Patent GB-190800197-A (GB)
Title: Improvements in Switching Apparatus for Interconnecting the Lines of a Telephone Exchange System.
Inventor: KINGSBURY JOHN EDWARD
Filed: 1908-01-03
Granted: 1908-12-17
Abstract: 197. Kingsbury, J. E., [Western Electric Co.]. Jan. 3. Switches.-In a semi-automatic telephone system, the contact-wipers of the selector switches are carried by rods which are moved by motormechanism to a point determined by electromagnetic stop-setting mechanism, responsive to the selecting impulses. In the form of selector described, the five, hundred sets of terminals in each selector are arranged one above the other in a flat panel, and the contact-brushes of each selector receive a movement in one direction only. To reduce this movement as far as possible, each selector may have five sets of. contact-brushes, each set moving over one-fifth of the complete panel, so that, in a final selector, the selecting-impulses select first the set of contact-brushes, and then the required contact in the zone served by them. In the group selectors, the terminals are divided into five zones leading to selectors serving the lines 1 to 2000, 2001 to 4000, 4001 to 6000, &c., and each zone is divided into four divisions containing terminals leading to selectors serving the lines 1 to 500, 501 to 1000, and so on. The selecting impulses must thus choose the contact brushes serving the zone required, and then the division of that zone, in which the brushes hunt for an idle final selector. The district, office, trunk, group, and final selectors are all constructed on the same general plan, differing, however, in certain details. The switchboard is built up in flat-faced panels, with rows of terminals on both the front and rear faces thereof. The multipled terminals 61, 62, 63, Fig. 6, are made from punchings or strips set in horizontal slots in the face of the switchboard panels, each strip having a series of projecting contacts associated with the several brush-carriers. The contact-brushes 51, 52, 53 have spring-pressed arms which pass over and make contact with the side edges of the fixed contacts. The brushcarriers, which receive a movement in one direction only, are fixed to the rods 50, which are moved by motor-mechanism to a point determined by electromagnetic stop-setting mechanism responsive to the selecting impulses. Figs. 9 and 14 show the stopsetting mechanism. The rods 50 are supported by steel ribbon from the pulley 71, which can be connected to the constantly-rotating shaft 72 by the clutch-members 80, 81 controlled by the electromagnet 70. The stop-mechanism consists of a wide pawl 75 co-operating with a toothed wheel 78 and two notched disks 73, 74, the notches of which are arranged on the principle of the vernier. The notches on the disks 73, 74 are spaced apart a distance corresponding to nine and ten teeth respectively of the wheel 78, the teeth of which are so spaced that the travel of the pawl from one tooth to the next corresponds to the movement of the contact-brushes from one set of terminals to the next. The disks 73, 74 are carried by tubular sleeves provided with ratchets 83, 84 by which the vernier-disks are set by a step-magnet. The ratchets 83, 84 are provided with separate detents under the control of the magnets 91, 90, and, in order that any effective rotation of the disk 73 or 74 may take place, the magnet 91 or 90 must be energized. In operation, the holding-magnet 91 and the step-magnet are first operated to turn the disk 73 the required number of steps to bring the point of coincidence of the notches in the disks 73, 74 into the position corresponding to the required bank of 'tens' terminals, the disk 74 during this operation being returned to its normal position after each stroke of the step-magnet, since its detent is not in action. The shift-magnet 90 is then energized to bring the detent of disk 74 into action, so that further operations of the stepmagnet advance both disks 73, 74 the required number of steps to reach the units' point desired. The 'stop' being thus set, the clutch-magnet 70 is energized, whereby the rotating shaft 72 is coupled to drive the pulley 71 and raise the brush-carrier 50, and, at the same time, the disk 76 and pawl 75 are advanced until the latter reaches the point at which the notches in the disks 73, 74, 78 coincide. At this point, the pawl 75 drops in, and moves the disk 78 sufficiently to open a contact 79 in the circuit of the clutch-magnet 70, and disconnect the clutch. Other sets of contacts are controlled by the armature of the holding-magnet and by the pulley 71.