Hawkins Electrical Guide v. 01 (of 10) / Questions, Answers, & Illustrations, A progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications

by N. Hawkins

Ques. How is the yoke usually divided?

Ans. Across its horizontal diameter into an upper and lower half, as shown in fig. 206, the lower half being seated on, or more frequently cast in one piece with the bed plate.

Ques. What is the objection to dividing a yoke?

Ans. The joints introduced, even if carefully faced and well bolted together, add a little reluctance to the magnetic circuit.

Ques. How does this affect the poles adjacent to the points, and what provision is made?

Ans. It weakens them, and in order to overcome this, the coils of these poles are given a few extra turns.

Ques. How is the reluctance of a yoke joint reduced?

Ans. By enlarging the area of contact; the flange for the bolts furnishes the necessary increase.

Ques. What determines chiefly the cost of field magnets?