Electric Car Co. of America v. Hartford & W. H. R. Co.

87 F. 733, 1898 U.S. App. LEXIS 2738
U.S. Circuit Court for the District of Connecticut·Decided May 19, 1898·Published·Cited by 4 cases

Opinion

TOWNSEND, District Judge.

The patent in suit (No. 393,323, granted to complainants as assignees of George II. Condict) is for a controlling switch, adapted to be applied to electric motors. The issues herein relate to its use in connection with electrically propelled cars on ordinary trolley lines. The particular apparatus under consideration is the cylinder shaped switch or controller located on the ends of such cars. The current of electricity supplied from the generator and delivered to the motor is necessarily of unvarying potential; that is, it must always have a capacity to supply the full [734] amount of current required at any time. In the practical operation of such cars, however, it is generally unnecessary to use more than a small quantity of such current. Various constructions have been devised to regulate the supply of current according to the requirements of the motor. Originally the supply was regulated by coils of wire, known as “rheostatic” or “resistance” coils. In the first or series arrangement, the total resistance was the sum of the number of coils. In the second or parallel arrangement, the total resistance was decreased in proportion to the number of parallel paths. This method, known as the “rheostatic” or “dead resistance” method, was' defective, because of its waste of energy, inasmuch as the potential thus obstructed, and not expended in propelling the car, was converted into heat, and lost. A second method of controlling the current, called the “series parallel control method,” consisted in substituting for the rheostatic coils the coils of the motor itself. Inasmuch as the passage of the current through these coils develops' energy in the motor, they are called -“live resistance coils,” as distinguished from the rheostatic or dead resistance coils. By utilizing the motor coils, the objectionable element .of loss of energy was almost entirely obviated. These coils were either switched in series into a single-wire circuit carrying the current from generator to motor, or into parallel or multiple wire paths or circuits. This sec- ■ ond or series parallel method, while theoretically of great value, for various reasons, not necessary to be here considered, proved to be impracticable, and was abandoned. In the patent in suit the inventor, George H. Conflict, describes his invention as follows:

“This invention is particularly useful where the supply of electricity is great, — such, for instance, as when storage batteries or electric accumulators are used on cars, and in which the motors are regulated by varying their internal resistance, which may be done by connecting their coils in different ways. In practice, I have found that switches for regulating the power and speed of electric motors under these conditions were easily burned out, not only causing great annoyance in the operation of the cars or machine, but rendering the operator liable to injury. The trouble is mainly due to the fact that at the time of changing the motor connections the resistance of the motors' is more or less cut out,- and in making the new connections there is a great danger from sparking, which often short-circuits the connections, with danger of completely destroying the switch and burning out the motors. To overcome these objections, I have constructed my switch so that at the time of changing the connections I insert resistances more or less great according as to the resistance of the motor connections; that is to say, if the motor resistance is great, the auxiliary resistances would be small, and vice versa. I also so arrange the switch that the resistances art-all cut out of circuit as soon as the new motor connection is made. Their function is to reduce the current flowing, so that at the time of making the change in the motor connections the current is small compared with what it would' be if- these resistances were not inserted; and, furthermore, these resistances are gradually cut in and out,- so as not to suddenly change the resistance to the current beyond a given amount. Another portion of my invention is the-reversing switch, which is arranged in the same frame olease with the controlling switch, and combined with a locking device which is operated by the controlling switch, so that when current is flowing through the motors the reversing switch cannot be moved, but when the controlling-switch is turned so that all, or substantially all, of the current is cut out from the motors, then the reversing switch may be moved to reverse the motors.”

[735] It appears from the foregoing statement that in changing from no current at all, or a very low current, to a higher current, the inventor so arranged the switch as to momentarily or temporarily introduce dead resistance coils into the circuit, and then cut them out again, so that in passing from one running point, where the current was at a. given rafe, to another running point, there should he a reduction of energy or current, by means of which the. switch and motors were protected, and sparking, shocks, and all evils which would result from an excess of current, were prevented. This is the chief feature of' the Condict invention. Three, other features thereof will he considered later. Complainants’ and defendants’ devices cannot he satisfactorily described or compared without, the aid of drawings or models. The exhibits introduced upon the hearing clearly show their construction and operation, and the distinctions by reason of which noninfríngement is claimed. For these reasons this opinion will not attempt to state mechanical details.

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Electric Car Co. of America v. Hartford & W. H. R. Co., 87 F. 733, 1898 U.S. App. LEXIS 2738 (circtdct 1898).

87 F. 733 (Electric Car Co. of America v. Hartford & W. H. R. Co.) — published by Counsel Stack Legal Research, free access to 12M+ legal documents.

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