1290 THE BEIL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1954 



of friction to values between 9.65 and 12.0 piils(;s per second during life 

 for dials initially adjusted to 10.00 pulses per second. An increase in speed 

 may result from a decrease in stud friction due to the existence of lubri- 

 cant or high humidity in the stud operating region or, the speed may 

 decrease due to high friction. 



The above changes represent the extremes in dial speed determined 

 solely by reaction of the governor to change in stud friction. In practice 

 it is anticipated that dials adjusted to 10 pulses per second initially can 

 vary from 9 to 11 pulses per second during normal usage. A reduction in 

 speed will occur as more torque is required to compensate for the in- 

 crease in bearing friction caused by the accumulation of dirt and wear 

 products during ordinary life. This additional bearing drag will cause a 

 decrease in the torc^ue available for governoring and therefore the dial 

 will be regulated at reduced speed. For extreme cases of wear and con- 

 tamination, it is of course possible that the dial will stop altogether dur- 

 ing run-down. Such cases are not controllable by the governor. They 

 result from the expected attrition during extended life or unfavorable 

 environment. 



To guard against excessive increase in dial speed from the value at 

 time of initial adjustment, precaution is taken during manufacture. As 

 stated previously, lubricant traveling into the governor case after initial 

 adjustment will cause a marked increase in dial speed. To avoid this 

 sort of contamination, the governor case is washed after machining and 

 swabbed with clean chamois prior to insertion of the governor onto the 

 shaft. Care is also taken to see that no lubricant is placed in the governor 

 case during lubrication of the shaft bearings. These practices assure that 

 initially the friction surfaces are relatively free from contamination. The 

 increase in dial speed up to the 11 pulses per second possible during dial 

 life will result primarily as a result of stud wear, increase in efficiency of 

 the mechanism, and operation during periods of high humidity. 



Dial Speed Versus Governor Input Torque 



To substantiate the theoretical conclusion that the drive-bar governor 

 should exhibit better regulation due to changes in input torque, experi- 

 mental data were compiled on the dials equipped with the two type 

 governors. The results of this test are plotted on Fig. 13, along with 

 theoretical forcing curves for both governors. A coefficient of friction 

 value of 0.25 was assumed in arriving at the theoretical curves. 



The dials were initially adjusted to 10.00 pulses per second by bending 

 the governor spring to have proper tension. Loads of 1, 3 and 5 lb were 



