The Richmond palladium and sun-telegram. [volume] (Richmond, Ind.) 1907-1939, 1919-11-15

will also take place; that Is, when a
current of electricity is made to flow
through the loop of wire in the field
the loop Will be made to revOlve out OF
the field. In the first case (the gener- |
ator) by revolving the loop Of wire il
the field. current will flow through the
wire; in the second case Che motor,
by making current flow through the
wire the loop IS made to rcvOlve out Ct
the field. on the latter principle all
electric motors are designed.
Thus an electrical generator can be
made to act as a motor, or a motor :
a generator.
There j., however, q practical differ
ence in the two machines. The pro-
portions are different but the greatest
difference is in the wiring Of the field
coils. In the last lesson, you We're
shown how the field coils Of the
generator are shunt wound or COM
pound wound The motor, however. IS
practically always series wound; that
Is, the current as it comes from tn"
battery first passes through the field
coils, then through the armature wind
ings, and then back TO the battery.
Thus you see the field coils and arma-
ture are in q series.
1t requires a high amperaEe to give
the motor the required turning power
to crank the heavy engine, ranging
from 100 to 500. depending upon the
size OF the motor. tie siz" of the en-
CINE and the gear ratio between
them.
It is important to remember the
above. as not only does it show how
the battery is quickly discharged
when the starting motor is used (as
lai ir1 hot hut
It shows why great care must be tai ken
not to get anv other units Of tho start
ing and lighting syst EN-. in series With
the starting motor. and why the wires
leading TO the starting motor. and III"
starting switch must be large. Tn"
generator lights, ignition anmeter,
etc. are all built to work on a low
amperage. seldom higher than Il, and
should the high anDeragc motor cur
rent flow through them, they would
instantly be burned out and ruined.
The above mistake is seldom made
where tn" generator and motor are
two scN9rate units. but is very often
made where they are built together
Many man has tried to install All
2nmotCr on his car. to tell him tho
condition Of the ch1rcing Of his bat
terry, and has soften il in series with
the motor. with tLo result that 1t was
Instantly burned cat.
The feet that a motor will act as 4
generation. or generator as a motor. is
Uti'i-r0 IN many cases. the two IN
;tr"rn"n+% hnirg built together. When
s. h~nt tosether If * known as i
MOI "-EC Y orator. and the car is sal
20 be oq1ip"oi with a single unir.
while when the two are separate. it Is
said TO be tWo-unit system.
The designs Of tho motor generators
vary. In some cases, the machine has
two COmmutatOrS, two aTInature wind
ings, and two field windings, others
have but one CommutatOr, but two
sets of brushes, while still others have
only two field windinss; a series. 10
be used when the machine acts as
B motor; and a shunt. to be used when
it acts as q generator.
The motor seldom gives trouble.
what troubles It is subject to being
about the same as those of the gen.
orator Placing too great a load upon
the motor, as is sometimes done by
using the motor while the car is in
gear, so that in addition to cranklng
the engine, the motor must drive the
car may result in the motor overhead