Question 20 3AE01 - Third Assistant Engineer

The Correct Answer is A. **Explanation for A (fuel oil pump):** In large, slow-speed main propulsion diesel engines (like a two-stroke crosshead engine, which MO-0003 typically depicts), the fuel injection system is critical. Each cylinder has a dedicated high-pressure fuel pump designed to meter and inject fuel precisely at the extremely high pressures required (often 1000–2000 bar or more). In standard engine layouts (like MAN B&W or Wärtsilä-Sulzer designs), the fuel pumps are mounted high on the engine block, often driven directly by the camshaft (if applicable) or by a dedicated mechanism. The location labeled "G" in standard illustrations of this type of engine configuration points directly to one of these large, reciprocating, high-pressure fuel oil pumps located near the top middle section of the cylinder unit, responsible for delivering fuel to the injector (fuel valve) in the cylinder head. **Why the other options are incorrect:** * **B) jacket water pump:** The jacket (cooling) water pumps are typically large centrifugal pumps located off the engine block in the engine room, responsible for circulating the cooling water through the engine’s jackets and cylinder heads. They are rarely small components mounted individually high on the block like the part labeled G. * **C) lube oil pump:** The main lubrication oil pumps (for bearings and crosshead) are usually large displacement pumps (gear or screw type) located low down in the engine room or built into the engine base (sump), designed to move very high volumes of oil. The location G is too high and the component is sized incorrectly for a main lube oil circulating pump. * **D) crankcase exhaust fan:** The crankcase exhaust (or ventilation) fan is used to maintain a slight negative pressure in the crankcase to prevent oil mist escape. This is typically a small, separate electrical fan unit mounted near the crankcase relief valves or venting system, not a large reciprocating pump mounted high on the cylinder section.