12 



nilLJ. SYSTEM ri-.CIlXICAL JOURK.II. 



instead of the cap. The knitc ctlgc armalun- hinjif and the graNitv 

 control of the free armature were the fundamental jiriiuiples re- 

 tained in the new dcsijfii. 



7 — I'jirly siipCTMs 



The tubular >hield for the return magnetic path was abandoned 

 for a retinii pule piece which pro\-ided a means for mounting both 

 the armature and the air gap adjusting screw. The cover prolecti'd 

 the contacts from dust but it was soon foimd that magnetic intiT- 

 ference between adjacent relays was res[-)<)n>ible for both faults in 



Substation Loop 



' WW — »— W/, ' 



Subscribers Jack 



Line Relay 



3 



Cut Off \ ^ 



Relay 



Line Lamp 



ImK. 8— Line aii.l ciUolT ix-la: 



X 



I'ircuit 



operation and crosstalk, so the co\er had to meet the additional 

 requirement 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 



