US1767862A - Telephone system - Google Patents

Description

June 24, 1930. R. F. STEHLIK 1,767,362

TBLEPrioNE SYSTEM Original Filed July s, 1926 4 Sheets-Sheet 1 1m; Rudnl h P? Ema-1k I R. F. STEHLIK TELEPHONE SYSTEM June 24, 1930' 4 Sheets-Sheet 2 Original Filed July 6, 1926 Invlnlur' fiud l ah F STEhlik 7 m Hit- June 24, 1930. R. F. STEHLIK I TELEPHONE sys'rsu Original Filed July 6. 1926 4 Shoots-Sheet 3 June :24, 1930. R; F. STEHLIK 7,8

I TELEPHONE SYSTEI Original Filed July 6, 1925 4 Shoots-Sheet 4 Patented June 24, 1930 I UNITED STATES PATENT OFFICE RUDOLPH F. STEHLIK, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- WARE TELEPHONE SYSTEM Original application filed July 6, 1926, Serial No. 120,547. Divided and this application filed October 27,

1927. Serial This invention relates in general to telephone systems but is concerned particularly with such systems in which line finders are employed to connect an idle trunk line with a calling line; and the principal object of the invention briefly stated, is the production of a new and improved finder switch system,

which is so designed as to permit cheapness in manufacture and maintenance without impairing the reliability and ciiiciency of the system.

Finder switch systems which have been devised heretofore employ one or more relays individual to each line in the system, those relays being operated, when that line makes a call, to start a finder in operation to con nect with that line. In addition to the relays individual to the lines such systems have employed a certain amount of control equipment common to a group of lines, through which equipment the actual setting of the various finders of the system is exercised. The combination of individual line relays and common control equipment for a group of lines, makes the initial cost of the system and the expense of maintenance, so high to be objectionable. A relay is not an expensive device, however and individual relay for every line in an exchange runs into considerable money, as obviously there would be ten thousand of such relays in a ten thousand line exchange.

In accordance with one of the objects of my invention I provide a tinder switch system which uses no individual relays to connect the lines with the control equipment but rather uses a single line and cutofi' relay set common to a relatively large group of lines.

As the principal and further object of the application I provide a new and improved line equipment of the constantly moving type, to search over the group of lines to which it is common, and to associate calling ones of said lines with the line relay which is common thereto that relay energizing to control a finder and equipment, to operate that finder into connection with that'linc.

As a further object of my invention I arrange the constantly moving line equipment so that it acts as an impulse sender, delivering impulses to the motor magnets of a finder switch to step that switch into connection with the calling line.

As a further object of my invention I use finder switches similar in structure to the well known rotary line switch whose wipers have no normal position remaining when not in use on the contacts last used, modified and improved by the inclusion of a marking wiper and associated control 7 apparatus, through which the position in which the finder is standing is marked in the control equipment, to determine the number of impulses which must be delivered to the finder magnet to position its wipers upon the contacts of the calling line.

In the instant application, the claims are directed to the constantly moving switch mechanism. The features of the other objects are being claimed in my co-pending application Ser. No. 120,547, filed July 6, 1926, of which this application is a division.

Automatic telephone systems of the well known type employ a connector switch which depends upon the finding of a battery potential on the test contact of a called line for the establishment of a connection to that line. That battery potential is supplied to the testing contact through one of the individual relays associated with that line. Since in the finder system of the present invention there are no individual relays associated with the line, it is necessary to provide a connector arranged to establish a connection with one of these lines.

Further objects of my invention not specifically mentioned here will be apparentfrom the detailed specification and claims which follow.

The drawings comprising Figs. 1 to 7, inclusive show sufficient mechanical and electrical details to enable a clear understanding of my invention. Figs. 1 and 2, when arranged with Fig. 2 beneath Fig. 1 with correspondingly numbered lines in alignment, show the usual circuit details of an embodiment of my invention. Figs. 3 and 4 are respectively side and front views of the constantly rotating line equipment switch used i .z i

H r in l lgh. o

more Fctail. I t

ill tinder l 'onneclcd tor l). and having ac. subscrihens lines. The selector E i the w ll lcnown vipers are lnoved ii a vertical direction under the control of the calling device at the subscribe station. an: the: r -d automatically u...cr t. 1 control a local testing circuitv to picl; out the ti "e trunk in the i ltrowg'er tvpe ot twoonotion switch. whose selected griun. in this c *se liil leading to the connector (j: eourse it will he inider=tood tln oral and third eel lines that can he be increased. but essential part oi the inclusion ol se(: the to number ol showi. and the selector i1 ehown only in outlined form. The eonncct'n' I1. may he of the well known Stronger t vp t-wo-niotuin type switch. whos wipers are a vertical direction to $0.1m. hanks. and then in a hori; to select the desired line in connector di "in o from the -1 both the vertical and rotary motions of the shaft are under the control of the 'a l n device at the subacribcrs station. canineotor H ditlers from the well knov-cn rltrowt'er conne tor in that the private or testing wiper does not have to lind battery in order to Switch through and connect with the called line. In the well known Strowg'cr autoinatic telephone e: c1 an idle line designated by a high lt" stance battery potoi tial found on the contacts enoounipred by the testing wiper. and a busy line is de natcd lrv a ground po contacts. ln the anvil system it is necess the conector an'xountcrs order to switch hroug' an the walled line. n lilOillif-Yll connector in accordmwe wthis invention, l have retained the busy guarding feature. that is; a circuit is proviocd such that the coni'iector will not switch through and connec w't l a call-2d l ne it the test wiper oi the con :tor eneonrters ground potential on the test contact of tint line. however. I have noditied the ciroui of the connector :so that it un'nccesaarv for t in .l direction level, the or in that the same ed in thin wiper o'l potential in connect w n he idai'd the objects of the gears 31 and I-lll. .l also show i iber tation B which is identical in every respect with the subscribers station A in Fig. 1. It will he noted that the lines leading from the subscribers stations A, and i3 terminate only in the l'JtlllliR ot the finder l5 and ot the line equipment LE, being dcvoid of the usual individual line and cutoli' relay through which the tinder switches u--zed licretolbre have lfiLQi: controlled. Amociated with and individual to tlri line equipment LE is the relay equipment R, through i i the finders arc control ed to pink-up ..in;; line in the manner which will he explained in detail hcrciiniltcr. In Fig. 2 I also show the finder al otter FA, which is mechanically similar to the well known rotar e switch. whose wipers move in a tor vnrd direction only. and stand when idle upon the contacts last uanl.

I l 3 and -l I show the inecluini 'al or the line equipment LE of Fig. .2. that equipment being oincxxhat similar to the vmil known Strowg'jcr rotary line switch. in that the wipers move in one dire tion only. The line equipment in thi raw nu chanically larger than the Linc ;--:witch and turihi-r arranged so ll'lsli the wipcrh ariconstantly moving over no haul: (,'o.'lt(lCl-T.

which consists of? tllc hank ;l il)l!1l1l\' 2-311. which eoinpri: live rov-v of contacts placed in SJllli-(fllt'lt. there being: contacts in hzrlt. h viper iuxtlll llics are carried on the rivc shaft Illa which is (ll'iYz-ll Eli! ar ya: 3 and i313. and which is sup by thrn 1 .--,upportin 'l'ranic coiinn'is'ng 2-;Ul. 2):?2 :i. lll). Contact with l the rota:

f wipers is obtained by means. of and brush. the brushes being do as 307. s and 30$). I (Enrin shown dcaignatcd us 2. be noted that th: slip ring for a such as the rin; 12 for the wiper placed at the side so that till that wiper wet li iictwccn it and the Drill set. That i:-'. the brush engaging ring 312 will lie belwcen wiper :ets 11'' and iginited n vi the i;

115. In the well known rotary line switch after which this line equipment is patterned, the brush through which connection made to a wiper set, lies between the memhe of that set. Since the mechanism LE is constantly moving, the line switch brush arrangement will result in excess ve wear, and I have therefore provided the arrangement mentoned aboy'e to reduce this wear much as possible.

Figs. and 6 show respectively the front and side view of the finder switch such as F of Fig. 1 which I propose to use in an embodiment of the invention. It will be noted that this finder is quite similar to the aforementioned rotary line switch, and that I have added another wiper 32, and a control magnet 10, which controls the movement of the wiper 32 through the. retaining pawl. 502. This wiper 152 is mounted upon the same shaft as the main wipers, to 3;}, inelusive, and is arrangcd to rotate with them, or to rotate imlependently. Attached to the main wiper .Jembly, is the m. p 506, and attached to the wiper 32 is the stop 509. Lying over on the main shaft 510 is the retaining spring 507, which wound up when the wipers 30, 31 and 83 are advanced, and the wiper 32 is held stationary by the retaining pawl 502. Subsequent ci'iergizatiou ot the magnet 10, with draws the pawl -52 from the ratchet wheel 508 of the wiper assembly 32, permitting the springs 507 to unwind and advance the wiper until the step 509 (engages the stop 506 of the main wiper assembly, at which time wiper 2 32 will come to rest in line with the remaining wii'iers of the switch. The wipers of the switch have access to a semicircular bank, containing 25 contacts in each row, and in this 0 there are four rows of these contacts. 1110 number of contacts in each row, and the number of rows of contacts of the finder F can be increased or decreased, it being necessary only to keep the number of contacts in the row the same as the number of contacts in the rows of the banks of the line equipment LE shown in Fig. 3. In Fig. 5, and Fig. 6, the Wiper 32 is shown in different positions with respect to the main wipers 30, 31, 33, the positions being altered to enable a clearer understanding of the structure.

Fig. 7 shows a schematic representation of the bank contacts of the line equipment LE, showing the order in which the wipers 115 to 119 encounter their respective contacts. It will be noted that with the wipers moving in the direction shown by the arrow in F in. 2, wiper 117 first encounters the contact S belonging to a particular line. li ipers 115 and 119 engage the contacts 2 and 1 respectively, at the same time, wiper 11G engagi contact 1 a brief interval later. and wiper 118 engages cont a-ct \V after wipers 115, 117 and 119 have swung free from their re spective contacts. Contacts S, 2' 1', i, and \V comprise a group of contacts which is individual to one line, there being 25 such groups in the line equipment as shown in Figs. 3 and 4.

In order to sii iplif y the drawings as much as possible I have shown a. plurality of batteries, whereas in an actual installation these would be but one battery, preferably with its positive pole grounded.

The operation of the system of my invention is briefly as follows: The constantl moving line equipment LE together Witi the relay group R, takes the place of the usual individual line and. cut-off relays of the well known finder switch systems, and operate jointly to control the positioning of the wipers of the finders such as F, upon the contacts leading to a calling line such as A. When a line initiates a call, for example, the receiver is removed from the heck of substation A, that line is in a position to pick up a fii tor and start a call. The removal of the receiver from substation A does not accomplish any function until the wipers of the line equipment LE engage the bank contacts associated with that line. When the contacts 115 and 119 of the line lpment engage the contacts 1' and 2 which are associated with the calling line A, a. circuit is completed over the loop of the calling line for thestart relay in the relay equipment R. That relay energizing to prepare 0' *cuits for the subsequent control ot the finder F. Since the finder F has no normal position, it may happen that its wipers are standing upon the contacts associated with the line A, in which case it will not be necessary to deliver any impulses to the finder F, but only necessary to switch that finder through and connect the calling line with the first selector E. After the wipers 115 and 119 have found a closed loop and energized the start relay, the marking wiper 116 has to determine the position of the finder F, and if that finder is standing upon the contacts of the line A, a circuit is completed through the marking wiper 116, and the control equipment R switches the finder through without delivering impulses to it. In. a majority of instances it will be necessary that the finder he stepped one or more steps to setnts wipers upon the contacts of the calling line, in which case no circuit will be completed through the marking wiper 116. As the line equipment LE continues to move, pulse wiper 11S encounters the contact V, closing a circuit through the control equipment R and the finder allotter FA to the motor magi of the finder F, energizing it preparato v to advancing the finder wipers one step The energization of the motor magnet of the finder F advances all of the wipers except the marking wiper 32, which is under the control of the individual magnet 10. When the control equipment R is taken into use. all oi the wipers except wipers 118 and 116 or LE are temporarily cut out of service, since they have no further function in. connection with the setting of the present call. V1191; the equipment rotates so that the wiper 116 er gages the next contact in its row. it tests that contact to determine wl ether or not the wipers of the tinder have been moved a sutlieient numher of st ps to position'them upon the eonacts lling line, and it the wipers are so p ed a circ tit completed through wiper 116 to switch through the finder and open the pulsing circuit so thatno further impulses will he delivered to it. In this --er the finder is advanced under the con rol o-t wipers 11S and 116 of the line equipment LE. hen the calling line i: found, and the finder smtehes through, th line eouipment and the relay group R are releas fthe tinder allotter FA stepped ahead, to automatically preseleet the next idle finder of the group, and ociate it with the equipment R in readiness for the next call.

To explain a little more tully the ope ation of the marking wipers in conjunction with the control equipment R and the line cuuiru'nent LE. it will lie noted that wiper 110 of the tinder allotter FA places ground po ential upon the conductor i l) and the wiper 3-2 of th tinder 1. ll ith the wipers of F and FA in the position shown in Figs. 1 and and a call is 11. ited on the line terminating in the cor tarts o t wh ich the wipers 115 and 119 are resting, hat line will also appear in the contacts upon which wipers 30 and 3 of the finder l are rest uo, a circuit may then be traced from ground on conductor 80 through wiper contact on, conductor a, contact g, wiper 116, through springs 128 which are now closed. through the cu-otl' relay 106 4-1 the control equipment that relay energizing:

to prepare a switch-through circuit to sp nos 1% and to open the impulsing circuit at springs 132. 11 a call is init ated by line one space ahead or where the w pers of the tinder F are no,

inc. wiper 116 which is then er in with the contact .71. will not lllll a ground potential and the switclbthrough circuitrill not be completed. LC(',l'(llilfl:ly an impulse will be sent to the finder F, to more the wipers 30, 31 and 33 one step in the direction indicated by the arrow. Similarly the wipers 115 and 119 of the line equipment LE are moved one step, at wlnch time wiper 116 again engages contact ,1. and the circuit for 'ela 106 is completed as be fore and the finder F is switched through after llZtYlllQ taken one. step. Magnet 10 of the finder F is then energized, and the wiper 32 released and moved under the control of spring DOT into alignment with the remaining wipers of the switch. It the 11115 A is the cei ing hue. with the wipers oi toe rant u: l; in the position shown in lug. 1. it will be net, i r to more the wip rs two ste go the contacts of that. line. The ciituit th sirirt relay will be complet d when lh u :15 engages the contact 2, the wiper 1 engages the contact 1.

and. the, wipe. 111 engages the contact 1'. "clay 1W will not he closed,

the finder more in opposite directions, that is the wipers oi" the tinder F move.

from line 1 to line 2:),

while the wipers of lin event LE more from line 27) 1 rue wipers of the finder F were on line 1. and line called, it be new .y to more the wipers of the finder l 21 steps in order to engage the c ntacts ot the calling line. Similarly it the ipers oi the tinder are standing: on the contacts in [he 10. and line 15 calls itwill he nc essar to more the 'ipers steps in on. n to hri a them in engagement with the onta ts of the calling line.

Having thus described my invention in general. I will now proceed with a detailed description of its operation.

to i 1e 1 hen the receiver is removed from the hook switch oi the station A, a bridge is completed across the line conductors ,1 and :3. that bridge in 'ludinp: the t *ansniitter. receirer. and mpulse fut-.pgs in series. The closure of the dire t current bridge across the line conductors is without ell'ect until the crs of the constantl moving line equipment LE engages the contacts of that line, in this case the contacts 1' and 2 at which time a circuit for the start relay 103 of the etpiiprnent P. is closed. that circuit being tracethte trrnn ,Qrorud through springs conductor 131), wiper 119 now engaging contact 1. conductor 1. through the suhscribens loop and the SlllJrliltlOll to conductor 2, contact i3. wiper 115. conductor 116. through springs 12:). through the upper winding o'l relay to grounde battery. Relay 10 1: and its br ak contact, springs 122.

thence over two paths in parallel, the one through the upper winding of relay 105 to grounded battery, and the other through the lower winding of relay 103, through the lower winding of relay 102, to grounded battery, energizing relays 102 and 105. Relay 103 is thus maintained energized independent of its initial circuit which is broken by the energization of relay 102 to operate springs 120 and 121. Relay 105energizes and at spring 127 and its make contact closes a circuit through conductor 1 15, through the winding of the motor magnet 101 of the finder allotter FA, energizing that magnet preparatory to advancing the wipers of the allotter one step. Relay 105 at springs 128 closes a point in the circuit of relay 106, that circuit being held open elsewhere at the moment. Relay 105 at springs 126 closes a high resistance ground through conductor 140 to the finder F, that circuit being traceable from ground through resistance 129, spring 126 and its make contact, conductor 140, wiper 111 of allotter FA, conductor 81, through the winding of relay 11, through resistance to grounded battery. Relay 11 when energized in series with resistances 129 and 35 is capable of closing springs 34, but not sufliciently strong to operate the remaining springs in its assembly. The closure of springs 34, prepares a testing circuit which will be explained in detail hereinafter. Relay 103 upon energizing, closes at spring 123 a point in the impulsing circuit, preparatory to stepping the wipers of the finder if necessary. The operation of the system from this point on depends upon whether or not the wipers of the finder F happen to be standing upon the contacts of the calling line A at the time.

Fin/(707 standing on calling Zinc Assume first that the wipers of the finder F are standing on the contacts of the calling line, that is wiper 30 engaging contact 2",

' and wi )cr 33 en a in contact 1" and wi er 32 is engaging the contact 0. In this case it will not be necessary to send any impulses to the finder, and. the circuit will. be closed through wiper 1.10 of the finder allotter FA, conductor 80, wiper 32 of the finder F now engaging contact 0, conductor 0, contact 2', wiper 116 which is engaging that contact, conductor 1 17, through springs 128, through the winding of relay 106 to negative battery. Relay 106 energizes and at springs 132 opens a point in the impulsing circuit, to prevent the delivery of any impulses to the motor magnet of the finder. Relay 106 at springs 131 closes parallel circuits for the lower winding of relay 105 to grounded battery, to maintain that relay in its energised position independent of the previously traced circuit through springs 125, and through the lower winding of relay 104 to grounded battery to energize that relay. Relay 104 upon energizing at spring 125 opens the circuit previously traced for relays 102, 103, and 105, and at springs 121 and closes a substitute circuit through the upper winding of relay 102 thereby maintaining that relay energized and permitting the relay 103 to deenergize. Relay 103 upon deenergizing opens an additional pointin the impulsin g circuit at springs 123.

The operation of relay 106 closes at spring 130 a circuit traceable from ground through that spring, through spring 126 and its make contact, conductor 1e10, through wiper 111 of the fineer allotter FA, conductor 81 to springs 37, through the winding of magnet 10 ot the finder F to grounded battery, with a parallel branch to the winding of relay 11, through resistance to grounded battery. Magnet 10 and relay 11 energize over this circuit, the former to release the wiper to permit it to align itself with the remail'iing wipers oi the switch, but since the finder is assumed to be standing upon the contacts of the calling line, this wiper 32 is already aligned with the remaining wipers of the switch, and the energization of relay 10 therefore performs no useful function. The complete energization of relay 11 connects the calling line to the line relay oi" the first selector E, that circuit extending from ground through the lower winding of the line relay of E, conductor 30",through the springs 39, wiper 32%, line conductor 1, thrtuigh the subscribers loop to line conductor 2, wiper 30, springs 38, conductor 3 through the upper winding of said line relay to grounded battery. lhe line relay energizes and closes a circuit for the release relay of the selector, that relay energizing to send back ground over the conductor 31 in the well known manner, that ground serving to maintain relay 11 in. its energized position. Relay 11 upon energizing ope-rates spring 36, to close ground through the wiper 31, which is now engaging the private conductor 6 associated with the calling line A, to guard the connection against intrusion by a connector.

The calling subscriber is now connected to the first selector and the usual dial tone is audible to notify that the equipment is in readiness to receive the impulses from the calling device, to extend the connection to the desired line. Returning now to the equipment R, the wiper 116 of the line equipment LE continues to revolve and fter a brief. interval loses the ground which is present upon the contact 7?, thereby opening the circuit of relay 106 which falls back after a briei": interval. Relay 106 upon falling back opens the circuit of relays 105 and 10 i, permitting those relays to deenergize, the former to open at springs 127 the circuit of the magnet 101 of the finder allotter F A, that magnet deenergizing to advance the wipers lit) to 1 l3 onto the next rontzirts in thew-w ll lino znzuiner. Th nation (it 1 Wid 1ft.

itlj.

l eeenew i023, there- .ipinent R to normal in mess nu die net-t (111. 1

letter EA t'unetix her to pres group. us i.

innit-3r.

on minted equently huppen that the inder not It will most of the i r F will not be standin contacts of the calling line when a cult ited. and thut the control equipment wipers one or more to bring them into engzgedes Assume here to L cont-nets. time line A is calling. the wipers of F standing in the position shown in Fig. l. in which use it will be necessary to more them two steps in order to bring them into engagement with contacts and 1" in which the calling line termiengl'ee'e contacts "3" and 1. respectively, i'iper 11G enguges the contest i'. which renot the tinder F. Since 1* is not standing upon the eontuet o. wiper 116 will not romplete (he Circuit hr the winding of relay 106, d the pi eireuit will be left intact preparatory to sending impulses to the mug 1 ot the tinder F. \Vhen the wiper 11S Zh'l lkfi to engage the Contact F, a circuit tiny be trueed from ground through contact wijer 118. conductor H9. springs 12 5. "s 132. to eeiiduetor 1'12. wiper 113 of tinder all tter FA, conductor 83 and wiper 32 of the tinder l .nee over two paths in purillel, the one hreug'h springs 79 through the winding of l ntor magnet '75 oi" the finder F to ttery energizing thut magnet if ii l iinlieztted by the arrow. the wiper 32 renaming upon the net 122. being held there JV pawl whieh is controlled by the mag- U. Since two steps we required to ring); the wipers ot 1* into engagement with tot-ts ot' the walling line. and siure the wiper 116 r the line equipment LE :ow engaging the tentmt having moved to the Contact i wh n the wiper 118 moved ott (rt contact \V, no circuit will be (ompleted tor the relay 106. and an additional impulse will he sent to the nmgi'net '75 when the wiper 11S eneounters contact \V, the eireuit heing the same as before. \Vheu the znzi net T53 uguiu ful 4 buck and udrunees the wipers 3U :31 and. 33 another step. wiper 3O engegt the eontu-t 2" and wiper 2-33 enres (-oi'zturt 1 those rntricts being the bun-t ot the milling line. \Viper 32 still retxined by Bra-min ng lJIlWl 502. re-

in. h it contact in and at the end of the inn when wiper 11(3 ot the line equipnu. Ll'l moves lIltU engugrcinent with the Pon'uet g, u I may be traced from irround through w 110 of the tinder uh letter FA, eondir-t r 8 wiper 32 now ening eontuet I). render-tor (z. contort y. wiper 116. eondn-vtor HT. springs 128, through the wint'iing et relay 106 to grounded butter energizing that reluv whirl: muses the linder to he switched through in the manner hereinbetore exple 'ihe rri: Slll)FCT'il)tl' then heirs 41,. mp1 i /v up 1 hit. it it... mu intihpu Li tr: llL ta ling derirs in uwroz'di .3 with the digits of the number of the cur ..d station. the first digit operating the first selector E to elevate the wipers 4U. 41 and if. \erti :dy upper e the desired level. The r-releetor E then rotates :uitomutienlly under eo '(d of the testing; eireuit through wiger 1, coming: to rest upon the eontzu-ts of the first idle trunk line. assumed to he the mutants ll 44 and 45 oi the trunk line lending to the eoz'ineetor H.

ing station. Relay 1 eirruit and closes a eirem" ill. which niergizes to prepare the iinpui- Mg; irireuit nt springs 5:2. s pplies ground to holding; eonduetor at 52. and upuiies .e'i-oiuzil to the release l eondurttir ll the .)';)(.';li((l relnys of the i tinder F in their oper- :iied position. When the iripulsing device :it the substation A interrupts the eirvuit 0t" reluy 13 in :iectu'dnnee with the next digit sit m UL

of the call number, line relay 13 falls back, and delivers impulses first to the vertical magnet 15 over the circuit including relay 16 in series, that magnet and relay operating to elevate the shaf" and wipers 68 to 70, inclusive, vertically, the latter ren'iaiir ing energizedv throughout the impulsing to perform certain control functions. The first vertical step of the shaft operates the offnormal spring 55, in the well known manner, so that when the relay 16 falls back at the end of the impulse series, a circuit is extended to the rotary magnet 22 and the rotary multiple relay 19, to which the next digit dialled into the line relay 13 is delivered. Atthe end of the second digit dialled into the connector H, the wipers G8, (39, and 70 are positioned upon the contacts of the calling line, assumed to be the contacts 71, 72, and 73, which are connected by the usual multiple cables 4t, 5 and 8 to the lines 3, 4, and 5, of the substation B. In order to avoid unnecessary complications of the .drawing this multiple cable is omitted,

being indicated by correspondingly numbered wires. The operation of the connecor H from this point on depends upon whether or not the called. line is busy at the moment. Asslnne first that it is busy. Contact 72, associated with the called line, will contain a ground potential if the line is busy. After the wipers have come to rest on the contact and before the slow acting multiple relay 19 falls back a circuit may be traced from ground on contact 72, through wiper 69, spring 90 and its make contact, springs through the winding of busy relay 18 to grounded battery, energizing that relay which looks itself to release trunk conduct-or grounded at spring 50, through spring 59, the normally closed c011- tacts controlled by spring 90, those contacts being closed when the relay 19 restores an instant later, through spring and then through the winding of the relay to grounded battery. The calling subscriber is informed of the busy condition of the line by the busy tone from the busy generator placed on the line through springs 62, in the well known manner. The calling subscriber upon hearing this tone will replace the receiver and release the connection in the manner which will be explained hereinafter. Assume however that the calling line is idle at the time the Wipers (38 to 70, inclusive, are positioned upon the contacts associated with it. In this case the contact 72 will contain neither battery nor ground potential, and the connector H will establish the connection to the contacts 71 to 73, inclusive. During the operation of the rotary magnet 22, to rotate the shaft bearing wipers 68 to 70 into connection with the contacts 71 to 73, cam 93 is opera-ted upon the first rotary step, closing springs 92 preparatory to switching the connector through if the called line be idle. When the relay 19 falls back after the wiper (39 is positioned on contacts 72 and found that that contact contains no ground potential, a circuit may be traced from ground through springs 51, OifdlOIlDitl springs 92, springs 60, spring 94, winding of switching relay 20 to grounded battery, energizing that relay which looks itself from ground on spring 51, through springs 65 and then through the winding of the relay to battery. Switching relay 20 upon energizing places ground on contact 72 at springs 6-1 through the wiper 69, that ground marking the line busy to other connectors to prevent intrusion upon the pending call. Relay 20 at springs (33 and 67 connects the wipers 68 and 7 O to the remainder of the connector, establishing a ringing connection to the called line. Interrupted ringing current projected out over this connection from the generator Gen. under the control of the ringing interrupter RI, the circuit that the ringing current traverses being the usual and well known circuit which is conductive to alternating current and open circuited to the direct current, because of the condenser at the substation B. lVhen the called station B responds to the call, by removing the receiver from the hook switch, a direct current bridge is closed across the conductor to the line, energizing the ring cut-oif relay 17, which cuts off the ring and switches the connector through as usual. Ring cut-ofi relay 17 upon energizing operates springs 56 and 58, extending the connection from the called line through to the back ridge relay 12, which furnishes battery to the transmitter of the called station. Relay 12 energizes and at springs 47 and 18 reverses the polarity of the calling line A in the usual manner, placing the two stations in a telephonic connection over which the conversation is carried on.

Release lVhen the station A and 13 have completed their conversation, and both replace their receivers, ground is removed from the release trunk conductor at springs 50 by the deenergization of relay 14, and from the connector holding conductor by the deenergization of back bridge relay 12 and release relay 14 at springs to and 51, respectively, whereupon all relays which were locked to the conductors are released, and restored to normal in the well known manner, placing the equipment in its normal position in readiness for the next call. It will be understood of course, that the wipers of the finder F, remain upon the contacts leading to the calling line A, until the finder F is seized again and operated into connection with some other line.

Line equipment rem/ting aver Busy line After the finder F has connected. with the calling line A, and at springs Z113 supplied ground to the private conductor 6,

and after the connector H is connected with the *alled line B, and at springs 61 applied ground to the prirate conductor 5, those lines are protected from intrusion either by a connector or by another tinder. The line equipment LE continues to revolve, the wiper 117 testing the private conductors of the Various lines in order. \Vhen the wiper 117 engages the contacts of the private conductor (3 of the calling line A, a circui "an be traced from ground upon that conductor, through wiper 1.1T, conductor 1%, through normally elo'ed springs 121:, through the upper windn f 1 relay grounded battery, which at springs 121 ground and start re circuit from the is 113) and 115, res nc irely. Since the r g line A is in use at is time a direct current bridge is closed across it, and iii the relay 102 were not provided to open the testinc" circuit, the relay would e1, each time the \x'ipers 110 and 118? on;

the con c s ass ciated with the line This would result in nnn vssary operation ot the hnder, am in a would protilt. 11110 31151111113115 duce an undes the callir' wipersof in Fig. "2', the private ages the coals.

mince the 1 the receiver from the substation A does not applv ground to the private condn 1- a there rith.

.1 1 and since too 1 grounded until the tin-L h the calling connector he receiver is r 1 d betoie die ma call the 1' moved from the switc tinder has connected with t The line coi'iductors 1 a 1 associated pilrate conductor 1; are connectei to the banlts oi the connectors through the usual normal gized during the initiation of a call, a

ground was connected through re stance iii), springs lili, C()ll{l1l(t0l 11 through the wiper 111 to the conductor 81, hence Li on the windirn ot rcnay 11 and re- .icc to grounded battery. Relay 11 so constructed that the springs 3-1 close before the remainder of the springs are moved. that constriwion being old and well known to those i the art. When the "e r 11 s in serie with rei-1s sulticic'. strcn gth uowcrer i does not igth 1011! l v energize and ainder of its springs. When iclts up the ground on con- .11 is short circuited troni that wiper, through and 115 break \"UliLIH'l, springs 31, L.;l'(. 1l ':ll tne upper terminal or the relay, the liner terminal havin the wiper '21 I 1 din-(or n,

Y been grounded P bi. \Vhcn the i oni conductor 100 of the eipiipnient ll energizes to tch through, the finder, rexij. 11, is prercd tron: cntrn'hcing bccai'se o? the shorteuit, but the equipment It and the finder ailotter 1 A are operated in the usual manu 1, the former to restore to normal and latter to see out the next idle tinder of t e group. \Yhen the line equipment Ll) re a es far enough s; that the wiper 111 in engages the contact 6 ground potenial will be present on that contact, and the relay 10' will energize to guard that line from intrusion by the control equipment R.

leturniug now to the deencrgization of magnet 101 01 the tinder allottcr FA to ad- \JHLQ the wipers lid-11 1 one step in s arch ot' the next idle. Assume that the step positioned the wipers on the contacts to which coinluctors 80S3 are connecterl and that the finder F is busy at the moment. Conductor 81 will receive a ground potential from the release trunl: conductor, as explained above, that ground being picked up by wiper 11.1 to complete a circuit over which magnet 101 is again energized, that circuit being trace able through wiper 111, conductor 140, spring 126 and its break contact, conductor H3, springs 11 1, conductor 114, spring 127 and its break contact, conductor 115, through the winding of magnet 101 to grounded battery. Magnet 101 again energizes and opens the above circuit at springs 114, falling back to advance the wipers of FA one step. If the finder associated therewith is busy, wiper 111 will pick up another ground, and the magnet 101 will operate in the above buzzer like fashion until that wiper loses ground, at which time the wipers 110-113 will be brought to rest upon the contacts of the idle finder.

From the foregoing description it is apparent that I have designed a new useful finder system which is simple in its construction and which can be easily maintained. In order to avoid unnecessary complications of the drawings, I have shown the system in its simplest form, that is with the calling line multipled only through one finder group and through one line equipment group. In a commercial installation however, I propose to multiple the line conductors to two or more finder groups and to two or more line equipments, thereby increasing the reliability and speed of the system. With the line equipment such as shown in Figs. 3 and 4, I am able to rotate the wipers at the speed of about 25 revolutions per second, since the wipers are double ending, the lines are tested at the rate of 50 per second. By multipling each line conductors to two of the line equipments, and by spacing the wipers of the two line equipments degrees apart, each line is tested every quar- .1 ter of a second instead of every half a second as is the case when a single line equipment is used. Since the line equipments are being driven by a common motor, it is not difficult to space the wipers in this manner and to maintain that spacing. Each line equipment and its associated control equipment R, has access to a different group of finders, through the finder allotter such as FA. In this manner the calls are doubly tested, so that in the event one line equipment fails to function properly due to a mechanical or electrical defect, the other line equipment will pick up the call a quarter of a second later and handle it in the usual manner. In the event of serious trouble in one of the line equipments, the wipers can be thrown out of gear, and repaired at leisure, without in any way interrupting the service of the line group, since the other line equipment will handle all of the calls occurring therein at that time. Moreover, I have shown the invention applied to a twenty-five line system, that being a convenient size and is shown by way of example only, as it is entirely possible to appl the same principles to larger line units 0 50 or lines or more.

\Vhile I have chosen to show the invention in connection with the equipment of a particular design, I have done so merely by way of example as there are many modifications and adaptations which can be made by one skilled in the art without departing from the scope of the invention.

Having thus described my invention, what I consider new and desire to have protected by Letters Patent is pointed out in the ap pended claims.

1. In a telephone system, a switch mechanism containing a shaft, a plurality of wipers mounted on said shaft, the entire contacting surface of said wipers being disposed in a plane containing the axis of said shaft, a plurality of contact sets arranged in a semicircular bank and accessible to the contact surface of said wipers, a plurality of contacts in each of said sets, one for each of said wipers, means for rotating said shaft to move said wipers from one contact set to another, said contacts being so shaped and arranged with respect to each other that the wipers engage their respective contacts of a set at different times in a definite sequence and depart therefrom at different times in another definite sequence.

2. In a telephone system, a switch mechanism containing a shaft, a plurality of wipers mounted on said shaft, the ends of said wipers being disposed in a plane containing the axis of said shaft, a plurality of contact sets arranged in a semicircular bank and accessible to said wipers, each of said contact sets comprising a private contact, two line contacts, a marking contact and a pulsing contact, said wiper assembly containing a wiper for each of said contacts, said contacts being so spaced that the private wiper engages its contact first, the two line wipers engage their respective contacts simultaneously and before said private wiper has disengaged its contact, said marking wiper engages its contact before said line wipers disengage their contacts, and said pulsing wiper engages its contact after said private and line wipers have disengaged their respective contacts and before said marking wiper has disengaged its contact.

3. In a telephone system, a switch mechanism containing a shaft, a plurality of wipers mounted on said shaft, a plurality of contact sets arranged in a semicircular bank and accessible to said wipers, a plurality of contacts in each of said sets, means for rotating said shaft to move said wipers from one contact set to another, said contacts being so shaped and arranged with respect to each other that the wipers engage their respective contacts of a set in a definite sequence, and all wipers leave the contacts of one set before any wiper engages a contact of the next set.

4. In a telephone system, a switch mechanism containing a shaft, a plurality of contact sets arranged in a semicircular bank, each of said contact sets comprising a prillO vate contact, two line contacts, a marking contact and a pulsing contact, a set of wipers mounted on said shaft comprising a wiper for each of the contacts in said contact sets, means for moving said shaft and wipers at a uniform speed said wipers engaging their respective contacts in the order named, and impulsing wiper engaging its contacts less than one half of the time during said movement.

The combination with a shaft carrying a plurality of wipers having knife edge bearing surfaces aligned in a plane through the axis of said shaft and a means for rotating said shaft, of a bank contact arrangement wherein the wipers engage their respective contacts in a definite sequence, remain engaged with their respective contacts for different periods, and depart from their respective contacts in a different definite sequence while said shaft is rotating at a uniform rate.

(3. In a telephone system, a switch mechanism containing a shaft, a plurality of double end wipers on said shaft disposed in. planes lying at right angles to the axis of said shaft, a collecting ring for each of said wipers having its contacting surface parallel with said shaft and disposed concentrically to said shaft, and a brush for engaging the contacting surface of each collecting ring, said brushes lying in planes parallel to the planes of said wipers and midway between adjacent wipers.

In witness whereof, I hereunto subscribe my name this 7th day of October, A. D. 1927.

RUDOLPH F. QTEHLIK.

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