Patent GB-191313976-A (GB)
Title: Improvements in or relating to Electric Signalling Systems, suitable for Party Line Telephone and like Systems.
IPC: H04Q5/22
Filed: 1913-06-17
Granted: 1914-07-17
Abstract: 13,976. Automatic Telephone Manufacturing Co., and Harrison, H. H. June 17. Party-line systems and apparatus.-Relates to a signalling system of the kind using selectors having a contact-maker moved step-by-step to close a circuit by impulses arranged in groups, means to release the contact-maker being operated between the groups, and the selectors having stops, differently arranged on each selector, to render the releasing means ineffective when the proper code-signal is received. Means for calling the main station from the way stations over a phantom circuit are provided. The groups of impulses are all of one polarity and are separated by an impulse of reversed polarity. Impulses of either polarity energize the magnet 224, Fig. 1, to step around the ratchet-wheel 228, which carries a contact 231 adapted to engage a fixed contact 232. The armature 219 of the polarized magnet 218 is rocked by the impulses of the groups in a direction to move the flexible arm 245 away from the ratchet-wheel 228, but the reversed impulses cause the arm 245 to strike the retaining-pawl 234 and disengage it from the wheel 228, so that the wheel is restored to its normal position by a spring, when, on the cessation of the impulse, the pawl 227 is disengaged from the wheel 228 by the pin 229. The pawl 234 is counterweighted so as to return only slowly into engagement with the wheel 228. Pins 233 are fixed in the wheel at predetermined points so that, when the proper groups of impulses are received, a pin comes into the path of the arm 245 each time a reversed impulse arrives, so preventing the release of the ratchet-wheel and allowing the contacts 231, 232 to engage. The pins 233 may be adjusted to any required positions by providing holes in the wheel 228. All the selectors can be released at any time by sending two reversed impulses in succession. The way-stations can call the main station over a phantom circuit, a battery and a relay controlling a bell being connected to earth from the middle point of a resistance bridged across the lines at the main stations, the way-stations effecting a call by means of a key which earths the middle point of a local resistance also bridged across the lines. Impulse - transmitters.-A calling - device is shown diagrammatically in Fig. 6. A spindle 66 carries a number of notched disks 67<1>...67<10>, which normally engage the springs 68<1> ... 68<10>, but when a notch in a disk comes opposite its spring, the spring passes through and engages the fixed contact behind it. The disks are all connected to a relay 34 through the spindle 66, disk 71, and brush 72, the fixed contacts are all connected together to a second relay 35, and the springs 68<1> ... 68<10> are separately connected to a number of contacts 69<2> ... 69<11>. These contacts are situated so as to he wiped over by the brush 70 mounted on the spindle of a device similar to the single calling device described in Specification 21,815/11. In operation, the spindle 66 is turned until a pointer carried by it indicates the number of the required station, and the calling device is wound up by turning the usual finger-hold-disk until a finger-stop is struck. The brush 70 then moves along the contacts 69<0> ... 69<13>, so closing the circuits of the relays 34 or 35, the former serving to send to line the group impulses, and the latter the reversed impulses. The contacts 69<0> ... 69<1> send two preliminary reversed impulses to return all the selectors to zero; the contacts 69<2> ... 69<11> send the groups of impulses and the reversed impulses separating them, the notched disks being so arranged that. in any position of the spindle, the proper impulses are sent for the corresponding station; the contact 69<12> sends the reversed impulse which moves the proper selector the last step to close its circuit, and, after an interval, the contact 69<13> sends a final reversed impulse to restore this selector to zero. In a modification, the notched disks 67' ... 67<10> are replaced by a single disk, the springs 68<1> ... 68<10> pressing on it along a radial line, holes being made in the disk differently arranged in different radii, corresponding with the notches of the disks 67<1> ... 67<10>. A master-call may be arranged for by providing a further disk, which in the master position disconnects all the reversed impulses so that all the selectors are stepped round to the circuit-closing position.