Patent GB-350508-A (GB)
Title: Improvements in or relating to printing telegraph exchange systems
IPC: H04L12/06
Filed: 1930-02-08
Abstract: 350,508. Telegraph exchange systems. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. Feb. 8, 1930, No. 4358. Convention date, Nov. 19, 1929. Addition to 342,479. [Class 40 (iii).] The apparatus which on the establishment of a call effects the transmission to the calling subscriber of the name or number of the called subscriber and which, according to the parent Specification, is located at each subscriber station, is replaced by one or more return signalling apparatus arranged in common at the exchange for a group or the whole of the lines. To each transmitting' apparatus is allocated a rotary selector which automatically adjusts itself on to the 'called line, and the sequence of current impulses for the separate letters or numbers is controlled by a rotary selector allocated to each preselector. When a final selector LW makes connection with the desired line, a relay H1 in the test lead completes the circuit of a rotary magnet D2 which switches forward a line finder as, until it finds the called line (shown as the third contact), the arms as2 .. as8 being moved at the same time to corresponding contacts. A continuously rotating switch STW1 closes during each revolution through a contact 16k and the arm as2 the circuit of a rotary magnet D1 which steps forward a rotary selector DW1 with a switch arm dw1 and arms dw2 .. dw6 moving over contacts wired according to the name and/or town and the number of the called subscriber. Subsequently during each revolution of the switch STW1 a contact 18k energizes a magnet M1 which couples for a single revolution a cam member NW1 closing in succession contacts 20k .. 24k connecting through the arm as3 to the line b, a series of five impulses according to the position of the arms dw2 .. dw6 on the contact bank wired appropriately tc the called subscriber. When the switch arm dw1 engages its final contact a relay U1 is energized, and at the contact 27ul the called line is switched through to the calling subscriber, and at 26u1 the return singalling apparatus is disconnected. According to Fig. 2 (not shown) the step-by-step switch, controlled by the continuously moving control member, has a second arm which is stepped over contacts successively connected according to the name and/or town of the called subscriber to the springs of contacts engaged by cams shaped to transmit during their rotation current impulses representing the letters a, b, c, .. , and mounted on a spindle periodically clutched to the continuously rotating control member. In a modified arrangement, Fig. 3 (not shown), when the final selector is taken into use, a second switch of the Strowger type, which has been automatically associated with the final selector by a pre-selecting finder switch, is operated together with the final selector by the two last digits of the wanted number. This switch is associated with cam means for transmitting current impulses corresponding to the particular exchange and the wanted number, the sequence of the successive groups of impulses being regulated by a chain of relays.