Pump 1 delivers hydraulic fluid to boiler 2 which is filled partly with fluid and partly with air, and serves as an accumulator. Upon normal pressure in the boiler, by-pass valve 3 directs fluid from the boiler back to the tank. When the pressure drops in the boiler, valve 3 closes and fluid is delivered by the pump into boiler 2. Fluid from the boiler is directed to the valve of spool 9, which has positive overlapping. The width of the lands on the spool is somewhat greater than the width of the valve ports. In the central position of spool 9 its lands block off the ports in the valve body and no fluid flows in from the boiler. Upon a change in speed, the sleeve of centrifugal governor 4 moves to the right or left, shifting valve spool 9 by means of lever 5. Fluid delivered to the valve is directed to servomotor 6, moving piston 7 and turning the regulating member. As piston 7 moves, lever 8 puts the frictional transient feedback mechanism into operation.
$4262$CHP,Rg$