Upon an increase in speed of the shaft being regulated, the sleeve of centrifugal governor 1 moves to the right, shifting valve spool 2 to the left. Hydraulic fluid is delivered to the valve by continuously rotating gear pump 3. The valve has negative overlap, since the width of the spool lands is somewhat less than the width of the ports in the valve body. In the central position of the spool, fluid flows past the lands and is drained to the tank. When the spool is shifted to the left, the clearance at the right edge of the left land increases and that at the left edge of the right land decreases. The fluid is admitted through the left land clearance into the left end of the servomotor; fluid from the right end is discharged to the tank. Piston 4 moves to the right, actuating the regulating member so that the shaft speed is reduced. This also turns lever 5 to put the frictional transient feedback mechanism 6 into operation. Upon a reduction in shaft speed, the elements of the regulator operate in the reverse direction.
$4263$CHP,Rg$