Ques. What may be said of teeth with inclined sides?
Ans. A tooth of this type is shown in [fig. 356], being slightly narrower at the root than at the top, the resulting slot having parallel sides.
Fig. 355.—Western Electric slotted armature core. The laminations are of sheet steel, annealed and japanned. They are mounted directly on the shaft, (except in the large sizes) and held in place by substantial end plates.
Ques. What are the features of the projecting type of tooth?
Ans. The projecting type is shown in figs. 357 and 358 in which the tops project; this gives a larger core area around the circumference of the armature which reduces the reluctance of the air gap, and provides projecting surfaces for retaining the inductors in the slots by the insertion of wedges.
Ques. What is the object of cutting notches in teeth?
Ans. They are provided for the insertion of retaining wedges, as in [fig. 361]; this results in less area at the top of the teeth.
Ques. How should teeth be proportioned to secure most efficient operation?
Ans. The width of the tooth should be about equal to the width of the slot minus twice the thickness of the slot insulation; that is, the cross sectional area of the teeth should be equal to that of the slots.