GOVERNORS 335 
For the Porter governor, piWene eee: 4, 
WtRtw. g 
ke ee 
The formule just given for the Porter governor will also apply to the 
simple governor when the upper joints of the suspension links are at the 
centres of the pendulum weights, but W will 
then be the weight of the sleeve. If the 
suspension links are jointed to the pendulum 
arms, as shown in Fig. 526, then W+R must 
be changed to (W+R). The reason for the 
foregoing statement will be obvious from the 
following considerations. Draw AC parallel 
to A’C’. Let T’* be the tension in the 
suspension link when it is at A’C’, and let 
T be the tension in that link when it is 
transferred to AC. Then since the moment 
of T’ about B has to balance the moments Fic. 526. 
of F and w about B, also since the moment of 
T about B bas to balance the moments of F and w about B, it follows 
that T’a must be equal to T/, or T= 7 hence W +R at C’ must become 
and when 
q=1,h= 
(W+R)¥ at C. 
If the speed of a governor and the lift of the sleeve, or the lift of the 
pendulum weights, be plotted, (1) neglecting friction, and (2) taking the 
friction into account, instructive curves, such 
as are shown in Fig. 527, are obtained. HK age a 
1s the lift of the sleeve. When the sleeve is 
at Y the speed, say in revolutions per minute, —?t7— 
is YL when friction is neglected, YL, when 
friction is considered and the sleeve is de- —K— 
scending, and YL, when friction is considered 
and the sleeve is ascending. Preferably the 
speeds are measured from a vertical axis some distance to the left of HK 
in order that a larger scale may be used for the speeds, and so cause the 
points L,, L, and L, to be further apart. The abscisse and ordinates of 
the curve ALB represent the speed and lift respectively when friction is 
neglected. The abscisse and ordinates of the curve A,L,B, represent 
the speed and lift respectively when friction is considered and the sleeve 
is descending. Lastly, the abscisse and ordinates of the curve A,L,B, 
represent the speed and lift os ica when friction is considered and 
the sleeve is ascending. 
287. Sensitiveness of Governors. —The greater the change in the 
level of the revolving balls of a governor for a given percentage or 
fractional change in speed the greater is its sensitiveness, and the 
sensitiveness may be defined as the change in level of the revolving balls, 
due to a change of speed of, say, 1 per cent. 
Consider the case where the axis of the top joint intersects the main 
Fig. 527. 
