Patent GB-200210-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H01H63/30
Filed: 1922-04-08
Abstract: 200,210. Conrad, H. S. April 8, 1922. Automatic exchange systems and selectors.- All the switches used in extending a connection in an automatic telephone exchange are driven by fluid-operated motors, the operation of at least one of the switchesbeing effected step-by-step under the control of dialling impulses. In the system described when a subscriber removes his receiver to make a call, a line relay 96, Fig. 6, opens a valve 97 which admits compressed air to the driving motor 98 of his individual line switch, which extends connection to an idle group selector, a line relay 118, Fig. 7, associated with which opens the air supply to this switch. In response to the hundreds impulses the wipers of the seized group selector are moved longitudinally to a column of contacts leading to the wanted hundreds section of the exchange, and thereafter are raised vertically until a trunk extending to an idle connector is engaged. A line relay 180, Fig. 8, of the connector then opens the fluid supply to this switch, the wipers of which are first moved horizontally and then vertically to select the wanted line, the stepping movements in both directions being effected by escapements controlled by the tens and units impulses. The calling line is extended to the line wipers of the connector by the relapse of an auxiliary fluid motor 58, which however remains actuated if the wanted line is engaged. Construction of line switches. These are single co-ordinate panel switches, the wipers 105, 126, 117, 121, Fig. 6, of which are mounted on the cap of a fluid motor 98, which also carries a ratchet co-operating with a stopping pawl 110 and a holding pawl 114. The stopping and holding pawls 110, 114 engage the ratchet when the wipers reach an idle line, the former being actuated by a test relay 100, which opens a valve 111 to admit air to fluid motors 112, 113. The motor 113 actuates the pawl 114 with a force sufficient to hold the cap in its elevated position after the fluid supply to the driving motor 98 has been cut off. Construction of group selectors. These are of the kind described in Specification 200,208. Construction of connectors. The wipers 86 - - 89, Fig. 1, are mounted on the cap of the vertical driving motor 15, which is carried by a frame 17 fixed to the cap of the horizontal driving motor 19, the weight of the frame 17 and its associated parts being taken by a roller 22 riding over a track 23. The cap of the motor 19 is formed with a rack 26 coacting with a gear wheel 25 journaled in the framework and fixed to an escapment wheel 31, actuated by an escapement lever 30 connected to the armature 29 of a stepping magnet 28. A spring connected to the wheel 25 and contained in a housing 27 tends to hold the motor 19 to the left. The movable part of the motor 19 is also furnished with a ratchet bar 48, coacting with which are two holding pawls 50, 53, Fig. 5, pivoted on the framework. A tail piece 51 of the pawl 50 normally rests upon a collar 47 of a fluid motor 40 and is held away from the ratchet 48, but when the motor 40 is actuated the pawl falls into engagement. An arm 55 on a shaft 35 normally holds the other pawl 53 out of engagement. The movable part of the vertical motor 15 is provided with two racks 32, Fig. 1, coacting with two gear wheels 33 mounted on a sleeve 34 which moves with the frame 17 along a squared portion of the shaft 35. Fixed on the end of the shaft 35 is an escapement wheel 39 associated with which is an escapement lever 38 controlled by the armature of a stepping magnet 36. A holding pawl 45 is normally held out of engagement with a second toothed wheel 43 on the shaft 35 bv the collar 47 of the motor 40, but is brought into use when the motor 40 is actuated. According to a modification, the escapements may be operated by pneumatic motors. A three-position side-switch comprises a toothed plate 57 journaled in the framework and provided with wiper arms adapted to engage three pairs of contacts mounted in an arcuate framework 74. In the second position, a projection 73 on the plate 57 actuates a pivoted member 71 to open a valve 69. The plate 57 is stepped round by a pawl 63 mounted on an arm 59 which is raised by a fluid motor 58 and is retracted by a spring 61. A holding pawl 66 connected by a rod 67 to the frame 17 is brought into operative relation with the teeth on the plate 57 when the horizontal motor 19 advances out of its normal position. Operation of system; line switch, Fig. 6. When a calling party removes his receiver a circuit is closed for the line relay 96 over the normallyclosed springs 90, 91, 94, 95, and the valve 97 is opened to admit air to the driving motor 98 which raises the wipers 105, 126, 117, 121. When an idle line is reached the slow-release test relay 100 is energized in a circuit X, 99, 102, 103, test wiper 105, test wire 105<a>, arm 107, Fig. 7, of the group selector side-switch 150 in its first position, 109, X1. The stopping pawl 110 is thereby actuated to arrest the line-switch wipers, and a valve 111 is opened to admit air to the motors 112, 113- The operation of motor 112 is without effect at this time, but the motor 113 inserts the holding pawl 114 and actuates the associated spring group, extending the calling line 92, 93 to the line wipers 117, 121 over contacts 115, 119, and opening the circuit of the line relay 96, which cuts off air from the driving motor 98. The line relay 118 of the group selector, Fig. 7, is now energized over the calling line, and the circuit of the relay 100, Fig. 6. is transferred over spring 102, wiper 126, springs 128, 129, battery X<1>. Group selector, Fig. 7. The operation of this switch is fully described in Specification 200,208- The line relay 118 opens valve 132 to admit air to the local pipe system, and closes a circuit for magnet 139 which opens the valve 146 to admit air to the motor 148, which drives the side switch to its second position, and to the horizontal driving motor 152. The hundreds dialling impulsesare now sent and repeated by the line relay 118 to the magnet 157 which controls the escapement to regulate the horizontal stepping movement of the motor 152. On the cessation of these impulses the relay 139 relapses and cuts off air from the motors 146, 152. The relapse of the motor 148 opens the valve 160, admitting air to the vertical driving motor 161, which raises the wipers until a trunk leading to an idle connector is engaged, when the magnet 139 is energized and arrests the forward movement. The side swith is also driven into its final position in which the calling line 122, 123 is extended to the selected trunk over the side-switch arms 151, 107. Connector, Fig. 8. The line relay 180 of this switch is provided with a fast armature 182 which opens the springs 203, 204, and a sluggish armature 183 which closes the springs 188, 189 and opens a valve 184 to admit air to the local supply pipe 78. A slow release magnet 76 is energized in a circuit X<2>, 188, 189, 191, 192, arm 193 of the side-switch in its first position, 195, 196, 197, 166, and opens a valve 77 which admits air to the horizontal driving motor 19 and the side switch motor 58. The motor 58 actuates to open springs 217, 220, disconnecting the calling line from the line wipers, and prepares the sideswitch for subsequent movement, while the motor 19 moves the wiper carriage just far enough to permit the off normal springs 164, 165 to open (see Fig. 1). The motor 40. Fig. 1. is also actuated over the branch pipe 235 and permits the holding pawls 50, 45 to fall. On the tens impulses now being sent, the intermittent closure of the contacts 203, 204 completes a circuit for the horizontal escapement magnet 28 over X<2>, 181, 188, 189, 190, 199, 201, 203, 204, 167, and the wipers are stepped beneath a particular vertical row of contacts. At the first step of the motor 19 the movement of pin 187, Fig. 1, permits the springs 196, 197 to open and the springs 196, 205 to close, thereby opening the steady current circuit through magnet 76 and substituting therefor a pulsating current which flows in a circuit X<2>, 188, 189, 191, 192, 193, 195, 196, 205, 202, 203, 204, 167. On the springs 203, 204 remaining open during the pause after the tens impulses, the slow-release magnet 76 relapses, the valve, 77 closes and air is shut off from the horizontal and side-switch driving motors 19, 58. The relapse of motor 58 drives the side-switch into its second position in which the lever 71 opens the valve 69 to admit air to the vertical driving motor 15. On the units impulses now being transmitted, pulsating current is sent over the springs 203, 204 and the side-switch arm 199 (in its second position) to the magnet 36 controlling the vertical motor escapement and the wipers are raised to the wanted contact set. The armature of the escapement magnet 36 also closes springs 210, 211 and completes a circuit X<2>, 188, 189, 191, 192, 209, 198, 166. for the magnet 76 which again actuates the side-switch motor 58. At the end of the units impulses this motor falls away and the side-switch is advanced to its third position, in which the calling line 173, 178 is extended to the wanted line over springs 217, 220. Busy test. If the wanted line is engaged, the magnet 76 remains energized on the cessation of the units impulses in a circuit X<2>, 188, 189, 191, 192, 193, 223, test wiper 87, test wire 225, test wiper 87 of the connector already engaging the wanted line, and the springs 214, 215 closed by the side-switch of this connector in its third position. The motor 58 is thereby held operated and the calling line remains disconnected from the line wipers at springs 217, 220. If the wanted line is idle, the connection is extended as described in the previous paragraph. Operation of wanted subscriber's line switch and completion of talking circuit. The magnet 100 in the wanted subscriber's line switch (shown at the right of Fig. 6) is