516 BELL SYSTEM TECHNICAL JOURNAL 



cords, the width of the position can be increased to include the number 

 of cords required. 



The switchboard is divided into sections, each having two panels and 

 each arranged for a position circuit. The section is an arbitrary 

 division of the switchboard for constructional purposes and has no 

 bearing on the position boundaries. All keys and cords in a section 

 are terminated on terminal strips in the rear. The cord relay equip- 

 ment is furnished in units of 10 circuits, each unit being equipped 

 with terminal strips so located that, when a unit is placed in the rear 

 of a section, the terminal strips come directly under the section 

 terminal strips. Distributing rings above the two rows of terminal 

 strips provide facilities which permit any relay equipment to be 

 cross-connected to any keyshelf cord equipment. 



The engineering of this switchboard is thus reduced to a very 

 simple process. The number of cords required per operator is deter- 

 mined by the anticipated trafhc data. From this information the 

 width of each position is determined. The sum of the positions 

 required to handle the peak load represents the total length of the 

 switchboard and determines the total number of sections required. 

 Cord units are then provided in the rear of the switchboard. The 

 cords required for each position are then cross-connected to relay 

 circuits on the cord units which are in turn cross-connected to the 

 nearest position circuit. Teletypewriters are moved in front of the 

 various groups of cords and plugged into the jacks for their position 

 circuits. Should conditions require a different assignment of cords, 

 they may be recross-connected to meet the new requirements and the 

 teletypewriters moved to new positions. 



No. 3 A Teletypewriter Multiple Equipment 

 For convenience, the operator's vertical reach for lines with answer- 

 ing lamps has been defined as 30 inches above the standard type of 

 keyshelf. From the lower edge of the keyself, which prevents the 

 operator from rising to reach farther, the permissible reach is 35 inches. 

 Deducting the space required for the teletypewriter and keyshelf 

 equipment, there remains 14^ inches available for multiple below the 

 35 inch reach limit. About 2f inches of this space is required for 

 unattended line terminations and miscellaneous multiple, leaving a 

 space of 11| inches for the subscriber line multiple. 



This space provides for the capacities shown in Fig. 8, which are in 

 terms of ratios of subscribers lines to inter-toll trunks. This curve is 

 based on the use of a 6-panel multiple which, with the lOj inch panel 

 r(>f|uirod for the type 49 jack used, results in a horizt)ntal reach of 



