Question 17 3AE01 - Third Assistant Engineer

The Correct Answer is C **Why Option C is Correct:** The stationary parts of a diesel engine—such as the cylinder block, cylinder head, and crankcase (or engine frame)—form the rigid structural foundation of the engine. Their primary function is to provide the necessary structure and mounting points to hold the moving parts (like the pistons, connecting rods, and crankshaft) precisely in place. This fixed structure ensures that the moving parts maintain their correct alignments, clearances, and relative positions, which is essential for the engine's proper timing, compression, and mechanical operation. **Why the Other Options are Incorrect:** * **A) To add power to the engine.** Stationary parts do not add power; they merely contain the forces generated by the combustion of fuel. Power generation is the function of the combustion process acting upon the moving parts (pistons and crankshaft). * **B) To keep the engine firmly attached to its auxiliary pumps.** While stationary parts (the block or crankcase) provide mounting locations for auxiliary equipment (like oil pumps, water pumps, etc.), this is a secondary function. The primary structural role is maintaining the integrity and alignment of the core combustion and power-conversion mechanism. * **D) To rotate the crankshaft.** Rotating the crankshaft is the function of the combustion process driving the pistons, which are linked to the crankshaft via the connecting rods (all moving parts). The stationary parts hold the crankshaft bearings in place but do not contribute to its rotation.