1294 THE BELL SYSTEM TECHXICAL JOURXAL, XOVEMBER 1954 



This expression must be satisfied if there is to be no chattering during 

 operation. A comparison of this ecjuation with that determined for the 

 fly-bar governor, equation (19), shows an additional term (nrj/e). Sub- 

 stitution of the design constants for the drive-bar governor given in 

 Table I leads to the following. 



, . < 7,500(0.390 - (0.25)(0.361) - (0.25) (1.18) (0.236)7(0.498)) 

 rf.y^y»Uj = 2(1.18)(0.25)(1.092) 



or 



3,820 dyne-cm ^ 1,862 dyne-cm. 



This indicates that instability should be present in this governor, and 

 that the additional term (nrj/e) causes a greater difference between the 

 mass term and the torque tenn, than for the conventional fly-bar gover- 

 nor. This is to be expected, since for the drive-bar governor also, adequate 

 speed regulation, and a design w'hich has no chatter, are totally incom- 

 patible. The sensitivity of speed to torque change and changes in co- 

 efficient of friction, 



dd) _ 1 (d — fxc — ijLVJ/e) 

 dG ~ 2 McoM ~ 



and 



ao) Gd 



dfx 2Mo}fi 



were made as small as possible for best regulation and this results in a 

 small value to oppose chatter. 



This chatter analysis indicates that a new approach in design is 

 needed in order to provide a governor which will operate without 

 excessive noise and still regulate speed as required for use in the 7-type 

 dial. This is found in a design which prohibits rapid movement of the 

 governor weights during the unstable period. 



Referring to the assembly drawing of the drive-bar governor, Fig. 3, 

 which shows the governor in the rest position, one can see that each 

 governor weigh rests on the end of one of the arms of the drive-bar. By 

 supporting the weights in this manner the following two beneficial effects 

 are achieved. One, during operation in new assemblies, the weights mov^e 

 outward to touch the case only a nominal distance of 0.007". This small 

 allowable motion in the drive-bar governor results in a low velocity of 

 the weight at closure and hence, less impact noise. Two, because the 

 drive-bar presses to rotate the governor weights, impact occurs as the 



