CROSSBAR DIAL TELEPHONE SWITCHING SYSTEM 



83 



crosspoint contacts will remain latched and the contacts held closed 

 by the holding bar until the holding magnet is released at the end of 

 the connection. The selecting fingers are each provided with a 

 damping spring to reduce vibration on the operation and release of 

 the fingers. 



ADJUSTABLE 

 SUPPORT FOR 

 SELECTING 

 FINGER . 



OPERATING 

 SPRING 



CONTACT 

 MULTIPLE 



Fig. 2 — Crossbar switch selecting mechanism. 



It will be noted that the selection operation is performed by five 

 horizontal bars although there are ten horizontal rows of contacts. 

 This is accomplished by operating the bars in either of two directions. 

 As shown in Fig. 1, two magnets are associated with each bar, one 

 whose armature is on top of the bar, the operation of which causes 

 the selecting fingers to move in a downward direction, and the other 

 whose armature is below the bar causing the fingers to move upward. 

 The selecting bars are restored to the normal or mid-position by the 

 centering springs located on the end of the switch adjacent to the 

 magnets. 



Figure 3 shows the vertical unit of the crossbar switch with its ten 

 sets of normally open ' ' make " type contact springs, the holding magnet 

 at the bottom, and the long vertical armature to which is attached 



