a pioneer, since it is pratically conceded in this case, and justly observed by the court below, 'one of the highest value to the public,' and conspicuously one 'which entitles the proprietor to a liberal protection from the courts in construing the claim.' The very fact that this invention resulted in placing it within the power of an engineer, running a long train, to stop in about half the time and half the distance within which any similar train had been stopped, is certainly deserving of recognition. The claims of such patents have from time out of mind been allowed a liberal construction, and considered as entitled to the fullest benefit of the doctrine of mechanical equivalents.
It in no wise detracts from the merit of this invention that later devices have been adopted which render its practical operation more efficient. The very term 'pioneer patent' signifies that the invention has been followed by others. A pioneer patent does not shut, but opens, the door for subsequent invention.
The particular patent in suit was, as I understand it to be admitted, an entire success in supplying passenger trains and short freight trains with a 'quick-action' brake; but, while it enabled even the longest freight trains to stop in half the time and half the distance previously occupied, there remained difficulties which required further devices to give to the invention the perfect success which it has nowa ttained.
I cannot assent to what is perhaps rather intimated than decided in the opinion of the court,—that what is called a "process,' in order to be patentable, must involve a chemical or other similar elemental action.' The term 'process or method,' as describing the subject of a patent, is not found in the statutes. No reason is given in the authorities, and I can think of none in the nature of things, why a new process or method may not be patentable, even though a mechanical device or a mechanical combination may be necessary to render the new process practicable. It seems to be used by the courts as descriptive of an invention which, from its novelty and priority in the art to which it belongs, is not to be construed as inhering only in the particular means described in the letters patent as sufficient to exemplify the invention and bring it into practical use.
In Machine Co. v. Lancaster, 129 U. S. 263, 9 Sup. Ct. 299, there was also a question of an alleged invention of a primary character, and wherein the invention was embodied in a mechanical combination; and it was held that in a pioneer patent, such as that of Morley, the patentee, the special devices set forth by Morley were not necessary constituents of the claims; that his patent was to receive a liberal construction, in view of the fact that he was a pioneer in the construction of an automatic button-sewing machine; and that his patent was not to be limited to the particular devices or instrumentalities described by him.
'After the construction first put upon the patent by the learned judges of the exchequer, I think the patent must be taken to extend to all machines, of whatever construction, whereby the air is heated intermediately between the blowing apparatus and the blast furnace. That being so, the learned judge was perfectly justified in telling the jury that it was unnecessary for them to compare one apparatus with another, because, confessedly, that system of conduit pipes was a mode of heating air by an intermediate vessel between the blowing apparatus and the blast furnace, and therefore it was an infringement of the patent.' Webst. Pat. Cas. 715.
Very applicable to the present case is the doctrine of Tilghman v. Procter, 102 U. S. 767. It was there held (overruling the case of Mitchell v. Tilghman, 19 Wall. 284) that a patent may be validly granted for carrying a principle into effect; and if the patentee suggests and discovers not only the principle, but suggests and invents how it may be applied to a practical result by mechanical contrivances and apparatus, and shows that he is aware that no particular sort or modification of form of apparatus is essential to obtain benefit from the principle, then he may take his patent for the mode of carrying it into effect, and is not under the necessity of confining himself to one form of apparatus.
'In this art, or, what is the same thing under the patent law, this process, this way of transmitting speech, electricity, one of the forces of nature, is employed; but electricity, left to itself, will not do what is wanted. The art consists in so controlling the force as to make it accomplish the purpose. It had long been believed that, if the vibrations of air caused by the voice in speaking could be reproduced at a distance by means of electricity, the speech itself would be reproduced and understood. How to do it was the question.
The conclusion justified by the authorities is that whether you call Westinghouse's discovery, that 'quick action' may be accomplished by the co-operation of the main-pipe air and that from the car reservoir, a 'process,' or a 'mode of operation,' yet if he was the first to disclose it, and to describe a mechanical means to give practical effect to the invention, he must be regarded as a pioneer inventor, and as entitled to protection against those who, availing themselves of the discovery, seek to justify themselves by pointing to mere differences in form in the mechanical devices used.
Much stress was laid in the argument on an alleged disclaimer by the patentee while the application was pending in the patent office, whereby, it is said, Westinghouse must be understood to have abandoned thes econd claim, or at any rate to have consented that that claim should be interpreted by the courts as if it contained an auxiliary valve as a material element in the claim.
There are cases, no doubt, in which it has been held that when a claimant has, under objection in the patent office, withdrawn certain claims, or has modified them by adding or striking out terms or phrases, and accepts a patent which does not grant the abandoned or unmodified claims, he cannot be heard to insist upon such a construction of the allowed claims as would cover what had been previously rejected. Shepard v. Carrigan, 116 U. S. 593, 6 Sup. Ct. 493; Roemer v. Peddie, 132 U. S. 313, 10 Sup. Ct. 98; Corbin Cabinet Lock Co. v. Eagle Lock Co., 150 U. S. 38, 14 Sup. Ct. 28.
An examination of the cited cases, however, will disclose, as I think, that they turned upon matters of construction,—in other words, were cases where it was questionable what the patent, as actually granted, meant. In such cases, as in other cases of ambiguity, it may be allowable to consult the application and file wrapper, and possibly written communications, which may throw light upon claims that are ambiguous, or capable of different constructions.
But, where the claims allowed are not uncertain or ambiguous, the courts should be slow to permit their construction of a patent, actually granted and delivered, to be affected or controlled by alleged interlocutions between the officers in the patent office and the claimant. No doubt, in proceedings to revoke or cancel a patent granted by inadvertence or by fraudulent representations, it would be competent to show what had taken place in the patent office pending the application. But when we consider that often the employees in the patent office are inexperienced persons, and that the mass of the business is so vast that it is impossible for the commissioner or the chief examiner to review it, except in a perfunctory way, it can be readily seen how dangerous it would be to modify or invalidate a patent, clear and definite in its terms, by resorting to such uncertain sources of information.
However this may be, I do not perceive that the matters alleged in the present case are entitled to any weight in the construction of the patent. Even if the letter of the claimant's attorney, written on January 19, 1887, can be looked to as helping us to understand the meaning of a patent granted on March 29, 1887, it only appears to be an argument as to the meaning or legal effect of the language used in the claims, and does not amount to a withdrawal or modification of them.
Accordingly the second claim of the patent is before us for construction on its own terms, and, to avoid protracting this discussion, the opinion of Judge Morris in the circuit court is referred to and adopted as a sound construction of that claim. 66 Fed. 997. This claim is not, as I read it, open to the objection that it aims to patent a principle. It sets forth the discovery that, by a co-operation of the air from the auxiliary reservoir and that from the main air pipe, the action of the brakes is quickened, and the air vented from the main air pipe directly to the brake cylinder.
But, even if the second claim must, as argued in the opinion of the court, be read, by reason of the letter of the claimant's attorney, as if it called for the auxiliary valve described in the first and fourth claims, and even if, when not so read, it can be regarded as void because simply for a function or principle, nevertheless the invention, as described in the other claims and specifications, is clearly set forth, and, under the evidence as to the state of the art, is entitled to be regarded as a pioneer. Regarding the second claim as a mere statement of the idea or invention, and the other claims as describing a form or combination of mechanism which embodies the invention and renders it operative, all the requisites of the law are sufficiently complied with.
The only remaining question is that of the infringement,a nd that is readily disposed of; for it is conceded in the opinion of the majority of the court that, if the patent in suit is entitled to a broad construction as a pioneer, embodying a new mode of operation, not limited to the particular means described in the specification, then the defendants' device is an adoption of the idea or principle of the Westinghouse patent with a mechanical equivalent or substitute for the auxiliary valve.
Upon the whole, I am of the opinion that the decree of the circuit court of appeals should be reversed, and that the cause should be remanded, with directions to restore the decree of the circuit court.

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