Patent GB-200212-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H01H63/30
Filed: 1922-04-08
Abstract: 200,212. Conrad, H. S. April 8, 1922. Automatic exchange systems and selectors; party-line systems.-A side-switch for enabling various operations such as testing, ringing &c. to be carried out in a definite order, is operated stepby-step by a. fluid-driven motor. The invention is described as applied to the connectors in a small exchange in which each subscriber is provided with an individual connector, and also as applied to the final connectors in a larger system. In the latter system, provision is made for party-line ringing by furnishing each final connector with a fluid-driven step-by-step switch which in response to an extra digit selects a particular ring- ing frequency. Construction of side switch. A lever 30, Fig. 1, pivoted at a point 31 and held under strain throughout the operation of the connector by a fluid-operated motor 29, is connected at its lower end to a pawl 38, pivoted to a sliding frame 40 carrying a contact head 63. Adjacent to the pawl 38 is an escapement 41 along the length of which extend two flanges formed with teeth 47, 48 &c. spaced as shown. The escapement is adapted to be rocked in its bearings 42 by the expansion or retraction of a fluid motor 45, in order to bring one or other of the toothed flanges above the pawl 38. When the motor 29 is first operated, the actuation of the lever 30 turns the pawl 38 until its tail strikes a stop on the slide 40, after which further movement of the lever 30 moves the slide to the right until the pawl strikes the first tooth 47. On the escapement 41 being rocked by the operation of the motor 45, the pawl 38 is released from the tooth 47 moving under the tension of the lever 30 to the tooth 48, and when the escapement is again rocked bv the retraction of the motor 45, the pawl moves from tooth 48 to the next tooth 49. In this manner the contact head 63 is stepped from one contact set to another, whilst the lever 30 and the slide 40 in their different positions operate contacts and fluid supply controlling valves. Operation of first system. Fig. 1. On a subscriber T removing his receiver to make a call, the line relav L of his connector FS is energized to open a valve 25 and close a valve 26. Fluid is thereby admitted to the slow-return motor 29 which actuates the lever 30 to cause the pawl 38 to engage the first tooth 47 as described in the previous paragraph. On the first movement of the slide 40 the springs 60, 61 close, grounding the test wire 59 to mark the calling line busy. At the same time a lever 34 is released and opens a valve 35. The calling party now dials the tens impulses of the wanted number, the intermittent relapse of the line relay armature 24 opening the valve 26 to admit air pulsations through the pipe 43 to the switch stepping motor 51 and to the escapement motor 45. The motor 45, which is rendered slow to return by a check valve 44. rooks the escapement 41, causing the pawl 38 to advance to the tooth 48, and its retraction on the cessation of these impulses again rocks the escapement and moves the pawl a further step to the tooth 49. The motor 51 advances the connector wipers in their first direction in any desired manner. The units impulses in like manrer advance the connector wipers to the wanted line T<1>, and cause the motor 45 to again operate and relapse, thereby advancing the pawl 38 two more teeth to the tooth 54. in which position springs 19, 55 are closed and the circuit of the line relay L is opened at the spring 20. If the called line is busy, the line relay L will remain energized over the earthed test wiper 57, wire 56, and springs 55, 19, and the side switch will continue in this position in which busy tone is transmitted to the calling line over the wires BB, the contact head 63 (engaging the first contact set) and the condensers 64. A pin 65 on the lever 30 also opens a valve 67, admitting air to a slow-tooperate motor 68 which locks the motor 45 and prevents further advance of the slide 40. If, however, the wanted line is idle, the relapse of the line relay L operates the motor 45 and causes the slide to be quickly advanced to the tooth 71. In this position the head 63 engages the second contact set and ringing current from a generator GEN is sent to the wanted party. At the same time the relay L is re-energized by the closure of the springs 19, 20 and the slide advances a short step to the tooth 72 : the length of this step is insufficient to move the head 63 from the contacts engaged in the ringing position. During ringing, the called subscriber's line relay L<1> is disconnected by his cut-off relay C<1> which is energized in a circuit 76, 75, 57, 59<1>. 60<1>, 62<1>, 73<1>. When the called party answers, the calling subscriber's cut-off relay C is energized over the called line and interrupts the circuit of the line relay L, which causes the slide 40 to be advanced to the tooth 93, carrying the head 63 to its last and talking position and breaking the circuits of the cutoff relays C, C<1>. The line relays L, L<1> are thereby energized, causing the slide 40 at the switch FS to be advanced a further ineffective short-step to the last tooth, and moving the slide at the switch FS' from its normal position to close the springs 60<1>, 61<1> and mark the wanted line busy. On the subscribers hanging up, the continued deenergization of the line relays L, L<1> causes the relapse of the side-switch motors 29, which restore the slides 40 to normal. The connector wipers may be restored in any suitable manner, for example, by the continued closure of the valve 25. Operation of second system, Fig. 2. On the extension of a calling line over conductors 102, 103 to a final connector FS<3>, the line relay L<3> is energized, permitting a valve 113 to close, and opening a valve 112 to operate a slow-return motor 115 which opens a valve 117 in the main supply pipe 114. Air is thereby admitted to the slow-return motor 120 which actuates the lever 121 to advance the pawl 124 and the slide 125 to the first escapement tooth 127. Pivoted to the slide 125 is the plunger 139 of a distributor 135 into the top of which is led the supply pipe 134. A passage 140 extends from the upper end of the plunger 139 to an opening in its side adapted to register (according to the position of the sideswitch) with pipes 141, 145, 100 leading respectively to the vertical stepping motor 142, the rotary stepping motor 146, and the ringing switch stepping motor 201. When the calling party transmits the tens impulses, the first relapse of the line relay armature 111 opens valve 113 and actuates the slow return escapement motor 130, which rocks the escapement 126 and causes the pawl 124 to move to the tooth 138. In this position the channel 140 registers with the pipe 141, and air pulsations are transmitted through the valve 113 to the vertical motor 142 which steps up the wipers 164, 165, 154, 193 to the wanted tens level. The movement of the slide 125 from its normal position opens the springs 131, 132 and removes earth from the test wire 133 to mark the switch 'busy. On the cessation of the tens impulses, the relapse of the slow-return motor 130 advances the pawl 124 to the tooth 144, and the channel 140 is brought into register with the pipe 145. The dialling of the units impulses now causes air pulsations to be transmitted to the rotary motor 146 and the escapement motor 130, the latter releasing the pawl 124 from the tooth 144 and permitting it to advance a preparatory ineffective short step to the tooth 147. On the termination of these impulses, the motor 130 retracts and the slide 125 is moved a long step to the tooth 148. The contact-head 149 is thus brought to a first operative position in which the busy tone conductors BB are connected to the calling line and the line relay L<3> is connected to the test wiper 154 over the springs 152, 156. If the wanted line is engaged, the relay L<3> continues to be energized over the earthed wiper 154 and the contact head 149 remains in the busy position, but if the wanted party is idle, the line relay L<3> relapses and causes the pawl 124 to advance immediately to the tooth 155. The springs 106, 107 then close again and the re-energization of the line relay L<3> advances the slide 125 a short step to the tooth 156. In this position the contact head 149 engages the second contact set and the called subscriber is rung over the wipers 157 of the ringing switch in its normal position. When the called party answers, the cut-off relay C<3> interrupts the circuit of the line relay L<3> at springs 109, 110, and the pawl 124 is advanced as before to the tooth 173. In this position the contact head 149 engages the third set of contacts, completing the talking circuit and breaking the circuit of the cut-off relay C', which again closes the circuit of the line relay L', thereby causing the slide 125 to advance a final ineffective short step. When the wanted line is first engaged, an insulated portion 177 of the slide 125 engages a pivoted member 178, which earths the test wiper 154 over contacts 180, 181, and marks the called line busy. When the subscriber hangs up, the continued de-energization of the line relav L<3> causes the relapse, of the motor 120 which restores the side switch to normal. The connector may be released in any suitable manner. Partly-line working. Party lines are provided with an additional earthed test wire 194 connected to a contact engaged by the fourth wiper 193. When the wipers are brought to a party line, a relay 184 is energized over the fourth wiper 193, contacts 190, 191 closed in the normal position of the ringing switch, and contacts 186, 187 closed by the member 178. The relay 184 opens a valve 196 admitting air to a motor 197 which causes a bell-crank lever 199 to lock the escapement 126 and open the contacts 159, 160 in the ringing circuit. When the contact head 149 is advanced to the ringing position as described in the previo