Improvements relating to Electro-Magnetic Switch Apparatus for Railway Signalling and other Purposes.
Year: 1897

page_text: Date of Application, 9th Nov., 1897-Accepted, 22nd Jan., 1898
Improvements relating to Electro-Magnetic Switch Apparatus for
Railway Signalling and other Purposes.
I, CHARLES ARTHUR ALLISON, Patent Agent, of 52, Chancery Lane, London,
in the County of Middlesex, do hereby declare the nature of this invention (which
has been communicated to me from abroad by William Charles Banks, Electrical
Engineer, of 407, Temple Court, Beekman Street, in the City of New York,
State of New York, U.S.A.), and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement:
-
My invention relates to Electrical Instruments adapted to substitute a resist-
ance in a circuit to supply the place of another resistance theretofore cut out,
and it consists in the combinations of devices set forth in the claims, some forms
of which are hereinafter described and shown in the drawings, in which;
Figure 1, is a plan view, representing a block of a railroad signal system in
which one of my instruments has been placed;
Figure 2, shows a similar block and instrument, except that the connection
from coil C to coil C5 is modified.
Figure 3, is a side elevation of the preferred form of my instrument;
Figure 4, is a plan view of the said instrument; and
Figure 5, is a plan and sectional view of the same.
In many arrangements of electrical devices, especially those used in railroad
block signal systems, two conductors are provided which are to have something
(say a car) move over and upon them, from an adjacent situation, and a relay
or other electrical instrument connected with one part of said conductors is in
circuit, through them, with a battery or other source of electrical power con-
nected with said conductors at other points than those where the relay is
connected, with some space between, so that when the moving body passes upon
the conductors, between the relay connections and the battery connections, there
may be a short circuit established between the poles of the battery within the
line of the relay connections, which will cause the relay to operate in a given
way. The disadvantage of this arrangement with ordinary systems of this
character is, that when the battery is thus short circuited, the relay resistance
is, as it were, cut out and the power is wasted, if the body running upon the two
conductors, and creating the short circuit, should remain for any appreciable
time between the location of the points where the relay connects with the con-
ductors and those where the battery connects with the conductors.
For instance, if R and R¹ were the rails of a railroad with a battery B con-
nected to them at p and p¹ and a signalling relay connected to them at p², p³,
then (assuming my instrument to be a mere inactive connection) the circuit is
from one pole of the battery to one rail, thence to one relay connection, thence
through the relay and its other connection to the other rail of the road and
through it to the other pole of the battery.
Normally the resistance of the relay is included in the circuit and prevents the
rapid deterioration of the battery at B, the resistance of many such relays in

page_text: use, being from 4 to 10 ohms. Now when a train runs upon such a block, the
battery, as is apparent, is short circuited, the line being from one pole to one
rail, thence by the car wheels and axles of the train to the other rail and back
to the other pole of the battery, and the resistance of the relay is not encountered
in that circuit, wherefore the battery begins to waste, and if the train, as is often
the case, should remain on the block for a considerable time, the life of the
battery would be correspondingly short. To provide for this I have placed near
the battery an additional resistance, normally out of the battery circuit, (or
rather normally short circuited) but with a switch operated by an electro-magnet
in the battery and relay circuit, and controlled by a spring or equivalent, the
tension of which is such that when the relay resistance is operating against
the current, that will not produce sufficient power in the switch magnet to close the
switch, but when the short circuit about the relay is established, then the current,
relieved of the relay resistance, will give sufficient power to the switch magnet
to move its armature and cut into the battery circuit, the new resistance (or
rather to break a short circuit of low resistance leaving only a circuit through a
relatively high resistance) which taking the place of the relay resistance will effec-
tually prevent the objectionable waste of battery power noted.
The battery, relay, rails etc., need no especial description, they are all well
known, and I would add that in carrying out my invention I do not limit myself
to the instrument I now intend to describe, as many possible variations of form
and arrangement will readily present themselves to skilled electricians and
mechanicians.
The form shown in Figures 3, 4 and 5, consists of a suitable base, on which
I mount an electro magnet E, (of very low resistance, often 4/10 ohms,) sup-
ported in a yoke Y at one end and by a post P, with an adjusting screw at the
other end. prefer to use two coils C, C but one could be omitted. The battery
connection is made at one binding post or terminal t, and the rail connection at
another t. The other ends of these coils are joined to spring pieces s, s¹, sup-
ported on an upright U connected to the yoke. These spring pieces at their
supports are insulated one from the other, but their free ends are normally in
contact, and the circuit is therefore normally through coils C and C¹. The
armature A swings on trunnions or pivots in a position in front of the poles of
the magnet and is held retracted by a spring S¹ secured to an adjusting post P¹.
This armature carries a non-conducting wedge circuit breaker w, lying adjacent
to and in front of the point where the springs s, s¹, make contact with each other.
Secondary coils C, C (of higher resistance, often 10 ohms) wound on the same
cores respectively with coils C and C¹ are connected to the respective wires of
said coils at or near their points of issuance from the coils C, C¹, and these
coils C, Care connected to each other at the opposite ends, as shown at w¹. A
stop s2, limits the movement of armature A and wedge w.
The operation is manifest, when relay G is in the circuit, the current passing
through C and C is not sufficiently strong to attract armature A with such power
as to cause the wedge w, to force spring pieces s, s¹, apart against the stress of
said springs and the adjustment spring S. But when the train has short-
circuited the battery B, the relay being outside of that short circuit, the current
through the electro-magnet is stronger. It attracts magnet A with sufficient
force to draw it forward, wedge w enters between and breaks the contact of s
and s¹, and the circuit must not only be through coils C and C¹ but also through
the additional coils C, C³, which are of such a character as to furnish the
additional resistance required to replace that of the relay, cut out by the short
circuiting caused by the running on the block, of train T, indeed I frequently
make the resistance of coils C2 and C3 greater than that of relay G. It will
thus be seen that though there is always a complete circuit, never wholly broken,
that I am enabled, the instant relay Ġ is short circuited, by the very result of
that short circuiting, to switch a supplemental resistance into the battery circuit.
as thus established, to take the place of that short circuited.

page_text: I prefer the instrument of Figures 3, 4, and 5, as it is compact and the winding
of two coils on one core adds to the magnetic effect produced on armature A,
when the short circuit is established within the relay lines, but, as illustrated
in Figures 1 and 2, I could vary the arrangement.
That the device may be more readily understood, I trace the connections of
Figure 5 which are identical with those of Figures 3 and 4. From terminal t,
supposed to be connected with rail R of the block, a wire leads to coil C of the
magnet. The other end of said coil is connected to contact springs, and also
(as shown) to the left hand end of coil C2, and the left hand end of coil C¹, is
connected to contact spring s¹, and also to the left hand end of coil C³. The
right hand ends of coils C and C³ are connected together by wire w', here shown
as partially covered with insulating material, and the right hand end of coil C¹
is connected to terminal t, which is supposed to be connected to battery B, which
in turn is connected to rail R¹. When springs, makes contact with spring s¹
the circuit through the instrument is from terminal t, by wire to coil C, thence
by springs, to spring s¹, and thence by coil C₁ to the wire leading to terminal t¹,
the short circuit about the resistance C2 or both resistance coils C and C being
substantially the contact, coil C' and the wire from it to terminal t¹.
At this time coils C2 and 03 are also (in the instrument shown in Figure 5)
actually in the circuit (though not necessarily so) but the so called short circuit
about them presenting less resistance, the main portion of the current manifests
itself accordingly. When contacts s and s¹ are separated, the short circuit is
broken and the circuit is then only complete through the resistance coils, that is,
from terminal t to coil C, from its left hand end to the same end of coil C³, across
by wire w¹ from the right hand end of coil C², to coil C³, and from the left hand
end of coil C³, to terminal t¹, by way of coil C¹.
In Figure 1 the circuit is as follows; starting from battery B, it is by wire 6
to rail R¹, wire 5, relay G, wire 4, rail R, wire 11, terminal wire 10 coil C
spring post P, short circuit wire ², terminal 1, and wire 7 to battery B. At
the same time the circuit through coil C is similar as far as spring 3, and thence
by wire 9 to coil C, and from it to terminal t¹, by wire 8 and by wire 7 to
battery B.
The only difference in Figure 2 is that the connection from spring s³ to coil C
is by means of arm a, (which may be insulated from armature A), and wire 9ª.
As armature A, moves inward by reason of the attraction of the electro magnet,
arma makes contact with spring 3, and the resistance circuit is thus established,
before the short circuit is broken by forcing the end of spring ³, away from
post P². This instrument may also be used in electric light circuits.
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 of a circuit, including a resistance, a generator, an electro-
magnetic circuit breaker, (the latter two of which are always in circuit) a second
resistance and a short circuit about it, all arranged substantially as set forth,
whereby the removal of the first resistance will operate the circuit breaker to
open the short circuit about the second resistance and constitute its circuit a
part of the only complete circuit through the generator.
2. The combination of a closed circuit including a resistance, a generator, an
electro magnetic circuit breaker, (the latter two of which are always in circuit) a
second resistance and a short circuit about it, all arranged substantially as set
forth, whereby the removal of the first resistance will operate the circuit breaker
to open the short circuit about the second resistance and constitute its circuit
a part of the only complete circuit through the generator.
3. The combination of a circuit including a first resistance, a generator and an
electro-magnetic circuit breaker (the latter two of which are always in circuit)
the armature of the magnet of which circuit breaker when the first resistance is

page_text: in unobstructed circuit, is held by a force greater than the force of the electro-
magnet, but less than the force of said electro-magnet when a short circuit is
established around said first resistance, and a short circuit about it, whereby
when the force of said circuit breaker magnet is augmented as described it will
open the short circuit about the second resistance and constitute the circuit of
said second resistance a part of the only complete circuit through the generator.
4. The combination of a circuit including a relay and a generator, of an electro-
magnet whose coil is continuously a part of the generator circuit, a second
resistance, a circuit including said second resistance and said electro-magnet,
circuit connections from said electro-magnet to said generator not including said
second resistance, two contact points, at least one of which is in that circuit
which excludes the second resistance, and one of which is sustained upon a yield-
ing support, an armature to said electro-magnet adapted as described to force
back said point on that yielding support and break the circuit, which excludes
the second resistance, when a short circuit is established about the relay, all
substantially as set forth.
5. An electrical instrument, composed of an electro-magnet provided with an
armatare, two terminals one connected to one end of the magnet coil, a resist-
ance one end in circuit with the second end of the magnet coil, the other end
connected to the second terminal, two contact points adapted to break and make
contact with each other, one connected to an end of the magnet coil, other than
that which is connected to the first terminal, a short circuit, (not including the
resistance) electrically connecting the second terminal and the second contact
point, one of which contact points is mounted upon a yielding support in the
line of movement of the magnet armature, whereby a sufficient excitation of
said electro-magnet will cause its armature to force and hold the contact points
apart and break and hold open the short circuit thus making the only complete
circuit from terminal to terminal include the resistance, and will yet leave the
magnet coil in the said circuit from terminal to terminal, substantially as set
forth.
6. An electrical instrument, composed of an electro-magnet provided with an
armature, two terminals one connected to one end of the magnet coil, a resistance,
(arranged substantially as described, with its core constituting a pole of an
electro-magnet whose armature is the same as that of the electro-magnet proper)
said resistance having one end in circuit with the second end of the magnet
coil, the other end connected to the second terminal, two contact points adapted
to break and make contact with each other, one connected to an end of the
magnet coil, other than that which is connected to the first terminal, a short
circuit, (not including the resistance) electrically connecting the second terminal
and the second contact point, one of which contact points is mounted upon a
yielding support in the line of movement of the magnet armature, whereby a
sufficient excitation of said electro-magnet will cause it's armature to force and
hold the contact points apart and break and hold open the short circuit, thus
making the only complete circuit from terminal to terminal include the resist-
ance, and will yet leave the magnet coil in the said circuit from terminal to
terminal, substantially as set forth.
7. An electrical instrument, composed of an electro-magnet provided with an
armature, two terminals one connected to one end of the magnet coil, a resistance
one end in circuit with the second end of the magnet coil, the other end con-
nected to the second terminal, two contact points adapted to break and make
contact with each other, one connected to an end of the magnet coil, other than
that which is connected to the first terminal, a short circuit, (not including the
resistance) electrically connecting the second terminal and the second contact
point, one of which contact points is mounted upon a yielding support in line
of movement of the magnet armature (a spring whose stress is opposed to that
attractive force of the electro-magnet operating upon it's armature) whereby a
sufficient excitation of said electro magnet will cause its armature to force and

page_text: hold the contact points apart and break and hold open the short circuit, thus
making the only complete circuit from terminal to terminal include the resist-
ance, and will yet leave the magnet coil in the said circuit from terminal to
terminal, but upon a diminution of said magnetic force said contact points will
be again brought together and the short circuit about the resistance automatically
re-established, all substantially as set forth.
8. An electrical instrument composed of an electro-magnet provided with an
armature, two terminals, one connected to one end of the magnet coil, a resist
ance coil wound upon the same core with the coil of the electro-magnet, one
end in circuit with the second end of the magnet coil and the other end in
circuit with the second terminal, two contact points adapted to break and make
contact with each other, one connected to one end of the magnet coil other than
that connected to the first terminal, a short-circuit not including the resistance
coil, electrically connecting the second point and the second terminal, one of
which points is mounted on a yielding support in the line of movement of the
magnet armature, all substantially as set forth.
9. An electrical instrument composed of a two coil electro-magnet, each double
wound, two terminals, one connected to one end of one coil, the other connected
to an end of the other similar coil, connections between the respective ends of the
first coils which are not directly connected to the terminals and the adjacent
respective ends of the second coils, a connection between the respective opposite
ends of said second coils, two contact points, one or both carried on yielding
supports and connected respectively to those ends of the first coils which are not
directly connected to the terminals, and an armature to the so constituted electro-
magnet supported and adapted to move in line with the yielding support of at
least one contact point, all substantially as set forth.
10. An electrical instrument composed of a two coil electro-magnet, each
double wound, two terminals, one connected to one end of one coil, the other
connected to an end of the other similar coil, connections between the respective
ends of the first coils which are not directly connected to the terminals and the
adjacent respective ends of the second coils, two spring contact pieces, connected
respectively to those ends of the first coils which are not directly connected to
the terminals, and having faces inclined toward their mutual point of contact,
and an armature to the so constituted electro-magnet carrying a finger adapted
as described to force said spring contacts apart and means substantially as set
forth, for normally holding said finger from separating said contact pieces, all
substantially as set forth.
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