Underspeed On speed Overspeed  and feathering Drain Pressure Relief valve (set 275 psi) Adjusting worm Pilot valve plunger Minimum rpm adjustment (feathering valve adjustment) Lift rod Speed adjusting control lever Drive gear shaft Bypass plug A (part 187824) Engine oil inlet Passage C Propeller control line Bypass plug B Counterweight head Toe Flyweight Speeder spring Oil supply tap for unfeathering and reversing Figure 7-16.  Typical governor.  the governor counterweights and the tension on the speeder  spring are equal; the propeller blades are not moving or  changing pitch. If something happens to unbalance these  forces, such as if the aircraft dive or climbs, or the pilot selects  new rpm range through the propeller control (changes tension  on the speeder spring), then these forces are unequal and an  underspeed or overspeed condition would result. A change  in rpm comes about in the governing mode by pilot selection  of a new position of the propeller control, which changes  the tension of the governor speeder spring or by the aircraft  7-11