Question 97Motor Plants - QMED

The correct answer is C) reduce high diesel engine RPM to an efficient propeller RPM. The main purpose of the reduction gears in a ship's diesel engine system is to convert the high rotational speed of the diesel engine (typically 800-1200 RPM) to a lower, more efficient rotational speed for the ship's propeller (typically 100-300 RPM). This reduction in RPM allows the propeller to operate at its optimum efficiency, providing the best thrust and fuel economy for the vessel. The other answer choices are incorrect because: A) the reduction gears do not transmit vibration or thrust to the hull, B) the reduction gears do not provide a means of reversing the engines, and D) the reduction gears do not reduce engine room noise levels, which is typically accomplished through other sound-dampening measures.