Improvements in or relating to Electrically Controlled Railway Signals.
Year: 1896

page_text: Date of Application, 16th June, 1896-Accepted, 18th July, 1896
COMPLETE SPECIFICATION.
Improvements in or relating to Electrically Controlled Railway
Signals.
A communication by FRANK MCBRIEN, of No. 239 Bloomfield Avenue, Newark,
in the County of Essex and State of New Jersey, United States of America,
Electrician, and JAMES WAYLAND, of No. 1, Rowland Street, Newark
aforesaid, Inventor, and JAMES H. FLEMING, of No. 1076 Broad Street,
Newark aforesaid, Manufacturer.
I, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E. of The Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, 118, New Street, Birmingham, in
the County of Warwick, and 322, High Holborn, in the County of Middlesex,
Civil Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
"
The invention relates to electrically controlled railway signals, the object of
the invention being to provide a system which will effectually guard the move-
ment of trains and will permit the rails of the track to serve as the only
conductors connecting the several sections. According to the invention the road
is divided into a number of sections and sub-sections or "overlaps the
controlling electromagnets which actuate the signals being placed at or near the
junctions. The signals are preferably operated on a normal "danger" principle
and are automatically thrown to safety when a train passes a signal-station if
the track ahead be clear, but will remain at danger if the track ahead be occupied,
thus warning the engineer against entering the section. The signal is automatically
restored to danger by the movement of the train. The signal device is positively
drawn to a safety position by an electromagnetic device, such for example as an
electric motor, the circuit of which is controlled by polar and neutral relays the
circuits of which include the track rails. The relays are so connected that any
interference with the track, as a broken joint or a displaced rail or a short-circuit
of the two rails, will render it impossible for an approaching train to get a clear
signal, and a determinate distance before and behind a signal will be guarded.
The accompanying drawing diagrammatically illustrates a system embodying the
invention.
A and B represent two sections of a railway track, and a and b adjoining sub-
sections or overlaps. The sections and overlaps are bonded or otherwise connected
at the several rail joints so as to form of each side of the track a continuous
electric conductor for the length of the section or overlap. The several sections
and overlaps are insulated from one another by mounting the ends of the rails on
an insulating support and leaving an open space between adjoining rails. At the
junction of a section and overlap are placed the controlling devices for the signal
operating circuit. These devices comprise two neutral relays, 1, 2, the former
being normally open circuited and the latter normally on closed circuit, and a polar
relay 3. The circuit of relay 1 leads through the front contact 4 of a relay 2 and
includes the track rails on the side of the insulating break of the track nearest an
approaching train; the circuit includes a battery 5 of sufficient power to energize
a relay such as 10 bridging the rails at, the rearward end of the section. The
relay 2 as shown is connected between the track rails of the section and, is

page_text: wound to a higher resistance than relay 1; for example, the latter may have
a resistance of one half ohm and the former eight ohms; relay 2 may, if desired,
be placed in series with the polar relay instead of parallel. The armatures of
relays 1 and 2 control the circuit of a battery 6, the armature 7 of polar relay 3
being also included in the circuit; this circuit. contains an electromagnetic
device, as a motor 8, which when actuated draws down the semaphore 9, or other
visual signal, to a position of safety. The controlling circuit for the signal is thus
dependent upon the position of three circuit-breakers, all of which must be closed
at the same time before a clear signal can be given. If the integrity of the
rail circuit, in front of or behind the signal, is impaired in any way, as by a
broken bond or fish-plate, a displaced rail, a short-circuit of the track rails, or
otherwise in any way which would rupture its continuity or unbalance its
electrical condition, it is evident that relay 2 will drop its armature thus
opening the signal operating circuit, as well as incapacitating relay 1, keeping
the danger signal continuously set until the circuit is repaired. At the end
of each overlap is placed an organization for controlling the movements of
a polar relay, for maintaining the rails normally charged with current to
excite relay, and for guarding the advance track section as B. This
comprises a high resistance relay 10 bridging the rails of section B and a
low resistance relay 11 in circuit with a circuit-closer 12 actuated by relay 10
and the two rails of overlap a. The armature 13 of relay 11 controls a circuit-
closer for a normally open shunt circuit across the rails of section B, which
prevents polar relay 3 shifting its contact to an active position when section a, B,
or b is occupied. The armature 12 of relay 10 plays between two contacts
connected with opposite poles of a battery 14, the middle point of which connects
with one rail of section a through relay 11, the pivot of armature 12 being connected
with the other rail; the battery is thus "split," being always connected with the
rails but capable of changing its poles with relation thereto. A similar arrange-
ment of circuits and apparatus is provided for the other sections and overlaps of
the system, as seen by the similarly lettered parts in sections B and b. Let us
suppose, first, that the track in section B and overlaps a and b is clear, and that a
train is in A. Relay 2 will be energized by current from battery 14; the open
point 4 of the controlling circuit for relay 1 is therefore closed and the car-axles
in section A complete it and close two points of the signal operating circuit, one
of these points being under control of the armature of relay 1, and the other under
control of the armature of auxiliary relay 2. Relay 10 would be on its front stop,
being energized by current from battery 5 in section B, and polar relay 3 would
close the third point of the signal operating circuit at 7. To render the action
of the polar relay reliable it may be given a bias toward its open stop by a light
spring. Battery 6 would thus drive motor 8 and draw down semaphore 9,
indicating a clear track. If, however, a train or a single pair of wheels stood in
section a, B, or the motor circuit would be open; if the train were in B the
relay 10 would drop its armature and reverse battery 14, thus throwing relay 3.to
its open stop; if the train were in b, relay 2 would be short-circuited, opening
rail-circuit B at the battery 5b and de-energizing relay 10, thus reversing polar
relay 3; if the train were in a, relay 2 would be short-circuited, thus opening the
signal ope rating circuit and preventing a clear signal being given. Let us suppose
now that a train enters overlap a and that the track of section B and its overlap
are clear of trains. The conditions will then be as shown in the drawing; relays 2
and 3 are short-circuited by the wheels, relay 11 is energized by battery 14, the
circuit being completed by rails of section a and the car-wheels; the short-circuit
at 13 for rails of section B is therefore completed and relay 1 is energized;
armature of relay 2 is held up and the operating circuit of semaphore 9 is
closed, thus throwing it to safety. Relay 2, however, is short-circuited by the
wheels in section a and battery 6 is opened, thus permitting a weight or spring to
restore semaphore. 9 to danger for a following train. It will be seen that low
resistance relay.1' is in series relation to high resistance relay 10; in the normal

page_text: condition of affairs the current is amply sufficient to lift the armature of the high
resistance relay but too weak to lift the armature of the low resistance relay,
which however acts when the strength of current is increased by a low resistance
across the rails made by a pair of car-wheels.
It will thus be seen that but little battery power is required, since the main
batteries employed to operate the signals are in service only for short periods
during the transit of a train, the normal functions of the system being subserved
by the small batteries 5, 5, and 14, 14%, the only work of which is to energize
the high resistance and polar relays; the expense of maintenance is therefore
low, and the expense of equipment is obviously low because all wiring along the
track is dispensed with.
The system has been described as a normal danger system; it must be under-
stood, however, that certain features may be applied also to a normal safety system.
But a slight change in the organization is needed to convert the organization
shown into a normal safety system. This may be accomplished by dispensing
with the low resistance relays 1, 1, leaving only the high resistance relay and
polar at the signal station. With such an organization, the polar relay normally
holds its armature on the front stop and the neutral relay holds up its armature
thus closing the signal operating circuit and positively holding the signal at safety
when the track is clear. Dotted lines have been placed on the drawing to indicate
this organization. Let us suppose a train enters section a; relay 2 is short-
circuited and opens the motor circuit, thus putting the signal to danger: but if a
train is standing or moving in sections B or 6 or a the signal would have been
thrown to danger before the following train reached the signal; if in a, relay 2
will drop its armature and open the motor circuit, thereby setting a danger signal;
if in B, relay 10 will drop its armature and reverse polar relay 3, thus setting a
danger signal; if in b, relay 2b is de-energized, also relay 10, and the polar
armature is thrus shifted to the left, thus setting a danger signal. The signal
having been put to danger by a passing train will be automatically restored to
safety when the last pair of wheels pass out of overlap b.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to me
by my foreign correspondents I declare that what I claim is :-
1. A railway signal system comprising a plurality of track sections insulated
from one another, a plurality of signal devices, a motor for operating each signal
device, a neutral and a polar relay at each signal station controlled by a track
circuit common to both, and an operating circuit for the motor including two
circuit-closers controlled by the two relays.
2. A railway signal system comprising a plurality of track sections insulated
from one another, a plurality of signal devices, a motor for operating each signal
device, a neutral relay and à polar relay controlling the motor circuit, a circuit
including the track common to both relays, and electromagnetic devices for
reversing a battery with relation to the track circuit when a train leaves the
protected region of the track.
:75
3. A railway signal system comprising a plurality of insulated main sections and
overlaps, an electrically controlled signal at or near the junction of each section
and its overlap, a normally charged neutral relay and a polar relay bridging the
rails of the overlap, a signal operating circuit including circuit-closers actuated by
the relays, and a current reversing device at the end of the overlap for operating
the polar relay.
4. A railway signal system comprising a plurality of main sections and overlap
sectious insulated from one another, an electrically controlled signal at or near the
junction of each main section and overlap, a neutral and a polar relay at or near
each signal bridging the rails of the overlap section, and two neutral relays
bridging the rails at adjacent ends of each main section and overlap one energized
by the presence and the other by the absence of a train the latter controlling a
S

page_text: pole-changer for a track circuit including a battery, and the former adapted to
short-circuit the latter in the presence of a train in the overlap section.
5. A railway signal system comprising a plurality of track sections, a signal
controlling circuit including the rails, a battery for charging the rail circuit,
neutral and polar relays bridging the rails at or near the several signals, a signal
operating circuit containing two circuit-closers operated by said relays, an electro-
magnetic device in said circuit positively operating the signal, and a pole-changer
for reversing the battery actuated by a train leaving the protected region of the
track.
6. A railway signal system comprising a plurality of main sections and adjacent
overlaps, a polar relay bridging the rails of each overlap at or near the signal, a
signal operating circuit controlled by said relay, a neutral relay bridging the rails
of the overlap at or near the signal, a battery controlled thereby for charging the
track of the adjacent rearward main section, a relay at the end of the overlap
distant from the signal and a battery controlled thereby for reversing the polar
relay.
7. A railway signal system comprising a plurality of main track sections and
corresponding adjacent overlaps, track-circuits including the rails, a polar and a
neutral relay controlled by the overlap track circuit, a circuit-closer controlled by
the neutral relay for cutting a battery into or out of the main section, a pole-
changer at the end of each overlap for actuating the polar relay, a low resistance
relay in series with the main section battery, and circuit closers in a signal
-operating circuit controlled by the several relays.
8. A railway signal system comprising a series of track sections and overlaps
insulated from one another, a signal device for each section, a motor controlling
the same, a polar relay as 3 and neutral relay as 2 bridging the rails of the overlap
the armatures thereof controlling contacts in the motor operating circuit, a battery
normally charging the rails of the overlap, a neutral relay as 10 bridging the rails
of the next section in advance, a pole-changer controlled by said relay, an
auxiliary neutral relay as 11 in circuit with the pole-changer as described, and a
normally open short-circuit for the rails of the advance section controlled by said
auxiliary relay.
9. A railway signal system comprising a plurality of track sections and overlaps
insulated from one another, circuits therefor composed of the track rails, a signal
normally held at danger in each section, a motor and its circuit for drawing the
same to safety, neutral relays 1 and 2 and polar relay 3 controlling the motor and
track circuits as described, battery 14, relay 10 and pole-changer controlled
thereby, auxiliary relay 11 and a short-circuit of the advance section controlled by
said relay.
Dated this 15th day of June 1896.
WM. P. THOMPSON & Co.,
Agents.