Patent GB-274871-A (GB)
Title: Improvements in or relating to telegraph systems
IPC: H04L5/18
Filed: 1927-07-19
Abstract: 274,871. Western Electric Co., Inc., and Western Union Telegraph Co., (Assignees of Locke, G. A., and Haglund, H. H.). July 21, 1926, [Convention date]. Type-printing telegraphs; distributor systems; repeating systems using contact-making relays. -In an arrangement for controlling automatically the duration of traffic passing alternately in opposite directions over a system employing synchronous distributors at the several stations, switching devices are provided at each station for reversing the direction of transmission simultaneously at all the stations, and means are provided at one of the stations for starting the reversing devices simultaneously through connections between corresponding distributor contacts. The invention is described with reference to a five-channel multiplex system including a terminal station A, Fig. 1, connected by a land line 10 to a shore station B, Fig. 2, connected by a cable 11 to a station C at which certain of the channels, e.g. channel 1, terminate as shown in Fig. 3a while others, e.g. channel 5, are connected for retransmission over a cable 12 as shown in Fig. 3<b> to a terminal station D (not shown). For transmission in the direction A to D switches 100, Fig. 1. 101, Fig. 2, 103, Fig. 3<a>, and 104, Fig. 3<b>, are held in the positions shown by cams 225, 225<b>, 225<c>, and 225<c1> respectively, and for transmission in the direction D to A these cams are rotated as described below to reverse the switches. The circuits for channels 1 and 5 only are shown on the drawings. Transmitting circuits at station A. The connection to line 10 of the transmitter 18, Fig. 1, for channel 1 is from earth 111 through switch 100, line 10, switch 101 and relay 65, Fig. 2, return line 10, switch 100, transmitting contacts of distributor 30, contacts of transmitter 18, battery, and contact 112, controlled by cam 279, to earth. The circuit of the tape-feed magnet 26 extends in parallel through the left-hand winding and upper contacts of differential relay 106 and through the right-hand winding of this relay, contact 108, and contact 121, controlled by cam 131, to contacts 58 of distributor 30 and' thence to earth through brush 59 and distributor ring 57. Retransmitting circuits at station B for direction A to D. The contacts of relay 65, Fig. 2, connect battery through the ring 120, brush 123, and contacts 122 of distributor 70 and relays 141 - - 145 to earth, and the armatures of these relays close circuits from battery through alternate contacts 127, brush 128, and ring 125 of distributor 70, lead 133, network 134, 135, and switch 102, to cable 11. The switch 102 is actuated by a polarized magnet for which the direction of the energizing current is controlled bv a cam 225<b1>. Receiving circuits at station C, (channel 1), for direction A to D. The cable 11 is connected to earth through switch 103, amplifier 89, and relay 90, Fig. 3<a>, and the relay armature, closes circuits from battery through the ring 164, brush 160, and contacts 165 of distributor 300, selecting magnets 161 of printer 162, and contact 156 controlled by cam 286, to earth. Retransmitting circuits at station C, (channel 5), for direction A to D. The distributor contacts 165 for channel 5 are connected to earth through windings of relays 163 of which the armature close circuits from battery through alternate contacts 167, brush 169, and ring 166 of the distributor, network 176, lead 175, and switch 104, to cable 12, Fig. 3b. Transmitting circuits at station C, (channel 1), for direction A to D. The alternate distributor contacts 167 for channel 1 are connected to battery and earth through the contacts of automatic transmitter 170 and contact 177 controlled by cam 177<1>. Retransmitting circuits at station C, (channel 5), for direction D to A. Signals received from cable 12 pass through switch 104, amplifier 95, and relay 96, Fig. 3<b>. The relay armature closes circuits from battery through the ring 186, brush 180, and contacts 187 of distributor 300, and windings of relays 185 to earth, and the armatures of these relays close circuits from battery through alternate contacts 189, brush 191, and ring 188 of distributor 300, network 194, conductor 193, and switch 103 to cable 11. Receiving circuits at station C, (for channel 1), for direction D to A. The distributor contacts 187 for channel 1 are connected to earth through the selecting magnets 181 of printer 182, and contact 183 controlled by cam 288. Transmitting circuits at station C, (channel 1), for direction D to A. The alternate distributor contacts 189 for channel 1 are connected to battery and earth through the contacts of automatic transmitter 192 and contact 199 controlled by cam 289. Retransmitting circuits at station B for direction D to A. Signals received from cable 11 pass through switch 102, amplifier 75, and relay 76, Fig. 2, and the relay armature connects + or - battery through switch 101 to line 10 thus effecting retransmission in this direction without use of the distributor at station B. Receiving circuits at station A. Signals received for channel 1 from line 10 pass through a relay 15, and the relay armature connects + or - battery to earth through the ring 33, brush 35, and contacts 34 of distributor 30, selecting magnets 20 of printer 16, and contact 116 controlled by cam 273. The circuit of the printing magnet 21 extends through contacts 38, brush 39, and ring 37 of distributor 30. Reversing-switch control arrangements. Apparatus similar to that described below with reference to Fig. 1 is provided at each station for this purpose. The driving-shaft 254 of the distributor is connected through a clutch 255 and gearing to a shaft 260 for driving at different speeds three countershafts carrying cams 251, 252, and 253 controlling timing switches 235, 236, and 237 respectively. The gears carried by the shaft 260 are adapted to be disengaged to facilitate the initial adjustment of the cams 251 to 253 by releasing a latch 312 and rotating a cam 311 to lower the left-hand bearing 310 of the shaft. The clutch 255 is held in disengaged position by a latch 257 which is tripped by energizing a magnet 258 over a circuit including contact 319 of a switch 315, switch 325, and contacts 58, brush 59, and ring 57 of distributor 30. The cams 251 to 253 and their associated gearing may be such that switches 235, 236, and 237 close respectively, e.g. once every 6 minutes, for 30 seconds, once per minute for 15 seconds, and 4 times per minute for 4 seconds. This corresponds to a reversal of the direction of traffic once every six minutes, and reversals at other predetermined intervals may be obtained by substituting other shapes of the cam 251. During each closure of switch 235 a period occurs in which switches 236 and 237 are both closed, whereupon a circuit is closed intermittently energizing a magnet 230 through distributor contacts 40 or 60 and one or other contact of a switch 242 according to the position of its controlling cam 241, lead 250, and switches 235 to 237. The magnet 230 controls an escapement 229 on the cam shaft 226 which therefore receives a step-bystep rotation through a friction clutch 228 from a motor 227. the circuit of which has been completed by the simultaneous closure of switches 235 and 236. Cam 267 then closes at contact 266 a locking circuit for magnet 230, which enables the shaft 226 to make one half revolution for reversing the direction of transmission before the circuit of the magnet 230 is opened. During this half revolution the circuit through the switches 235 to 237 is also opened. The connections of the distributor contacts 40 and 60 and the number of teeth of the escapement 229 may be such that the distributor makes, e.g. 30 revolutions for one half revolution of shaft 226, and during this period the cams effect the various connections and disconnections necessitated by the reversal of the direction of traffic. To enable the reversals at the several stations to be effected simultaneously the shapes, speeds, and phase relations of the cams 251 to 253 at all stations are the same and the clutches 255 are initially engaged simultaneously by simultaneous energizing of the release magnets 258, 258b, and 258<c>, as follows. The switch 315, Fig. 1, when moved to the right connects the first three distributor segments of channel 5 to - of battery through contacts 316 to 318 instead of to the transmitter contacts. At station B a switch 330, Fig. 2, normally closes a circuit from the third distributor contact 122 of channel 5 through relay 143, but when moved to the right connects the contact 122 to earth through the magnet 258<b>, whereupon the clutch lever 331 returns the switch to normal position. At station C a switch 335, Fig. 3<a>, closes at its left-hand contact a circuit from the second distributor contact 165 of channel 5 through the corresponding relay 163, and at its right-hand contact connects the contact 165 to earth through the magnet 258<c>. To start the reversing devices into operation, switches 330, Fig. 2, and 335, Fig. 3<a>, are moved to the right, and when the brush has passed the contact connected to contact 318 of switch 315 but before it has reached the contact connected to contact 316 on the next revolution, switch 315 is moved to the right. Three successive - impulses are thereupon transmitted to line 10 over the contacts 316, 317, and 318 simultaneously with the energizing of magnet 258 through contact 319 and distributor contact 58. The first, second, and third of these impulses effect through the circuits described above the energizing of the clutch release magnet at station D, the magnet 258<c> at station C, and the magnet 258<b> at station B respectively, the intervals between the impulses compensating for the lag on the cables 11 and 12. Curbing at transmitter. The transmitting and retransmitting distributor contacts 127, Fig. 2, 167, Fig. 3a, and 189, F