This motor differs from those which have already been described, in that no wire is wound on the armature.
The Field Coils consist of two electro-magnets wound upon iron cores one and one-eighth inches long and five-sixteenths inches in diameter. Each core is fitted with two fibre heads, one-sixteenth of an inch thick and seven-eighths of an inch in diameter so as to form a bobbin as shown in Figure 33. The bobbins are wound with No. 22 B. & S. Gauge single cotton-covered magnet wire. The magnets are connected in series so that the current flows through them in opposite directions.
FIG. 33.—Details of the Magnet Bobbins.
The Armature is a strip of soft iron one and three-quarters inches long, three-eighths of an inch wide and three thirty-seconds thick. A one-eighth inch hole bored through the center of the armature and the latter forced upon a shaft one and seven-eighths inches long.
The lower end of the shaft is pointed and rests in a small hole in the magnet yoke, half way between the two coils.
The magnet-yoke is a strip of soft Iron or steel two and one-half inches long, seven-eighths inches wide and one-eighth of an inch thick.
FIG. 34.—The completed Electromagnets mounted on the Yoke.
The magnets are mounted on a wooden base, five inches long, three inches wide and three-eighths of an inch thick, by means of two 8-32 machine screws which pass upward from the bottom of the base into the bottom of the magnets. The yoke is placed under the' magnets, between them and the base. The screws pass through two holes, one and one-eighth inches apart.