Reference / Paper · 1925

AT&T Step-by-Step Equipment Engineering Notes, Bulletin 21.5 (part 1)

Early Bell engineering notes on SxS equipment design and trunking.

Author: AT&T Dept. of Development and Research
Year: 1925
Type: Reference / Paper
Credit: Telephone Collectors International (TCI) Library, telephonecollectors.info (retrieved via Internet Archive Wayback Machine)

Bulletin No. 21.5 AfJZRI C AN TELEPSOKE AiJ2 TELZGFAPil C 3 6 i A P k ' Depaft~enUof Develop~entand Resesrch SIXP-EY-SIFF 'LACEINZ Si.'II?IiINS; SYSIT;,; CISIII1BUTTI;G Th:i?GF:IN4¿ ASS¿T?"DLY FCR ZELECSOE;, BCIAFDS TCI Library: www.telephonecollectors.info Bulletin Po. 215 Page Introduction 1 , General 1 Functions 1 Desc.ription 2 Outline 2 Bank Terminal Strips 3 Distributing Terminal'Strips 4 Cross-connection Facilities 5 Doors 6 Cross-conneetion and Wiring Practicee 6 Wiring for Vacant Level Tone and Intercepting Trunks 9 Advantages 10 Limitations 12 Elimination of Divisions of Five Selectors PHO T0GRP. PHS Front View . I Side View DFAWINGS Assembly and Details (707-119) Form for Terminal A~sernbiyDrawing (707-137) Bank Terminal Strip - Assembly (7071121) Bank Terminal Strip Designation6 - - Details (707-122) Distributing Terminal Strips (,707-136) TCI Library: www.telephonecollectors.info Bulletin Wo'.' 215 Introduction General This b u l l e t l n d e s c r i b e s a new terminal aseembly f o r s e l e c t o r boards i n step- by- step o f f i c e s , which will be f u r n i s h e d i n t h e f u t u r e on boards rnounting s e l e c t u r s which are assoc i a t e d w i t h three- wire trunks. The netv assembly o f f e r s important advantages i n maintenance and s i m p l e r and more economical f a c i l i t i e s f o r making changes i n t h e grouping of F'unctions I n g e n e r a l , t h e dietribut i n g t e r m i n a l asssmbly prov i d e s means f o r performing t h e following f u n c t i o n s : (a) Terminating the t e r m i n a l (bank m u l t i p l e ) c a b l e s from t h e s e l e c t o r banks, (b) Terminating t h e long m u l t i p l e ( t i e ) and outgoing trunk cables. ( C ) Mult i p l i n g tru.nks through various numbers of s e l e c t o r d i v i s i o n s i n accordance w i t h t r a f f i c requirements. (d) Cross- connecting the trunks from t h e v a r i o u s l e v e l s t o the trunk c a b l e s t o succeeding boards f o r e q u a l i z f n g t h e t r a f f i c t o d i f f e r e n t subgroups of switches. TCI Library: www.telephonecollectors.info Description Outline The distributing terminal assembly is essentially the Same in framework construction as the present terminal assembly and will o~cupythe same space. Attached are two photugraphs of a selector board equipped with the new assembli and Drawing No, 707-119, shdwing the assembly and equiprnent* From these it will be Seen that the assembly Oonsists, in general, of three elements, as follbws! (a) 24 rows of 16-bank terminal btrips each for terminating the bank multiple Cablea fr6m the selector banks, the vertical strap wires for grouping the various divisionß of selectors, and the distributing frame wire cross-connections for as8oCiating the selectors with the outgoing trunks or long multiple cables. (b) A maximum of 5 rows of 5 distributing terminal strips each at the top of the assembly for terminating ca<blesto and from other boards and the cross-connections from Che bank terminal strips. (C) Distributing rings muunted on the vertical members through which the distributing frame wire Crossconnections may be run between the distributing terminal strips and the bank terminal strips. TCI Library: www.telephonecollectors.info Bulletin' Mo. 21'5 Bank Terminal Striye The construction of t h e bank terminal s t r i p is shown on Drawings Nos. 707-121 and 707-122, The 3 rows of terminale i n o r d e r from t h e top Ldawnprovide f o r t h e t i p , r i n g anb sleeve conductors of one l e v e l of a half s h e l f of 10 s e l e c t o r s . Ten terminal s t r i p s a r e , therefore, required i n each row f o r t h e The 10 l e v e l s of a h a l f s h e l f and 24 rows f o r t h e 1 2 shelvesl. various l e v e l s of a s e l e c t o r d i v i s i o n a r e thus terminated n independently on individual terminal s t r i p s and the t i p , r i n g and aleeve terminale of each c i r c u i t a r e kept adjacent i s t e a d of being i n segregated terminal groups, as on the f l a t type terminal assembly, It w i l l be noted an Drawing No. 707-122, t h a t f r o n t end of the bank terminal i s s l o t t e d . t he I n general, the 1 corresponding terminals i n the successive rows of termin 1 s t r i p s , which a r e a s s o c i a t e d w i t h a complete o r p a r t i a l w i l l be connected b y means of v e r t i c a l s t r a p wtres. roup Theee wires w i l l be of No. 22-gauge tinned braided s t r a p wire. V They w i l l be of s u f f i c i e n t length t o connect as many successi e rows of bank terminal s t r i p s as a r e required t o be grouped without reversal. date two No. 22-gauge wires, \ C The s l o t i n the terminal i s l a r g e enough t o a commo- Where i t i s d e s i r a b l e ' t o introduce a r e v e r s a l between adjacent rows on c e r t a i n l e v e l s , a small l o c a l form w i l l be used i n place of t h s v e r t i c a l s t r a p .wires a t the point where such r e v e r s a l is desired. This form w i l l be of tinned braided TCI Library: www.telephonecollectors.info B u l l e t i n No. 215 ~ t r a pwire. I The c o n s t r u ~ t i a nand arrangement of t h e t e r m i n a l s t r i p s provide f o r such a form. ri There w i l l be Gases where one o r more a d j a c e n t rows of bank t e r m i n a l s t r i p s w i l l be omitted, though t h e s e l e c t o r s a s s o c i a t e d with t h e rows of bank t e r m i n a l s t r i p s irnmediately above and below t h e gap w i l l be r e q u i r e d t o be grouped t o g e t h e r . I n such c a s e s i t i s f e l t t h a t t h e v e r t i c a l s t r a p w i r e s can be used s u c c e s s f u l l y a c r o s s one o r two blank bank t e r m i n a l spaces I ! i i b u t t h a t jumpers should be used where t h r e e o r more rows of bank t e r m i n a l s t r i p s a r e omitted. The bank m u l t i p l e c a b l e from t h e s e l e c t o r banks w i l l be s o l d e r e d t o t h e bank t e r m i n a l s t r i p s a t t h e f a c t o r y . w i l l be no s l i p o r r e v e r s a l i n t h i s cable. There The wires w i l l be a t t a c h e d t o t h o s e notches on t h e t e r m i n a l s which a r e n e a r e r t h e t e r m i n a l s t r i p block, The bank m u l t i p l e c a b l e s from t h e two h a l v e s of each s h e l f t o t h e a s s o c i a t e d bank t e r m i n a l s t r i p 6 w i l l be sewed i n t o one c a b l e form. D i s t r i b u t i n g Terminal S t r i p s The method o f mounting t h e d i s t r i b u t i n g t e r m i n a l s t r i p s at t h e t o p o f t 4 e assembly i s shown on Drawing No. 707-119. Mounting space i s provided f o r a maximum of 25 t h r e e o r s i x p o i n t t e r m i n a l s t r i p s as required. I n g e n e r a l , t h e t o p row of 5 t e r m i n a l s t r i p s w i l l be used f o r t e r m i n a t i n g l o n g m u l t i p l e ( t i e ) c a b l e s t o and from o t h e r boards and o t h e r miscellaneous c i r c u i t s such as tone and i n t e r c e p t i n g t r u n k s f o r vacant l e v e l s . With t h r e e - p o i n t t e r m i n a l TCI Library: www.telephonecollectors.info I I I 1 I B u l l e t i n No. 215 s t r i p s , c a p a c i t y i s provided f o r 1 G O c i r c u i t s , 3y t h e use of s i x - p o i n t s - b r i p s t h i s c a p a c i t y may be doubled., The f o u r l o w e r rows of terminal s t r i p s w i l l be uscd f o r t e r m i n a t i n g outgoing t r u c k cables. With three-po!.nt strips througliout, c a p a c i t y i s provided f o r 400 oirtgoing t r u ~ i kc i r c u i t s , I n case the ~ l t i m a t erequirements excsed t h i s capacity, sixp o i n t s t r i p s w i l l be r e q u i r e d i n some o r a l l of t h e rows, Tte u 2 r i g h t s w i l l be d r i l l e d s o t h a t t h r e e rows of e a u d l l y spaced outgoing trurik d i s t r i b u t i n g t e r m i n a l s t r i p s can be mouEted i n t h e Same v e r % i c a l space as i s r e q u i r e d by t h e f o u r rows cf tenminal s t r l p ~u s u z l l y furisished. This w i l l perinit t h e usa of wider v e r t i c a l mo~intingc e n t a r s and s o f a c i l i t a t e a s i x t e n a n c s i x C a s u s where ~ i x - p o i n t t e r x i n a l s t r i p & ase required, This arrangvmsrit can be used only where of ouxgoing tr72iiFs does not enceed 5 0 0 , t h e crltirnate n~nn~ber The d e s l g n a t i o n s which w i l l ba used on t h e d i s t r i b u t i n g t e r m i n a l strips a r e i c d i c a t e d on Drawicg No, 707-130, Cross-c3nnection Fa~ilit%es ----Crozs-connections are provided f r o ~ n-Lhe bank t e r m i n a l s-krips t o t h e d i s t r i t u t i n g t e r m i n a l s t r i p s . ( a ) To connvct t r u n k s of complete o r p a r t i a l groaps of seleu-cors t o outgoing t r u n k cables. (b) To connect t r u n k s of p a r t i a l groups of s e l e c t o r s t o l o c g m u l t i p l e ( t i e ) c a b l e s t o p a r c f a l groups of s e l e s t o r s on c t h e r boards o f t h e Same c l a s s o r those having t h e Same m u l t i p l e . TCI Library: www.telephonecollectors.info B u l l e t i n No. 215 6 ( C ) To connect vacant l e v e l trunks t o vacant l e v e l tone o r i n t e r c e p t i n g trunks, as reguired. The cross- connecting wires a r e terminated on t h e bank terminal s t r i p s on t h e notch neaxer t h e epd on the r e a r of the This notch i s a l s o used f o r tezkinating t h e s t r a p s terminals. f o r m u l t i p l i n g unused w i t h working trunk8 on leve3.s where al1 4 t e n trunks a r e not equipped, Doors S e l e c t o r boards equipped with t h e d i s . t r i b u t i n g terminal assembly w i l l o r d i n a r i l y be f u r n i s h e d wit.hout doors. Guard r a i l s w i l l be added, however, t o prevent damage t o t h e terminals* Since t h e board is Open on a l l s i d e s , it i s f e l t t h a t t h e grotect i o n which t h e doors a l f o r d i s too s l i g h t t o warrant t h e i r use. Vhen a c a s i n g i s s p e c i f i e d f o r t h e s e l e c t o r board on account of severe humidity conditions o r f o r o t h e r reassns, doors w i l l be f u r n i s h e d f o r t h e terminal end of t h e board which w i l l cover t h e bank terminals. A ~ e p a r a t ecover w i l l a l s o be provided f o r t h e p r o j e c t i n g terminal s t r i p s at t h e t o p of t h e assembly. Cross-Connection and Wixing P r a c t i c e s The minimum l e n g t h of d i s t r i b u t i n g f.rame wire w i l l , of Course, be r e q u i r e d i f attachment i s made t o the h i g h e s t bank terminal s t r i p on which each trunk appears and t h i s is t h e preferred practice. I n some cases, however, it may be d e s i r a b l e t o terminate t h e cross- connection a t some o t h e r appearance of t h e trunk i n o r d e r t o avoid congestion of cross- connections,. TCI Library: www.telephonecollectors.info Bulletin No. 215 7 interference with the bank multiple cable form or to pr.eserve regularity of numbering aß noted hereafter. The outgoing trunk and long multiple (tie) cables should be so located on the distributing terminal strips that crossing of the cross-connections between the bank'terminal strips and distributing terminal stri~swill be eliminated. This will keep ti~econgestion of wiring behind the assernbly to a minimum and will facilitate the tracing.of cross-connections. Thus, the trunks and long multiple cables associated with the higher numbered levels, which appear on the rigbt-band side of the rows of bank terminal strips, should be assigned as f a r as possible, to terminals in the ,right-handhalf of the rows of distributing terminal strips, and sirnilarly for the left-hand side. The assignment should be so made that approximately one-half of the cross-connections are run through the distributing rings on each side of the rear of the assernbly. Partial groups may sometimes d~videbetween boards at the point where a reversal is indicated. In such cases it will be considered standard to make the reversal in the crossconnections to the long multiple (tie) cable on the lower numbered board, In the case of graded multiple groups, it is preferable, in general, to take the outgoing trunks from the board on which the majority of trunks in an outgoing trunk cable appear before selectors. In oraer t o preserve regularity of nimbering and TCI Library: www.telephonecollectors.info TCI Library: www.telephonecollectors.info 9 EuPletin No. ,215 befose s e l e c t o r s on boar@ "BM may be brought i n a t i e cable t o board, l l B U i n order t o .be in-. cluded i n an outgoing cable from board "B." (b) In case a group of 20 s e l e c t o r s i s s p l i t .between two boards it muld be necessary, on one boardt t o jumper from one bank t e r p i n a l s t r i p t o an otatgoing trunk t e r h i n a l s t r i p and t o a t i e . cable terminal s t r i p . however, I t i s fel:, can be, that two jumpers on gne terminal. > -, accommodated on a Western E l e c t r i c Gdmpany type d i s t r i b u t i n g terminal s t r i p b e t t e r than on a bank terminal strip. It w i l l , therefora, be considered standard, ehouid t h i s p a r t i c u l a r case a r i s e , t o jumper fern the bank termi,pai s t r i p t o the outgoing terminal s t r i p only and from there t o the t i e cable terminal s t r & p avd W. thus avoid double jimpers on the bank terminal , , strip. Wiring f o r Vacant Level Tone and I n t e ~ c e p t i n aTrunks Five vacant l e v e l tone and two d i r e c t o r y e r r o r i n t e r cepting trunks w i l l be termanated on the middle terminal S t r i p of t h e top row of d i s t r i b u t i n g terminal6 on every s e l e c t o r Y- board equipped w i t h t h e d i e t r i b u t i n g terminal assembly regarä$ees <- of whether o r not t h e r e a r e any vacant l e v e l s a t t h e tLme of installation. I These seven trunks w i l l be mult+pled once on t h e I TCI Library: www.telephonecollectors.info B u l l e t i n Mo. 215 , 10 terminal strip i n o r d e r t o provide tna appearancfis. The left- hand appearance w i l l eerve l e v e l s 1 t o 5 inclusive and t h e s e t of jumpers w i l l be rw through the left-hand d i s t r i b u t i n g r i n g s and terminated on the lowest numbered vacant o r intercepted l e v e l , Siinilarly, t h e right-hand appearance w i l l serve l e v e l s 5 t o 10 inclueive and t h e jumpers w i l l be run through the right-hand d i s t r i b u t i n g rings and terminated on the highest numbered vacant o r intercepted level. In case t h e r e a r e two o r more vacant o r i n t e r cepted l e v e l s i n e i t h e r half of the assembly, the a d d i t i o n a l l e v e l s w i l l be connected t o the one on which the. jumpers from the d i s t r i b u t i n g terminal s t r i p are terminated, This con- nection w i l l be made with d i s l r i b u t i n g frame wire looped t h r o u ~ ht h e nearest d i s t r i b u t i n g ~ i n g . Far t h i s +aonnection, a l o c a t i o n should be chosen whic'ri m i l l r e s u l t i n ,the . l e $ s t i n t e r f e r e n c e with o t h e r jumpers, With t h e arrangement out1 ined abave t h e r e will never be more than two s e t s of jumpers between t h e bank terminals and the d i s t r i b u t i n g terminals f o r vacant l e v e i purposes, Advantages Vhen it becomes necessary t o make changes i n t h e grouping of s e l e c t o r s a t the time of i n s t a l l i n g a d d i t i o n a l equipment o r f o r o t h e r reasons, the d i s t r i b u t i n g terminal assembly a f f o r d s a simple means f o r accomplishing t h e deeired TCI Library: www.telephonecollectors.info ... results. A l 1 minor changes can o r d i n a r i l y be e f f e c t e d by rearrangement of the v e r t i c a l str8p : w i r e s and cmssconnections and the necessity f o r d i s t r i b u t i n g the switchboard cables should be inf requent. The terminal assembly will be simple and substantial. Drawing No. 707-137 shows a form which may be used i n making up t h e terminal assembly drawing. Methods of i n d i c a t i n g c e r t a i n t y p i c a l connections on the frame a r e shom. Maintenance advantages r e s u l t from t h e regularity and a c c e s s i b i l i t y of t h e arrangement and from the fact that the t i p , r i n g and sleeve terrninals ot each c i r c u i t a r e adjacent. In general, t h e separation of the terminal strips f o r t h e switchboard sable and those for t h e bank multiple cable makes a l l terminals more accessible and t h e i r associat i o n w i t h any p a r t i c u l a r c i r c u i t nore evident. With the present arrangernent, e f f o r t s t o l o c a t e trouble by i s o l a t i n g c e r t a i n switches may r e s u l t i n p u t t i n g a l a r g e group of s e l e c t o r s oüt of sesvice unless temporary miring a,rrangements a r e used. On the d i s t r i b u t i n g terminal assembly, t h e i s o l a t i o n of any p a r t i c u l a r trunk i s easily accomplished by unsoldering the v e r t i c a l s t r a p wires from the proper bank terrninals. Otber trunks i n t h e group need not be disturbed. On both t h e present and new type terminal assemblies the terminal s t r i p a a r e soldered t o the terminal TCI Library: www.telephonecollectors.info Bulletin No. 215 12 cables in the shop, The flat type strips of the present type must, however, be piled in proper order with the various other strips to which the loag and short down multiple and other cables are soldered, whereas on the new type of piacing of the bank terminal Strips in regular order is a simple matter, In addition to these installatfon and operating 1 advantages there should 5e a substantial saving in the c 0 8 t I of engineering and drafting and of the rearrangement of trunk 1 grouping, particularly at the time of inatalling additional I equipment. The distributing terminal assembly affords a Simple means for employing graded aultiple grou3s. Vith the cross- connection facilities provided by tne distributi~gterminal assembly, a fairly even distribution of traffic over succeeding sub-groups of switches is possible when graded multiple is used. Limitations Outgoing trunk circuits hav:ng four or Eore aires are not provided for in the design of the distributing terminal assembly as there is not sufficient space t o r bank terminal strips with more than three points, Terminal assernblies of the present ty-pe with flat type terminal strips will, tker5fore, Continue to be furnished on frames in which sul=';l circuits appear. For this reason, it will be desirable to segregate, as far as possible, a i 1 sslectors which ars TCI Library: www.telephonecollectors.info Bulletin No. 215 13 a s s o c i a t e d with outgoing t r ~ n kc i r c u i t s having more than t h r e e wires. I t i s n o t convenient t o arrange f o r m u l t i p l e s l i p ~ without s a c r i f i c i n g o t h e r advantages. The i n t r o d u c t i o n 0f m u l t i p l e s l i p would n e c e s s i t a t e t h e use of s p e c i a l forms between each row of bank terminals, which would not 0nly i n c r e a s e t h e f i r s t c o s t b u t nould a l s o d e t r a c t fram t h e regul a r i t y and conveniecce of arrangement of t h e assembly. A reversak i n t h e middle of each group may be used, howeoer, without disadvantage. -Elimination of Divisions of Five S e l e c t a r s The d i s t r i b u t i n g terminal assembly i s not adapted t o t h e use of d i v i s i o n s of f i v e s e l e c t o r s because t h e bank terminal s t r i p occupies a somewhat g r e a t e r amount of v e r t i c a l space than t h e f l a t t y s e terminal s t r i p s which are r e q u i r e d f o r t h e same purpose. Any convenient l a y o u t consequently provides f o r 24 rows of bank terminal s t r i p s only, which is j u s t s u f f i c i e n t t o s e r v e d i v i s i o n s of t e n s e l e c t o r s throughout. Vfhile t h i s appears t o be a l i m i t a t i o n of t h e d i s t r f b u t i r i g terminal assembly, i t does xot seem t o be a s e r i o u s dis; advantage s i n c e t h e f l e x i b i i i t y of t h i s frame permits the use of graded m u l t i p l e arrangenents f o r those c a s e s where d i v i s i o n s o I f i v e have been s t a n d a r d n i t h t h e p r e s e n t type terminal assembly. Furthermore, Same saving i n t h e c o s t of t h e bank , eqciprnent will be realized through t h e elimination of divisions TCI Library: www.telephonecollectors.info Bullstin No. 215 ~ ~ 14 of f ive, since these are proport%oriat&lp morg expensive th8.n divisions of ten, With divisions of ten a regular arrangement of the frame is made possible in which the terminals for any particular half-shelf of selectors will be in the Same definite location on a l l frames, A variety or" special terminal cable forms,is required I with the present arrangement. The elimination of divisions of I five will reduce the number of forms required. TCI Library: www.telephonecollectors.info TCI Library: www.telephonecollectors.info TCI Library: www.telephonecollectors.info TCI Library: www.telephonecollectors.info S..m.. - ."" mIOU RLZiUDI. <*um. L...." m. L.. .I -Y T l . y ' -""J q 8; 17"..irr 1.m.I1.1. , Lw$ @ Lir.0 w s m - s s a 8.E ' ,L. . . T ).1 I") 7U.l. rm-4 . ' Lr.4 Uy.8 P g~ qap W IQ-' 1 ii. I. T*. V* ."".<". W. I I*, U.",.,...>,. ..8 I,"","., .n,., 011.1 .,T 3. I M i i 7". ri".. - * Y. ,m -"D<" .Si." ., . 1. 7°C ." W . ". i .aY..... ,,L& -1 . I,.Mo V=7- .W".. n i n"",.." .-..".W W...t I lil.<i0..7. VU. ,". . . I m,".,i,i,lU. rinn u . *.sr.u.r... .". .I U... M.". i ~.T.U I N L L .--C.m . L. .1 ,.,ein-"-*L .,,L .* iu ,..L .i...iiP i. -.Ti,. ,,Y ~ nuI-1n,,.I.UIIY ~1u.1 i- i.i1. ~ N. i I.L ib r .. " -.C. SI-m I. ... . .: . ... = ; uini.i.~i.iii wrl ,r a i m i i i t i e n.r i i i r u s u i n . n i v o i u .u 4. nu u n r i wnoii. . , .T C. n V. 1 , . uwi. 1r n o i r R" .r*i. r -I ni i n . . r u -r. .L. .0 9. L~O.U :: 2 ,. ... ,.. .*... .,. ,",,.... ,.*I --, ,. "..., I. , I *.P. C..0 .U.. . .#" - 6. I.. P ,.I"..V UI IU,.,. . a r o .T .I,.. ,i.UN . i r i.,",. .,L. ,.L .W V. . i.iu.i ...U V,, kti. ,.,U ... .-.U-<. . . „." .-". -3"„,.. ." ,...I. r oiioii n i i .,.L ..Si ..0 .s 3 1 1 I,. U ..V,-. La,. n..,.., 1ii *L.. <.I W. . . .1 vn. r r i . I- 7,-2 1- 8.. " . U ..I,. .V. .T- ..„W, I 51.1 .Y. .o . 1.U," O.I.I. i*i*,." $".C" -,.- ,+ "- *iii ro nie. 1 8. .T.i& IC 8. T. i in u r ir-.0 7. T i ,..ur..". .Ti. @*E. i*r. i. i" . i i r . u r i i. n .*,.I in r i i uiu. 7 s r i u r s i n <I.M. r u r i .i W.. 8. Lr..n. u <Iii...-Li. @..T. , . . . . I "U L 8. "-1 ."L.," "0 .r r 0.0.1. TI-. <-I". ."l. 10. " lu . m. .V,.. .""I.,L"- ,U." IT r Y*,. u uui . I <! . I .V< All..*.. 78. .iiu n.u i. irr.- W. 9 r. 14 iir-ir .,."U.. L"'" -W* 0. IIIIWr n - i u i r-u .,.,.... EC."'"n.. "," .W W.". .T, 4 ,-~- 111111 1111111 ..F " 1.7 L.. 8 C XI".Im". T0O.A... L.,. 7s mu&.".m. ." &!." *.*!V. 8.T.D.T. TCI Library: www.telephonecollectors.info .,,L," 1 *uni... .rn.r.. -. .., .",M B , . . . " .,"W.- nM.V.0.P. i Y r n 0. 1.1.0.r. 7," .,L L,."I,.. Li. Liq.ri8l W #rar. 1 1 - 1 i 1 T 1 1 ] I . ! .- 11 b. = 2 0 0 L z. W 4 0 0 == .o L D 5 Y 0 C - i" s 0 I z :$2 C 0 X-: U. !E =I -.a; W P 0 0 I .YD- L t s -*; Y C O C L C Y O I A = a 1 0 z's 0.: r I U $5 mW - .I01 i 0 0 0 1W L - > a> 4 IW = Y, "E I P TCI Library: www.telephonecollectors.info a o o 7SPkRI C +U +- k - E++4 - e YOYLDEO BLIELITE Tor AND Boirni Rom DETAILB Fta. r U'' C+ (~LAOK) YIDOLE Rom DETAIL (OTWLI o!uru8loW 8rur r i I N F I ~ . I ) TCI Library: www.telephonecollectors.info TCI Library: www.telephonecollectors.info S!RQmJ3Y-S-~'IJP ?i%9CRIlE SWITCHING SYSTEM TCI Library: www.telephonecollectors.info Index Yay 1, 1922. General F e a t u r e s of t h e S t e w b y - S t e g Y[ach ine S w i t c h i n ß Sm tem. General &Tumbering Schemee S i n g l e O f f i c e D i s t r i c ts Multi- Office D i s t r i c t s General Cpera t i n g Plen Ca11 from a Edachine S w i t c h i n g Station t o h o t h e r Uechine S w i t c h i n g S t a t ion Ca11 from a k c h i n e S w i t c h i n g S t a t i o n t o a Manual S t a t i o n C a 1 1 f r o m a Manual t o a h c h i n e Switching S t e tion T o l l S w i t c h i n g Trunk Connections t o a Xacfiine Sw i t c h i n g Off i c e Special Service Calls--Single Office D i s t r i c t s S p e c i a l Service Calle--tdultiOffice G i a t r i c t s Prel i n i n a r y P u l s e s Naming of C e n t r a l Office U n i t s TCI Library: www.telephonecollectors.info Index May 1, 1922. DIVISION 11---TYPE OF EQUIPmNT -- Section S u b s t a t ions General Dial Changing Manual S t a t i o n s t o h c h i n e Switching S t a t i o n s l n s t a l l i n g S u b s t a t i o n Squipment i n Yrep3ra.t ion f o r Machine S ~ i i t c h i n gOperation Tiiring Plans Substation Protection Terminal Equipment &in U i s t r i b u t i n g Frame I n t e r u e d i a t e B i s t r i b u t in$ Frame P r o v i s i o n f o r Nelays Message R e g i s t e r &ck Protectors P r o v i s i o n f o r Fuses Svritching E y u i ~ m e n t Plunger Type Line Switch Solenoid Type Master Switch Priinary Line Switch Pritnary W s t e r S v i t c h Priinary Line Saitchboard TCI Library: www.telephonecollectors.info Page Index May 1, 1920, DIVISION -I I=-( CONTITWED~ S e c t ion Switchiw Xquiprnent Secondary Line Switch Secondary & 8 t er Swi t ch Secondary Line Switchboard Outgoing Trunk Secondary Switch Outgoing 2runk Secondary Master Swi t ch Outgo ing Trunk Secondary Swi tchboard St ep-by- S t ep Se1ector S e l e c t o r Action S e l e c t o r Mechaniem M u l t i p l e Banka and Bruehee S e l e c t o r Bearde The Connector Connectors f o r Subscribere' L i 3 e s Only (Excluding P ,B.X, Trunks). - Trunk-hunt ing Connectore Connector Boarde TlIe Repeater Repeater Boards TCI Library: www.telephonecollectors.info Page Index May 1, 1922. DIVISION 111---CIRCGITS Secti. I _ Substation Circuits I n d i v i d u a l , Two- party and r ' o u r - p a r t y Serci-Selective Lines rour- party S e l e c t i v e Lines C e n t r a l Of'fjce C i r c u i t s S u b s c r i L e r Vs L i n e C i r c u i t w i t h P l u n g e r Type Prirnary L i n e Cwitch and w i t h o u t S e c o n d a r y L i n e S w i t c h Met e r i n g Ae lays Su'cscri'LerVsLine C i r c u i t w i t h P l u n g e r Type ?rirr.ary and Secondary Line Switches S u t s c r i b e r l s Line C i r c i l i t w i t h Plunger Type L i n e S w i t c h e s . Arranged f o r Message H e g i s t e r Serv i ce negular Selectar C i r c u i t D i a 1 tone n e p e a t e r C i r c u i t f o r One-wa;y I n t e r of'fi c e T r u n k s L o c a l r i e ~ x l a rConnect.or C i r c u i t for I n d i v i a u a l o r S e l e c t i v e Party Line S e r v i c e . Arranged t o Aelease C o n n e c t o r a.f'ter Both P a r t i e s Have Hung t'p. C a l l t d Line Found I d l e f i e l e a s e Vdhen C a l l i n g P a r t y Hangs Up Y i r s t Release When C a l l e d P a r t y Fangs Cp Yirst C a l l e d L i n e Found Busy TCI Library: www.telephonecollectors.info Index lday 1, 1320 DIVISION IV--mTUNT d T D M R A B c ~ T TOB S Q I J I ~ Z ~ ~ S ~ T Section Primary L i n e Switches General Priuiary BSse t er Swi t ch es Average and Average P l u a D e v i a t i o n Tablee Secondary Line Switches Regular Groupal-General Nwnber o f Prirnary Sub-groupe p e r Regular Group Mumber o f Secondary Line Swi t c h e s Per Sub-group Cro 88- csnnect i o n Scharm f o r Trunke between Primry and Secondary Line S w i t c h e s i n a Regular Group Croas-Connectine Table P a r t i a l and Combined Groupe General P a r t i a l Group Plan Combined Group Plan Offices Raving Lese Than One Regular Grotrp Cross- connecting Tablee TCI Library: www.telephonecollectors.info Page Index Nay 1, 1920. Section Tr?anke t o F i r a t S e l e c t o r e Handling Coin Box T r a f f i c B i r e t Se1ec t o r s Regular S e l e c t o r s (Excluding T o l l ~electors) Selector U l t i p l e T e m i n a l S t r i p Arrangement Grouping of D i v i s i o n s U u l t i p l e S l i p and I L u l t i p l e Revereal ?Tumber of Regular S e l e c t o r s p e r Sub-group Combined and P a r t i a l Sub-groupa Graded I L u l t i y l e Cross-Cannections i n Trunks t o Regular Selectore Offices Where Secondary L i n e Switchee Are Xot I n s t a l l e d O f f i cee '#here Secondary L i n e Switches Are I n s t a l l e d Toll Selectore S e l e c t o r kaultiple Mumb~ro f S e l e c t o r s p e r Sub-group Second S e l e c t o r e Four-Digi t System Regular, S p e c i a l and T o l l S e l e c t o r s S e l e c t o r K u l t i ~ l e - - R e g u l a r and Special Selectors TCI Library: www.telephonecollectors.info Pwe Index k y 1, 1920. Section Page Selectors 4a 3 Xun3er o f S e l e c t o r e p e r Sah-groap 4a 5 Cooiblned Lo c a l an? T o l l Sub-groups 40 5 4b 1 Regular, Special ünd T o l l S e l e c t o r s 4b 1 Selec t o r l h l t i p l e 4b 6 Number of Se1e c t o r s p e r Sub-group 4b 7 Selector :iultinle--Toll J i v e - D i g i t System Third S e l e c t o r s R e g u l a r , S p e c i a l and T o l l S e l e c t o r s Selector Uultiple Selectoro. S e l e c t o r :.:ultiple - Regular ünd S p e c i a l - Toll Selec tore Number c f S e l e c t o r s p e r Sub-group Connectors General Connec tor Xult i p l e antl Terminal S t r i p Arrangement Test C ~ n n e c t o r e Arrangement of Connectore Grouping o f S u b s c r i S e r e V S e r n i n a l s P.B.X. Croupe of More Thun Ten Trunke TCI Library: www.telephonecollectors.info Index A u ~ ~ u s 1,~ 192U. NlunSering o f C e n t r a . 1 Office Equipment Linc S w i t c h Xqui;?m?nt Primary L i n e 3witch Equipment Secondary Line Switch Equipment S e l e c tor Xquipment Connec t o r Equ i s m e n t TCI Library: www.telephonecollectors.info Index May 1, 1922. DIVISION V - CABLING AND WIRING Seetion General Swi tchboard Cables Band-Pormed Cables Cross-Connecting Jumpers Cable Raaks Subscriber' s Line C i r a u i t I n d i v i d u a l F l a t Rate Lines I n d i v i d u a l Message Xeqister Lines Line s T e r ~ i n a t e dD i r e c t l y OLA F i r s t Selectors W o P a r t y Lines Pour P a r t y Line s Terminal hssembly on Line Swi tchhoards P r i ~ a r yLine Swi tohboards Seaondary Line Swi tchboards Trunks from Primary Line Switches t o Secondary Line S w i tchea Trunks fror? Seoonüary Line Switches t o Y i r s t Se1e c t o r s Trunks from F i r s t S e l e o t o r s t o Seoond SePectors S e l e o t o r Board T e m i n a l 4ssembly Mult i p i o Sf i p and Kultf p l e Beversal TCI Library: www.telephonecollectors.info Page Index LLay 1, 1920, Sect ion Outgo ing Trunke 5b Incomiag Trunke 5c T r u n k s f r o m Second S e l e c i o r s t o Third Selecture 6a Trunke from T h i r d S e l e c t o r s t o Connectore 6b Trunks from C o n n e c ~ o r et o I,ine I.D.3'. 6c TCI Library: www.telephonecollectors.info ~ndex July 1, 1921. Section Page General 1 Safe Floor Loads 1 CeiLing Heights 2 Auxiliary Framing 3 Cinder Fill 3 Yloor P l ~ nArrangements-Aisle Spacing 4 Relative Location of Xquipxent 6 Floor 31an Layout 9 Provision f or GrowZh 11 Tysical F l o o r Plans 12 TCI Library: www.telephonecollectors.info Index August 1, 1923 DIVISION VIII - L!AC)-TIl\rE SJJITCHING "At' BOiiRD Section General Purpose of Xachine Switching Board Classes of Positions Equipment Common to All Classes of Positions Outgoing Trunk Multiple Dia1 and Method of Dialing Supervisors Equipment Equipment Individual to the Different Classes of Positions Special Service Positions Cord Circuits Xastqr Ringing Keys Ca11 Circuit Keys Checking &lultiple Intercepting Positions Cord C i r c u i t s Trouble Observation and Test Trunks Trouble Intercepting Trunks Te s ti.ngEquipment Subscribers Positions Rural P~sitiona Ca11 \Vireless Trunks Rural Line Huitiple TCI Library: www.telephonecollectors.info Page Index A ~ u s t1, 1923. Section Equipment Individual to the Different Classes of Positions (~ontinued) Official Positions Section Framework Type of Section Installation of Checking Multiple Modification of the No. 1 Sectim Eodification o f No. l - D Section Cable Turning Sections End Panels Use of Existing Nanual Sectione ae Machine Switching "An Sections Eiscellaneous Keyshelves Type of Keyshelf Double Ended Common Battery Dialing Cord 3 i?ull Universal Cord Intercepting Cord Connector Terminal C w d Ca11 Yiireless Trunk Test C o r d Ca11 Circuit from Test Desk Checking Cord Dial and D i a l Nounting Xaster Keys Ca11 Circuit Keys TCI Library: www.telephonecollectors.info 3 Page Index August 1, 1923 Section Keyshelves- (Continued) Emergency Ca11 Circuit' Cord Miacellaneous Equipent Outgo ing Trunk -Xulti~le General Outgoing Dialing Trunk to Pirst Selectors Delayed Ca31 Equipment Outgoing T,tanual Trunks Interpo sition Trunks Supervisors Trunks Tone Trunlca Eaiscellaneous Trunks Answering Jack Equipment Location ings Jack 16fount Intercepting Trunks from Connector Terminals Intercepting Trunks from Vacant Selector Levels Plugging Up Lines Rural Linea Operated on a Nagneto Basis Multiple Answering Jacks Other Answering Jack Equipment Checking Eultiple Multiple Strip Construction TCI Library: www.telephonecollectors.info Page Index August 1, 1923 Section Checking libultiple (Continued) Capacity o f No. 1 and N o . 1-D Sections Nwnbering and Growth Location Miscelianeous Face Equiyrnent RuraJ and Off i c i a l Line t d u l t i p l e Pilot L a p s and D r i l l i n g s i n the P i l i n g Rail Fuse A l a r m Lamp Busy Back Jacks at Rural Foeii.tions Key Sleeve Holders Rear Equipinent General Arrangement o f No. 1 Board Arrangement of No. 1-3 Board Relay Rack Equi3ment Cabling and VJiring TCI Library: www.telephonecollectors.info Page Index Dec. 1, 1922. DIVISICN IX --- EQJJIPMENT IIEQUIFIXD FOR MAEJUAL OFFICES I N STEP BY STEP AREAS - CÄLL I N D I CATOR EQUIPM2NT Section Gene ral C a 1 1 I n d i o a t or Incoming Equipmsnt Recorders Operation of Ca11 I n d i c a t o r Equipment Ringing M u t i l s t e d Calls - Kaster Ringing Key Release of Equipment - Delayed Disconnect Signal. Recorder Busy Lanlp and Key Incompiete D i a l i n g C a l l e d Line Busy, Out of Order, e t c . Ca11 I n d i c a t o r Arrangement Calls t o Nmbers above 9999 Grouping Key Supervisor*E C i r c u i t Operat orl s Telephone C i r z u i t Make Busy Equipment Night P o s i t i o n s a.nd Night ~ i a r m s P i l o t Lamps TCI Library: www.telephonecollectors.info Page Index Dec. J . , 1922. Section PF;~ R e p e a t i n ~C o i l Rsak 3 2 R e c o r d e r Rack 3 2 R e c o r d e r Se3 e c t o r Uni t 3 3 R e c o r d e r Uni t 3 3 Jacke 3 4 Number of R e c o r d e r s 3 4 C&'cIinp an!-yA' Trunk Cakling R e c o r d e r Rack C a b l i r i g P o r i t i o n a l C a b l i n ~a n d W i r i n g Group Peg C 9 ~ n tRet:i~tere O p e r - z t c r o ' Pov C o x x t Regie ters - F l o o r Plane General Relative L o c n l i o n of Racke A i e l e Spacee Uiacellaneou~ Currtmt ---.. D r a i n Data TCI Library: www.telephonecollectors.info Index Nareh 1 , 102:: IYUNIT~~; OFFICES IN $TE?-BY-STEP AFiEAC PART "- - P m - " . . . - . " - DDIALI General Standard Nethod of Bialing B i a l Cord Plan Trunk Wesi stance Type of D i d Mounting and E o c a t i o n of D i a 1 Dial Key 'Eq'aipmelat D i a l Cord Equipment Trunk Cireuit Modif ications Provision 0% R e L w PTquipment Method o f CabBing Busy Tone TCI Library: www.telephonecollectors.info Index Auguut 1, 1.920, Sec t i o n T211 S w i t c h b c a r d No, 1, General - O p e r a t i n g and E q u i p ~ e n tF e a t u r e s Recordinc; P o s i t i o n s la - O p e r a t i n g and Equipment Features Outward and I n m r d 2 o s i t i o n s la Switchboard Sccti.ons Cable T u r n i n g S e c t i o n s End Panels P o s i t i o n and P a n e l Humbering Keyshelves - General Outvard K e y s h e l v e s Imard K e y s h e l v e s Coabined L i n c a n d Reoord i n g Keyshelves lc Pace Yquipmunt ld TCI Library: www.telephonecollectors.info timam. ---- General Foaturea of t h e Step-e~ 4 Machine S w i t c a q y s t e p n . YCCILI-3L.cIw.C'i.- L The YIeetern E l e c t r i c Company is p r e p s r e d t o f u r n i s h t o . t h s Associeted rompanier cent r11 o f f i c e equipment o f t h e st ep-bym I e t e p n.a.chii:e tlwitchinß type. ~ h e term astep-by-stepa i s applied f o t h i s system oaing t o t h e a c t i o n of t h e s e l e c t i n g mecher~liruns I i I m i c h a r e noved b y means of electro-megnets one s t e p a t a t b e . The equipment eqables a subscriker t o complete simple c a l l s n i t h o u t t h e a i d of an o p e r a t o r , end t s so arrranged t h a t t h e p r o p e r charge w i l l be msde i~ each case. It i s t h e purpose of t h e s e e n g i ~ e e r i r gn o t e s t o d e e c r i b r f - t h e etep-Dy-step m c h i n e snit c h i n e c e n t r a l of f ice equipnent , giaing f2 P s u f f i c i e n t icformation i n r e g a r d t o t h e a i z e , e.rrangement m d f w a t i o n s of t h e various p a r t s of t h e equipment t o aid t h e telephone companies i n engineerin.g arid o r d e r i n g such c e n t r a l o f f i c e s . I., , i A eubecribe$s e t ~ion t i n a etep-bx- rrtep machine mtch-. i n g ayotem i s provided with a d i a l i n g mechanism m i c h p e r m i t s a e u b s c r i b e r t o call t h e d e s i r e d nurnber. iiiechanical s e l e c t o r s ctre II provided at t h e c l t r r l o f f i c e f o r completice3. a connection from t h e c a l l i n g l i n e ' t o t h e s t a t i o n corresponding t o t h e number dialed. The s e l e c t o r s are Cescrib d i n d e t a i l ir, Division 11, S e c t i o n 3n1, P I of t h e a e notes. Each p u l s e I n a d i g i t d i a l e d d ) r e c t l y -Ses- the y l e c t i n g mechanism on onl o f t h e s s l e c t o r a t o sdvMce one goeition, t h e s e l e o t i o n e t h i s b e i n g n a d e i n o c c o r d w c e n i t h the dec-1 3 i. I The n i u l t i g l e benk of ertch s e l e c t o r contairie 100 a e t e of terminale w i t h which t h t b r u s b e s o f thc s e l e c t i n g m e c h w i u m k a oontrch. t e r m i n a l 8 are arrsnged i n t e n groups o r leve+r 0 f t o n 8.t I C b RY.*~* I TCI Library: I www.telephonecollectors.info r I d I- - Th. a Thie arrsngement l i m i t e t h e n m b e r of groups of t m k e t o -.ich p a r t i c u 1 e . r s e l e c t o r l-as acceee t o t e n and t a e number of t r u n k e i n any one of t h e groups t o ten. The step-by-etep -L/ s y s t m i s intended p r i m a r i l y f o r use i n \ 1 s i n p l e o f f i c e d i s t r i c t a , r l t h o u @ it i s a l s o s u i t a b l e f o r use i n &U multi- office d i s t r i c t a . Used i n eir.gle o f f i c e o r i n small multi- off i c e d i b t r i c t s , t h e erstem compares f a v o r a b l y n i t h t h e panel*'type system i n p o i n t of c o s t and i r ~f l e x i b i l i t y , a.nd it i s thou&t that t h e step- by- etep system ahould be considere6 f o r a l l s i c g l e o f f i c e d i e t r i c t s and f o r m u l t i - o f f i c e d i s t r i c t a where t h e nurrlber of o f f i c e e i n t h e u l t i m t e w i l l not exceed f i v e o r oix. V If t h e r e trre any t m - p a r t y neasage r a t e l i n e s i n a li4i".;? di~t*ict ,. + ! where t h e st ep-by-atep syet