1080 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1953 



immaterial insofar as reduction in the effective height of the card stack 

 light tunnels is concerned. The stresses developed are so low that fatigue 

 failures should not be experienced. 



Nylon is bonded to the top surface of the bars because of its proven 

 ability to resist the cutting action of the cards. Details made from 

 graphitized phenolic linen are secured to the bars at the lateral guide 

 points because of the superior ability of this material to resist wear under 

 the sUding action involved. This material also is well adapted to resist 

 the heavy loading that is developed where (top of center slot) the card 

 support bars are engaged by the tongues of the card support bar lift 

 magnets and it is, therefore, used here also. Beryllium copper details 

 are affixed to the ends of the bars where they are coupled to the asso- 

 ciated solenoids. Beryllium copper is used here because of its wear- 

 resistant and non-magnetic characteristics. For the same reasons it is 

 used for details that are secured to the bottom edge of the bars where 

 end guides are engaged and the bars cooperate with the latches. 



The beryllium copper details affixed to the bottom of the code select 

 bars are each provided with toe-like projections. The bottom of the toes 



MAGNESIUM 

 DIE CASTING 



NYLON CARD 

 ENGAGING SURFACE 



END TERMINATION 



TOP LATERAL GUIDE 

 (GRAPHITIZED PHENOLIC LINEN) 



D-^y^ 



TOE-LIKE PROJECTION 



Be CU COUPLING 

 DETAILS 



CODE SELECT BARS 



Be Cu DOWN STOP, 

 LONGITUDINAL GUIDE AND 

 LATCH ENGAGING APPENDAGE 



CARD SUPPORT LIFT 



MAGNET ENGAGING 



SURFACE (GRAPHITIZED 



PHENOLIC LINEN) 



BOTTOM LATERAL GUIDE 

 (GRAPHITIZED PHENOLIC LINEN) 



Be Cu DOWN STOP AND 

 LONGITUDINAL GUIDE 



CARD SUPPORT BAR 

 Fig. 29 — Code select and card support bars. 



