Patent GB-189841-A (GB)
Title: Automatic switching arrangements for telephone exchanges and the like
IPC: H01H67/06
Filed: 1921-08-06
Abstract: 189,841. Baron, H., (Aldendorff, F.). Aug. 6, 1921. Automatic exchange systems and apparatus; selectors.- The wipers of an automatic switch are first driven at a high speed by a continuouslyacting driving force to a group of contacts electrically or mechanically marked, after which they are moved at a lower speed to a wanted set of contacts in the marked group. A system is described in which such switches are used as callfinders, group selectors and connectors. They are also stated to be particularly suitable for use in by-path systems using transitorily and permanently-engaged switches. Construction of switches. A ratchet wheel 2, Figs. 1 and 2. provided with a sleeve 3 carrying brushes 14 - - 17, is loosely mounted on the shaft 1 and is held by a detent 8 and pawl 5 against the action of a spring 6, one end of which is attached to the ratchet 2, the other end being secured to a disc 4 fixed to the shaft 1 and carrying the pawl 5. The shaft 1 and the disc 4 are rotatable bv a ratchet 19 acted upon by a stepping magnet 21. The contact bank is divided into ten groups of ten sets of contacts each group being provided with a long marking contact 22 which is engaged by the wiper 14. On the energization of the starting magnet 13 the pawl 5 and detent 8 are released, and the ratchet 2 flies round in an anti-clockwise direction under the action of the spring 6, until the wiper 14 engages a long contact 22 marked by its disconnection from the current source, when the magnet 13 is de-energized and the pawl 5 is pressed into a tooth-cavity ty a spring 18, thereby coupling the ratchet 2 and disc 4 together. The stepping magnet 21, now rotates the disc 4, ratchet 2, and brushes 14 and 17 until the wanted contact set in the marked group is reached. The switch is restord by impulses transmitted to the stepping magnet 21, the disc 4 carrying with it the ratchet 2 until the detent 8 engages the projection 9, after which the dise 1 is rotated alone until an off-normal spring is operated, due to the registration of two notches in the collars 11', 11 formed on the ratchet 2 and the disc 4. The wiper 14 may be displaced relatively to the other wipers, or the long contacts 22 may be displaced relatively to their associated contact groups, so that when the first high-speed movement of the ratchet 2 is arrested, the wipers 15, 16, 17 are opposite the first contact set in the marked group. In a modification, Fig. 8, the group marking is effected mechanically. The wipers 306, 307, 308 are mounted on a sleeve 301 attached to a ratchet wheel 304 and keyed to the shaft 300, at the lower end of which is positioned a circular member 313 through which are guided the rods 314, 315, &c. each of which may be raised by a magnet 318, 319, &c. The switch is described in its application as a line finder serving 100 lines each of the magnets 318, 319, &c. being energizable over the contacts of a group of ten line relays 320, 321, 322, &c. On the response of a line relay, the release magnet 325 and the appropriate group magnet 318, 319 are simultaneously energized. The ratchet 304 with the sleeve 301 and wipers 306, 307, 308 thereupon fly round under the action of a spring 310 until a cam 328 on the shaft 300 strikes the end of the particular rod 314, 315 which has been raised above the upper surface of the member 313 by the energization of a magnet 318, 319. The striking surface of the cam 328 has an inclined portion 329 which causes an upward motion to be imparted to the shaft 300 before it is finally stopped by the vertical surface 330, thereby operating a switch 331 which de-energizes the release magnet 325 to arrest wiperrotation, and completes a circuit for a stepping magnet 323 which steps back the ratchet 304 and the wipers until the calling line is reached. The cam 328 is formed of a segment large enough to prevent another subsequently-energized magnet 318, 319 from raising its rod and thereby interfering with the restoration of the switch. In larger capacity switches of both constructions described above the wipers may be provided with three motions, namely, the continuous groupfinding movement, then long steps to a sub-group and finally short steps to a particular contact set. For this purpose long-step and short-step ratchets are fixed to the wiper-sleeve and two stepping magnets are provided. The fundamental features of both constructions may also be applied to panel switches, the rotary motion of the switch-shaft being caused to impart a vertical movement to brushes 342, Fig. 10, by means of a reel 301' and cord 340. According to another modification a ratchet wheel 501, Fig. 11, with coarse and fine teeth, is loosely mounted on the shaft 500. On the energization of the starting magnet 512, the ratchet wheel 501 is released and flies round under the action of a spring 510, taking with it a sleeve 504 carrying the wipers 506 - - 509, until the wiper 506 engages a long group contact 506<1> carrying a marking potential, when the magnet 514 is energized and the pawl 515 moved into the path of a coarse tooth 502. The springs 19, 520, 521 are thereby operated releasing the magnet 512 and energizing a stepping magnet 513, which acts upon the fine teeth 503 and steps back the wheel 501 until a wanted or idle set of contacts is reached. To restore the switch the stepping magnet 513 is operated until the springs 516, 517, 518 are operated by the movement of the spring 517 into a notch in the sleeve 504. During the first continuous movement of the wipers the group wiper 506 only may be arranged to wipe over its contacts, the other wipers only contacting with their terminals when the wanted group is reached. The coarse teeth and the long contacts may be made of varying size to campensate for the diminishing tension of the spring as the wipers are rotated, and the long contacts 506<1> may be displaced relative to their groups to ensure that the group wiper 506 reaches a particular group contact before the pawl 515 is opposite the tooth it is to strike. Clutch and power driving mechanism or a cord and weight may be used in place of driving springs in all the modifications described. In the modification shown in Fig. 11 all the long contacts subsequent to the long contact of the wanted group may also be marked. so that if the stopping pawl fails to act when the brushes are traversing the wanted group it will act in a subsequent group, after which the wipers are stepped back to the wanted contact in the wanted group. Circuit arrangements; call finder, Fig. 5. The energization of the line relay 101 of a calling substation 100 disconnects battery from the long contact 120 of the group to which the calling subscriber belongs, in each of the call-finders serving the subscriber's group, and puts a selectable potential on the test contact 116<1> of the calling line in each marked group. A circuit is also closed over armature 117 and off-normal springs 119 for the starting magnet 13 of the first idle call-finder the wipers of which are released in the manner already described with reference to Figs. 1 and 2. When the wiper 14 reaches the marked group contact 120, the magnet 13 relapses, arrests the wipers and completes a circuit for the stepping magnet 21, which rotates the wipers at a slower speed until the earthed contact 116<1> is engaged, when the test relay 125 is energized in series with the cut-off relay 102. The latter locks up and disconnects the line relay 101, whilst the test relay 125 extends the calling line to a group selector, Fig. 6, over contacts 129. 130, and by short-circuiting a part of its winding marks the calling line busy. Group selector, Fig. 6. Energization of the line relay 131 causes the response of a series relay 137, and subsequent de-energizations of the line relay 131 on the first series of impulses being dialled, energize the stepping magnet 139 of an auxiliary switch 153, comprising a ring which normally applies negative potential to all the group contacts of the group selector. When this switch 153 is stepped round a gap in the ring is caused to register with one of studs 154, thereby removing negative potential from the appropriate group contact 22<1>. On the cessation of the first series of impulses the series relay 155, maintained energized during dialling over contact 140, is short-circuited over armature 134 and completes a circuit 140, 157, 166, 14' for the starting magnet 13', which releases the wipers 14' - - 17'. The wipers are whirled round until the wiper 14' engages the marked group contact 22<1> when the magnet 13<1> relapses and completes a circuit 158, 161, 163 for a stepping magnet 21<1>, which steps rcund the wipers to find an idle trunk in the selected group. When the test wiper 15<1> engages an earthed contact the test relay 160 is energized, breaking the circuit of the stepping magnet 21' and extending the calling line to the selected trunk 200, 201 over contacts 182, 183. If the call had been abandoned before any dialling impulses were sent, en the relapse of the line relay 131 an impulse is sent over armature 140 to the magnet 139, to drive the auxiliary switch 153 out of its normal position opening the circuit of the test relay 125 of the call-finder, and energizing relay 147 which locks up and completes a circuit 127, 128, 149, 21 129<1> for the stepping magnet 21, which restores the call-finder. On the relapse of the slow release relay 137 a circuit is completed over an interrupter 141 for the stepping magnet 139 of the switch 153 which is also restored to normal. Connector, Fig. 7. On the response of the line relay 207 of the connector a slow release relay 208 is also energized, and on the transmission of the second series of impulses the stepping magnet 222 is energized to set the auxiliary group marking switch 223 as described with reference to the group selector, Fig. 6. On the cessation of these impulses the series relay 216, held durin