THE DESIGN OF DIRECT-CURRENT 
DYNAMOS AND MOTORS. 
FINAL CALCULATION OF ARMATURE. 
26. Number of Inductors on Armature.—The size of 
the inductors having been ascertained, the designer may 
proceed to determine the number of them that can be 
properly placed upon the armature core, the approximate 
size of which has been computed. The number of induc- 
tors that can be placed upon the circumference of a smooth 
core, or into the slots of a toothed armature, depends upon 
the height to which it is expedient to wind the armature, 
this height, in a toothed core, corresponding to the depth 
of theslots. The height of the armature winding, h, (Figs. 
17 and 18, page 45), varies with the type and size of the 
armature, and can be taken approximately from Table 
14, which gives average values for various cases. 
The total winding space, S,, of a smooth-core armature is 
roughly given by the following formula, provided that 
h, is very small compared with D,, which is practically 
always the case : 
Pee eg Mi ciked cee scene ..(14) 
In ordinary smooth-core machines, from % to 4 of this total 
winding space is occupied by insulation, division strips, 
binding bands, etc., hence the available inductor space is: 
Su! = .55Sy = .55Daw X hy = 1.95 X Dy X Iige...(15) 
The number of inductors on the armature is the inductor 
space, S,’, divided by the space occupied by one induc- 
tor. Calling the diameter of the bare inductor d,, each 
inductor takes up the space d,*. The approximate total 
