Patent GB-190304682-A (GB)
Title: Improvements in or connected with Telephonic Exchange Apparatus.
Inventor: HANSON ALBERT PARKER
Filed: 1903-02-27
Granted: 1904-04-27
Abstract: 4682. Hanson, A. P. Feb. 27. Telephone systems.-In an automatic telephone exchange, the switch mechanism is readily detachable as a whole from the contact banks, the leads for the switch terminating in spring plates on the banks, with which an arm on each subscriber's switch-box makes connection when the box is in place. Shaft and barrel mechanism for moving the arm over cylindrical contact surfaces is described, and also forms of the bank contacts and arms. The cylindrical surfaces formed by the contacts are shown at X, Fig. 2, with the detachable switch-box F for one bank in position, provided with a glass front L and a contact-arm G in electrical connection with the calling-subscriber's line wire, the extremity of which arm can be brought by that subscriber to any contact on the bank, the springs K, on the bank-supporting frame, and studs 1, Fig. 3, on the switch box, effecting the connection to the external leads. The arm is moved when the electromagnets a, b, Figs. 3 and 6, are successively energized, of which the electromagnet a attracts the armature a<1>, and, by means of the spring-controlled pawl a<2> and rack on the spindle A, Fig. 4, pushes out the latter with its arm longitudinally from the barrel B, a retaining- pawl a<3> being provided to hold the spindle against the pull of the spring drum P, on the side of the case F, and a small steel band passing through the barrel. Rotation of the spindle is effected by successive attractions of the armature b<1>, to which is attached the pawl b<2> gearing with the ratchetwheel E upon the spindle, the position set being maintained by the detent pawl b<3>, Fig. 5. To return the spindle to normal position, both electromagnets are simultaneously energized, whereupon the soft-iron yoke H attracts the pawl b<2>, and its backward motion in this position throws the detent pawl out of gear, while the retaining-pawl a<3>, together with the whole spindle, now rotates under the influence of a spring within the drum D, and is finally lifted by the arm b<4> upon the armature b<1>, enabling the spindle to slide into the switch box, and the pawl a<2> being similarly thrown out of gear. In modifications of this method, the spindle may be supported by a bearing in a single plate, may be eccentrically centered either by means of end pivots or a sleeve, and may have an external rack to control the longitudinal movement, means for operating the mechanism by hand being provided. The circuits are shown in Fig. 18 ; the contact-arm G is in the inoperative position resting upon a normal contact, which may be double, as in Fig. 18<a>, a busy signal being sent by a contact made across terminals o', o<2> directly the arm leaves home. Switches N are provided to break circuit with the line-wires during testing, and contacts M for effecting local electric operation of the switch. Fig. 21 shows contact-arms G resting upon the ends of fixed bank contacts which are turned up to ensure that the passage of the arm may keep them clean, split arms being also employed for this purpose. Such contact-arms may be single or double.