US1960398A - Electric control system - Google Patents

Description

y 2-9, 1934- A. J. SORENSEN 1,960,398

ELECTRIC CONTROL SYSTEM Filed Sept. 9, 1932 3 Sheets-Sheet 2 5 Generazop Modulazons Vane I N VEN TOR. Andrew J So ensen HIS ATTORNEY.

y 1934- A. J. SORENSEN ,960,398

ELECTRIC CONTROL SYSTEM Filed Sept. 9, 1932 3 Sheets-Sheet 5 '12) Input 01 AM 7 INVENTOR. AndrewJ Jorensezz BY QQW 1113 A TTORNEY.

Patented May 29, 1934 siren stares PATEl ELECTRIC CONTROL SYSTEM Application September 9, 1932, Serial No. 632,336

8 Claims.

My invention relates to electric control systems, and particularly to electric control systems adaptable to the operation of railway trains.

I will describe certain forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In control systems such as here involved, control and code signaling influences are conveyed between a control station and a remote station over a single communication circuit by transmitting between the two stations alternating current im pulses on which there has been superimposed a distinctive modulation. A feature of my invention is the provision of novel and improved apparatus for control systems such as here involved,

whereby an operating mechanism located at the remote station is governed by the transmitting of a control current from the control station only during a short interval of time, and after that it is maintained in the established condition by local energy until another control influence is sent out from the control station. The local energy suffices at the same time to check all the equipment at the remote station so as to insure that it is in operative condition. The apparatus at the remote station at the same time transmits back to the control station a checking or indication influence to indicate the actual condition of the operating mechanism and also indicate that the communication circuit is in the proper condition. A further feature of my invention is provision of apparatus whereby the operativeness of ie control equipment at the control station is continuously checked by local energy. A still further feature of my invention is provision of apparatus whereby the carrier frequency of the control current can be quickly and readily varied at times to avoid interference from nearby control apparatus of other and similar systems. Other features of my invention will appear as the specification progresses.

In the accompanying drawings, Figs. 1 and 2, when taken together constitute a diagrammatic view of one form of apparatus embodying my in r vention when applied to a railway train for the control of the train brakes at two spaced points on the train, and for code signaling between these spaced points. The apparatus of Fig. 1 is that located at the control point, which in this instance, is on the locomotive, and the apparatus of Fig. 2 is that located at another point on the train. While the apparatus of Fig. 2 may be located at any point on the train, it will be referred to in this description as being in the caboose of a freight train. Fig. 3 is a diagrammatic View of a preferred form of generator of carrier frequency current that may be used with my system, means being provided whereby the carrier frequency may be readily varied to establish different communicating channels. Fig. 4 is a diagram- 6 matic view of an input filter that may be used with my system, and which is capable of being adjusted for different communicating channels. Fig. 5 is a diagrammatic view illustrating a manner of displaying on a train the communicating channel then in use, whereby two trains in close proximity can readily avoid interference by a change of channels.

In each of the several views like reference char acters designate similar parts.

The communication circuit from one location on the train to the other may take dilferent forms but a preferred form is that disclosed and claimed in an application for Letters Patent, Serial No. 450,135, filed by L. O. Grondahl on May 6, 1930, for Electric train signaling systems, whereby communication is maintained from one end of a train to the other through the medium of the trafiic rails.

Although I am here disclosing a specific application of my invention, it will be understood that I do not wish to limit myself to brake control systems for railway trains, as my invention is equally adaptable to other control systems where equipments at two spaced stations are operatively associated with each other.

Referring to Fig. l, the reference character EV designates the usual engineers brake valve of the standard type capable of establishing the release running, lap, service and emergency conditions of the train brake pipe pressure. Asshown schematically, a circuit contact assembly is asso ciated' with the brake valve EV in which the contact members 4, 5, 6 and 7 are connected to and actuated by the handle 3 of the brake valve. The contact member 4 is adapted to engage a contact segment 8 in both the release and running positions of handle 3, to engage a contact segment 9 in the lap position and to engage a contact segment 10 in both the service and emergency posiloll, tions. The contact member 5 is adapted to engage a contact segment 11 in both the service and emergency positions of handle 3. The contact member 6 is adapted to engage a contact segment 12 in all three, release, running and lap 105 positions of handle 3; and the contact member 7 is adapted to engage a contact segment 13 in both the release and running positions, a con-. tact segment 34 in the lap position only, and a contact segment 14 in both the service and emer- 11,0

' apparatus.

gency positions of handle 3. The function of this contact assembly associated with the brake valve EV will appear as the specification progresses.

The locomotive is equipped with a mechanically tuned oscillator or coder N. This coder may take any one of many fcrms well-known to the art such, for example, as that disclosed and claimed in the United States Letters Patent 1,858,876, issued May 17, 1932, to P. N. Bossart, on Coding It will suffice for this description to say that between the pole pieces P1 and P2 of the field structure J there is mounted, so as to swing freely, an armature H pivoted at O. The armature H is biased to a mid position in which the contact members 15 and 16 actuated by armature H, occupy the position shown by the heavy lines in Fig. 1. A field winding 17 is connected to a battery 18 by a simple circuit which includes a contact 19 and the contact member 15. The energizing of the field winding 17 causes the armature H to rotate in a clockwise direction as indicated by an arrow. After a slight movement of armature H the contact member 15 is swung to the left and becomes disengaged from the contact 19 to rupture the circuit to the field winding 17. Armature I-I will rotate a little farther and then due to its biasing force it will. reverse its movement until the contact member 15 again engages the contact 19 and the field winding 17 is reenergized, the inertia of armature I-I carrying it somewhat past its normal position in this reverse movement. During the interval the armature H is rotated clockwise due to the energizing of the field winding 17, the contact member 16 engages a left-hand contact 20 and during the reverse movement of armature H the contact member 16 engages a right-hand contact 21. The weight of armature H and its biasing force are made such that it will have a natural period of oscillation of say, sixty cycles per minute, although it will be understood other frequencies may be selected if desirable. 1 It follows, that the contact member 16 of coder N is oscillated between the left-hand 1 contact 20 and the right-hand contact 21 at the apparatus by which carrier frequency current is generated and supplied to the primary winding 2 of an output transformer T1, to be referred to later. The reference characters M1 and M2 each designate apparatus for generating a modulation frequency current of frequencies of say, thirty and forty cycles per second, respectively. To simplify Fig. 1 as much as possible in order that it may be more readily understood, the generator G and the modulators M1 and M2 are shown conventionally only. The modulation generators M1 and M2 may take any one of a number of forms their specific structure forming no part of my invention. Likewise, the generator G may take differ nt forms but a preferred form is that shown more in detail in Fig. 3. Referring to Fig. 3, the reference character 151 designates a vacuum tube of the usualstructure containing a filament 152, a plate 153 and a grid 154, The filament 152 is heated by a simple circuit which includes a battery 155. A grid circuit is provided which includes the follow ing elements: grid 15%, condenser 156, a portion of a coupling coil 157 and wire 158 connected to the filament 152. The plate circuit extends from the positive terminal of a battery 159 through a reactance coil 166, plate 153, intervening space of the tube, filament 152 and thence to the negative terminal of battery 159. The oscillating circuit which includes the coupling coil 'to the condenser 161, by the setting of a manually operated switch SW to the left to bring contact 165 to its dotted line position, the oscillations appearing in the output coil 164 will havea frequency of say, thirty-five hundred cycles per second. As will appear later, oscillations of the frequency of four thousand will be referred to as constituting a No. 1 communicating or control channel and oscillations of the frequency of thirty-five hundred as constituting a No. 2 control channel. The switch SW is provided with a contact 166 which, when the switch is set in its normal or right-hand position, completes a simple circuit to an indicating device 167 adapted to display the numeral 1 to indicate that the generated oscillations are of the 'No. 1 control channel. When the switch SW is set in the eft-hand position to bring the condenser 162 into play, the contact 166 closes a circuit to indicator 168 which is adapted to display the numeral 2 indicating thereby that the oscillations generated are of the No. 2 control channel. it follows that the generator G can readily be made to supply carrier frequency current of the No. 1 or of the No. 2 channel by the positioning of the switchSW in its right-hand or left-hand position, respectively, and there will be displayed the numeral 1 or 2 indicating the active channel.

Referring again to Fig. 1, with the brake valve handle 3 occupying either the release or running position, the output of the generator G, be it either of the No. 1 or the No. 2 control channel, is modulated by the current of modulator M1 each onehalf second period the contactmember 16 of coder N is swung to the right and is modulated by the current from modulator M2 each one-half second tact segment 8, contact member i, wire 24, gen- .erator G and wire 25 to the lower and opposite terminal of modulator M1. The circuit for modulator M2 extends from its lower terminal to the left-hand contact 20, contact member 16, wire 23, contact segment 8, contact member 4:, wire 2 1,

generator G and wire 25 to the upper and opposite terminal of modulator M2. That is to say, with the brake valve handle 3 at either the release or running position the output of the generator G is alternately modulated at the frequency of modulators' M1 and M2 for periods of approximately one-half second each. Moving the handle 3 to its lap position'and thus bringing the contact member 4 into engagement with the contact segment 9, the output of the generator G will be continu- 1' ously modulated by current from modulator M1 by virtue of a circuit extending from the upper terminal of modulator M1 along wires 22 and 28, contact segment 9, contact member 4, and thence through generator G to the lower terminal of M1 as before traced. With handle 3 moved to either its service or emergency position the modulator M2 is made continuously active to modulate the output of generator G by virtue of a circuit extending from the lower terminal of modulator M2 through Wire 2'7, contact segment 10, contact member 4 and thence to generator G and to the opposite terminal of modulator M2. Consequently, the release and running positions of the brake valve EV are identified in the output of the generator G by the alternate modulation frequencies of the modulators M1 and M2 for periods of approximately one-half second. each, the lap position by the continuous modulation frequency of modulator M1 and the service and emergency positions by the continuous modulation frequency ofmodulator M2.

The locomotive equipment also includes two relays 28 and 29 controlled by the contact assembly associated with the brake valve EV in the following manner. Normally relay 28 is energized by virtue of a stick circuit extending from the positive terminal B of a convenient source of current such as a battery, not shown, wire 39, front contact 31 of relay 28, winding of relay 28, wire 32, contact segment 13 assuming the valve EV to be in its running or release position, contact member 7 and to the opposite terminal 0 of the current source; while the relay 29 is normally retained energized by a circuit extending from the terminal B of the current source through winding of relay 29, front contact of relay 28 and thence by the same circuit just traced for elay 28 to the opposite terminal C of the current source. Sun pose the brake valve handle 3 is suddenly changed from its running position to its lap position. After the contact member 7 leaves its running position and before it reaches its lap position the circuits to both the relays 28 and 29 are opened and relay 28 immediately drops but relay 29 remains picked up fora period of say three seconds, due to its being slow-releasing in character. The contact member '7 now reaches its lap position and engages the contact segment 34 but'the relay 28 remains deenergized as its stick circuit is now open and relay 29 is still retained picked up, holding open the pick-up circuit for relay 28. This pick-up circuit extends from terminal B through wire 30, back contact 35 of relay 28, winding of relay 28, wire 32, contact segment 34 and contact member 7 to the terminal C of the current source. After the slow release period of relay 29 has elapsed. that relay drops to close its back contact 35 and completes the pick-up circuit just traced for relay 28, causing relay 28 to be reenergized and then to be retained energized by its stick circuit. The relay 28 in picking up closes at its front contact 33 the circuit for relay 29 and that relay is again picked up. Both relays 28 and 29 will now be retained energized as long as the brake valve EV remains in the lap position. In the event the handle 3 of valve EV is moved from the lap positionto either the service or emergency position so that member 7 first becomes disengaged from the contact segment 34 and then later engages the contact segment 14, or if the handle 3 is moved from its lap position back to the running position so that contact member 7 first becomes disengaged from contact segment 34 and then later engages the contact segment 13, the circuits for the relays 28 and 29 will be momentarily interrupted causing these relays to function in the manner described above. It follows, that when the brake valve EV is moved from a running position to either the lap or a brake applying position, or is imoved from the lap position to either a running or a brake applying position, or is moved from a brake applying position to either the lap or a running position, the above described operation of relays 28 and 29 is effected.

61 62 are inductor coils located on the locomotive in inductive relation with the traffic rails l and 1 respectively. By means of these inductor coils 61 and 82 energy is transmitted to and received from the trains rails by the locomotive apparatus and to this end they are at times connected to a transmitting circuit and at other times to a receiving circuit. Assuming the brake valve EV to occupy either the running, release, or lap position so that contact member 6 engagesthe contact segment 12 and also that relay 28 is picked up due to the contact member 7 being in engagement With the contact segment 13 or 34, the coils 61 and 82 are connected to the receiving circuit which can be traced from the left-hand terminal of coil 61 through wire 63, front contact 64 of relay 28, normally closed and upper contact 65 of a signaling hey ii to be referred to later, wire 66, contact 1 ember 6, contact segment 12, wire 67, input filt r l and thence wire 68 to the right-hand terminal of the coil 62. The input filter F1 is band iilter adaptable to be so proportioned and adjusted as to pass to the input of an amplif er All/l over the wires 69 and 79, modu tted car frequency current either the No. i or of the No. 2 control channel. Amplifier AM is adapted to amplify detect modulated carrier frequency current received through the filter Fl. so that there appears in its output circuit curruit having the modulation frequency only. Part of the output curr from amplifier AM is supplied to an output filter F2 which is so proportioned and adjusted as to pass current of the frequency of the modulator M1, to a relay 71 through a rectifier 72. In like manner part of the output of amplifier is supplied to an output filter F3 which is so proportioned and adjusted as to pass to relay 73 through the rectifier 74, current of the frequency of the modulator M2. Amplifier AM and the output filters F2 and F3 may take any one of a number of different forms for such devices and as the specific type of these devices forms no part of my invention, they are each shown conventionally only.

The input filter Fl, shown conventionally in Fig. 1 for the sake of simp icity, may take different forms but it is pref biy a band pass filter of the form disclosed in Fig. i. Referring to Fig. i a conden e 1691's included in the receiving circuit compi ng the inductor coils and a portion of the reactor coil 123*. This condenser is adapted to broadly tune this circuit to resonance at the frequency range of the two control channels No. 1 and No. 2. The reactor coil 179 together with the condenser 171 are so proportioned and adjusted as to pass frequencies of the range of control channel No. 1, while, when the contact 173, .ctuated by the switch SW, is set in the left-hand position so as to add the condenser 172 to the circuit, the filter F1 is adapted to pass frequencies of control channe No. 2.

At such time as both relays '21 and 73 of Fig. 1 are energized a circuit for a signaling lamp 75 is closed at the front contacts 76 and 77 of relays 71 and 73, respectively. When relay 71 is picked up to close its front contact 76 and relay '73 is down to close its back contact 78, an indication lamp '19 is energized. When relay 71 is down to close its back contact 80 and relay '73 is picked up to close its front contact 81, an indication lamp 82 is energized. As both relays 71 and 73 are slow-releasing in character, it is clear that when impulses of carrier current of either the control channel No. 1 or of the control channel No. 2, and having the modulation-frequency of modulator M1, are received from the traffic rails by the coils 61 and 62, the role? 71 is picked up and the indication lamp 79 is displayed, while if the modulation frequency is that of the modulator M2, the relay '13 is picked up and the indication lamp 82 is displayed. At such time as the modulation of the frequency of modulator M1 is closely followed by the frequency of the modulator, M2, or vice versa, both relays 71 and '73 will be picked up for a period and the signaling lamp will be displayed for a corresponding period.

During the interval the relay 28 is deenergized, ordinarily due to a change in the position of the brake valve handle 3 as described hereinbefore, the inductor coils 61 and 62 are disconnected from the receiving circuit by the opening of the front contact 64 of relay 28 and are connected to the transmitting circuit by the closing of the back contact 83 of relay 28. This transmitting circuit can be traced from the left-hand terinal of the coil 61 through wire 53, back contact 83, wire 84, secondary winding 85 of the output transformer T1 and wires 86 and 58 to the right-hand terminal of coil 62. At such time as the handle 3 is moved to either the service or emergency position the receiving circuit on the locomotive held open at the contact member 6 and the. inductor coils 61 and 52 are continuously connected to the secondary 35 of the output transformer T1, by virtue of a transmitting circuit extending from the left-hand terminal of the coil 61 along wires 63 and 8'7, contact segment 11, contact member 5, wires 88 and 84, secondary winding 85 and thence by the wires 86 and 58 to the right-hand terminal of the coil 62. Again, the depressing of the signaling key K to bring the contact 65 to its dotted line position transfers the inductor coils 61 and 62 from the receiving circuit to the secondary 85 of the output terminal T1 as will be readily understood by an inspection of Fig. 1.

To check the operativeness of the generator G, the modulators M1 and M2, coder N and relays 28 and 29, the output transforiner'Tl is provided with a secondary winding 36 from which current is supplied to two selectively tuned circuit networks 37 and 38, through a full wave rectifier or detector 39, the circuit being controlled both by the relay 28 and by the manually operated signaling key K. To be explicit, the secondary 36 of the output transformer T1 is connected to the input terminals to and 41 of the rectifier 39 by a circuit that includes the front contact 42 of relay 28 on one side and by the normally closed contact 4:3 of the signaling key K on the other side, as will be readily understood by an inspection of Fig. 1. The out- 'put terminals 44 and 45 of the rectifier 39 are connected to the terminals of a condenser 45 and the primary winding 4"! of a transformer 48 in parallel. It follows that the modulated carrier current supplied by the secondary 36 of the output transformer T1 when applied to the rec tifier 39 will cause a pulsating voltage to appear at the terminals of the condenser 46 of a frequency of the modulation of the carrier cur.- rent and this pulsating voltage will in turn cause an alternating voltage of a corresponding frequency to be induced in the secondary 49 of the modulation frequency transformer 48. The output of the secondary 49 of transformer 43 is supplied to the two tuned circuit networks 37 and 38. The circuit network 37 includes a condenser 50 and a reactor 51 in series, a portion of reactor 51 being connected to the input terminals of a full wave rectifier 52 the output terminals of which are connected to the winding of a relay 53 which is slow-releasing in character. The parts of this circuit network are so proportioned and adjusted as to respond to current having the frequency corresponding to the modulation frequency of modulator M1. The circuit network 38 includes a condenser 54 and a reactor 55 in series, a portion of reactor 55 being connected to the input terminals of a full wave rectifier 56, the output terminals of which are connected to the winding of a relay 57 which is slow-releasing in character. The parts of this circuit network are so proportioned and adjusted that it responds to current of a frequency corresponding to the modulation frequency of modulator M2. Thus, it is clear that when the brake valve EV occupies either the release or running position and the oulaeut of the generator G is alternately modulated at the frequencies of modulators M1 and M2 for periods of approximately one-half second each, the current supplied by the secondary 36 is alternately modulated at the frequencies of modulators M1 and M2 and the relays 53 and 57 are both picked up. An indication 58 is supplied with current over a simple circuitthat includes the front contacts 59 and 50 of relays 53 and 57, respectively, in series and thus it follows that the indication lamp 58 will be displayed as long as the brake valve EV occupies a running position and the generator G, modulators M1 and M2, coder N and relay 28 are operative. It is apparent that by providing relays 53 and 57 with additional contacts other indication lamps can be controlled to check the operative condition of the locomotive equipment in the lap and brake applying positions when only one modulator is active, should it seem desirable to do so.

Referring to Fig. 2, the'caboose is provide with a coder N1 preferably similar in all respects to the coder N on the locomotive, and thus its contact member 89 will be continuously oscillated between a left-hand contact 90 and a righthand contact 91 at the rate of sixty times per .inute alternately engaging these contacts for periods of approximately one-half second each.

The function of' coder N1 will appear later in.

the description.

92 and 93 are inductor coils located in inductive relation with the trafiic rails 1 and 1 at the caboose. These inductor coils at the caboose are connected either to a receiving circuit or to a transmitting circuit in the following manner. Assume that a relay designated by the reference character 95 and to be described later, is deenergized and its back contact 95 closed, the receiving circuit is completed from the left-hand terminal of coil 92 along wire 97, input filter F1, wire 98, back contact 95 and thence to the right-hand terminal of coil 93. When relay 95 is energized and its front contact 99 closed, the transmitting circuit is completed from the left-hand terminal of coil 92 along wires 97 and 100, secondary winding 101 of an output transformer T2 to be referred to later, wire 102 and front contact 99 to the righthand terminal of coil 93. It follows that whenever relay is energized the inductor coils 92 and 93 are connected to the transmitting circuit of the caboose equipment, and whenever the relay 95 is deenergized, they are transferred to its receiving circuit. Filter F1 of Fig. 2 is preferably similar to that disclosed in Fig. 4 and is adaptable to be set to pass modulated carrier frequency current of the frequencies of either control channel No. 1 or control channel No. 2. The amplifier AM of Fig. 2 is adapted to amplify and detect current received through the filter F1 causing thereby current of the modulation frequency only to appear in its output circuit. Part of the output of amplifier AM is supplied to an output filter F2 which is preferably similar to the output niter F2 of Fig. 1, and is adjusted to pass current of the modulation frequency of modulator M1, to a relay 103 through a rectifier 104. The remaining portion of the output of amplifier AM is applied to an output filter F3 which is similar to the filter F3 of Fig. 1, and which is so proportioned as to pass current of the modulation frequency of the modulator M2 to a relay 105 through. rectifier 106.

At such time as relay 103 is picked up, current is supplied from the terminal B of a convenient source of current such as a battery, not shown, to a circuit including the winding of a relay 107, front contact 108 of relay 103, wire 109, the top winding of a relay 119 and thence to the opposite terminal C of the battery, causing thereby both relays 107 and 110 to be energized in series in response to the picking up of the relay 103. At such time as relay 105 is picked up, current is supplied from the terminal B through winding of a relay 111, front contact 112 of relay 105, wire 109, top winding of relay 110 and to the terminal C of the current source, causing thereby relays 111 and 110 to be energized in series in response to the picking up of the relay 105. Once relay 110 is picked up and the contact member 89 of coder N1 is swung to its left-hand position, an extra or stick circuit is provided for the relay 11o which extends from the terminal B of the current source through a lower winding of relay 110, its own front contact 113, left-hand contact 90 and contact member 89 to the opposite terminal C. Once relay 110 is picked up, therefore, it is prevented from dropping until the contact member 89 of coder N1 is swung to the right. With contact member 89 of coder N1 swung to the right to disengage contact 90 and to engage contact 91, the relay 110 immediately drops and the relay 95 is then supplied with current from the terminal. 18 of the current source through winding of relay 95, wire 114, back contact 115 of relay 110, righ hand contact 91 and contact member 89 to the opposite terminal C. It is to be noted that relay 95 can also be energized by the depressing of a signaling key K1 to bring the contact 116 to its dotted line position, the circuit extending from terminal B through winding of relay 95, wires 114 and 117, contact 116 and to the opposite terminal C of the current source.

Whenever relay 110 is: picked up to close its front contact 120 current is supplied to the leihand half of the primary winding 118 of a transformer 119, and whenever the relay 110 is down to close the back contact 121 current is supplied to the right-hand half of primary winding 113 as will be readily understood by an inspection of Fig. 2. It follows, that operation of relay 110 will alternately energize the two halves of the primary winding 118 whereby an alternating voltage will be induced in the secondary 122 of transformer 119. The current induced in the secondary 122 is supplied through a full wave rectifier 123 to the Winding of a relay 124 which is slow-releasing in character, and consequently, as long as relay 110 is operated the relay 124 is picked up, but whenever relay 110 remains either energized or deenergized for a period longer than the release pericd of relay 124, that relay drops.

The caboose is equipped with an auxiliary brake controlling mechanism which comprises a main reservoir MR, a feed valve FV and two electropneumatic valves DR and DS. The caboose, of course, will also be equipped with a compressor, air gages and all other equipment necessary to insure ample supply of air pressure in the main reservoir MR independent of the usual sup-, ply of air pressure on the locomotive. Valve DR is biased to the closed position and is lifted to the open position whenever its associated magnet 125 is energized. The valve 133 is biased to the open position and is held closed when its associated magnet 126 is. energized. With the valve DR. held open and the valve DS held closed, the train brake pipe B1? is connected to the feed valve FV and the auxiliary brake controlling mechanism reproduces the usual running condition of the engineers brake valve EV on the locomotive. When the valve DS is open, the brake pipe BP is vented to the atmosphere through a vent of such characteristics as to produce a service rate of recluction of the brake pipe pressure to effect a service application of the train brakes. Whenever the valve DR is closed and the valve DS held closed both the supply and the exhaust of the brake pipe BP are blanked and the auxiliary mechanism in the caboose reproduces the lap condition of the usual brake valve EV on the locomotive.

Relays 107, 111 and 124 in conjunction control the two magnets 125 and 126. Suppose both relays 124 and 111 to be picked up, the magnet 125 is supplied with current from battery terminal B through winding of magnet 125, front contact 127 of relay 111, front contact 123 of relay 124 and to the opposite terminal C of the current source, while the magnet 126 is supplied with current from terminal B through winding of magnet 126, front contact 129 operated by valve DR and closed only when that valve is lifted to its open position, and thence to the opposite terminal C by the same circuit just traced for magnet 125. In the event relays 107 and 111 are picked up, the magnets 125 and 126 are energized by the same circuits just traced except the connection to the terminal C is now through the front contact 130 of relay 107 instead of by the front contact 128 of relay 124. At such time as relay 107 only is picked up, the magnet 126 is supplied with current from terminal B through winding of magnet 126, back contact 131 of relay 111 and the front contact 132 of relay 107 to the terminal C. It is to be noted that whenever the valve DS is held in the closed position and a contact 133 operated thereby is closed, and the relay 124 is down to close its back contact 134, a circuit is completed to a signaling device 135.

The caboose is further provided with a generator G of carrier frequency current and two generators M1 and M2 of modulation frequency current all of which are preferably similar to the corresponding devices of Fig. 1. Furthermore, the generator G of Fig. 2 is adaptable to be set to generate carrier frequency current of the fre- T2 supplies current to the inductor coils 92 and 93 quency of channel No. 1 or of the frequency of channel No. 2 in the manner described in reference to Fig. 3. The output of the generator G is supplied to the primary winding 136 of the output transformer T2.

When the valve DR is held open and the valve DS held closed so that the auxiliary brake controlling mechanism establishes the running condition of the train brakes, the modulator M2 is made active to modulate the output of generator G by virtue of a circuit extending from the lower terminal of modulator M2 through contact 137 of the signaling key K1, wire 138, front contact 139 operated by valve DR andclosed only when that valve is open, front contact 140 operated by valve DS and closed only when that valve is closed, wire 141, generator G and wire 142 to the opposite terminal of modulator M2. With both valves DR and DS closed and the auxiliary brake controlling mechanism reproducing the lap condition of the train brakes, the modulator M1 is rendered active to modulate the output of the generator G, the circuit this time extending from the lower terminal of modulator M1 through contact 143 of the signaling key K1, wire 144, back contact 145 of valve DR, closed only when that valve is closed, contact 140, wire 141, generator G and wire 142 to the opposite terminal of modulator M1. In the event the signaling key K1 is depressed to bring the contacts 137 and 143 to the position indicated by dotted lines in Fig. 2, at a time when valve DR is held open and valve DS held closed to establish the running condition, the modulation of the output of generator G is changed from that j of M2 to that of M1, while at such time as both valves DR and D8 are closed to establish the lap condition, the modulation is changed from that of M1 to that of M2.

t has already been pointed out how the secondary winding 101 of the output transformer whenever the relay 95 is energized. As will appear when the operation of the system is described, the output transformer T2 is provided with a second secondary winding 146 by means of which energy is obtained for locally retaining the auxiliary mechanism in the condition established by a control impulse and to check the operativeness of the caboose apparatus. Sup- 1 pose relays 95 and 110 both to be deenergized at the same time, current is then supplied from the extra secondary winding 146 to an auxiliary coil 147 inductively coupled with the inductor coils 92 and 93. This circuit can be traced from the upper terminal of winding 146 through back contact 148 of relay 110, back contact 149 of relay 95, coil 147 and wire 150 to the opposite terminal of winding 146. The parts of this circuit should be so proportioned and adjusted that the current flowing therein will be of such mag- 93 of such strength as to readily operate the relays 103 and 105, but it should not be strong enough to swamp any incoming control or signaling impulse received through the trafiic rails.

In describing the operation of my system I shall first assume that the apparatus both on the locomotive and in the caboose is set to operate at the carrier frequency of control channel No. 1 and that the running condition prevails. I shall further assume that the locomotive operator now moves the brake valve handle 3 from the running position to the lap position. The relay 28 on the locomotive drops as the handle 3 is being moved and then remains down for several seconds before it is again picked up due to the slow release action of the relay. With the handle 3 in the lap position the modulator M1 on the locomotive is rendered active to modulate the output of the locomotive generator G and consequently impulse of carrier frequency current modulated at the frequency of M1 is supplied to the traffic rails for several seconds. At the caboose the inductor coils 92 and 93 will be connected to the receiving circuit due to the reiay 95 being down as will later appear, and thus this impulse transmitted from the locomotive will be picked up and applied through filter F1 to the input of the caboose amplifier AM causing thereby the relay 103 to be picked up. Relay 163 will remain picked up as long as the impulse lasts and thus relays 107 and 110 are both energized and the magnet 126 of valve DS is energized by the circuit that includes the front contact 132 of relay 107. With magnet 126 energized the valve DS is closed, and as valve DR will be closed due to its magnet 125 being now without energy, the auxiliary brake controlling mechanism in the caboose reproduces the lap condition of the train brakes established by the brake valve EV on the locomotive.

When the relay 28 picks up due to the dropping of relay 29 at the end of its slow release period, the inductor coils 61 and 62 on the locomotive are transferred from the transmitting circuit to the receiving circuit and the control impulse of carrier frequency modulated at the frequency of M1 is terminated. Relay 103 in the caboose immediately drops at the end of the control impulse but relay 110 will be retained energized by its stick circuit until the contact member 89 of coder N1 next swings to the right, unless contact member 89 is already in the right-hand position at the termination of the control impulse. With contact member 69 swung to the right the relay 110 drops and the relay 95 is supplied with current and that relay is picked up to transfer the inductor coils 92 and 93 from the receiving circuit to the transmitting circuit. Both valves DR and DS being now closed, the output of the caboose generator G is modulated at the frequency of modulator M1 and consequently an indication impulse of carrier frequency current modulated at the frequency of M1 is transmitted to the traflic rails by the caboose apparatus. On the next swing of contactmember 89 to the left the circuit to relay 95 is opened at the right-hand contact 91 and that relay immediately drops to transfer the inductor coils 92 and 93 from the transmitting circuit back to the receiving circuit and thus the impulse supplied to the traffic rails is terminated. Since both relays 95 and 110 are now down, the circuit to the auxiliary coil 147 is completed at the back contacts 149 and 148 and an impulse of current from the caboose generator G is induced in the inductor coils 92 and 93 which are now connected to the receiving circuit. As pointed out hereinbefore, this impulse of local energy suffices to influence the local receiving circuit, and as the impulse is now modulated at the frequency of M1, the relay 103 will respond and in turn pick up the relays 197 and 110 the same as before. When relay 110 picks up, the circuit to the auxiliary coil 147 is interrupted and the impulse of local energy induced in the coils 92 and 93 ceases, but meanwhile the stick circuit through the lower wind! tion, so that even though relay 103 immediately drops at the end of the impulse of local energy, the relay 110 remains energized as long as the contact member 89 remains in the left-hand position. As soon as the contact member 89 next swings to the right the relay 110 is first deenergized and then the relay 95 will be picked up to transfer the coils 92 and 93 from the receiving circuit back to the transmitting circuit and an indication impulse of current from the secondary winding 101 of the output transformer T2 is again supplied to the trafiic rails. Hereafter for each cycle of operation of coder N1 the relays 95 and no will function to alternately connect the inductor coils 92 and 93 to the receiving and transmitting circuits, and there will be supplied an impulse of local energy to inductor coils 92 and 93 through the auxiliary cell 147 during the receiving period, and an indication impulse to the traffic rails through coils 92 and 93 during each transmitting period. Relay 107 being slow-releasing in character it remains picked up from one impulse of local energy to the next and thus the magnet 126 of valve DS is maintained steadily energized to establish the lap condition of the train brakes in response to these impulses of local energy. It is to be noted that as relay 110 is operated in step with the coder N1 the relay 124 is picked up and the signaling device 135 deenergized.

On the locomotive the inductor coils 61 and 62 are constantly connected to the receiving circuit, after the termination of the control impulse, by means of the contact member 6 of the contact assembly in its lap position and the front contact 64 of the relay 28, so that for each impulse of current supplied to the traffic rails at the caboose a corresponding impulse is picked up at the locomotive and applied to its amplifier AM, causing the relay '71 to be energized inasmuch as the modulation of the impulse is in accordance with modulator M1. Relay '71 being slow-releasing in character, it will remain picked up from one impulse to the next and consequently the indication lamp 79 will be continuously displayed to indicate to the locomotive operator that the caboose equipment is in the lap condition, and that the communication circuit is in the proper condition. As long as the brake valve handle 3 remains at the lap position, the caboose apparatus will alternate between its receiving and transmitting conditions whereby during each receiving period an impulse of local energy is impresse upon its receiving circuit through the medium of the auxiliary coil l-il for maintaining the auxiliary brake controlling mechanism in the lap position, and with each transmitting period an impulse of current is supplied to the traffic rails to eliect the display of the indication lamp '79 on the locomotive.

If the brake valve handle 3 is now moved back to the running or release position, the relay 28 drops during the movement of the handle 3 and then remains down for several seconds due to the slow release action of the relay 29. During the several seconds relay 28 is down, the inductor coils 61 and 62 are connected to the transmitting circuit. The contact member 4 of the contact assembly being in engagement with the contact segment 8, the output of the generator G on the locomotive is alternately modulated at the frequencies of modulators M1 and M2 for periods of approximately one-half second each, and hence the control impulse supplied to the trailic rails during the several second period the relay 28 remains down is alternately modulated at the frequencies of modulators Ml and M2 for periods of approximately one-half second each. The next time the caboose apparatus is in its receiving condition this control impulse being new transmitted from the locomotive will be picked up by the coils 92 and 93 and superimposed upon the impulse originating in the local caboose generator G. The latter impulse being of a duration of approximately one-half cycle of the coder N1 the former impulse Will still persist after the latter has been interrupted since its duration is of, say, three seconds, and hence the relays 103 and 105 will be alt rnately picked up in step with the modulation periods of the control impulse and relays 1&7, 116 and 111 will all be retained picked up, since relays 107 and 111 are slowreleasing in character and relay 110 will receive current one-half the time in series with relay i0? and the other half of the time in series with relay 111. With both relays 107 and 111 picked up, the two magnets 125 and 126 for valves DR and DS are both energized and the auxiliary brake controlling mechanism establishes the running condition for the train brakes.

At the end of the release period of relay 29 on the locomotive this relay drops and relays 28 and 29 are then both picked up in the manner described hereinbefore, to terminate the sending of the control impulse. In the caboose, after the termination of the control impulse transmitted from the locomotive, the two relays 95 and 110 will function in conjunction with the coder N1 in the same manner as previously pointed out. Since valve DH is now held open and valve DS is held closed, the output of the caboose generator G is modulated in accordance with the modulator M2 so that both the impulse supplied to the traflic rails and the impulse supplied to the auxiliary coil 147 will be modulated in accordance with the modulator M2. The relay 105 will now respond to each impulse of local energy causing relay ill to be held picked up, and as the operation of the relay 119 causes the relay 124 to be picked up, the two magnets 1.25 and 128 will be retained energized by the circuit which includes the front contact 127 of relay 111 and the front contact 128 of relay 124. At the 10- comotive the receipt of impulses modulated in accordance with modulator M2 causes relay 73 to respond with the result that the indication lamp 82 is continuously displayed to indicate to the locomotive operator the running condition of the caboose equipment and the proper operative condition of the communication circuit. As long as the brake valve EV remains in the running or release position the caboose equipment Will continue to alternately supply impulses to the local receiving circuit for retaining the auxiliary mechanism in the running condition, and check or indication impulses to the traffic rails for causing the continuous display of the indication lamp 82 on the locomotive.

On the locomotive the secondary Winding 36 of the output transformer T1 will now continuously supply to the rectifier 39 current alter nately modulated at the frequencies of modulators M1 and M2 whereby both relays 53 and 57 will be retained picked up and the indication lamp 58 continuously energized to indicate the operativeness of the locomotive generator G, modulators M1 and M2, coder N1 and relays 28 and 29.

If the brake valve EV is next moved to a brake 1 service application of the train brakes.

applying position, that is, to either the service or emergency position, the modulator M2 is made continuously active to modulate the output of the generator G on the locomotive and the inductor coils 61 and 62 are continuously con-- nected to the secondary 85 of the output transformer Tl by the circuit that includes the contact member 5 and the contact segment 11. It follows that as long as the brake valve EV is kept in a brake applying condition control current is continuously transmitted. to the traffic rails by the locomotive equipment, the modulation being in accordance with modulator M2. At the caboose the elay 105 will be held continuously energized in response to the control current now being transmitted from the locomotive, stopping the operation of relays 95 and 110 inasmuch as relay 116 is nowcontinuously held energized in series with the relay lll. Relay llO being held continuously picked up, the relay 12d increases at the end of its release period and as relay 167 is also now down, both magnets 125 and 126 are without current and the euro iliary brake controlling mechanism, effects a Relay 95 remaining continuously down and relay 110 being held continuously energized, the circuit for both secondary windings 101 and 146 of the caboose output transformer T2 are held open and hence neither local energy norindication energy is supplied by the caboose apparatus as long as the brake application condition persists. If the brake valve EV is now moved to either the lap position or to a running position, the operation of the equipment will be as described hereinbefore.

With the engineers brake handle in the release, running or lap positions, signaling influences can be sent from the locomotive by the operator depressing the signaling key Ii for a short time and then restoring it to its normal and upper position. While the signalin key K1 is depressed, the inductor coils 6i and 62 are connected directly to the secondary 85 and a control impulse is supplied to the trafiic rails. This impulse when picked up at the caboose will hold the relay 110 energized for a period somewhat longer than is the case in normal operation and relay 124 therefore drops closing at its back contact 134 the circuit to signaling device 135. Since the impulse thus transmitted from the locomotive will be modulated in accordance with the prevailing brake condition of the valve EV and of the brake valves on the caboose no loss of brake control will occur. Hence, by depressing signaling key K in accordance with a prearranged code a code message can be transmitted from the locomotive which will be conveyed to the caboose crew by means of the signaling device 135.

Signaling influences can also be sent from the caboose to the locomotive by depressing the signaling key K1 for short periods. When this is done, the relay 95 is held energized by the circuit that includes the contact 116 of the key K1 to close the transmitting circuit, and at the same time, the modulation of the impulses being trans mitted from the caboose to the traffic rails is changed by the shifting of contacts 137 and 143, so that if modulator M1 is used normally, modulator M2 is rendered active for signaling, and vice versa. The result on the locomotive will be that if relay 71 is up before the transmitting of the signaling impulse, the signaling impulse will cause relay '73 to be picked up, or if relay 73 is up before signaling is begun, the relay '71 is picked up by the signaling impulse. It is clear, therefore, that both relays 71 and '23 Will bepicked up for a short period in response to the signaling impulse inasmuch as both of these relays are slowreleasing in character. With both relays '71 and 73 picked up for a period the signaling device "75 will be energized for a corresponding period.

By operating the signaling key K1 in accordance with prearranged code a code message can therefore be conveyed to the locomotive operator by means of the signaling device 75. It is to be noted that the signaling impulse transmitted from the caboose should be barely long enough to cause the second relay to be picked up. If made too long, relay '71 will drop while relay '73 is still picked up, or vice versa, and the result will be that for each signaling impulse sent from the caboose, the signaling device 75 will be energized for two periods.

It was pointed out how the depressing of the signaling key K on the locomotive transmits an impulse which is modulated in accordance with the prevailing condition of the brake valve handle 3. It is clear, therefore, if at any time the proper return indication is not received on the locomotive, control impulse last transmitted can be repeated by the depressing of the signaling key K for a short time, without the necessity of a movement of the valve handle 3. That is to say, a control impulse can be repeated by the locomotive operator operating the signaling key K without a change in the condition of the brake equipment. If after such operation of the signaling key K the proper indication is not displayed on the locomotive, the train should be brought to a stop.

Since in this system impulses are normally transmitted by the caboose apparatus only, interference between the equipment of two different trains will occur only when the two cabooses are passsing. Consequently, instead of using a separate and distinctive carrier frequency channel for each train of a railway it is possible with my system to limit the number of control channels for all the trains of the railway to two. The train crews will then change control channels whenever another train using the same control channel, is to be passed or approached. As pointed out in connection with Figs. 3 and 4, the frequency of the carrier current generated by both the generator G on the locomotive and by the generator G in the caboose and the adjustment of the input filters is determined by the setting of the associated switch SW, and furthermore, there is to be displayed the numeral 1 or the runner-a1 2 to indicate the active control channel. As shown Fig. 5 these numerals are to be displayed in a conspicuous place on the locomotive and on the caboose and are to be displayed in such a manner as to be clearly visible from points outside or" the train both during daytime and at night. Hence, the display of the numeral 1 at the two ends of a train is an indication that that train is operated on the No. 1 control channel, or the display of the numeral 2 at the two ends of a train is an indication that it is using the No. 2 channel. In operating between two terminals X and Y, of a railway, all trains equipped with my invention will thus carry prominently displayed on a time to avoid possible interference between the control equipment of the two trains. An operating rule for the railway in question would be that when two trains meet, the one headed toward terminal X must change control channels if necessary, and when a train overtakes another, the following train must change channels. The change of channels should, of course, be ordered from the locomotive and can be carried out in the caboose in response to a prearranged code signal sent from the locomotive. With such arrangement for changing control channels while en route, much greater separation between channels in use on a railway can be obtained and simpler equipment is possible if each caboose is to be so equipped that it can be attached to a train hauled by any one of the railway locomotives. Furthermore, better discrimination between the two carrier frequencies can be ob tamed by a comparatively simple input filter.

A control system such as here described requires but few moving parts that are in con tinuous operation, and a small number of control channels only is necessary to insure noninterference between trains if, for instance, all the trains of a railway were to be equipped.

Although I have herein shown and described only certain forms of apparatus for electric con' trol systems embodying my invention, it is un-- derstood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Control apparatus for railway trains including, a transmitting and a receiving means at each of two spaced points on a train and capable of establishing communication in either direction between said points for controlling the train, a generator of carrier current for each transmitting means and capable of supplying carrier current of the frequency of either a first or a second control channel, an input filter for each receiving means adaptable to pass carrier current of the frequency of either the first or the second control channel, manually controlled means at each point for selecting the control channel for the generator and input filter located at the same point to establish the control channel for the train, and means at each point adapted to display a signal to indicate the control channel in use by the train whereby two approaching trains can select opposite channels to avoid possible interference between the control apparatus of the two trains.

2. Control apparatus for railway trains including control means located at each of the opposite ends of a train adapted to exchange control influences between the two ends of the train on either a first or a second control channel of carrier frequency current, a manually controlled means at each end of the train adapted to select the channel for the control means at its end of the train to establish the control channel for that train, a signaling means governed by each manually controlled means and adapted to indicate to other trains the control channel in use whereby two approaching trains can so select channels as to avoid interference between the control apparatusof the two trains.

3. A control system for railway trains including, a train-carried traflic controlling mechanism having difierent conditions, control means having different positions and effective when moved from one position to another to supply to the traffic rails a control impulse of current of a frequency peculiar to that position, traincarried receiving means inductively coupled with the traflic rails and selectively responsive to the diiferent frequencies of the control impulse to establish the different conditions of the controlling mechanism, a train-carried local circuit inductively coupled with said receiving means, means governed by said mechanism to supply to said local circuit impulses of current having a frequency eifectlve to maintain said mechanism in the established condition, and means governed by the receiving means when influenced by a control impulse to render the local circuit ineffective.

4. A control system for railway trains including, atrain-carried tramc controlling mechanism having different conditions, means having different positions and efiective when moved to a position to supply to the traffic rails a control impulse of current of a frequency peculiar to that position, said control impulse having a' relatively long duration, train-carried receiving means inductively coupled with the traffic rails and selectively responsive to the different frequencies of the control impulse to establish the different conditions of the controlling mechanism, a traincarried local circuit inductively coupled with said receiving means, means governed by said mechanism to supply to the local circuit current impulses of a frequency effective to retain said mechanism in the established condition, said local impulses being of relatively short duration whereby the receiving means is responsive to a control impulse and agreement betweenthe condition of said mechanism and the frequency of a second control impulse is assured.

5. A control system for railway trains including, a train-carried traffic controlling mechanism having different conditions, a train-carried inductor inductively coupled with the traffic rails, a receiving circuit adapted to receive current from said inductor and selectively responsive to current of diiferent frequencies for establishing the different conditions of the controlling mechanism, control means adapted to supply current of different frequencies, manually operated means having different positions for causing said control means to supply to the traffic rails a single control impulse of a given duration and having a frequency according to its position for estabtermination of the control impulse to supply to I the local circuit impulses of current having a frequency adapted to maintain the mechanism in the established condition, and said local means arranged to supply impulses of shorter duration than said given duration whereby the receiving circuit is responsive to any incoming control impulse.

6. A control system for railway trains including, a traffic controlling mechanism located at one point on a train and having an active condition, indication means located at a second point on the train and inductively coupled with the traffic rails, manually controlled means at said second point effective at times to supply to the traffic rails a control impulse of current, an inductor at said one point inductively coupled with the traffic rails, a receiving circuit adapted to receive current from said inductor and responsive to the control impulse to establish the active condition of said controlling mechanism, a local circuit inductively coupled with the inductor, a transmitting circuit adapted to supply current to said inductor, a current source governed by said mechanism and effective in its active condition to supply current to both the local circuit and to the transmitting circuit, means governed by the receiving circuit and operating at the termination of the control impulse to alternately connect the inductor with the receiving circuit and the transmitting circuit and to close the local circuit each time the inductor is connected with the receiving circuit whereby the controlling mechanism is maintained in the active condition and the indication means at said second point is caused to indicate this active condition.

'7. Apparatus for the control of the brakes of a railway train comprising in combination with the usual engineers brake valve on the locomotive, an auxiliary mechanism located at another point on the train and capable of reproducing diiferent operating conditions of the engineers brake valve, means controlled by the engineers brake valve to supply to the trafiic rails for a given interval a control impulse of current of peculiar frequencies in accordance with the condition of said brake valve, an inductor located at said other point on the train and inductively coupled with the traffic rails, a receiving circuit adapted to receive current from the inductor and selectively responsive to the difierent frequencies of the control impulse to cause the auxiliary mechanism to register with the engineers brake valve,

- a local circuit inductively coupled with said inductor, local means governed by the auxiliary mechanism and effective at the termination of a control impulse to supply impulses of current to the local circuit of a frequency to maintain the auxiliary mechanism in the established condition, and said local means arranged to supply impulses of shorter duration than said control im pulses whereby the receiving circuit is responsive to any incoming control impulse.

8. Apparatus for the control of the brakes of a railway train comprising in combination with the usual engineers brake valve on the locomotive, an auxiliary mechanism located at another point on the train and capable of reproducing different operating conditions of the engineers brake valve, indication means on the locomotive and inductively coupled with the traffic rails, means controlled by the engineers brake valve when moved a position to supply to the traffic rails a control impulse of a given duration, said control impulse having a distinctive frequency corresponding to the position of said engineers valve, an inductor located at said other point and inductively coupled with the traffic rails, a

receiving circuit adapted to receive current from said inductor and selectively responsive to the different frequencies of the control impulse for causing the auxiliary mechanism to register with the engineers valve, a local circuit inductively coupled With said inductor, a transmitting circuit adapted to supply current to said inductor, a current source to supply current to both the -local circuit and the transmitting circuit of a frequency determined by the position of the auxiliary mechanism, means operating at the termination of a control impulse to alternately connect the inductor with the receiving circuit and the transmitting circuit and operating to close the local circuit each time the inductor is connected with the receiving circuit whereby the controlling mechanism is maintained in the established condition and the indication means is caused to indicate at the locomotive the established condition of the auxiliary mechanism.

ANDREW J. SORENSEN.

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