Question 394Motor Plants - Assistant Engineer

The correct answer is C) decrease to a slightly lower value. If governor Item No.19 in the illustration were to break on a diesel engine operating under full load, the engine RPM would decrease to a slightly lower value. This is because the governor is responsible for maintaining the engine RPM at the desired setpoint. When the governor fails, the engine is no longer able to maintain the full load RPM, and the RPM will drop slightly to a new, lower equilibrium value. The other answer choices are incorrect. The engine RPM would not increase until the overspeed trip actuated (A), as the governor failure would cause a decrease in RPM, not an increase. The engine would not "hunt until stabilized by droop rod" (B), as the droop rod is part of the governor system that has failed. The RPM would not remain the same until manually changed (D), as the governor failure would immediately cause the RPM to decrease.