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The commutators, as regards their brushes, are so arranged that when M and M are in action, S and S are out of action, and vice versa. The spindle and commutators are rotated by the pulley, P. L is an incandescent lamp in the shunt circuit.
He liked to hear the squeak of the belting and the steady chug-chug of the water-wheels; the purr of the dynamos was music, and he kept the commutators free from dust with loving care. But these moments alone in the power-house were high-lights in a world of shadows.
Let us now suppose the apparatus at rest, and the brushes in electrical contact with the main commutators, M and M. The current from an alternating dynamo passes into the magnet, E, and rapidly reverses its polarity.
Besides his telephone, each reporter, as the reader is aware, has in front of him a set of commutators, which enable him to communicate with any desired telephotic line. Thus the subscribers not only hear the news but see the occurrences. When an incident is described that is already past, photographs of its main features are transmitted with the narrative. And there is no confusion withal.
Or, "Watch your valves, Miss, and be keerful they don't gum on you." Or, "Them commutators are often the seat of trouble, for oftentimes they wear down and don't break the spark right." When I'd grow dizzy with these explanations he would reassure me by saying that "I'd soon fall into it, like he did." But I didn't fall into it nearly so well as I could have wished.
Smaltz's face wore a look of keenest interest, as with one shoulder braced against the side of the building, his hands in his pockets, he watched the plant burn up. Down below, Banule had thrown out the switch and the machinery was running away. A rim of fire encircled the commutators.
At Gratz he saw and operated a Gramme machine for the first time, and was so struck with the objections to the use of commutators and brushes that he made up his mind there and then to remedy that defect in dynamo-electric machines. In the second year of his course he abandoned the intention of becoming a teacher and took up the engineering curriculum.
The heating of solid armatures, the only kind then known, and poor insulation in the commutators, also gave rise to serious losses.
By actuating the pulley, P, the commutators are rotated, when M and M go out of, and the shunt commutators, S and S, come into action, enabling the after current set up in the magnet to light the lamp, L, in the shunt circuit. In order to make comparative tests, the same apparatus may be supplied with continuous instead of alternating currents.
Such generators and motors, however, possessed inconveniences that prevented extensive commercial transmission of power, since, as we have seen, high pressure was necessary for efficiency in such transmission, and the collecting-brushes and commutators employed in all direct-current generators and motors to carry the current from the machine or to the motor, were a constant source of trouble and danger.
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