Patent GB-190709833-A (GB)
Title: Improvements in and relating to Telephone Systems, and Apparatus therefor.
Inventor: TURNER HERSCHEL ROY
Filed: 1907-04-27
Granted: 1907-12-12
Abstract: 9833. Turner, H. R. May 12, 1906, [date applied for under Paterats Act, 1901]. Telephone systems ; telephone calls.- Relates to partyline telephone systems in which step-by-step selectors are employed, lock-out mechanism and "engaged" indicators being provided, and provision being also made for calling simultaneously all the subscribers' on the line. Fig. 2 shows three stations A, B, C on a party line 1, 2, the circuits used in calling being shown in full lines. At each telephone station is a direct current generator 3 having associated with it a centrifugal governor 4 adapted to move a switch blade 5 over into the position shown at station A when the generator is in use. The subscribers' apparatus is shown in front elevation in Fig. 5. The dial 31 is provided with a series of numbers corresponding with the number of subscribers, and one extra number for use in connexion with "line" or simultaneous calls. The movable index or pointer 33 is normally resting over its own number, but when it is desired to call up any other subscriber it is turned to the corresponding number. A contact-arm 38 is carried by the shaft of the pointer 33, and moves with it. In each position of the pointer, a projection upon it engages with a notch or recess 32 on the dial. A switch 17, Fig. 2, is mechanically related with the index 33 in such a manner that, when the index is pointing to the number of the home station, it is in its right-hand or normal position, making contact at 47, but if the pointer is turned into any other position, for calling purposes, the switch is in the left-hand position, making contact at 16, as shown at A, Fig. 2. Assuming station A to be calling some other station on the line, say C, the procedure is as follows : The subscriber at station A sets his index 33 with its contact-arm 38 to the number of station C, and sets his generator 3 in motion, The governor 4 throws over the switch 5, which movement serves also to lock the pawl-carrying armature 24 to the pivoted and weighted circuit-breaker 11. Current flows from one brush of the generator through the wire 10 to the circuit-breaker 11, and thence through the contact 14 and wire 15 to the contact 16, switch 17, hook-switch 19, and main line 1. At each station on the party line the current flows through the hook switch 19, switch 17, contact 47, switch 5, and polarized relay 8 to the line 2. The polarized relays are provided with two tongues oppositely polarized, and co-operating respectively with the contact 28, 76. From the line 2 the current returns to the other brash of the generator at the calling station through the relay 8, switch 5, and contact 9. The current is in such a direction that the relay tongues 25 are actuated, and contact made at 28. The batteries 27 at all the stations consequently energize the electro-magnets 30, which attract their armatures 24. At the calling station the armature 24 has been locked to the contact-breaker 11 ; this interrupts the supply of current from the generator, but the circuit is again closed when the armature 24 falls back. An intermittent or pulsating current is therefor sent to line. At each station a disk 39, carrying a contact-arm 41, is turned step by step by the action of a pawl 42 carried by the armature 24. When the arm 41 at the calling station A has reached the contact 38 which has been set to the number of the called subscriber, a local circuit is closed from the generator through the wire 10, arm 41, contact 38, relay 8, and switch 5, the armature 24 then remaining in the attracted position, and the intermittent current ceasing in the line. At the called station C the arm 41 is also making contact at 38, but at all other stations the contact 38 is in a position at which no such contact is made. Owing to the fact that at the calling station the switch 52 is open, no signal is given when the arm 41 reaches the contact 38, but at the called station the circuit of the bell 57 is closed as follows : from battery 27 to bell 57, switch 58, armature 24, pawl 42, disk 39, arm 41, contact 38, switch 51, switch 52, and wire 55 back to the battery. The bell continues ringing until the receiver is lifted from the hook or until the calling subscriber rings off." A momentary signal is given at all stations having a number lower than that called, as the contact-arms 41 pass over the contacts 38, but this is not interpreted as a calling signal, but serves as a notification that the line is busy. When the receivers are removed from their hooks, the talking circuits are closed, each receiver 67 being connected to the line 1 through the induction coil 66, contact 63, and hook 19, and to the line 2 through the wire 68, disk 39, contact 38, and wire 7. The transmitter circuit comprises the battery 27, transmitter 71, coil 66, and contacts 63, 64. In ringing off, the generator connexions are reversed, or it is rotated in the opposite direction, so as to send a reverse current to line. This causes the actuation of the other tongue of the polarized relay 8 at each station, contact being made at 76 so as to energize an electro-magnet 74 and release the detent pawl 78 and allow the disk 39 and arm 41 to resume their normal or zero position. The lock-out mechanism for preventing interference on the part of subscribers not concerned in the call comprises link-work by means of which as soon as the disks 39 begin to turn all the shafts of the index pointers 33 are locked against axial movement, and consequently, owing to the notches 32, cannot be moved on the dials 31. They are not released until the magnets 74 are energized by the ring-off current. In order that all the stations may be simultaneously connected to line to receive a message of general interest, the shaft of each index 33 causes an extra contact 89 in addition to the contact 38, so placed that when the index is opposite the home number it is in a position to be engaged by the arm 41 when the disk 39 is stepped round to the maximum extent. In that case the contact is made at the same time at all the stations on the line. The disks 39 are visible through a glass-covered opening in the case of the instrument. A subscriber can thus ascertain by inspection whether the line is engaged.