554 THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1953 



2a and 25 be the sides of the rectangular cross section of the terminal. 

 A = lead of wire helix on long side (2a). 

 4 = lead of wire helix on short side (26). 

 N = number of turns of wire 

 The classical formula for Torsion is 



Torque X Length 



e 



Su 



(1) 



For an equivalent "spring" attached to the long side the axial length 

 of the terminal is ^i , the torque is WFb* and hence the deflection 

 WFMi/Su ; for the short side the length is 4 , the torque is WFa* and 

 the deflection WFa^2/Su . For a complete turn of the helix the length 

 of the terminal is therefore, 2(^i + 4) = p, and the torsional deflection 

 is 



5 = ?W (^^_ ^ ^^^^ 



Su 



It is logical to assume that 



(2) 



(3) 



Fig. 36 — Equivalent structure of wrapped connection (only half turn shown), 



* This is approximate and holds closely for A «C 2a and (i <^ 2b 



