Patent GB-191319271-A (GB)
Title: Improved Electric Devices for Calling Any One of Several Stations connected to the same Line.
IPC: H04Q5/16
Filed: 1913-08-25
Granted: 1914-08-07
Abstract: 19,271. Siemens & Halske Akt.-Ges. Aug. 24, 1912, [Convention date]. Party-line systems are described in which each station is called by a definite number of current impulses, which drive a step - by - step wheel so that at the desired station a succeeding impulse of long duration, or on a second line, can pass over a circuit to ring the bell. At the calling station, the sector m is moved to expose the proper number of notches k<2> and the inductor a is then actuated to send the current impulses to line over the brush i, arm h, brush g, notches k<2>, disk k, and lead 1. At each station, the impulses actuate the relay R, thus completing the circuit of the magnet t, which drives the ratchet-wheel o, Figs. 1 and 3. The wheel o drives the contact arm q, and when the proper number of impulses have been received to call a certain station, the arm q there is opposite the contact v. The succeeding long impulse caused by the brush g reaching the sector m is sufficient to cause the magnet n to attract its retarded armature u<1>, thus bringing the parts q<2>, v into contact at the selected station. The arm u<2> releases the wheel o at all stations, and the arm q also returns to zero at all stations except the selected one where it is held by the arm v. The ringing current passes from line over the lead 6, contact v, q<2>, brush q<4> to bell W. The bell W at the calling station is rung when the contact m<3> is reached by the brush g, and when the working of the inductor is stopped, the one-way clutch c opens, and the brush g is returned to a zero position by the spring f. An arrangement of apparatus for a two-wire system is shown in Fig. 4. The leads X, Z are earthed at both ends through opposed batteries LB1, LB2, and each station is provided with keys y1, y2 adapted to connect the lines to earth. The depression of the key y1 at the calling station energizes the relays R1, thus completing the circuit of the magnets u, which release the ratchet-wheels o by withdrawing the arm u<1>2 from the path of the stop o<1>2. Number impulses sent by the key y<2> energize the relays R2, and the magnets t move forward the ratchet-wheels o. When the proper number of impulses for the desired station have been sent, and the magnet u is again energized, the pin z1 enters a notch w1 at the selected station and the contact z<2> z' is closed to ring the bell W. The apparatus is brought to a zero position by sending impulses by the key y2 to bring the stop o2<1> against the arm u2<1> again. In a modified arrangement of circuits, a central station is provided with a plug by which number keys are connected to line to call a station, and each station is provided with an inductor for sending ringing current to the central station. The function of the keys y1, y2, Fig. 4, may be performed by a number disk of the kind used in automatic telephone systems, and if a number disk and battery are used with the apparatus of Fig. 1, the relays R may be omitted, and the line currents allowed to operate the magnets t, u directly.