US1135427A - Signaling system. - Google Patents

Description

C. E. BEACH.

SIGNALING SYSTEM.

APPLICATION FILED MAI/Is, |914.

Patented A131113, 1915.

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CLARENCE E. BEACH, 0F BINGHAM'ION, NEW YORK, ASSXGNB, TO GEORGE O. KNAPP, 0F NEW YQRK, N. 'SZ'.

SIGNALING SYSTEM. i '1 f Application filed May 18, 1914.-.

T0 all whom it may concern Be it known that I, CLARENCE E. BEACH, a citizen of the United States, residing at Binghamton, in the county of Broome and State oit New York, have invented certain new and useful improvements in Signaling Systems, ci which the following is a specication.

My invention relates to signaling1 systems and particularly to systems in which the line wires are maintained under constant test for their continuity by the use of a minimum amount of energy, and having means whereby the flow of current through the receiving devices will be greatly increased during the transmission of a signal.

din object of my invention is to provide such a system in which a plurality of transmitting devices are so a 1ranged in a simple series circuit that their contacts merely control a weak current.

Another object of my invention is to provide means whereby a constant test for ground (or leakage from the line wires to ground) may be maintained without thereby rendering it possible to so shunt any of' the receiving devices as to prevent their acting to transmit an alarm, and at the same time minimize the chance of disabling any ot the alarm transmitting devices through the development of a leali between the line wires and the ground.

.it still further object of my invention is to obtain a reversal of the current through the receiving` devices for each stroke of a signal, such reversal to be substantially coincident and co-extensive with the increase in the current while requiring but a single series loop for the transmitting devices and a single series loop for the receiving` devices; both of said loops being1 normally fed from the same battery in series with each other, but said loops being connected in parallel with each other during1 the transmission of signals.

itiy present invention is in the nature of an improvement over that shown in my prior patent dated May 20, 1913, No. lttl, and also over that shown in my co-pending application Serial No. 808,572.

ln both said patent and said application l have shown a type of signaling1 system in which three current paths are provided, in two of which paths are connected comparatively high resistances and in the third ot Specification of Letters Patent.

Patented Apr. t3, i915..

serial No. essere.

which paths is connected a loop including a plurality of signal receiving devices ol' comparatively loiY resistance, a source of current being supplied and circuit changing mechanism being provided whereby the paths may be connected in series or in parallel with each other. ln my said foregoing patent there is shown but one circuit changing device and suitable circuit connections and two resistances adapted to be located near the source of energy, wiile a loop adapted to communicate with signal receiving devices at distant points and to include said devices in series with each other was provided, which loop is herein referred to as a receiving' device loop. ln my said copending` application a number of circuit changing devices were provided, each capable of changing,` the circuit relations ot the three current paths from series to parallel, and each controlled by a signal transmitting mechanism, but in employing the system shown in my said co-pending application, it is necessary to equip each transmitting, device with a circuit changing device having` two sets ot circuit controllers, and it is further necessary to provide tour condu ctors for connecting1 such tra-nsmittingl devices, between which conductors the circuit controlling' contacts of the various transmitting devices are connected in parallel, and on account of such parallel connection, the condition of the contacting` surfaces of these circuit controllers .is not under constant test, and not only is a comparatively expensive system of wiring` required, but extra heavy circuit controlling contacts are required for each transmitting device, on account of their being called upon to both malte and break the eXtra heavy current used in si gnaling.

ln my present invention but one set of circuit controllers is provided tor each transmitting device, and these circuit controllers are arranged in series in a simple loop which is herein referred to as a transmitting' device loop, a suitable circuit changino; device being;` provided at a convenient point having a magnet so connected with the transmitting device loop as to be controlled by all of the tranemitting` devices, and to, in turn, control circuit changing mechanism for three loops, so that said loops may be connected with the source of current either in series with each other or in parallel with cach other, by said circuit changing 11a device. Thus the circuit controllers of the various transmitting devices are merely called upon to break the Vweak current which passes over the line when the three loops are connected to the source of current in series with each other, and when acting to close the circuit are only called upon to carry such current as will pass through the transmitting loop and its resistance when said loop is connected across the terminals of the source of current. The third loop controlled by the circuit changing device is of relatively highresistance and is provided to enable the other two loops to be subjected to proper tests by the use of a comparatively weak current when such loops are not connected in parallel with each other, and this third loop is herein referred to as a continuity loop.

1n order that my invention may be better understood, 1 show in the drawing annexed to and forming part of this specification a signaling system embodying my invention, but I do not limit myself to the particular arrangement shown, as it is evident that features of my invention are adapted for use either separately or in combination with each other, and the particular descriptions hereinafter contained of the typical system shown in annexed drawing are given for the clearer illustration of my invention, and many changes in construction and arrangement and insertion or omission of parts may be made without departing from the spirit of my invention.

1n the accompanying drawing 1 is the source of current, one terminal of which is connected through wire 2 to contact 102, and the other terminal of which is connected through the wire 18 to contact 103.

rlhe transmitting loop comprising the wires 2, 3, 4, 5, 6 and 7 ,is connected between Contact 102 and contact 106 and includes resistance 9 connected between the wires 2 and 3, winding of magnetically controlled circuit changing device 10 ecnnected between wires 3 and 4, circuit controlling contacts 11, 12 and 13 connected between wires 4 and 5, 5 and 6, and 6 and 7, respectively, which contacts are shown as forming part of transmitting devices A, B and C, the remaining structure of which devices is represented by the characteristic signal wheels 14, 15 and 16.

The continuity loop comprising the wires 18, 19 and 20 is connected between contacts 103 'and 105and said loop serially includes the continuity loop resistance 21 connected between wires 18 and 19 and th'e winding of ground test relay 22 connected between wires 19 and 20.

The receiving loop is connected between contacts 105 and 106, said receiving loop consisting of the wires 23, 24, 25, 26, 27 and 28, and said loop serially including the winding of the receiving devices shown by characteristic representations of gongs or bells, D, E, F, G and H, whose windings are connected between the wires 23 and 24, 24 and 25, 25 and 26, 26 and 27, and 27 and 28, respectively.

The circuit changing device 10 is shown as having magnet 101 and contacts 102, 103 and 104 controlled thereby, said contacts being adapted to connect with the contacts 105, 106 and 107, respectively.

A typical local signal consisting of the bell 30 and battery 31 is shown connected to the contacts 104 and 107 associated with the circuit changing device 10, to be suitably controlled thereby, and said local signal is shown as also being suitably controlled by the ground test relay 22.

It is desirable that the local signal should be operated at least as soon as, and preferably a little in advance of, the contacts 102 and 103, and 105 and 106 oi the circuit changing device 10 so that the local signal will sound whenever these contacts or either of them come together.

rlhe circuit controlling contacts of the transmitting devices are arranged to stand normally closed, and the magnet of the circuit changing device 10 is thus normally energized and the connection between contacts 102, 103 and 104 and contacts 105, 106 and 107, respectively, is thereby interrupted. lhile said contacts are separated, the path of current is from the source 1 through wires 2, 2, transmitting loop resistance 9, wire 3, winding of circuit changing device 10, wire 4, circuit controlling contacts 11, wire 5, circuit controlling contacts 12, wire 6, circuit controlling contacts 13, wire 7 to contact 106, thence through wire 28, winding of receiving device H, wire 27, winding of receiving device G, wire 26, winding of receiving device F, wire 25, winding of receiving device E, wire 24, winding of receiving device D and wire 23 to contact 105, thence through wire 20, winding of ground test relay 22, wire 19, continuity loop resistance 21 and wire 18 to contact 103, thence through wire 18 to other terminal oi current source 1. Vhile the circuit conditions just described are maintained, the contacts of relay 22 will be held open, and the cont- acts 104 and 107 of circuit changing device 10 being also held open as already described, the local signal device 30 will be silent.

The combined resistance of the receiving devices D, E, F, G and H, added to the rcisistances 9 and 21, as well as the resistance of the magnet 101 of the circuit changing device 10 and the relay 22, is such that the current flow through the path including the transmitting, receiving and continuity loops when connected in series as just described, will not be sufiicient to cause the l l L1 insane? magnets provided in the alarm receiving devices to actuate their armatures, although said current is su licient to cause the magnet of the circuit changing device and ground test relay 2a to retain their respective armatures. lit', under these conditions, one of the signal transmitting devices be operated, lic" example, the device at station il, the rotation oiI Wheel la Will permit the separat-ion of contacts 11, whereupon the rloiv of current through the path just described will be interrupted and the circuit changing device 10 will thereupon act to close its contacts and thereby connect the Vtransmitting loop, receiving loop and continuit7 loop in parallel With each other, While leaving them connected With the source oli current 1. The current paths 'from the source 1 will then be as follows From one terminal ol said source through the Wire 2 to the contact 102 to contact 105 from which tivo current paths will be provided, one oi which Will be through the continuity loop and the other of which will he through the receiving` loop to the contact 103, thence to the other terminal of the current source 1 through the vvire 18.

The current path between contact 105 and contact 103 through the receiving loop will be as follows:lhrough Wire 23, Winding of receiving device D, Wire 24e, winding o5 receiving device lll, Wire 25, Winding of receiving device ll, Wire 26, Winding of receiving device G, Wire 27, Winding ol' recci ving device ll, and Wire 28 to contact 106 uhich ivill be touching contact 103.

.llhe path of current through the continuity loop will he from contact 105 through Wire 520, Winding of ground test relay 92, Wire 10, resistance 21, and Wire 18 to contact 10B.

lllhenever the receiving and continuity loops are connected in parallel through the path just described, the transmitting loop will als he connected to the source 1 through 'the contact 100 in addition to its permanent connection at the contact 102, but no current will liovv through the transmitting loop as long as the contacts 11 remain open, but upon the closing of the contacts l1` a third current path through the transmitti1 -g loop will he established from the sourccl lthrough ivires 2, il, transmitting loop resistance 0, ivire 3, magnet 101, wire d, ciiicuit controlling contacts 11, vvire 5, circuit controlling contacts 12, ivire 0, circuit controlling contacts 13, and wire 7 to contact 100, thence through contact 108 and vire 18 to the other terminal olE the current source 1.

llpon the establishment of the current iloiv through the transmitting loop resulting from such closure oit' the circuit controlling contacts 11, the circuit changing device l0 acts to break connection hetiveen its various contacts and thus change the circuit relations of the three loops from parallel to series, whereupon the current path would be first described.

During the time that the receiving loop ivas directly connected to the source of current through the engagement ot contacts 109J and 103 with contacts 105 and 106, the cur'ent tloiv through the inagnets of the recei. ng devices ivould be limited only hy the resistance ci? the magnets or said devices and the conductors connecting them directly with the source olI current through th contacts of the circuit changing device 10. rlhus, the current tloiv through these devices would be greatly increased, and it Will be -noted that in changing the circuit relations of the three loops from series to parallel, the direction of the current llo v in 'the receiving loop is always reversed, as, when the loops are connected in series relation, the current path from the terminal oi the current source connected by Wire 2 is through the transmitting loop to contact 100. and thence through ivire E28 ot the receiving loop, While the current path when the loops are connected in parallel is from the terminal of the current source connected by Wire 18 through contacts 103 and 106 to .Wire 28 of the receiving loop.

lt will thus ce seen that the magnets of the receiving devices will he alternately subjected to a heavy tloivo'l current in one direction in response to breaks .in the transmitting loog and to a ivealr iloiv of current in the opposite direction during the closed circuit condition ot the transmitting loop, thus assuring eilective operation of the niagnetic mechanism oli' the receiving devices, not only through the application oli the strong current for the strokes ot a signal, but also through the use olE a Weak reversed current between strokes, having a tendency to demagnetize or vercome residual inagnetism in the electro-magnetic structures oit the receiving devices.

his the rotation of the si gual ivheel 1lwill first produce tivo breals and then, after a suitable interval, produce Vtour hrealrs in the transmitting loop., it is evident that the signal Zwei ivill he eiliectively indicated oy the receiving devices and during the transmission of this signal the local signal 30 ivill sound in response to the breaks in the transmitting loop, but upon the completion oit the rotation ot the signal Wheel 111 and the consequent closing oit the transmitting loop, the local signal rvill he silenced through the disengagement of the contacts 1 0-l and 107 upon the final energization o the magnet 101 of the circuit changing device. lt is desirable that the resistances 9 and 21, the circuit changing device 10, ground test rela;7 22, local signals 30 and hattery 31 should be located in close proximity to each cther,'so that the wires 18, 19 and 20 and the wires connecting the local signal device may be as short as possible, and, in fact, may be in the form of bus bars or heavy conductors mounted upon a terminal hoard or similar structure, so Vthat these conductors will be protected as far as possible Yfrom rupture or grounding.

lr" it is desired to practically eliminate the sparking between contacts 102 and 103 and the contacts 105 and 106, a suitable condenser 32 may be connected at any convenient point on either the wire 7 or the wire 28 and either the wire 20 or the wire 23.

ln the event of an accidental break in the transmitting loop, it is evident that the magnet 101 of the circuit changing device 10 will immediately fail and the contacts 102, 103 and 104 will connect with the contacts 105, 100 and 107, respectively, thus causing the local signal to sound continuously and subjecting the devices in the receiving loop to heavy signaling current.

ln the event of an accidental break in the receiving loop, the magnet 101 of the circuit changing device 10 will likewise fail, but upon the contact 103 connecting with the contact 100, current will be re-established through the transmitting loop and thereupon again energize magnet 101, whereupon a vibrating action ot the contacts 102, 103 and 10lV willibe set up, and during the periods when said contacts connect with Vtheir cooperating contacts 105, 10G and 107, the local signal will be sounded as the result of the connection between contacts 104 and 107, and during such periods as these contacts are apart, leaving the continuity loop in series relation with the receiving loop, it is evident that the accidental break in the receiving loop will cause the magnet of relay 22 to fail, and thus the circuit through local signal 30 will be maintained almost continuously, being alternately closed through the action of relay 22 and circuit changing device 10. i lVith proper construction of parts, the chance of an accidental break in the continuity loop may be reduced to a minimum, as hereinbefere suggested, but should a Y break occur in this loop the relay 22 will immediately act tc cause the local signal to sound while the circuit changing device 10 will vibrate as already explained.

Should the connection between current source 1 and contacts 102 or 103 be accidentally broken, both the circuit changing device 10 and the ground test relay 22 will act to cause the local signal 30 to sound.

ln signaling systems such as herein described, it is frequently desirable that means should be provided whereby an accidental ground connection may be instantly indicated, and while keeping the circuit under test for this purpose, it is also desirable that no condition will be produced which would result in rendering the receiving devices unresponsive to signaling circuit changes. For the purpose of applying such a test, a ground connection is provided in the signaling system at a point between the terminals of the resistance 21, and while this ground connection may be applied at various points between the terminal oil the resistance 21 connected to wire 18 and the terminal connected to wire 19, the most desirable results will be obtained if this ground connection is applied at a point between the terminal of the ground test relay 22 which is connected to the wire 20 and the terminal of the resistance 21 which is connected to the wire 18 which is electrically midway between said points.

rThe advantage obtained through applying the ground connection at a point electrically midway between wire 18 and wire 20 will be manifest when it is considered that if the ground connection was applied directly to wire 18 and an accidental connection developed between wire 23 and the ground, if the circuit changing device 10 acted to close its contacts while such accidental ground connection existed, the current source 1 would be short-circuited through the iollowing path: From source 1 through wire 2', contact 102, contact 105, wire 23 to accidental connection between said wire and ground, thence to permanent connection between wire 18 and ground, through wire 1 to contact 103, thence through wire 18 to other terminal of the source of current.

On the other hand, if the resistance of the winding of ground test relay 22 is comparatively low and the permanent ground connection is applied to wire 19, in the event of an accidental connection between wire 28 and the ground, the winding of ground test relay 22 would be connected directly across the source of current through the following path (assuming, as before, that the circuit changing device 10 has acted to close its contacts) From current source 1 through wire 2, contact 102, contact 105, wire 20, winding of ground test relay 22 to permanent ground connection applied to wire 10, thence through the accidental ground connection to wire 28 and through wire 28 to contact 106, contact 103 and through wire 18 to other terminal of current source 1.

It is evident `from the foregoing that the resistance between ground connection 33 and either the wire 18 or the wire 20 must be such as will prevent an excessive iiow of current as the result of any accidental ground, regardless of whether the loops are connected in series or in parallel.

With the ground connection thus established, it is evident that the development of a connection, as, for example, between the wire 25 and the ground, while the transof the resistance 21 between the ground con-;

nection and the wire 19 and also shunt the ground test relay 22 and receiving devices D and E, thus causing local signal 30 to sound through the closing oi the contacts of ground test relay 22, but leaving the signaling system in operative condition in that the circuit changing device 10 will remain responsive to the transmitting devices A, B and C and the signal receiving devices D and E will remain responsive to the connection of the three loops in parallel instead of series, as the ground connection willI merely aiiord a high resistance path in parallel with these signaling devices and not materially decrease the current ilow therethrough, as the fall of potential between contact 105 and the wire 25 will be only that incidental to the iiow of the heavy signaling current through receiving devices D and it, while the resistance of the portion oi" resistance 21 and the relay 22 in parallel with these devices would be much greater than the resistance of all of the receiving devices.

it a connection should develop between wire 28 and the ground, the low of current during closures of contacts 102 and 103 with contacts 105 and 106 through the receiving loop would not be noticeably decreased, but a fourth loop would, in effect, be established as follows z-mhe transmitting loop would remain unchanged between contacts 102 and 103 via contact 106. lThe receiving loop would remain unchanged between contacts 105 and 106. A portion of the continuity loop would be shunted, the current path from contact 103 through wire 18H and the portion of resistance 21 between the ground connection and wire 18 being in parallel with a path from contact 103, throughcontact 106 and wire 2S to acci- ,dental ground, thence through ground connection to point in resistance 21 connected thereto. From this point the current flow would be through the portion of re- `sistance 21 between the ground connection 33 and the wire 19, wire 19, the winding of relay 22, wire 20, through contact 105 to Contact 102. a

1n the use oithis system, the action `oli the circuit changing device is made more positive and effective through the fact that when the transmitting loop is closed while the armature of this device is in retracted position, the current flow through the magnet of the circuit changing device will be much greater than normal until the armature moves far enough toward attracted position to open the contacts controlled thereby, and although the current direction through the receiving loop is reversed for each impulse of a signal, the current flow through the transmitting loop is at all times in one direction.

Such amount of resistance should be distributed between the resistance 9 and magnet 101, resistance 21 and magnet 22 as to cut the current liowing through the loops when in series down to a point which will barely hold the armature of ground test relay 22 and the armature of circuit changing device 10 in attracted position, but insuihcient to move either of said armatures to attracted position, so that a very slight decrease in the electro-motive orce of the eurrent source 1 will be promptly indicated by the failure of one or both of these devices, as it is evident that whenever the circuit changing device 10 acts to group the loops in parallel, the current flow through either the continuity loop or the transmitting loop when closed will be so increased as to et fectively energize these magnets.

As the current flow through the continuity loop during signaling periods is practically wasted, the resistance of this loop should preferably be relatively high and the resistance of the transmitting loop should be relatively low, in comparison with the resistance of the continuity loop, while relatively high in comparison with the resistance of the receiving loop.

As an example of a desirable relation of resistances for the various loops in the system shown, it may be assumed: That the source of current 1 maintains a constant potential of' 50 volts, while the receiving devices D, E, F, Gr and H are direct acting bells operable at greatest eiliciency at a current flow of one (1) ampere, and having such winding that the resistance of the receiving loop will be about ohms, these gongs being unresponsive to a current flow of 10 milliamperes. That the circuit changing device 10 is sowound as to be adapted for most eliective operation to break its contacts when energized by a current strength of 100 milliamperes, and to hold its contacts apart at a current strength of 10 milliamperes, the resistance 9 being such as to bring the total resistance of the transmitting loop to 500 ohms. That the ground test relay 22 is adapted to attract and retain its armature at a current flow through its magnet windings of 11 milliamperes and to retain its armature at a current flow of 10 milliamperes, the resistance 21 being such that the entire resistance of the continuity loop is 41450 ohms. Employing these resistances, it is evident that when the three loops are in series, the total resistance between the terminals of the current source 1 will be about 5000 ohms, and with the assumed voltage of 50 volts a normal test current of 10 milliamperes will pass, thus maintaining the armatures of the circuit changing device 10 and ground test relay 22 in attracted position.

Ylso

It is also evident that upon the circuit changing device 10 acting to close the contacts controlled thereby, the current lloiv through'the receiving loop will be reversed in direction and increasedto a strength of l ampere, but the current flow through the continuity loop vvill be neither reversed nor greatly increased, but will merely rise to a value betvveen ll and l2 milliamperes; but When thetransmitting loop is again closed, the current therethrough Will immediately rise to a value of about 100 milliamperes and continue at that strength until the circuit changing device 10 has acted to connect the 'three loops in series when the current fioW through all of said loops will return to 'normal strength of about l() milliamperes.

The foregoing resistances and operating values are only assumed for purposes of illustration and may be varied at will to adapt my system for use .vith any desired arrangement of relays, receiving devices, or circuit changing conditions, vand the ground test connection and relay may or may'not be employed, as desired.

- l/Vhat I claim is 1. In a signaling circuit, a plurality of transmitting devices in one loop thereof, a plurality of receiving devices in a second loop thereof, said loops being normally connected in series With each other, and means controlled by each and every one of said transmitting devices for connecting said loops in multiple With eachother.

2. Asignaling system comprising a circuit having in series therein a source of current, a plurality of transmitting devices each adapted to break the current flow therethrough, a magnet responsive to such breaks of said current flow, and a plurality of receiving devices, in combination with means controlled by said magnet for causing an operatively abnormal current flow through said receiving devices during each of said interruptions in the current fiovv through said transmitting devices.

3. In a signaling circuit, a plurality of transmitting devices in one loop thereof, a

plurality of receiving devices in a second loop thereof, said loops being normally connected in series With each other, and means -controlled by any transmitting device for connecting said loops in multiple with each other, and for reversing the current through the loop including said receiving devices.

t. In a signaling circuit, a plurality-of transmitting devices and a relay in one loop thereof, said relay being responsive to the signals of said transmitting devices, a plurality of receiving devicesin a second loop thereof,said loops being normally connected in series With each other, and means con'- trolled by said relay for connecting the ends of said loops in multiple with each other to the current source.

5. In a signaling circuit, a plurality of transmitting devices and a relay in one loop thereof, said relay being responsive to the operation of said transmitting devices, a plurality of receiving devices in a second loop thereof, said loops being normally connected in series with each other, and means controlled by said relay for reversing the current through the loop including said receiving devices.

6. In a signaling circuit, a plurality of transmitting devices and a relay in one loop thereof, said relay being responsive to the operation of Vsaid transmitting devices, a plurality of receiving devices in a second loop thereof, said loops being normally connected in series with each other, and means controlled by said relay for connecting said loops in multiple with each other and for reversing the current through the loop including said receiving devices.

7. In a signaling circuit, a plurality of transmitting devices in one loop thereof, a plurality of receiving devices in a second loop thereof, a resistance in a third loop thereof, said loops being normally connected in series with each other, and means controlled by any transmitting device for connecting said loops in multiple with each other.

8. In a signaling circuit, a plurality of transmiting devices in one loop thereof, a plurality of receiving devices in a second loop thereof, a resistance in a third loop thereof, said loops being normally connected in series With each other, and means controlled by any transmitting device for reversing the current through the loop including said receiving devices.

9. In a signaling circuit, a plurality of transmitting devices in one loop thereof, a plurality of receiving devices in a second loop thereof, a resistance in a third loop thereof, said loops being normally connected in series With each other, and means controlled by any transmitting device for con necting said loops in multiple with each other, and for reversing the current through the loop including said receiving devices.

l0. In a signaling circuit, a plurality of transmitting devices and a relay in one loop thereof, said relay being responsive to the operation of said transmitting devices, a plurality of receiving devices in a second loop thereof, a resistance in a third loop thereof, said loops being normally connected in series with each other, and means controlled by said relay for connecting said loops in multiple with each other.

l1. In a signaling circuit, plurality of transmitting devices and a relay in one loop thereof, said relay being responsive to the operation of said transmitting devices, a plurality of receiving devices in a second loop thereof, a resistance in a third loop thereof, said loops being normally connected in series with each other, and means con-a trolled by said relay for reversing the current through the loop including said receiving devices.

l2. lln a signaling circuit, a plurality of transmitting devices and a relay in one loop thereof, said relay being responsive to the operation of said transmitting devices, a plurality of receiving devices in a second loop thereof, a resistance in a third loop thereof, said loops being normally connected in series with each other, and means controlled by said relay for connecting said loops in multiple with each other for reversing the current through the loop including said receiving devices.

13. ln a signaling circuit, a plurality of transmitting devices and a relay in one loop thereof, said relay being responsive to the operation of said transmitting devices, a plurality of receiving devices in a second loop thereof, a resistance and a second relay in a third loop thereof, a ground connection between the terminals of said loop, said loops being normally connected in series with each other, local signal mechanism controlled by both said relays, and means controlled by said first named relay for operatively altering the current through said receiving devices.

ll. ln aA signaling circuit, a plurality of transmitting devices and a resistance and a relay in one loop thereof, said relay being responsive to the operation of said transmitting devices, a plurality of receiving devices in a second loop thereof, a second resistance and second relay in a third loop thereof, a ground connection between the terminals .of said second resistance, said loops being normally connected in series with each other, local signal mechanism con trolled by both said relays, and means conJ trolled by said irst named relay for operatively altering the currentY through said receiving devices.

l5. it signal system comprising a circuit having therein signal transmitting devices and signal receiving devices, a source of current, a ground connection, two normally energized relays, two resistances, one resistance and one of said relays being connected between one terminal of said source of current and one wire of the signal circuit, the second resistance having one terminal connected to the other terminal of the source of current, a portion of its resistance between said terminal and said ground connection, and its other terminal connected to one terminal of the other of said relays, the other terminal of said second relay being connected to another wire of the signal circuit, local signal mechanism controlled by said relays, and means controlled by any transmitting device for connecting said resistances in multiple with each other and with the receiving devices, and for reversing the current through said receiving devices.

1G. A signal system comprising a circuit having therein signal transmitting devices and signal receiving devices, a source of current, a ground connection, two normally energized relays, two resistances, one resistance and one of said relays being connected between one terminal of said source of cur- '7 17. A, signal system comprising a circuit l having therein signal transmitting devices and signal receiving devices, a source of current, a ground connectiomtwo normally energized relays, two resistances, one resistance and one of said relays being connected f" between one terminal of said source of current andV one wire of the signal circuit, the second resistance having one terminal connected to the other terminal of the source of said terminal and said ground connection, and its other terminal connected to one terminal of the other of said relays, the other terminal of said second rela-y being connected to another wire of the signal circuit, local signal mechanism controlled by said relays, and means controlled by Vany transmitting device for reversing the current through said receiving devices.

18. A signal system comprising a circuit having thereinvsignal transmitting devices current, a portion of its resistance between and signal receiving devices, a source of current, a normally energized relay, two resistances, one resistance and said relay being connected between one terminal of said source of current and one wire of the signal circuit, said relay being responsive to the operation of said transmitting devices, the second resistance having one terminal connected to the other terminal of the source of current and its other terminal connected to another wire of the signal circuit, and means controlled by said relay for so connecting said resistances in multiple with each other and with the receiving devices, as to reverse the current through said receiving devices.V

19. A signal system comprising a circuit having therein signal transmitting devices and signal receiving devices, a source of current, a normally energized relay, two resistances, one resistance and said relay being connected betvveen one terminal of said source of current and one Wire of the signal circuit, said relay being responsive to the operation of said transmitting devices, the second resistance having one terminal connected to the other terminal of the source oi' current and its other terminal connected to another Wire of the signal circuit, and means controlled by said relay for connecting said resistances in multiple vvith each other and With the receiving devices.

20. A signal system comprising a circuit having therein signal transmitting devices and signal receiving devices, a source of current, a normally energized relay, tWo resistances, one resistance and said relay being connected between one terminal of said source of current and one Wire of the signal circuit, said relayv being responsive to the operation of said transmitting devices, the second resistance having one terminal connected to the other terminal of the source of current and its other terminal connected to another Wire of the signal circuit, and means controlled by said relay for reversing the current through said receiving devices.

2l. A signaling system comprising a circuit having in series therein a source ot current, a plurality of receiving devices having a relatively low total resistance, a plurality of transmitting devices, a relay responsive to the operation ot said transmitting devices, and a vresistanceWhose combined resistance is relatively high in' comparison with the resistance of the receiving devices, and a second resistance relatively high in comparison With the combined resistance ot the transmitting devices, relay and Iii-st named resistance, and means controlled by the relay or operatively altering the current through said receiving` devices.

22. In a signaling circuit', a plurality of transmitting devices and a relay in one loop thereof, said relay being responsive to the operation of said transmitting devices, a

plurality of receiving devices in a second loop thereof, a resistance in a third loop thereof, said loops being normally connected in series with each other, the resistance of said first named loop being relatively high in comparison with the resistance of said second loop, and being relatively low in comparison withthe resistance of said third loop, and means controlled by said relay for operatively altering the current through said receiving devices.

Q3. A signaling system comprising a circuit having in series therein a source of cui rent, a plurality of transmitting devices, a relay responsive to the operation olf said transmitting devices, and a plu ality of rcceiving devices, and means controlled by the relay for connecting that portion oit the circuit including said receiving devices directly to the terminals oit said source ot current.

Y 24. A signaling system comprising a circuit having in series therein a source of current, a resistance, a plurality oi transmitting devices, a relay responsive to the operation of said transmitting devices, and a plurality of receiving devices, and means controlled by the relay itor connecting said receiving devices in multiple with said resistance.

25. A signaling system cmnprising a cir cuit having in series therein a source of current, a resistance, a plurality ot transmitting devices, a relay responsive to the operation of said transmitting devices, and a plurality of receiving devices, and means controlled by the relay for reversing the current through said receiving devices, and for connecting said receiving devices in multiple with said resistance.

ln witness whereof, l hereunto subscribe my name, this 16th day ot' Mray, A. D., 1914-.

CLARENCE ll. gllAGll. lVitnesses:

C. M. CoNNnn'roN, lV. T. KENDALL BROWN.

l Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents,

Washington, I). C.

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