Detailed Operation of the Governor:

With the engine operating, oil from the engine lubrication system is supplied to the governor pump gears, as illustrated in Figure. The pump gears raise the oil pressure to a value determined through the spring relief valve. The oil pressure is maintained within the annular space among the undercut portion of the pilot valve plunger and the bore in the pilot valve bushing. For any provided speed setting, the spring speeder exerts a force which is opposed through the centrifugal force of the revolving flyweights. While the two forces are equivalent, the control land at the pilot valve plunger covers the lower ports in the pilot valve bushing.