Which of the following methods is used to transfer drive from the crankshaft to the camshaft on most commercial diesel engines?

The method used to transfer drive from the crankshaft to the camshaft on most commercial diesel engines is through gears. Gears provide a direct and durable connection that ensures precise timing between the crankshaft and camshaft. This is crucial for the engine's operation, as the camshaft needs to be synchronized with the crankshaft to open and close the engine’s valves at the correct times during the combustion cycle.

Using gears also allows for the transmission of high torque and improves the reliability of the connection under the varying loads found in commercial diesel engines. The mechanical nature of gear systems means they have less wear compared to other methods, and they maintain close tolerances, ensuring consistent and accurate performance over time.

While other methods like timing chains and sprockets or belts and pulleys can also be used in various engines, gears are more commonly found in heavy-duty applications like commercial diesel engines due to their efficiency and durability. Fluid coupling is not a practical option for transferring drive between the crankshaft and camshaft, as it is designed for fluid power transmission rather than direct mechanical engagement.