Question 65 MODE01 - Chief MODU Engineer

The Correct Answer is C ### Why option C ("Piece #9") is correct: Piece #9 in the typical illustration of a mechanical-hydraulic governor (like the Woodward PG or similar designs) represents the **flyweights** (or sometimes referred to as the speed sensing element). The flyweights are attached to a rotating vertical shaft driven by the engine. When the engine speed changes (due to a change in load), the centrifugal force acting on these flyweights changes almost instantaneously. If the speed increases, the flyweights move outward; if the speed decreases, they move inward. This movement is transmitted via linkages (like Piece #8) to the pilot valve (Piece #7), making the flyweights the **first component** in the governor system to physically react to the change in engine speed. ### Why the other options are incorrect: * **A) Piece #7:** Piece #7 typically represents the **pilot valve plunger**. This plunger controls the flow of pressurized oil to the power cylinder (Piece #10). It only moves *after* the flyweights (Piece #9) sense the speed change and transmit their motion through the linkages (Piece #8). Therefore, it is not the first component to react. * **B) Piece #8:** Piece #8 represents the **speeder rod, linkage, or thrust bearing**. This component acts as the intermediary mechanism, linking the movement of the flyweights (Piece #9) to the pilot valve plunger (Piece #7). While it moves simultaneously with the flyweights, the flyweights themselves are the primary speed-sensing elements generating the initial force/movement. In the sequence of causation, the flyweights react first, causing Piece #8 to move. * **D) Piece #10:** Piece #10 typically represents the **power piston (or servomotor)**, which is the output element of the hydraulic section. It physically moves the fuel rack or linkage to adjust the fuel supply. The power piston only moves *after* the pilot valve (Piece #7) directs pressurized oil to it, making it one of the last components to react in the control sequence.