Evening star. [volume] (Washington, D.C.) 1854-1972, 1900-08-07
INSTALLING THIRD RAIL
b. AND o. INTRODUCING SYSTEM ON
BALTIMORE BELT LINE.
One-MiIe of Track to Receive the Adj
ditiOn at This Time-A
New Departure.

A high official of the Baltimore and Ohio
| Railroad Company is authority for the
statement that about the middle of the
| present month the company will begin the
work of installing on the Belt line at Balti-
more the Murphy third-rail system of con-
ductive electric power. This method will
be installed on a section of about mile,
while the other six miles will be operated
by what is technically known as the sec
tiOnal conductor system. The third rail
Will be laid the entire length of the Belt
line but in some instances will be placed
at the side of the track.
The adoption of this system will not ne
ccssitate the purchase of new electric mo-
tors, a similar shoe which conducts the
current from the overhead wires will be
placed at the bottom of the engine which
is nothing more than changing the method
of contact. All the overhead wires used at
present will be removed. The track con-
struction for the new system will be about
the same as now used, but 1t is claimed
that no part Of the rail will be live" eX-
cept at the moment when the motor passes
over it.
Each rail in this system Is connected to
what is known as a solenoidal switch,
which has one winding of coarse and an
other of fine wire. When the car is ready
to start the switch is opened, and there Is
no electrical connection between the car
tIt IttutT W TN tnlS COnIrOller the
motorman connects the motor-dynamo to
the third rail and to the ground. and the
current passes through the fine wire of the
switch and causes 1t to operate. In re-
spnnse to this current the plunger rises
and first makes contact between the main
feeder and the rail, and then breaks the
current of the fine wire winding
Feeder Which Supplies Current.
The controller is opened and the current
comes from the feeder through the coarse
wire winding of the switch to the third rail
and from thence through the car motor to
the ground. causing the motor to revolve
and the car to move. The switch Is held
shut because of this current in the coarse
wire winding. In this closed condition the
switch will remain as long as the car is
taking current from the section to which
the switch is connected.
When the car leaves the section there is
no longer any current passing through the
switch feeding it. and it falls open first
breaking the electrical circuit from the sec
tional rail through the fine wire to the
ground The switch is then ready for the
next car. The car being thus started, the
motor-dynamo is no longer needed to op-
crate the switches, because the car is pro-
EiGed with two sets of shoes, which are
connected and placed sufficiently far apart
10 span the distance from section to sec
ton. The forward shoe as it impinges on a
section subjects It to the full-une potential
drawing Its source of current from the rail
preceding. 1t will then fall open from lack
OF current to hold it up, and there is then
no current to break
Individual Dynamo
The motor is provided with what might
be termed an individual dynamo start 1t
After car gets under Roadway however
the current from the third rail is depended
upon altogether. The motor-dynamo OBJ
ta1nS Its current from the storage battery
One advantage claimed for the Murphy
system is that there is comparatfveIv small
leakage of the electric current even when
the rails are immersed in salt or fresh
water and it is said that at Manhattan
Beach the cars have been operated sue
ceSsfully when the track was covered with
salt water. Arrangements are made 70
cross the tracks of other railroads without
interfering with the operations of the mo-
tor car.