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BELL SYSTEM TECHNICAL JOURNAL 



of the switch. Each of the circuit switching cams is associated with 

 four brushes and it is possible to so arrange the contact carrying 

 segments on these cams tliat 6024 ^IjfTe^ent circuit combinations can 

 be established by advancing the switch successively into each of the 

 18 positions. 



The switch is propelled !>>• a drising disc mounted on a power drixx-n 

 shaft that re\nl\cs constantK' at a speed of 3() r.ji.ni. The dri\en 

 disc on till- switth in associatiiin with llie drixiiisj disc rdnstitutes a 



Fig. 21 — 24 cam sequence switch 



friction clutch under the control of an electro-magnet which deflects 

 the driven disc to bring it into relation with the driving disc when it 

 is desired to advance the switch. The electro-magnet corresponds 

 to the winding of an indi\idual relay structure and the driven disc 

 is the armature, the combination of the winding and armature simpK- 

 serving as a means for controlling the contact relations of a mul- 

 tiplicity of springs. 



Till-: I'owicR I)ki\i:\ .Sklector 



The power driven selector shown in Fig. 22 is another example of 

 an entirely different form of multi-contact relay for transferring the 

 three contacts of any one of 500 circuits to the contact springs of a 

 brush that will relay that circuit to any desired point. These 500 

 circuits are assembled in five groups of 100 each in fi\'e banks that arc 

 mounted on a frame as shown in the figure. I-"ive brushes, one for 

 each bank, are assembled on a vertical rod in such relation to the 

 banks that the mechanical tripping or release, of any brush brings 

 its springs in contact with the terminals of the bank with which it 

 is associated. The corresponding springs of each of the lise brushes 



