The Opelousas courier., 1894-05-19
SECRET OF THE TROLLEY.
THE ELECTRIC soisrEm FOR PRO-
PELL1NG STREET CARS.

Below the Floor of the Car
Generating the Motive Power.
x S that electric system for pro-
N polling street cars, known as
~ the trolley, has already su-
. perseded horses on many
Lines, it will doubtless interest many
persons to learn just how the mysteri-
GUS force to which man has given the
name Electricity" operates in produce
ing a motion of the cars. OF course,
everybody knows that electricity is
generated in power houses situated in
various parts of the city, and is con-
Quoted along the wire which runs IN
midair above the tracks, but that the
mechanism is below the floor of the
motor car by which this wonderful
fluid is utilized in the way desired the
majority of people do not know.
The fact that power sufficient to
move so largo and heavy a mass finds
entrance through the slender trolley
pole seems almost incredible. This is
not remarkable, since nothing is posi-
lively known about this force, If it
may be called a force, except such
facts concerning its properties and ac-
lions as have been gathered by expert
ence and observation.
To explain without the use of OBJ
scure technical expressions the proper
ties and actions which move an electric
car is not easy. In order to give an
idea of the power required, however,
it will be necessary to explain a few
terms in common use.
The weight of n pound falling
through one foot in a second does
foot pound of work-this is one thirty
three thousandth of a horse power. A
horse power is somewhat more than
one horse can perform. 1t is said,
however, that certain draft horses in
England can accomplish this. An am
pere is fixed, determined quantity OF
electricity flowing through a wire in
one second. A volt is the force or
pressure required to push the ampere
through the wire. One ampere
pushed through a wire by a force OF
one volt represents an amount of work
called one watt. A watt is one even
hundred. and forty-sixth of a horse
power, and it requires from three to
four horse powers, or 3001 watts, to
move a car weighing 1900 pounds at
the rate of about eight miles an hour
upon a level track.
This power in the form of electricity
easily enters into a car by means of a
cable from the overhead wire through
the trolley pole, and thence to a brush
of the motor. which is situated be-
tween two of the car wheels and below
the floor of the car then, going
through the motor, it either comes
out through another brush and back
to the station by another wire o.
passes through the axle and wheels to
the track and back to the station
through a wire which is underground
down the centre of the track. The
brushes are two small pieces of carbon
or copper which make contact with a
part of the motor and allow the cleo
tricity to enter and leave.
The essential parts of the motor and
the forces which cause the car wheels
to turn may be explained as follows:
There is an iron frame shaped to the
form of a t~wo-legged stool with an OBJ
long seat. The legs are wound very
closely with a continuous piece of silk
on rubber covered wire, al a spool is
wound with cotton. leaving a short
space rnwound on each leg at the end
which rests upon the floor. This stool
is inverted and electricity allowed to
run through the wire. Now, while
the current is going around both legs
a force will exist between the ends
left unwound. This force, although
strong, is similar to the weak force
between the poles of an ordinary
horseshoe magnet. If a large knife be
passed between the uncovered ends,
resistance is offered and the knife is
drawn through with some difficulty.
In the motor two such frames may
be cast in one piece end to end, each
being connected to the adjoining leg
of the other by a curved bar of iron,
forming a partly closed circular space
in the center. Place wire, with the
electricity running through it, within
this space in a position parallel to the
direction an axle would take were this
space a wheel. Then this wire will be
forced in a direction, according to
which way the electricity flows through
it, sidewise toward either seat.
A number of coils of such wires are
wound longitudinally upon a frame re-
sembling a fishing float or bobber,
which is held within this space upon
holders which enable it to revolve.
Each length of wire, extending length
wise upon the frame. takes the direc-
tion of the wire mentioned above.
This wire is SO wound that the cleo.
tricity going through it may take op-
posite directions upon opposite sides
of the frame Thus pressures in OPP
posite directions will be exerted upon
opposite sides of this frame, causing
it to spin like a top or like a coin spun
by opposite pressures of the fingers.
At the end of the bobbers is a small
cylindrical arrangement composed ola
number of copper plates arranged
radially around a centre and separated
from each other by some substance
which prevents the flow of electricity.
Against these copper plates the brushes
are pressed by springs. The ends OF
the coils on the bobber frame are con-
nected each to a 81 separate copper plate,
each plate serving for two ends, one
from each of two coils, SO that the