200 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1952 



K,i = -^"(1 + A;,) 



(iR = vertical front stop location relative to e.g. 



kR = vertical heel stop location relative to e.g. 



^zR = horizontal heel stop location relative to e.g. 



m = mass of armature 



P = 



C ■ C ■■ 

 it 



Pl2 



1 + 



^ Mnf _k \ + h 



1 + Pnf k ki 



R = radius of gyration of armature about center of gravity 



Xafn 



t = time 



T 



ti = basic period of front after "zero" impact 



ti = basic period of heel after "zero" impact 



Tn = duration of n^^ free interval 



Xi = vertical front displacement 



X2 = vertical heel displacement 



rcs = horizontal heel displacement 



Xa = front velocity just prior to "zero" impact 



X 



y ^ ir 



XaT 



Yi = greatest excursion (rebound) of front 



