Reset spring Reset piston Feathering solenoid valve Counterweights Speed adjusting screw Governor spline drive Speed reset solenoid Speeder spring From CSU Reduces spring tension = lower O/S Speed reset oil activation Figure 7-54.  Propeller overspeed governor.  switch breaks the solenoid relay circuit, which shuts off the  feathering pump motor. The pressures in both the inboard  and outboard ends of the piston drop to zero, and, since all  the forces are balanced, the propeller blades remain in the  feathered position. Meanwhile, the governor high-pressure  transfer valve has shifted to its normal position as soon as  the pressure in the propeller governor line drops below that  required to hold the valve open. cam tracks used. (The low mechanical advantage portion lies  between the break and the outboard end of the track profile.)  Oil at engine pressure, displaced from the outboard piston  end, flows through the distributor valve outboard inlet, past  the outboard end of the valve land, through the valve port, into  the propeller shaft engine oil passage, and is finally delivered  into the engine lubricating system. Thus, the blades move  toward the full high-pitch (or feathered) angle. Having reached the full-feathered position, further movement  of the mechanism is prevented by contact between the high- angle stop ring in the base of the fixed cam and the stop  lugs set in the teeth of the rotating cam. The pressure in the  inboard piston end now increases rapidly, and upon reaching  a set pressure, the electric cutout switch automatically opens.  This cutout pressure is less than that required to shift the  distributor valve. To unfeather a hydromatic propeller, depress and hold in the  feathering switch push-button control switch. As in the case  of feathering a propeller, the low-current control circuits  from the battery through the holding coil and from the  battery through the solenoid are completed when the solenoid  closes. The high-current circuit from the battery starts the  motor-pump unit, and oil is supplied at a high pressure to  the governor transfer valve. Opening the switch deenergizes the holding coil and releases  the feathering push-button control switch. Release of this  7-39 Unfeathering Operation