The governor is a pressure compensated throttle. It has a fixed valve and throttle valve in series. Throttle valve before and after the pressure were cited to the right and left ends of the valve spool, when the load pressure increases, so the role of pressure in the left end of the spool valve hydraulic pressure increases, the valve spool to the right, decompression port Increase, the pressure drop is reduced, so that the throttle pressure difference (p2-p3) remains unchanged; and vice versa. This is the governor valve flow is constant (not affected by the load).