Patent GB-191309986-A (GB)
Title: Improvements in Selective System of Telephony.
Inventor: HASTINGS RUBEN CHRISTOPHER MIL
IPC: H04Q5/00
Filed: 1913-04-28
Granted: 1914-03-12
Abstract: 9986. Hastings, R. C. M. April 28. Party-line systems and apparatus. -- In a party-line system in which two stations on a line are connected through an exchange, the exchange is provided with an instrument to send a definite number of impulses to call a station, and the ratchet-driven shaft at each station controls apparatus for short-circuiting an uncalled station from the line, locking the hook-switch there, and opening the local battery circuit. Fig. 1 shows the circuits at the exchange E and those at one sub-station S. The answering plug J is inserted in the jack 1, and the calling plug J' in the jack 2, Impulse-transmitters. - To make a call, the exchange operator rotates the key 24, Figs. 2 and 4, which is geared to the shaft 4, to bring the pointer 20 opposite the number of the desired station, and then depresses the key. The cylinder 17 rotates with the shaft 4, and is pushed inward with the key 24. The rack 35 is also pushed inward with the key 24, and this rack and the rack 10 connected to the cylinder 17 are adapted to be returned to the left in Fig. 2 by the springs 44, 3' respectively under the action of escapements. These escapements are, however, controlled by a two-armed governor 51 in such a way that only one of the racks can move back at a time. When the cylinder 17 is pushed in, the contacts 66, Figs. 1 and 2, are closed by the cylinder and the magnet 56 is energized so that the governor 51 is moved to permit the return of the rack 10 and cylinder 17 as soon as the key 24 is released. During the inward movement of the cylinder the pin 23 and springs 65 move in the grooves 18 between the series of teeth a, but when the pins 62 reach the hook 70 the cylinder is rotated slightly to bring the springs 65 in contact with the teeth a. As the cylinder moves back the springs 65 are actuated by the teeth a to send impulses from the battery 111 over the lines L, L<1>. As soon as the cylinder has moved far enough for the notch 63 characteristic of the called station to allow the contacts 66 to open, the magnet 56 is de-energized, thus allowing the governor arm 51 to move to stop the movement of the frame 10 and cylinder 17, and to allow the movement of the frame 35. At the two extreme positions of the frame 35, notches 60, 61 in an arm on the frame allow the contacts 165, 166 to remain open, but during the movement of the frame, these contacts are closed to connect the calling-magnets M to line. By depressing the key 38, the frame 35 alone can be moved, thus repeating the call. At the end of a conversation, the removal of the plug J<1> from the jack 2 energizes the magnet 56 over the contacts 2', 2<a> and the frame 10 and cylinder 17 return to initial position, thus sending to line a series of impulses to bring the apparatus at all sub-stations to initial position. Sub-station apparatus. The impulses from the central station are repeated by the relay 101 to the magnet 95, Fig. 1, which drives the ratchet-wheels and the disks 74, 102. The disk 74 is provided with a number of studs 75 on its periphery, a stud being omitted at the zero point on the disk and at the point corresponding to the number of the station. These studs actuate a spring hook 78, 77, which controls the switch hook 80, 117, Fig. 1, in such a way that the hook is allowed to rise only at the called station. The disk 102 carries a series of pins 103 and studs 104. The studs 104 actuate contacts 106 to control a short-circuit for the bell 200, thus ensuring that only the desired station is called, and the pins 103 control contacts 105 in the circuit of a magnet 88. If a subscriber has left his receiver off the hook, and the central station calls another subscriber, the contacts 105 are closed and the magnet 88 energized, thus removing the armature 83, Fig. 12, from the arm 81 and allowing it to be pulled down by a weight on to the contacts 134, 168 beneath the switch hook. The effect of this is to close contacts 134, 135, thus shortcircuiting the station from the line, and to open contacts 167, 168 in the microphone circuit. These contacts are also controlled in this way at uncalled sub-stations by the non-rising of the switch-hook. The differently-coloured portions 107, 108 of the disk 102 indicate whether the line is busy or idle. The transmitter is connected in circuit with the battery B' and one winding of the induction coil 123 through the contacts 120, 121 and 167, 168 and the receiver R is connected across the lines L, L' in circuit with the other winding of the coil 123 through the contacts 117, 121. In a modified form of sub-station apparatus, the disk 74<1>, Fig. 16, takes the place of the disk 74 of Fig. 1. This disk is provided with slots 75<1> and notches 75<a>. A lug on the switch arm 135<1> normally rests on the periphery of the disk, and a pin on it rests on the face of the disk. When a station calls the central, and the magnet 88, Fig. 1, is thus energized, the disk 74<1> is moved against the spring 88<a> so that the pin at this station passes through the slot 75<1> and allows the contacts 134<1>, 135<1> to remain open. At a called station, the pin reaches the notch 75<a> when the impulses cease, thus again opening the contacts 134<1>, 135<1>. In another form of sub-station apparatus, the disk 74 is replaced by a cylinder 74<a>, Figs. 23 and 25, with a series of notched ribs d, e, f. The contact springs 134<1>, 135<1> are rotatably mounted, and carry the armature 202 of the magnet 88. The springs normally rest between the ribs d, e as shown. At a calling station, the magnet 88 is energized and a lug on the springs is moved through the notch g<1> on to the outside of the rib d thus allowing the springs to open contact. At other stations the lug passes through the notch i and the springs are held in contact by a pin resting on the rib f. A notch h<2> is arranged in position at the called station to enable this contact to be opened.