Inside a Crossbar Office

  
 

Central office ringing interrupter

  
 

 

Crossbar offices had very sturdy interrupters to provide subscriber ringing patterns. 

These could be driven by either AC or DC motors which shared a common shaft. Cutover to the DC motor during an AC power failure was nearly instantaneous, with no subscriber ringing effecting.

 

click images for better views

a ringgen 1 P6120072.jpg (49696 bytes)
Bob Dickensheets explaining interrupter.

 

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Contacts are made inside these mercury-filled disks; 
a partial cam makes contact with mercury on rotation.

 

 

 

  
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