1284 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1954 



developed similarly to give 



do3 

 dG 



lid 



2 



fxc) 



MfjiO} 



(14) 



Here also the design constants, 7n, ro , r and h, the coefficient of fric- 

 tion n, and the governor speed co, should all be high values. Minimum 

 change in dial speed would then occur for a given change in the input 

 torque. 



Inspection of the equations for do)/dG, indicates that it is possible to 

 have perfect torque regulation for at least one value of n. For this limit- 

 ing condition, doi/dG, would equal zero and equation (13), for the drive- 

 bar governor, equates to 



d — fxc — ixrj/e = (15) 



and equation (14) for the fly-bar type governor 



d — fxc = 



(16) 



If these equations were satisfied, there would be zero change in speed 

 for a given change in input torc^ue to the governor. As stated previously 

 n is predetermined and has in this design a maximum known value of 

 0.35. A margin of safety is considered by taking n = 0.425 for the limit- 

 ing case and equation (15) becomes for the new drive-bar governor 



d - 0.425 (c -f rj/e) = 

 and equation (16) for the fly-bar governor 



d - 0.425 c = 



(17) 



(18) 



dco 

 dG 



20 30 40 50 60 70 80 90 100 



GOVERNOR INPUT TORQUE IN DYNE CENTIMETERS 



120 

 XlO^ 



Fig. 8 — Derivative of governor speed with respect to coefficient of friction 

 versus input torque to the governor. 



