Patent GB-555097-A (GB)
Title: Improvements in telephone or like systems
IPC: H01H63/24
Filed: 1942-01-30
Abstract: 555,097. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. Jan. 30, 1942, No. 1321. Convention date, Feb. 7, 1941. [Class 40 (iv)] A two-co-ordinate switch is constructed so that it may be set as regards one or both directions of motion by a single interruption of the line circuit of variable duration instead of by a variable number of impulses. A system is described employing such switches as group and final selectors, the subscribers being provided with dials of the kind described in U.S.A. Specification 2,222,131 for controlling selection in the manner stated. Construction.-As shown in Figs. 1, 2, 3, a slide 127 carrying the wipers 10A is suspended from a chain 134 by a T-shaped member 133 which is located in a longitudinal groove 122 in a carriage 106. The chain 134 passes over three sprocket-wheels 115, 125, 126 mounted on a sleeve 113 on the operating shaft 105 and on rods 107, 108 which serve as guides for the carriage 106. The upper part of the carriage has a semi-circular recess for engagement with an annular groove 118 in the sleeve 113. The sleeve 113 is coupled to the shaft 105 by a pin 114 engaging in a helical groove 112 and is held alternately against axial movement and against rotation under the control of a shift or change-over magnet 30A. The shaft 105 is adapted to be coupled to a common constantly-driven shaft 15A through a friction clutch 168, 177 which is controlled by a pair of alternatelyenergized " go " and " stop " magnets 80A, 90A. The first movement of the shaft 105 rotates the sleeve 113 and drives the chain 134 to bring the wipers 10A opposite a desired row of contacts. The energization of the shift magnet 30A then advances a lever 157 into engagement with a ratchet 116 to prevent further rotation of the sleeve 113 and at the same time withdraws a stop 155 from an annular groove 119 to permit the sleeve to be shifted axially by the second movement of the shaft 105. This movement is imparted to the carriage 106 and slide 127 to bring the wipers 10A into engagement with the desired contacts in the previously selected row. A centrally-disposed strip 146 serves as a guide for the wipers. In each direction of motion, the slide 127 controls off-normal contacts 40A, 60A and extreme-position contacts 50A, 70A. A spiral spring 162 which is wound up by the rotation of the operating shaft 105 serves to restore the switch to normal when both the magnets 80A, 90A are released. In another construction, Figs. 4, 5 (not shown), the wipers are carried by a cylindrical sleeve which has a mainly helical but partly straight groove engaged by a pin on the operating shaft. The first movement of the latter rotates the sleeve to bring the wipers opposite a desired row of contacts, whereupon the energization of the shift magnet gives the sleeve an initial axial movement to make the pin operative on the helical part of the groove during the second movement of the operating shaft. Release is effected by a separate magnet which acts by withdrawing a holding pawl from a ratchet secured to the operating shaft. Circuits, Figs. 6, 7.-Upon seizure of the group selector 600, line relay R610 operates the stop magnet 90X in series with relay R640 which in energizing cuts out its shunt resistance 645. The dialling of the first digit interrupts the circuit of R610 for a variable period during which the go magnet 80X operates in series with relay R650 which cuts out its shunt resistance 655 and disconnects the stop magnet 90X. The closure of off-normal contacts 40X marks the selector busy independently of guard relay R620 and prepares a circuit for the shift magnet 30X which is completed when the stop magnet 90X re-operates to end the primary movement. The go magnet 80X immediately re-operates to effect the secondary or hunting movement, the continuance of which is dependent, after off-normal contacts 60X change over, on the presence of busy ground on the test contacts. The movement therefore ceases when an idle trunk is found, and the re-operation of the stop magnet 90X connects up switching relay R630. The final selector 700 is set in a similar manner except that both operations of the go magnet 80Y are dependent on the interruption of the line circuit. The wanted line is tested by relay R730 which pulls up if it is busy and applies busy tone, while if it is idle switching relay R750 energizes. Ringing relay R760 operates intermittently, and back-bridge relay R740 energizes upon reply. Release by the calling party causes the release of the stop magnet 90Y without the re-operation of the go magnet 80Y, so that the final selector restores by spring action, the release magnet 85Y being operated if it is provided. The shift magnet 30Y is disconnected when off-normal contacts 60Y restore. The removal of holding ground from the test wire disconnects the stop magnet 90X of the group selector, which restores in a similar way. If the group selector moves to the extreme position in its hunting movement, busy tone is applied over contacts 70X. If the calling subscriber hangs up without dialling, the group selector moves to the extreme position in both directions, and the operation of contacts 50X, 70X brings about restoration. Similar action occurs in the final selector if he hangs up after dialling one or two digits.