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BELL SYSTEM TECHNICAL JOURNAL 



Fig. 3 — Crossbar switch vertical unit. 



the vertical holding bar. The vertical unit shown has six pairs of 

 contacts at each of its ten crosspoints. Other vertical units are 

 provided with ten sets of 3, 4 and 5 pairs of contacts per set. One 

 spring of each pair as shown is a fixed spring consisting of a projection 

 of an insulated vertical metal strip, made in the shape of a comb. 

 This strip extends from the top to the bottom set of contacts of a 

 vertical row. Wiring lugs are provided at the lower end of these 

 vertical strips facing the rear to which are wired the lines or trunks 



