26 
DIRECT-CURRENT DYNAMOS AND MOTORS. 
dae 
258. 
259. 
260. 
261. 
262. 
263. 
264. 
265. 
ter, 12 inches long, which is wound with 96 turns and 
is required to generate 125 volts and 120 amperes at 
1,500 revolutions per minute. Assume the leakage 
factor to be 1.30, and take a density in the frame of 
80,000 lines per square inch. 
What would be the dimensions of the cores, if the arma- | 
ture in the preceding example had a toothed instead of 
a smooth core, the armature dimensions and number of 
conductors remaining the same? 
Find the dimensions of the polepieces and yoke of the 
machine considered in Question 25%, and show a 
cross-section of the complete magnet frame, making 
the sketch one-quarter size ; insert the dimensions of 
the various parts; show the inverted horseshoe type. 
Make a sketch similar to the one asked for in the preced- 
ing question, for the machine of Question 258, having 
a toothed armature. Draw to the same scale as before 
and give all the dimensions, assuming the slots to be _ 
# inch deep. 
How is the yoke of a bipolar machine usually dimen- 
sioned ? 
Give a formula expressing the height of the yoke of a bi- 
polar machine in terms of the core diameter, provided. 
that the yoke is of the same material as the cores. 
The diameter, D,,, of the magnet coresand the length, La, 
of the armature being given, express the thickness of 
the middle section of the polepieces of a bipolar dyna- 
mo, supposing the polepieces to be made of the same 
material as the cores. 
What effect has slotting of the core upon the dimensions. 
of a small ring armature? 
Compute the diameter and length of cast steel magnet. 
cores for a 6 pole machine having a smooth armature;. 
