The Waxahachie daily light. [volume] (Waxahachie, Tex.) 1894-current, 1908-07-17

rent with a. very trifling loss in eff
trcity is fed to the trolley wire at
pressure of about $50 volts. The troll
ley wire is familiar to all as heavy
copper wire suspended over tracks
from insulated guy-wires. In a few
instances, especially in New York,
London, Chicago, and other large
is laid underground and the trolley
contact is under the car, or for hea-
| Wy work the third rail- is used and
the current collected from rail by
sliding shoe.
In every case where electricity is
used for power purposes the cur
rent has to be grounded" for re-
turn or a return wire used SO as to
complete the circuit with the power
house. In the case of electric rail-
ways the rails are either welded or
bonded" together with strips Of
copper and used for this return cir
cult
When a car is to be run on a rail-
way line the trolley is released until
the little brass wheel presses against
the trolley wire. The wide flanges of
this wheel keep 1t from running off
and heavy spring keeps it tight
against the wire. The electricity
which is to drive the motors located
under the car, passes through the
brass wheel and down the metal
trolley rod to insulated cables con-
cealed in the roof of the car. These
cables lead to a Circuit breaker" in
the roof of the vestibule. The duty of
the Circuit breaker" is to break"
or shut off the current when the load
gets too heavy for the motors, be-
cause an overloaded motor would
destroy itself by burning out in an
effort to carry more than its capaci-
}ty. The circuit breaker, which is a
very simple contrivance, takes the
place of the old-time fuse" SO
prone to blow out" at the most in
opportune moments. From the cir
cult breaker the current is carried
to the controller, which is an upright
oval iron box in each end of the car.
1t may be stated here that the equip
ment is the same on either end of
the car so it can be run either way
without turning around. The con-
troller is worked by two adjustable
handles, the smaller of which is used
only to reverse the motors. With the
larger handle the contact points III
side the device are opened and closed
to increase OF decrease the speed
and pulling power of the motors.
Corresponding to the movements of
the handle the current passes from
the contact points to a series of re-
/ Stance grids located under the car.
The cast-iron grids resist the cur
rent or hold it back. When the con-
troller handle is moved up a notch
| one of these grids is cut out and the
resistance is reduced, increasing the
electricity which goes to the motors
AS the handle is moved from point
to point the resistance is lowered
until the full power of the line is be-
ing fed to the motors and the car is
running top speed.
Direct current motors are used be- |
cause of the great starting torque !!
which can be secured. A street car |
has to stop and start quickly and |
under full load. A direct current |
motor will quickly pick up its full |
load, whereas, the alternating cur
rent motor is not so ready to rapid
ly assume its load. The motors on an
ordinary car are from rs to 100
horse power, and on the largest cars |
four motors are used. The current
passes through these motors to the |
car wheels and returns to the power
house by way of the bonded rails.
The electric motors are geared to
the axle on the ear wheels and they |
differ but slightly from any other |