Hawkins Electrical Guide v. 02 (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

Fig. 351.—Sectional view of laminated smooth core armature showing end plates, flange and retaining nut. A key is provided to prevent rotation of the core with respect to the shaft.

Ques. How thick are the discs?

Ans. The thickness ranges from .014 inch to .025 inch, corresponding to 27 and 22 B and S gauge respectively, 27 gauge being mostly used.

Ques. How are the discs held in place?

Ans. By two end plates pressed together either by large nuts screwed directly on the shaft as in [fig. 351], or by bolts passing through the core from end to end, as in [fig. 352], holes being punched in the discs for the purpose.

Ques. What precaution is taken with respect to the core bolts?

Ans. They are insulated from the core by tubes and washers of mica or other insulating material.

Fig. 352.—Laminated armature core with through retaining bolts. In the larger sizes, these bolts are used instead of a nut threaded on the shaft on account of the large size of the latter.