Patent GB-100459-A (GB)
Title: Improvements in Machine Switching Telephone Systems.
IPC: H01H67/12
Filed: 1916-02-08
Abstract: 100,459. Western Electric Co., (Western Electric Co.). Feb. 8, 1916. Automatic @c r - change systems and apparatus.-One of a number of the normally inoperative brush sets of the corresponding sections of a number of call-finders is rendered operative by a tripping-device common to all the brush sets of these sections while only one tripping-device is in its operative position at the same time. Construction. In the arrangement shown, each panel is provided with five brush sets 6, Fig. 4, mounted on a rod 1 adapted to be moved longitudinally in front of the panel by a constantly rotating member 3, which engages an extension 2 of the rod 1 through the medium of a member 4 when a magnet 5 is energized. Each brush set is normally rendered inoperative by a device 8, the members 43 of which are located between the inner brushes of a set to place the brushes out of alinement with their contacts. Extending in a plane parallel to the plane containing the rods 1 are five trip rods 11 provided with a number of yokes 12, which are urged against stops 14 on the rods by springs 13. Each trip rod is common to the corresponding sections of all the call-finders and is rotated by means of a magnet 17, whereby the yokes 12 of the rod are placed over the trip levers 9 of the normal positioned brush sets of the corresponding sections, so that when a rod 1 is raised by the energization of its magnet 5, the spacing-members 43 are withdrawn from engagement with the inner brushes, thereby allowing the brushes to assume their operative positions, after which thev are moved over the contacts of the section. The members 43 are restored to their normal position on the downward movement of the rod 1 by the engagement of restoring-levers 10 with the trip rods 11. Operation. When a subscriber A, Fig. 3, removes his receiver, the line relay 21 is energized to place battery potential on the test terminal 37, Fig. 4, of his line through the right winding of the cut-off relay 19 and the lead 23, and to energize the lock-out magnet 20 through the armatures of the starting-relay 18 and cut-off relay 19 and the second armature of the relay 21. The starting- relay 18 is common to all the panels, while the cutoff relay 19 and lock-out magnet 20 are common to all the corresponding sections of the panels. The relay 20 completes a holding-circuit for itself through the winding of the starting-relay 18 and its left armature, and energizes the magnet 17, Fig. 4, through its right armature and the lead 23<a>. The operation of the relay 18 disconnects the common lead 24 from the battery, so that if a subscriber B in another section calls, his magnet 20<1> is not energized until the relay 18 is released. The energization of the magnet 17 rotates its trip rod 11 to place the yokes 12 over the top levers 9 of the inoperative brush sets of the sections at that level. The system is arranged so that the finder next to be employed is pre-selected, and only the sequence switch of this finder is in position 1. The energization of the starting-relay 18 grounds the circuit of the relay 25, Fig. 4, through the sequence switch contact 26 and lead 27, thereby causing the relay 25 to energize the sequence switch 28 through the contact 29, so that the sequence switch is moved to position 2. A circuit is then established through the clutch magnet 5 and contact 2 of switch 29 to earth, whereby the pre-selected rod 1 is moved upwards to render operative the brush set, by the action of the yoke 12 and trip lever 9, of a section in which the calling line terminates. When the sequence switch 28 is in position 2, a holding-circuit for the relay 25 is established through the contact 32 and interrupter 34, this circuit being broken by a brush 35 when the brushes of the set are centrally positioned. A second circuit is also established from the contact 32 to contact 52 and the test brush 36 adapted to engage the test terminals 37. Upon engagement of the brush 36 with the first test terminal 37 of a non-seeking line, the left winding of the relay 19 of this section is energized, whereby the relay 19 operates to break the holding- circuit of the relay 20, and magnet 17; and the relay 20 opens the circuit of the starting-relay 18 so that a call may be initiated by a subscriber in another section. The relay 25 is maintained alternately energized through the bushes 35, 36 until the brushes are centrally positioned on the contacts of the calling line, whereupon the relays 19, 25 are de-energized, since they are then connected in a circuit having no potential. The de-energization of the relay 25 completes a circuit for the sequence switch 28 through the contact 38, thereby causing the sequence switch to move to position 3 to complete a circuit through the contact 40, brush 41, and cut-off relay 22, Fig. 3. The energization of relay 22 breaks the circuit of the line relay 21, thereby earthing the test contact 37 through the left winding of relay 19. Simultaneous calling of two subscribers of different sections. If two subscribers A and B call at the same time, both relays 20, 20<1> are energized, and the operation of relay 20 breaks the normal circuit extending from relay 20' to the starting-relay 18, so that the magnet 17<1> cannot be energized until the relays 20, 18 are released by the operation of the finder of subscriber A when the selection for subscriber B immediately begins.