A GOVERNOR FOR TELEPHONE DIALS 1295 



unstable weight skids against its arm of the drive-bar. This introduces 

 fri(!tion damping to still further reduce the noise on closure of the weight. 

 Some additional damping is provided by making the drive-bar and weight 

 of powdered metal rather than wrought material. These features, which 

 result from the particular physical arrangements of the component parts 

 make possible the relatively quiet operation of the drive-bar governor. 

 Experience with dials eciuipped with drive-bar governors indicates that 

 they are effective since the noise due to chattering has been satis- 

 factorily reduced so as to not be objectionable. 



SUMMARY 



This study has carried forward the work of C. R. Moore by presenting 

 the derivation of theoretical equations which define speed for the drive- 

 bar type governor. Design considerations necessary for optimum speed 

 regulation indicated by the theory were applied in establishing the shape 

 and working relationship of various components in the drive-bar gover- 

 nor. Governors constructed to these dimensions have operated as forecast 

 by the theory. The excellent agreement between theory and practice 

 indicates that it is both desirable and practicable to apply the Moore 

 theory in the design of governors. 



The initial requirements imposed on the design of a governor for the 

 7-type dial were two-fold. The new governor had to provide speed regu- 

 lation at least equal to the conventional fly-bar type and no objectionable 

 noise could be created by the governor during operation. To better under- 

 stand the reasons for noise in governors, suitable theory was developed 

 for investigating this phenomenon. Application of this theory to any 

 type governor results in an equation which defines chatter in terms of 

 the constants of the governor. This equation and the ecjuations deter- 

 mined by the Moore theory for speed regulation indicate the existence 

 of an interrelationship between speed regulation and noise in governors. 

 The theory indicates that noise free operation and good regulation are 

 totally at variance. The fly-bar governor supports this conclusion since 

 this governor having fine control of speed also produces a chattering 

 noise during operation. To satisfy both requirements, good regulation 

 and quiet operation, it is first necessary to design a governor which will 

 regulate properly and secondlj^, if the constants selected indicate that 

 chattering will occur, prohibit excessive noise by providing means for 

 restraining the system during the unstable period. 



This method of attack was taken in the design of the new drive-bar 

 governor. By applying the Moore theory, a governor was developed for 



