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282 ILLUSTRATED WORLD
"It Permits a Steady Application of Power Which Is
Obtainable in the Mechanical Transmission Only by
a Multiplicity of Cylinders"
field and the armature, so that when it
is so desired the field may be revolved
at a greater rate of speed than the armature.
The means by which this change
in relation is accomplished through the
electric controller is quite simple to anyone
who understands an electric circuit,
as it is nothing more nor less than a
cutting out of more or less resistance in
the field.
When it is desired to run in the high
or direct speed there is no difference in
speed at all between armature and field.
When running in the lower speeds there
is a difference, just so much as is provided
for by the position of the controller
lever. Thus it is seen that all the effects
of clutch and gears are gained without
the use of them.
To carry it still further, it is known
that whenever there is a difference in
speed between armature and field a certain
amount of electric energy is gener­
ated there, just as heat is generated and
wasted in a slipping clutch. But in the
magnetic transmission this energy is not
allowed to go to waste. A second set
of armature and field is put in a little
further back on the driving line. The
field is rigid on the car frame and stationary,
the armature rigid on the drive
shaft, and may turn with it. Between
these two sets is placed a commutator or
series of collecting rings and brushes to
run in them. These collect the electrical
energy which otherwise would be wasted,
and apply it to the second set, which is
nothing more nor less than an ordinary
electric motor. This gives electric power
to the car as well as engine power when
it is most needed. The greater the difference
in speed between armature and
field, the more electric energy for the
motor is generated, so that when the
car is running in a very low speed the
motor is doing almost all the work, but
with all the power of the engine behind
it just the same.
The necessity for a separate starting
device is altogether eliminated. The
transmission itself is a very efficient engine
starter. The current from a storage
battery is turned into the unit. It excites
the field wdiich then revolves about the
armature and turns the whole of the
engine with it.
This battery is charged when the car
is running in high speed by the current
generated in the second motor, which is
then a dynamo, or it may be charged
when the car is stationary by using the
neutral effect plus a means of diverting
the current from the collecting rings to
the battery cells.
Another natural result of this construction
is the fact that when the controller
lever is brought to the neutral
position while the car is traveling at any
speed above a given minimum, the revolution
of the rear wheels sets up a reverse
potential in the second motor which
acts on the car as a very efficient and
dependable brake. This effect is gradually
lost as the speed is reduced but
grows more powerful if the tendency