Patent GB-191503774-A (GB)
Title: Improvements in Electric Signalling Apparatus.
Inventor: WALKER ERNEST
IPC: G08B26/00
Filed: 1915-03-09
Abstract: 3774. Walker, E. March 9. Mine signalling systems; order apparatus.-In a signalling system having a number of instruments adapted to be energized in succession, and in which each instrument is arranged, after giving its signal, to cut itself out and put the next instrument in circuit, each instrument is provided with a pair of electro-magnets, one of which operates the signal and momentarily closes the circuit of the other, which then becomes self-energized and breaks the circuit of the first magnet and puts the first magnet of the next instrument in a condition to be energized at the next operation of the signalling-circuit. A time-limit switch is provided, so that when the interval between the successive closures of the signalling-circuit does not exceed a predetermined value, the instruments are operated in succession, but if this value is exceeded, the first instrument of the group is operated. In the arrangement shown in Fig. 2, the first closure of the signalling- circuit b operates a switch a to place a signalling- solenoid C across a battery X through the contact e and the armature d' of a magnet D,-and to place the winding j of a time-switch across the battery X to close the contacts s, t. The energization of the solenoid C causes its core to operate a tape-punch and to close momentarily the circuit of a magnet k through the upper contacts of the switch f, thereby energizing the magnet k from a battery x. The energization of the magnet k operates the armaturas d, d<1>, thereby closing a holding-circuit for the magnet k and a pair of contacts in the circuit of a lamp l. When the switch a is opened, the core of the solenoid C falls, thereby closing the lower contacts of the switch f to energize momentarily the magnet D, which attracts its armatures d, d' to close a holding-circuit for the magnet D through the contacts s, t of the time-limit switch, and to break the circuit of the solenoid C at the contact e and make the circuit of the next solenoid C' at the contact e<1>. If the next closure of signalling-circuit b follows within a predetermined interval of time, the solenoid C' is energized, and the previous operation is repeated at the second instrument. If, however, the interval between the successive closures of the signalling-circuit exceeds a predetermined value, the hold-on circuit of the magnet D is broken at the contacts s, t, and the circuit of the lamps l is made at the contacts s<1>, t' ; while the next closure of the signalling-circuit operates the first instrument of the series. Clearing-switches q, r are provided in the lamp-magnet circuits, one of which may be operated by the winding-engine of a mine. In a modification, the lamp circuit and its controlling-circuits are dispensed with. When the receiving-station attendant fails to see a signal, or challenges the correctness of a received signal, he rings a bell at the sending-station and at the same time closes the circuit of a solenoid p, which causes the registration of his request for a fresh call and completes the circuit of a lamp l<1>.