DTNA Base Engine Practice Exam 2025 - Free Base Engine Practice Questions and Study Guide

The correct answer is that the APT (Auxiliary Power Transmission) transfers power to the crankshaft through a reduction gearset and a fluid coupler. This method is particularly effective because it allows the system to convert the high-speed rotation of the engine into a lower-speed, higher-torque output suitable for the crankshaft.

The reduction gearset reduces the rotational speed while simultaneously increasing the torque, which is an essential function to ensure that the power delivered is effective and appropriate for vehicle operation. Additionally, the fluid coupler, often a type of torque converter, provides smooth engagement and allows for slip during acceleration, which helps to reduce shock loads on the engine and improve efficiency.

This combination of a reduction gearset and a fluid coupler ensures that the power transfer is not only effective but also smooth, which enhances vehicle performance and operational reliability. The design also supports better fuel efficiency and allows the engine to run at optimal RPMs, contributing to overall engine longevity and effective power delivery.