GB102786A - Improvements in Intercommunication Telephone Systems. - Google Patents

Abstract

102,786. Dungey, J. W., and Kersting, C. B. May 16, 1916. Intercommunication systems and apparatus.- In an automatic system of the kind described in Specification 22549*/14, the selector switch is controlled by a solenoid in a local circuit which is wholly or partly controlled by the removal and replacement of the receiver. In the arrangement shown in Fig. 1, the selector arm 3 is operated by a solenoid S, the circuit of which contains three switches 21, 23; 24, 25; 26, 27. If a call is initiated at the station shown, when the receiver is removed from its hook 10, the circuit of the solenoid S is made by the closure of the switch 26, 27, and the arm 3 is moved to its limiting position when a projection K breaks the circuit of the solenoid at the switch 21, 23 and establishes the circuit of a hold-on magnet M at the switch 21, 22. If the station shown receives a call, the circuit of the solenoid S is made at the switch 26, 27 when the receiver is removed from its hook 10, and the arm 3 moves over its contacts until the calling-line is found, when the energization of the line magnet E operates its armature 18 to arrest the arm 3 and to break the circuit of the solenoid S at the switch 24, 25. In a modification, the circuit of the solenoid S is controlled by an independent switch. In the modification shown in Fig. 3, the selector arm 3 is normally held in its initial position by a latch CH, from which it is released when the receiver is removed from its hook 10. When a subscriber is calling, the arm 3 moves to its limiting position against the action of a retarding-device; but when a subscriber is called, the arm 3 of his selector moves until it is arrested by the energization of the magnet E. The circuit of the solenoid S contains two switches 28, 29 and 30, 31. When the receiver is removed from its hook, the switch 30, 31 is opened, and when the arm 3 has moved through a predetermined angle, the normally open switch 28, 29 is closed, in order that the restoring-solenoid S may be energized when the switch 30, 31 is closed by the replacement of the receiver. In the modification shown in Fig. 4, the selector arm 3 is moved quickly to its limiting position by the action of the solenoid S, when its circuit is made at the contacts 37, 38 by the removal of the receiver. At the end of its travel, a projection P engages a lever T to break the circuit of the solenoid at the contact 39. The arm 3 moves slowly back under the action of a spring SP until arrested by the energization of the magnet E in the case of a called subscriber, or back to its initial position in the case of a calling-subscriber. The lever T is returned to its normal position to engage contact 39 when the receiver is replaced.