. The Bell System technical journal . Relay 3 Cut Off \ ^ Relay Line Lamp ImK. 8—Line ciUolT ix-la: X Iircuit operation and crosstalk, so the co\er had to meet the additionalrequirement of l)eing an efTecti\e shield. This was eventualK accom-plished to best ad\antage by making the cover of copper. As has been shown two general t>pcs of structtires were now a\ail-ablc for common baller\- s\-stem rela\s. In one, the arnialure was RRi-ivs IX Till- .^ ■-usiuiidid 1>\ a riid iiiidiT Uii>i(in to prox idt a rrsUiriiii; forci. Inthe DtluT, whicli was niori. sfiisitixe I
. The Bell System technical journal . Relay 3 Cut Off \ ^ Relay Line Lamp ImK. 8—Line ciUolT ix-la: X Iircuit operation and crosstalk, so the co\er had to meet the additionalrequirement of l)eing an efTecti\e shield. This was eventualK accom-plished to best ad\antage by making the cover of copper. As has been shown two general t>pcs of structtires were now a\ail-ablc for common baller\- s\-stem rela\s. In one, the arnialure was RRi-ivs IX Till- .^ ■-usiuiidid 1>\ a riid iiiidiT Uii>i(in to prox idt a rrsUiriiii; forci. Inthe DtluT, whicli was niori. sfiisitixe Ijiit U-ss capable of carrying aheavy sjiring loatl, the armature operated in a knife edge hinge andthe restoring ft)rce was graxily. Kach subscribers line recinired a liie rela\- for ligliting a ) w lienthe substation receiver was reimned troni the hook, a cutoff relay forrenio\ing the line rela> from the circiiii w lu-n the operator responded,and a suiier\isor> rel<i\ for r<mtnillin!^ lamp signals to inform the. ,. 9— ;iii(l lUtiilT n-lays operator whether the substation switch hook cc)iil,ict> were open orclosed. The circuit arrangement for the line and cutoff relays isshown scheinatically in Fig. 8. The rapid extension of telephone ser\ice necessitated establishingstandards of , and definite requirements for apparatusunits were gradually formulated. At first, the available relays wereadapted as closch as possible to existing conditions, l)ut as require-ments became definiteh established, relays were designed specificalhto meet them and careful consideration was given to manufacturingcosts, mounting space, maintenance expense and all other factors ofeconomic importance. By 1010 se\eral million of the line and cutofTrela\s shown in Fig. f) and the super\isi)r\ relay of Fig. 7 were inservice. The cutoff relay armature was of reed hinge t\pe, while boththe line and supervisory relays were assembled with the more sen-sitive kn
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
