Automatic Railway Electric Signals.
Year: 1893

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VUBLE LEIE DI MUIFICATION.
Automatic Railway Electric Signals.
We, CHARLES HAMLIN BRADRICK and BURTON ALDEST KARR, respectively
President and Vice President of The National Railway Signal Company, both
residents of Omaha in the County of Douglas, State of Nebraska, 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:
Our invention relates to that class of electric signals for railways which employ
the main railway track as one line conductor, insulated central rails as the other
line conductor and a trolley carried by the car and running on the central track
and wherein each engine carries an alarm, a source of electricity and proper con-
nections for making a complete half circuit; the central insulated conductors being
divided into sections and the circuit through both engines being completed when
they arrive upon the same section. Our invention consists in certain novel
features in the construction and arrangement of the parts in such a system as
will hereinafter be fully described, and particularly pointed out in the claims.
In the accompanying drawings:
Figure 1 represents a locomotive, the cab of which is shown in section, and to
which is applied one of the two similarly constructed halves of the system which,
when brought together give the alarm in both cabs.
Figure 2 is a diagram showing the electrical connections which are employed on
each locomotive.
Figure 3 represents in transverse section the manner of mounting the elevated
central rails on the roadbed.
Figure 4 represents in plan and diagram the connections at a switch which serve,
when the switch is open to complete the circuit carried by any approaching engine
and thus give an alarm.
1 represents a locomotive adapted to run upon the main rails 2 and which carries
a trolley 3 of peculiar construction hereinafter referred to, which runs upon central
elevated rails 4. The trolley consists mainly of a frame 5 having vertical and
horizontal arms, pivoted at 6 and carrying an axle 7 upon which are mounted a
pair of wheels 8. This trolley is mounted in a bracket 10 from the lower end of
which projects a spring 9 whose outer end is attached to the trolley axle, in such
manner as to draw the forward end of the trolley-frame with its wheels backward
and owing to the shape of the frame press the wheels downward upon the track
upon which they run. This spring retains the wheels of the trolley upon the
track, with a yielding force, causes them to ride evenly, and prevents them being
displaced by obstructions such as slight unevennesses in the track. As will be
observed from Figures 2 and 4 the central elevated tracks and the trolley-wheels
that run thereon are spaced apart so that the rails form two independent conductors
and the trolley being supported by the single bar 5 attached near the center of
the axis receives current from either central rail. The trolley frame is also
provided with an extension 12 above its pivot 6 with which may be engaged by,
though not positively connected with the lower projection 13 of a controlling hand-
lever 14 pivoted at 15 in the cab. This hand lever is provided with a retaining
dog 16 which engages in the teeth of a rack segment 17 adjacent to which the
lever moves.
The operation of those parts is such as to permit the engineer to
conveniently elevate and retain in elevated position, the trolley wheels, at such

page_text: times as the engine may be travelling on switches or other portions of the track
where the central rails are not used, but may throw the lever rearward a sufficient
distance to wholly disengage the parts 12 and 13 and thus leave the trolley frame
intact with freedom of vibration in performing its intended functions.
18 represents an alarm in any suitable construction. 19 represents a battery or
other suitable source of electricity and 20 represents a switch-board. The alarm 18
has positive and negative binding posts 18+, 18-, connected respectively by
means of a wire 21 with an axle 22 of the engine and by a wire 23 with the
negative pole 19 of the source of electricity. The switch-board 20 has a switch-
arm 20 and two contacts 20°, 20°, connected respectively by wires 25, 24 to the
negative and positive poles of the battery. The switch-board is also connected
at its pivot 20 upon which the arm 20° turns, by means of wire 26 with the axle 7
of the trolley. From the foregoing it will be observed that when the switch-
arm 20 is turned upon the contacts 20 the following circuit will be established,
provided an engine, an open switch, an impaired bridge or similar cause for alarm
be present to wit:-From the car axle 22 through wire 21 to the alarm, from the
alarm through the wire 23 to the negative pole of the battery, from the positive
pole of the battery through wire 25 to the contact 20% of the switch, through
contact arm 20° of the switch and wire 26 to the trolley 3 along the central rails,
or that one of them with which contact is made by both the approaching objects,
through the circuit of the other of which is to be avoided, and back through the
main rails to the axle 22.
According to our system, it is intended that all engines going east or in any
other predetermined direction shall place the switch 20 so as to present, say the
positive to the trolley and through it to the central rails while all engines going in
the opposite direction will cut out the battery but leave electrical connections
otherwise intact to receive current from the battery of the other train or obstruction.
It will be seen that the wiring as we have described it is adapted for this particular
use. The change for cutting out the battery but leaving the connections ready
to receive the signal, is effected by moving the arm 20° of the switch from the
position shown in Figure 1 and in connection with which position the circuit has
just been described, and shifting said switch-arm over on the contact 20º, during
which latter position of the switch, the circuit will be as follows:-From the
positive pole of the battery (which according to the plan mentioned will now be
turned in circuit) on the other engine, to the central rails along that one of the
sections of the central rails with which both objects are simultaneously in contact,
up through the trolley 3 of the engine whose battery is cut out, along wire 26 to
pivot 20, through an arm 20° to contact 20%, through wire 24 to negative pole 19b
of the battery, then without going through the battery (because the conductor 25
from the positive pole 19" now terminates at the contact 20° of the switch-board)
but along the wire 23 to the alarm, then through wire 21 from the alarm to
axle 22 and through main track 2 to the other object from which the current is
supplied. Such a system will be found to be convenient because most roads give
even numbers to all trains going in one direction and odd numbers to all trains
going in the opposite direction. With such the rule would be that all even
numbers run with battery in circuit and all odd numbers run with battery out of
circuit.
The elevated central rails are divided into sections of equal length which are
laid so as to break joints, that is to say, each section on one side terminates opposite
the middle of the adjacent section on the other side. The ends of these rails
forming the central elevated track may either be simply spaced apart or they may
be insulated by interposing suitable insulating material. These rails I prefer to
mount on the cross tires 30 by means of blocks or chairs 31 at suitable intervals
apart, to which the rails 4 of said inner track are secured by bolts 32. The weight
upon the central rails being inconsiderable. The chairs 31 may be placed a
sufficient distance apart to leave the space between them, and beneath the rails 4
open and unobstructed. This is a very important point in the successful operation

page_text: of the system as it enables us to overcome one of the most frequent causes of
impracticability in systems of the class to which our invention belongs. We refer
to the effect of accumulating snow and ice between the rails which results in short
circuiting by connecting the inner and outer rails and thus giving an alarm
unnecessarily in the engine. With the rails set up as described it is an easy matter
to keep the space around them swept clean and free of obstruction.
In guarding switches, a simple battery 35 is used with wires 36 and 37 running
from its respective poles and connected at 33 and 39 to the main and central tracks
of the switch, which are adapted when thrown against corresponding rails of the
main line, to open the switch, close that half of the circuit, so that an engine
approaching will receive the alarm. If the road is working under a rule which
provides for the attachment of the positive wire to the trolley on the central track,
then the negative wire 36 of the local switch battery 35 will be connected to the
central track so that the currents of the locomotive and switch batteries will
re-enforce rather than oppose each other. When an engine is going in the opposite
direction and its battery is cut out according to rule, it receives current from the
local battery without interruption.
While we have shown what we consider to be the most convenient form of wiring
for the different parts of our system in connection with the mechanical features of
the system, we do not limit ourselves to the use of this precise wiring for the reason
that it may be found necessary to alter the same as circumstances and conditions of
the parts to which it is to be applied may dictate.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. In a railway electric signal, the combination of the main track, the locomotive
adapted to run thereon, the central track and the trolley carried by the locomotive
and adapted to run upon the central track and consisting of the pair of wheels, a
downwardly and forwardly projecting arm on which the wheels are mounted, and.
the spring for drawing the wheels down upon the track, attached to the forward
end of the frame and passing to a fixed point on the engine behind it, substantially
as herein set forth.
2. In a railway electric signal, adapted to operate substantially as described, the
trolley consisting of the pair of wheels, the downwardly and forwardly extending
frame on which the wheels are mounted and which is pivoted at its upper end to
the locomotive, the spring connecting the lower end of the trolley with a fixed
point on the locomotive for holding the wheels down, and the pivoted elevating
lever bearing against but disconnected with the frame of the trolley all sub-
stantially as herein set forth.
3. The herein described trolley for railway electric signals which consists of a
wheel running upon the conductor, the pivoted frame upon which the wheel is
mounted consisting of the vertical and horizontal arms and having a spring for
rocking it on its pivot and holding the wheels down upon the conductor, the
pivoted lever having its lower end adapted to come in contact with and bear
against the pivoted lever of the trolley, a dog on the lever and a rack segment in
proximity to which the lever moves, all substantially as and for the purposes
specified.
4. In a railway signal system, the combination of the main track and the central
two-rail trolley track formed of insulated brake-joint sections, a car running on the
main track and having a trolley running on the central track, the working
electrical connections in the car consisting of a suitable signal, a battery, a switch,
having its lever electrically connected with the trolley, and having two contacts
connected with the respective poles of the battery, electrical connections between
the negative pole of the battery and the car wheel and a railway switch having

page_text: main and trolley tracks arranged for movement to deflect the car and trolley, and
having a local battery with its negative pole connected to the central switch track
and its positive to the main track of the switch, whereby trains running in opposite
directions with their batteries in and out respectively will each get the signals from
the other and from the open switch, as explained.
Dated this 20th day of November 1893.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicants' Agents.