Patent GB-601965-A (GB)
Title: Automatic telephone system
IPC: H01H67/26
Filed: 1944-10-20
Abstract: 601,965. Automatic exchange switches. LEICH ELECTRIC CO. Oct. 20, 1944, No. 20388. Convention date, Sept. 29, 1943. [Class 40 (iv)) The invention relates to a unitary switch mechanism of cross-bar type, suitable for use as a finder, group selector or final selector, such as described in Specification 544,954, in which 300 conductors representative of 100 lines are arranged in 30 superposed horizontal layers and extend the whole length of a box-like structure which is divided into a number of sections, e.g. 10, each individual to an incoming or outgoing trunk, connections between any line and any trunk being made through the medium of 30 contact strips in each section extending across the 300 conductors. As many connections may exist simultaneously as there are trunk units, but they may not be set up simultaneously. Fig. 2 shows a front view of a switch having a selection control unit on the right and to the left a plurality of trunk units one of which is shown. Fig. 6 shows a view of the selection control unit as seen from the left in Fig. 2. Fig. 5 shows the trunk unit as seen from the left in Fig. 2. The comb-like lateral contact strips such as 82 have contacts 83, Fig. 21, which may be raised by projections 113 on the tens actuators fixed to bar 111 to make contact with line conductors such as 76. Units actuators such as 122 move end contacts such as 94 to connect the contact strip to contact 84 integral with terminal 85, which is multipled with like terminals to the appropriate trunk. Selection of the appropriate tens group is effected by the selector bar such as 140, which operates a spring clutch 115 which attaches the bar 111 to the tens actuating bar 110. A spring clutch actuated by units selector bar 144 likewise secures an appropriate units actuator 122 to the units actuating rod 127. On operation of 'the trunk magnet 29, its armature yoke 103 raises all the tens actuating bars 110 and the units actuating bar 127. Selection of the clutches by bars 140 and 144 determines which line is connected to the trunk at contacts such as 85, 100 and 101. The units actuator spring clutch, Fig. 28, is arranged to lock independently of the actuating bar 144 for the whole of the time the trunk magnet is operated. The spring 150, Fig. 28, in the unactuated (dotted) position fits loosely round the actuating rod 127 and is prevented from rising with the rod by the extension 155 lying below the cam 157. When the extension 155 is moved to the operated position by the selector bar 144 the spring tightens to grip the rod 127 and when this rod is raised the spring is maintained tightened by the cam 157 independent of the subsequent return motion of the selector bar. The clutch mechanism for the tens actuators operates similarly. A test unit is provided similar to the trunk units except that contact strips are provided only for the test conductors and that the eleventh contact finger is permanently soldered to the contact corresponding to the trunk contact in the trunk unit and these contacts are nut multipled up but included in separate circuits. Selection of the appropriate tens selector bar is effected by energizing the appropriate one of ten tens solenoids (Fig. 32), horizontally disposed in Fig. 6 and alternately staggered as seen from the position of solenoids 192, 191, Fig. 2. Energizing the solenoid causes the core 186 to be attracted to core 186 held fixed by the tensioning spring 217, Fig. 2. Spring 227 is compressed and springset 231, mounted on the armature yoke 173, operates to complete a circuit for the common tens operating magnet 53 which in operating moves the yoke 173 and its associated member 172 to the right, drawing the bar 140 with it. Operation of the units operating bars 144 is effected similarly by the units solenoid such as 262 and the common units operating magnet 57, the latter being provided with an auxiliary yoke 253 pivoted at 258 and 259 to enable its yoke 249 to effect the operation of any units selecting bar. The line conductor bars and tens and units selector bars are arranged to be readily longitudinally withdrawable, thereby facilitating the removal of any particular trunk unit. Operation as a line finder. Fig. 37 shows the connection of subscribers' line circuits 21, 22, 11 and 12 to the appropriate bars. Incoming loop from subscriber A operates line relay 307 and applies negative test potential over resistance 314 and cut-off relay 306 in parallel to the test wire, and also operates the tens solenoid 191 whose contacts change over to hold the solenoid operated and prevent any other tens solenoid from being operated at this time. Tens solenoid 191 also operates the tens operating magnet 53 to operate the appropriate tens selector bar. Contacts of magnet 53 operate the test unit operating magnet 320 thereby connecting the test conductors 78, 81 ... to the units solepoids 261, 262 ... and 262 energizes to negative battery over the subscriber's cut-off relay 306 and resistance 314 in parallel. Cut-off relay 306 shunted by resistance 314 does not operate. Contacts of units solenoid 262 change over to provide a holding circuit for itself and prevent any other units solenoid being energized. Other contacts energize the units operating magnet 57 to operate the appropriate units selector bar. Units operating magnet 57 energizes start relay 350 which opens the circuits of all other tens and units solenoids. If the first outlet is free and trunk distributing relay 331 is operated trunk test relay 341 operates to negative battery on the test wire 372 from the succeeding stage, and locks. Trunk operating magnet 29 then operates to energize the tens and units actuators and connect the calling line to the trunk. Magnet 29 locks and releases the trunk distributor relay 331. On seizure of the succeeding stage battery on conductor 372 is replaced by earth which holds the trunk magnet 29 locked after 341 is de-energized. Subscriber's cut-off relay 306 operates and locks to the earth on 372 and disconnects line relay 307, and tens solenoid 191, tens operating magnet 53 and test unit operating magnet 320 de-energize in turn. Earth on 372 short circuits units solenoid 262 upon whose release units operating magnet 57, start relay 350 and test relay 341 deenergize and the unit is ready to handle another call. As successive calls are handled by successive trunk units the successive trunk distributing relays 331, 332 ... fall back until, on the relapse of the last, a circuit is completed for relay 351 which operates momentarily to re-operate all the trunk distributing relays.