Patent GB-191213970-A (GB)
Title: Improvements in or relating to Telephone Systems.
IPC: H01H67/16
Filed: 1912-06-15
Granted: 1913-06-16
Abstract: 13,970. Automatic TelephoneManufacturing Co., [Automatic Electric Co.]. June 15. Automatic exchange systems. - Relates to a construction of selector in which the vertical and rotary movements of the wiper-shaft are continuous instead of step-by-step. The wipers are first lowered to a particular level of the bank-terminals and then rotated to the required set, both movements being controlled by a vertically-movable cylinder 12, which has a spiral slot 14 embracing a pin 13 on the wiper-shaft 6. In the operation of the switch, a spring 33 acting through a gear 16 which engages teeth 15 on the back of the cylinder 12 lowers the cylinder under the control of an escapement wheel 22 operated by the line relay 25 in response to impulses sent by the calling subscriber. The shaft 6 at first drops with the cylinder 12, the pin 13 resting in the bottom of the slot 14, but when the wipers are opposite the required level of terminals a catch 34 is released and engages one of the teeth 35, preventing further downward motion of the shaft 6, so that when the cylinder 12 is lowered a second time, in response to a further set of impulses, the shaft is constrained by the pin- and-slot device to move in a rotary manner. The movement of the cylinder 12 and shaft 6 is checked by a brake 26, 27, so that these parts move in a continuous manner and at a somewhat slower rate than that permitted by the escapement wheel. The brake consists of revolving weighted springs co-operating with a stationary cup, and is driven from a shaft 20 geared to a wheel 18, which is driven through a pawl and ratchet from the shaft 17. The escapement wheel 22 is loose on the shaft 20 and can turn in advance thereof under the influence of a coiled spring 21. When the shaft 20 has turned to the same extent as the escapement wheel, it is locked by the re-engagement of pins 23, 24 and the cylinder 12 and shaft 6 are brought to rest. A notched disk 45 serves to hold spring contacts 42, 44 away from a spring 43 as long as the shaft 20 is in rotation, but allows one or other of the springs 42, 44 to close with the spring 43 when the shaft 20 is at rest, accordingly as the escapement magnet 25 is left in an energized or a de-energized condition. This device controls the circuitchanges which takes place after each setting- operation and also the release of the switch. A slow - acting relay 61, operative when the selector has been set, has an arm 176 which then engages the escapement wheel 22 to prevent further movement being caused by additional impulses sent in error. The selector is restored to normal condition by a solenoid 30, having a toothed plunger engaging a gear on the shaft 17. Owing to the ratchet device previously mentioned, the shaft 20 with the escapement wheel, brake, and notched disk 45, is not rotated during the restoring operation. When the cylinder 12 has regained its uppermost position, a pin on the gear 16 opens an offnormal contact 59, 60 to de-energize the solenoid. Circuit arrangements. Fig. 7 shows the circuits of a switch of the above construction used as a connector in a two-wire system. The connector is reached through a line-switch and group selectors, the circuits of which are the same as in Specifications 1419/10 and 15,133/11. Connector. When the connector-trunk 144, 145 is seized by a selector, the line relay 25 is energized and permits the wipers 9, 10, 11 to drop an idle step, so that the off-normal contact 60 is closed and connects ground to the wire 146 to keep the selector release-relays energized in the usual manner. The next set of current-interruptions produced by the subscriber's impulse-sender controls the escapement 22 to lower the wipers to the required level. When this movement is completed the notched disk 45 comes to rest and permits the springs 44, 43 to come into contact, which closes a circuit through the lower winding of a relay 154 and a high-resistance relay 38. The relay 154 does not respond, but the relay 38 energizes and trips the catch 34, Fig. 1, to prevent further downward movement of the wipers. The current-interruptions representing the last digit now control the escapement 22 to rotate the wipers on to the terminals of the wanted subscriber. The contact 44, 43 is opened by the disk 45 during this movement, so as to de-energize the relay 38, but when the movement is completed the contact is again closed and completes the circuit of the relays 154, 38. Busy test and signal. If the wanted line is busy, the relay 38 will be short-circuited by the grounded test-terminal and will fail to energize, while the relay 154 will respond and connect the busy signal device L to the calling line, at the same time closing a locking-circuit through both its own windings at the contact 173. The calling subscriber then releases the connexion as described below. Supply of ringing-current. If, however, the wanted line is idle, the closure of the contact 44, 43 energizes the relay 38, which (1) connects together the incoming and outgoing talking wires, (2) connects ground to the test-wiper 9 to mark the selected line busy and to energize the cut-off winding 159 of the line-switch C<1>, and (3) closes the circuit of the ringing-relay 110. When the called subscriber replies, the back-bridge relay 168 becomes energized and reverses the current in the calling line, at the same time energizing the upper winding of the relay 154, which cuts out the ringing-relay 110. Release. The connector is locked in its set position by the armature of the line relay 25, and a further lock is provided by a relay 61, the armature of which moves a stop into engagement with the escapement 22. The relay 61 is energized, at the conclusion of the rotary movement of the wipers, by a circuit including the contact 174, closed at the commencement of the rotary movement, and the springs 44, 43, and locks itself up in a circuit through a front contact of the relay 25; and as the relay 61 is of slow-release type it remains energized in spite of momentary de-energizations of the relay 25 (due for instance to additional line - impulses sent in error) until the calling subscriber hangs up his instrument. The relays 25, 61 are then de-energized, and the notched disk 45 moves half a step forward so as to allow an engagement between the springs 43, 42, which completes the circuit of the restoring-solenoid 30.