Improvements in and relating to Electric Railways on a Road Contact System
Year: 1898

page_text: Date of Application, 1st Mar., 1898-Accepted, 2nd Apr., 1898
COMPLETE SPECIFICATION.
Improvements in and relating to Electric Railways on a Road
Contact System
:I, WILLIAM MILTON BROWN, of Johnstown, Cambria County, Pennsylvania, United
States of America, Electrical Engineer, do hereby declare the nature of this invention
and in what manner the same is to be perforined, to be particularly described
and ascertained in and by the following statement :-
My invention relates to that class of railways in which a bared conductor .in
disconnected sections, forms one side of the working circuit; in which normally.open
current conveyers are provided between the source of supply and the said conductor
sections; and in which a travelling magnet is provided to temporarily close the said
current conveyers.
Jn the Specification of a former application No. 28,225, dated November 30th 1897,
I have described and shown an improved winding for the travelling magnet composed
of a low resistance winding and a high resistance winding, the former being in series
with the car motors, while the latter is a shunt about the car motors. I have also
shown in the aforesaid application, a set of batteries carried by the car, and so
, connected to the circuits, that they may be used to pass current through the low
resistance magnet winding when the main circuit is opened, and means whereby
these batteries may be charged without delay in the operation of the car and
without the addition of any special apparatus for the purpose.
.
The use of the simultaneously operated series and shunt windings of the magnet
allows the magnet to be strongly energized even when a heavy current pull of the
motors tends to reduce the voltage across the shunt winding, for the reduction in the
strength of the shunt winding, to a large extent is compensated for by, the larger
amount of current passing through the series winding. This, however, is only true
.within certain limits and of course the strength of the magnet. must decidedly decrease
if the voltage falls to too low a figure.
The object of my present invention is to provide for this contingency by supplying a
normally open switch between the batteries and the magnet coils, which automatically
closes when the voltage drops below a predetermined figure, say, for example, 300 volts,
and thus enables the battery to still further energize the magnet by passing additional
current through the low resistance winding.
In the accompanying drawing I have represented a diagrammatic view of those
parts of the car wiring which have any bearing upon the present invention.
A represents the dynamo at the power station, one terminal of which is connected
to the rails B of the track, while the other terminal is connected by intermediate
feeders and sub-feeders, which are not shown here, to the switching mechanism
within the contact box C. This switching mechanism as before explained,
is ordinarily open, so that no current is delivered to the top of the box, but, it is
closed by the field of a magnet carried beneath the travelling vehicle.
At D I show a collecting shoe which makes contact with box C, only when the
aforesaid magnet is above the box. The current from the collecting shoe D passes to
the canopy switch E, so that when the canopy switch is opened, no current is delivered
to any of the circuits upon, the vehicle.

page_text: From E, connection is next made in multiple to the controller F through a series
winding G for energizing the switch closing magnet. The other connection from E
to F is through the batteries H which connection is normally kept open by means of
the switch I.
From the controller F, the current passes through the motors J-J and their 5
resistances, shunts, and so on, which are not here shown, to the ground side of the
circuit, which is represented by the car wheel K.
L represents a shunt winding for the coils of the magnetic closer.
The passage of the current when the car is travelling under normal conditions,
would be as follows: From the dynamo A to the contact box C, through the switching 1
mechanism, which would be closed by the presence of the magnetic closer, to the
collecting shoe D, to the canopy switch E, thence part would be shunted through the
coils L to energize the magnet, and part would pass through the low resistance coils G
still further energizing the magnet, the latter part then going through the controller F
and the motors J-J, returning to the power house by means of the wheel K and 1
the rail B.
If the car is at rest and there is a high enough resistance in the circuit between
the power house and the part of the line upon which the car is standing to cause a
heavy drop in voltage when the car is started, the shunt coils L may not energize the
magnet sufficiently, but the increased amount of current which passes through the
motors, and causes the said drop in voltage, also passes through the coils G and
increases their energizing power so that they will compensate for the loss of power
in the coils L.
If the car is at rest and the canopy switch E is opened so that no further current
is in either the coils G or L, the switching mechanism within the boxes C, would, of
course, be open and no current could, therefore, be received by the car. In this
event, the motorman closes the switch I, which is preferably a foot switch placed
near the operator's position, and a circuit is made through the coils G with the
battery H as the source of power. This will energize the magnet sufficiently to
close the switching mechanism and as soon as this is done, the switch I may again
be opened, the coils L being sufficient to keep the switching mechanism closed.
When the batteries need charging, it is only required that the motorman close the
switch I while he is passing current through the controller and motors. In this case,
the current received by the motors will pass in multiple from E to F through the
coils G and the battery H, the latter part of the current serving to charge the
batteries.
At M I show a magnet having a winding which is connected at one side by the
wire m³, to the high potential side of the circuit, while at the other side, it is
connected by the wire m² to the ground side of the circuit. N represents an
armature and P a spring which tends to draw the armature against the contact
point O.
The strength of this magnet M is so adjusted that when the voltage
between m¹ and m² is above a predetermined figure, say 300 volts, the armature N
will be attracted in opposition to the pull of the spring P, and there is, therefore, an
open circuit between N and ().
When, however, the voltage falls below this predetermined figure, the spring P
will draw the armature N against the contact and current will flow from the
batteries through the coils G of the magnet.
Under these conditions, it will be seen that there are three co-operating agencies
for energizing the magnet, a current passing through the shunt coils L, current
passing through the series coils G from the main line, and current passing through
the same coils from the battery.
The use of a switch between the batteries and the winding G which automatically
closes when the line voltage falls below a predetermined figure would be equally
advantageous whether the coils through which the battery current pass are in series
with the motors or not. I do not, therefore, limit myself to such a combination.
Those portions of my invention which are herein shown and described, but which

page_text: are not claimed, form the subject matter of the hereinbefore mentioned prior
application.
I have shown my invention entirely in diagram and do not limit myself to any
mechanical construction of the parts thereof. Further I have shown my invention
as applied to a vehicle apparently intended for normal travel in but one direction.
It is evident, however, that it will be mere duplication to so arrange the parts that
the car could be operated from either end, as is usually done at the present time.
It is also clear that I need not limit myself to the exact details shown and
described, for the scope of my invention is broader than the specific arrangement by
which the invention has been illustrated, and can, therefore, be readily modified by
any one skilled in the art.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that
what I claim is :-
1. The combination with the travelling magnet, energizing coils therefore
connected to opposite sides of the main circuit, and a second set of energizing coils there-
fore, of an independent source of current supply and a switch interposed in a circuit
between the independent source of supply and the said second set of energizing coils
and arranged to close whenever the voltage of the main circuit falls below a
predetermined figure.
2. The combination with a travelling magnetic closer and energizing coils therefore
comprising a shunt winding and a second winding in series with the motors, of an
independent source of current supply and a normally open switch between the said
independent source of supply and the said second winding arranged to close at a
predetermined drop in the voltage of the main circuit.
3. The combination of the shunt winding of the travelling magnet connected to
the main circuit, a comparatively low resistance winding, an independent source
of current supply, and means for passing current simultaneously through the shunt
winding from the main circuit and the low resistance winding from the independent
source of supply, said means being governed by a predetermined drop in the voltage
of the main circuit.
4. The combination of the shunt winding L, the series winding G, the batteries H,
and the automatically closing switch between the batteries and the said series
winding.
5. A travelling magnetic closer having a compound winding comprising a winding
receiving a shunt current from the main circuit, and a second winding receiving a
current from the main circuit only when the current is passing to the motors, in
combination with an independent source of current supply and means for passing
current therefrom through said second winding when the main circuit voltage. falls
abnormally.
Dated this 1st day of March 1898.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.