. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . he following manner: Suppose the ten shelves indicated in Fig. 125 tohave been originally installed without individual trunks but with thecustomary bank slip between the shelves. Then imagine the common TRUNKING, ITS PHYSICAL ARRANGEMENTS AND VARIATIONS 133 trunks to be removed from the first two contacts of each level and to bereplaced by individual trunks. The result is the condition of affairsshown in Fig. 125. By this means the out-trunking from 100 switches(ten shelves of ten switches each) is increa
. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . he following manner: Suppose the ten shelves indicated in Fig. 125 tohave been originally installed without individual trunks but with thecustomary bank slip between the shelves. Then imagine the common TRUNKING, ITS PHYSICAL ARRANGEMENTS AND VARIATIONS 133 trunks to be removed from the first two contacts of each level and to bereplaced by individual trunks. The result is the condition of affairsshown in Fig. 125. By this means the out-trunking from 100 switches(ten shelves of ten switches each) is increased from ten trunks to 30trunks. If we consider any given shelf the switches of which are multipled toeach other point-for-point (, without bank slip), we will see thatwhenever a switch seeks an idle trunk it will stop on the first one whichis found disengaged. This means that the first trunk will get the heaviesttraffic, the second trunk less, and so on, diminishing to the last trunkin the level, which may rarely, if ever, receive a call. Tests have shown Common Trunks2 3 4 5 6 7. Fig. 126.—Common trunks added to individual trunks, ELS-15. that from 50 to 75 per cent of all the calls handled by a fairly busy groupof ten trunks are handled by the first three trunks. From this we may draw the very natural conclusion that individualtrunks offer a powerful remedy to relieve overcrowded trunk groups, sothat if an exchange which has been installed in the usual way showssigns of overloading in any particular trunk group, this may be relievedby noting the most busy shelves which feed into this trunk group andinstalling individual trunks to divert enough of the traffic to bring downto a safe figure the total load remaining on common trunks. If the exchange is laid out from the start with individual trunks andcommon trunks, they may be arranged as shown in Fig. 126. There arefewer common trunks than found in Fig. 125, but they have much lesstraffic to carry than if they were part
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttelephone, bookyear19
