Governor oil pressure Centrifugal twisting moment Low pitch Engine oil pressure 1. Centrifugal twisting moment 2. Engine oil pressure 3. Governor oil pressure Battery Solenoid relay Oil tank Pressure cutoff switch Holding coil Feathering button Oil pump Figure 7-57.  Typical feathering installation.  Figure 7-56.  Diagram of hydromatic propeller operational forces.  When the engine speed has increased to approximately 1,000  rpm, the operator shuts off the feathering pump motor. The  pressure in the distributor valve and at the governor transfer  valve decreases, allowing the distributor valve to shift under  the action of the governor high-pressure transfer valve spring.  This action reconnects the governor with the propeller and  establishes the same oil passages through the distributor valve  that are used during constant-speed and feathering operations. The propeller governor incorporates an adjustable stop that  limits the maximum speed at which the engine can run. As  soon as the takeoff rpm is reached, the propeller moves off the  low-pitch stop. The larger propeller blade angle increases the  load on the engine, thus maintaining the prescribed maximum  engine speed. At the time of propeller, propeller governor,  or engine installation, the following steps are normally taken  to ensure that the powerplant obtains takeoff rpm. During  ground runup, move the throttle to takeoff position and note  the resultant rpm and manifold pressure. If the rpm obtained  is higher or lower than the takeoff rpm prescribed in the  manufacturer’s instructions, reset the adjustable stop on the  governor until the prescribed rpm is obtained. With the inboard end of the propeller piston connected to  drain and auxiliary pressure flowing to the outboard end of  the piston, the piston moves inboard, unfeathering the blades.  As the blades are unfeathered, they begin to windmill and  assist the unfeathering operation by the added force toward  low pitch brought about by the centrifugal twisting moment.  7-41 Setting the Propeller Governor