The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1900-02-27
TRYING TO GO HOME.
Efforts of the Current to Get
Back to the Power House.
what Makes the wheels of the Electric
Car Go Technical Expiane-
tion of the working of the Motor.
(Bangor Commercially


For the benefit OF Master Ignorance
who doesn't know what makes the trolley
car 90, and is not backward in saying go,
as well as for the knowing Ons, who
knows no ucrs, but fAucies he knows 1t
all, this effort is DIsde to explain, with
out oil, So approach to the technical, to
make the principles OF this motive power
so pain that even the schoolboy OF ten
may cease TO look on the trolley car as 1t
wbizzes along the street with wonder
ment akin TO awe
But right at the outset you are eau
toned against asking "Wby" This Is
simply a matter of how and what; for
the why Of electricity Is still rs great
mystery as life. Why does the electric
current do so and soS What 10 IT. As
well ask why o man crooks his finger,
why q dog follows scent or what Is life
There are questions men never have an
svered and are not likely ever to answer.
So let us be content with the manifesto
lions Of this mysterious force and not
trou BILE ourselves trJ ing to solve the IN
solvable
Setting aside, therefore, oil thought Of
electricity, save that In which IL mani.
TESTS lleth uuk cehoosf ~ We
be necessary first to get rome idea OF
how It 10 made and transmitted before
trying to discover how It makes the car
60. ARsln keeping clear OF technicalities.
IL IL only necessary 10 know. for the pnr
pose In hand, that the power which drives
the trolley car is nioe combination 1i
ele ctricity and magnetism-for although
these forces are intimately associated
with each other, they are radically dtfer-
emit. 1t Ia difficult. II not impossible, to
obtain one without the other, although
IL 10 q simple matter to make one Inactive
under certain conditions. In this lies
the main secret of the electric motor, Tor
1t 10 q simple N after to make one mac
tive under certain conditions In this
lies this main re rot of the electric motor,
for it 10 by alternating the attractive and
repulsiye properties of the two poles oil
an electric magnet that continuous re-
volu ton Ia impaired to the armaturo-
the iron core covered " it'll coils OF wire
which IeVolves when ths current reaches
the motor ami to which the driving PIN
ion or pulley Ia attached.
This alienation OF the poles Is accom-
plishsd by means of the commutator-a
bit of mechanism too complicated and
technical to attempt Its description or an
explanation of Its mode of operation hsre
SAinply let 1t be understood that this
commutator div ides the field OF the arm u
ture into two places, which, as they re
volve, reverse the negative and positive
poles Of the magnet and thus Keep the
revolution OF the armature continuous.
Having now the current generated at
the power house-for the generator is
simply the motor running In an opposite
direction, ami vioe versa-it Is led by
heavy feed wives of copper to the trolley
wire, along which IL Ia carried till IL
reaches o trolley wheel. When t ia point
Is tcuohrd. the current shows another OF
Its strong preferences Its main object
in leaving the power HOUSE. is to get back
there as soon and as easily as possible.
Without any trolley wheels touching the
copper trolley wire the current would
have to travel the entire langth of the
railway line, and even then IL would have
no noticeable D lwer unless contact were
made whereby it could reach the ground,
or some other medium by which 1t might
return to the generator or Its source.
But the trolley wheel furnishes this
contact between the ground and tbs
trolley wire, and the outrsnt darts along
the trolley pole to the wires reaching be-
meath the car. Here. again, 1t may be
stayed by the handle of the controller
in the motorman's hands. IL he has the
controller shut of, the current nust still
fret and fume with impatierce, for 1t
cannot continue Its journey back to the
power house.
Now the motormsn moves the handle
of thu controller little; the car begins
TO move, out only fraction of the full
current is passing through to the rails
The handle moves another notch, the
car inCreass In speed, anu so on till the
full current Is passing through the car
and ths height OF speed Is attained.
This controller Is another appliances
difficult TO OK plain without being Devil
deringly technical. But 1t may be sad
that the handle opens a series OF switches
and circuits through which the current
has to pass or Instance, the htst circuit
is TO one motor, the.seoond Is through one
meter under the Cur to the other, thus
giving increasing speed, Another circuit
lets the current into both motors direct.
but each under different conditions of
conn ection, and the higher speeds are at
tained. The highest speeds are given
when the current is equally divided be-
tween both motors.
New, when the current reaches the mo-
ter, reduced to safe strength by the
mechanism of the controller, Ii acts,
throu gh the influsncs of the oonmutator,
as a reyerssr ON the poles OF the magnet
and thus draws Ia one way Continuously
on the revolving arma5ure. 10 the axle
of this Ia attached n small geNred wheel
which engages into large one connected
with the axle of the oar wheels Thus
the turning OF the immature Of the motor
causes the wheels of the car to turn
also, the current meanwhile trying its
hes. to get baok to the power house
This II acocmI fishes by leaving tie oar
through this whesls and using the raj s.,
the earth, or any other convenient ms tai
lie substance which may serve to carry
it where 1t Is most disposed to go.