A GOVERNOR FOR TELEPHONE DIALS 



1291 



20 30 40 50 60 70 80 90 100 



GOVERNOR INPUT TORQUE IN DYNE CENTIMETERS 



120 

 XIO-' 



Fig. 13 — Dial speed versus governor input torque. 



suspended from the fingerwheel at %" radius and released. Average 

 experimental speeds were recorded for the three forcing conditions and 

 are noted in Fig. 13 for both the fly-bar and the new drive-bar governors. 

 Good agreement, between the theoretical and experimental values, is 

 evident. For a forcing condition of fifteen times normal motor spring 

 torque, an average speed of 15.6 pulses per second is shown for the fly-liar 

 governor Avhile an average speed of 13.4 pulses per second is noted for 

 the drive-bar type. Theoretically the speeds should be 15.3, and 13.2, 

 respectively. This type agreement is also present for the 1 and 3 lb 

 forcing conditions, and therefore, it may be concluded that for any input 

 torque resulting from forcing the fingerwheel a dial equipped with a 

 drive-bar governor will exhibit less speed increase than one having the 

 flj^-bar governor. 



The theoretical analysis indicates that for the torque available during 

 normal rundown, drive-bar governors as specified in Table I will de- 

 crease in speed from 10.00 to 9.80 pulses per second and fly -bar governors 

 as specified in Table III will decrease in speed to 9.70 pulses per second. 

 These theoretical speed changes were checked experimentally hy record- 

 ing on a rapid record oscillograph a trace of the make and break times of 

 the pulsing contacts during rundown of the dial from digit zero. This 

 information was used to determine the average dial speed in pulses per 

 second for each seciuence of make and break times. Actual loss in speed 

 from the first to the ninth pulse for dials equipped with drive-bar gover- 



