A GOVERNOR FOR TELEPHONE DIALS 



1285 



1.2 



!2o.8 



L. 



0.8 1.0 1 1.2 1.4 



C IN CENTIMETERS 



2.2 



^- 



FLY-BAR ARM LENGT 

 (0.920 CM) 





r = 1.18CM 



Fig. 9 — Design diagram for fly -bar type governor. 



Comparison of these two equations shows a very important differ- 

 ence in the term multiplied by [x = 0.425. For the drive-bar governor, 

 there are four variables which can be operated on to satisfy the eciuation; 

 i.e., c, r, i and e. For the fly-bar governor only c is available. The im- 

 portance of these additional terms can be realized when one considers 

 that the value for c results from our choice of d in making dw/dyi a mini- 

 mum. For both type governors c is equal to 0.361 cm. Substitution of 

 the d and c values in the limiting eciuation, (18), for the fly-bar governor 

 does not lead to a solution when p. = 0.425. Solving for this limiting ju 

 in the fly-bar governor gives 



(0.390) - (0.361) M = 



/x = 1.08 



This value of ju is far beyond that encountered in actual governor 

 operation and, in effect, represents useless margin. This is graphically 

 shown in Fig. 9 where all d and c values which conform to the geometry 

 of the fly -bar governor mechanism are plotted as a design diagram. The 

 three straight lines radiating from the origin represent plots of the 

 limiting equation for ju = 0.425, 0.25 and 0.05. The intersection of these 

 lines ^\'ith the d and c semicircle, noted at points 1, 2 and 3, give the 

 particular angle at which the stud should be located for optimum regula- 



