- Locomotive du physicien Charles PAGE
- Professeur de la Smithonian Institution, avec l'aide de subventions du Congrès américain.
Moteur électromagnétique à courant alternatif de 16 ch, vitesse 30 km/h.
Ligne ferroviaire Baltimore-Washington (5 miles).
Les cellules de la batterie (fabriquées en terre cuite) cèdent au retour.
Professor Page soon improved on the Gustin single-acting electric engine by adding another solenoid, which could pull the piston in the other direction without the assistance of gravity.
Fig. 23 shows this form of engine which takes electricity at both ends of the "cylinder," to borrow the expression of steam engineers. This having performed their work, the other series, working in connection with the opposite end of the working-beam, were in readiness to perform their work in like manner. The motion of the working-beams was communicated through their bearing-rods to the crank and fly-wheel, thereby producing rotary motion.
The most celebrated early motor next to that of Jacobi was undoubtedly that of Prof. C. G. Page, of the Smithsonian Institute. This depended upon a different principle from that of the others. When the end of a bar of iron was held near a hollow electro-magnetic coil or solenoid, the iron bar was attracted into the coil by a kind of a sucking action until the bar had passed half way through the coil, after which no further motion took place. Professor Page constructed an electric engine on this principle about 1850. The solenoid was placed vertically, like the cylinder of an upright engine. A rod of iron, by way of armature, was fastened to arrangement will be readily understood. There are two solenoids and each has its iron rod passing through it, though they are joined into one piston by a piece of non-magnetic material. The piston is attached to a frame ff' which slides through supports, and in this way it is free to move inside the solenoids. The current is sent alternately through each coil by an eccentric disc on the axle (which suggests a further resemblance of this motor to a steamengine). This eccentric touches first one and then the other of two springs e e, connected to the solenoids.
A large motor of this description was constructed by Professor Page, in 1850, which developed over ten horse-power. Professor Page sought to apply his motor to locomotion, and he actually constructed an electric locomotive to demonstrate the practicality of his scheme. But he never achieved much success, as might have been foreseen. Among the improvements which Professor Page introduced was that of making each solenoid double, so that the arms of a U magnet could slip into them, instead of one single bar. As the solenoids attracted most strongly when the cores were almost out of them, he wound his solenoids in short sections, and a sliding commutator worked by the motion of the cores successively cut out the sections of coil which the cores had entered and transferred the current to others ahead of them, and thus the range of attraction was greatly increased.
Professor Page, it is interesting now to recall, made the trial trip with- his electro-magnetic locomotive on Tuesday, April 29, 1851, starting from Washington, along the track of the Washington & Baltimore Railroad. His locomotive was of sixteen horse-power, employing 100 cells of Grove nitric acid battery, each having platinum plates eleven inches square. The progress of the locomotive was at first so slow that a boy was enabled to keep pace with it for several hundred feet. But the speed was soon increased, and Bladensburg, a distance of about five miles and a quarter, was reached, it is said, in thirtynine minutes. When within two miles of that place, the locomotive began to run, on nearly a level plane, at the rate of nineteen miles an hour, or seven miles faster than the greatest speed theretofore attained. This velocity was continued for a mile, when one of the cells cracked entirely open, which caused the acids to intermix, and, as a consequence, the propelling power was partially weakened. Two of the other cells subsequently met with a similar disaster. The professor proceeded cautiously, fearing obstructions on the way, such as the coming of cars in the opposite direction, and cattle on the road. Seven halts were made, occupying in all forty minutes. But, notwithstanding these hindrances and delays, the trip to and from Bladensburg was accomplished in one minute less than two hours. The cells were made of light earthenware, for the purpose of experiment merely, without reference to durability. This part of the apparatus could therefore easily be guarded against mishap. The great point established was that a locomotive, on the principle of Professor Page, could be made to travel nineteen miles an hour. But it was found on subsequent trials that the least jolt, such as that caused by the end of a rail a little above the level, threw the batteries out of working order, and the result was a halt. This, defect conJd not be overcome, and Professor Page reluctantly abandoned his experiments in this special direction.
It is interesting here to note that in 1847, the versatile and unwearying investigator, Professor Moses G. Farmer, constructed and exhibited in public an electro-magnetic locomotive, drawing a little car that carried two passengers on a track a foot and a half wide. He used forty-eight pint cup cells of Grove nitric acid battery. In 1851, Mr. Thomas Hall, of Boston, then at work for Mr. Daniel Davis, constructed and exhibited at the Charitable Mechanics Fair in Boston, the little locomotive, Fig. 24.
Our illustration is taken direct from the original woodcut of the locomotive. The block was made nearly thirty-seven years ago, and first appeared in Palmer & Hall's catalogue of 1850. The engine which it represented was on
the principle of an electro-magnet revolving between the poles of a permanent magnet. The armature had a worm on its shaft which matched into a gear attached to the drivingwheels, the latter being insulated by ivory. The track was laid in five-foot sections, and was about forty feet long and five inches wide. Under the platform of the car was a polechanger attached to a lever; when the engine reached the end of the track it ran against an inclined plane which reversed the pole-changer and sent the engine to the other end of the track, where the same thing was repeated: thus the engine was sent automatically from one end to the other. The current, produced by two Grove cells, was, it is well to note, conveyed to the engine by the rails. We have seen, also, a photograph of the "Volta," a finely-constructed model, which was made on the same principle as the above, but so as to resemble very closely a locomotive actuated by steam. Mr. Hall says that in 1852 he made, for Dr. A, L. Henderson, of Buffalo, a model line of railroad with electric engine, with depots, telegraph line, and electric railroad signals, together with a figure operating the signals at each end of the line automatically. This, he states, was the first model of railroad signals or trains worked hy telegraph signals.
Professor Page, in 1854, patented a modification of his early ideas.
Figs. 25 and 20. This later motor resembled in external appearance, to some extent, a double-action, slide-valve steam pump. This Page motor comprised two parallel axial bars working through two pairs of helices, and two fixed armatures arranged at either extremity of the parallel bars. The pitman-rod connected the crank of the fly-wheel to the cross-head of the axial bars. The two pairs of helices were each connected by wires with the two conducting springs shown in the detail view, each bearing alternately against the cut-off on the fly-wheel shaft. This connection was made by means of the wires passing down under the base-board and up through to their respective connections, as shown by the dotted lines. This fly-wheel cut-off or commutator consisted of two semi-cylindrical metallic segments insulated from each other and secured to a cylinder of wood upon the shaft. An entire metallic ring was fixed upon a part of the wooden cylinder of less diameter than that to which the insulated segments were attached. This ring was connected by a strip of metal with one of the metallic segments. The three conducting springs are shown in position in the detail view.
The spring in contact with the smaller ring connected with the positive pole of the source of electrical energy, and the current, therefore, passed through the metallic connections to the spring at the left-hand side of the detail figure. This latter spring was connected with one termination of the helices to the left of the drawing, the other being connected with the negative pole. The commutator revolved in the direction of the arrow. The axial bars are shown with thin poles passed entirely through the helices and within the influence of the armature. The instant the dead point was reached, the other pair of helices was charged to propel the frame of axial bars in the opposite direction. This was effected by the revolution of the commutator in the direction of the arrow, the metallic segments being reversed. The very short distance through which the magnets acted with power, and the rapid diminution of power as the magnets receded from each other, presented serious practical difficulties in this as in other electro^ magnetic engines, whether in the reciprocating or rotary form. Dr. Page asserted that by the employment of a reciprocating core arranged to move in the line of its length through an arrangement of helices, the magnetic power could be made to act with more uniformity through a considerable distance, as some portion of the magnetic core would be always in close proximity to the helix.
T.C. Martin et J. Wetzler, The Electric Motor and its applications, 1891
- Werner von SIEMENS (1816-1892), né à Lenthe, fonde, avec Johann Georg Halske, la société Siemens und Halske.
- Siemens est issu d'une famille d'ingénieurs et d'industriels allemands.
La société Siemens réalise les premières grandes liaisons télégraphiques européennes en Allemagne et en Russie, construit des machines électriques (première esquisse de la dynamo, mise au point ensuite par Zénobe Gramme), la première locomotive électrique et des lignes de tramway.
Son frère Wilhelm, 1823-1883, né à Lenthe, qui prit la nationalité britannique, se consacre à la métallurgie, perfectionne les procédés de dorure et d'argenture traditionnels, puis invente un four appliqué à la sidérurgie et à l'industrie du verre, four qui porte son nom et se généralisa ensuite en Europe, après avoir été perfectionné par Pierre Martin. Il est anobli sous le nom de sir William, peu avant sa mort en 1883.
Avant la Seconde Guerre mondiale, le groupe Siemens figurait déjà parmi les groupes industriels de premier plan, mais sa production se limitait au matériel pour téléphone, télégraphe et radio, et à la fabrication d'appareils de mesure. Son siège se situait à Munich et la firme possédait des filiales dans toute l'Allemagne, notamment à Berlin où ses installations formaient même un quartier baptisé Siemensstadt. Ruiné pendant la Seconde Guerre mondiale, Siemens s'est peu à peu reconstruit, en se diversifiant et en privilégiant la croissance externe (rachats, fusions, etc.).