When the air required for the combustion stroke of the stacker engine is sucked into the cylinder, which of the following is used to filter the dust and prevent the cylinder and piston from being worn?

The air filter plays a crucial role in the operation of a stacker engine by ensuring that the air entering the combustion chamber is clean. During the combustion stroke, air is drawn into the cylinder, and if this air contains dust and other particles, it can cause significant wear and damage to the cylinder and piston over time. The air filter effectively removes these contaminants from the incoming air, helping to maintain the engine's performance and extend its lifespan.

This filtering process is essential because any dirt or debris can lead to increased friction and abrasion within the engine components, ultimately resulting in costly repairs or diminished operational efficiency. By using an air filter, the engine can operate smoothly and efficiently, ensuring that only clean air enters the combustion chamber while preventing premature wear and tear.

The other options serve specific functions that do not pertain to filtering the air for the combustion process. An oil filter cleans the engine oil, a fuel filter cleans the fuel before it enters the combustion chamber, and a hydraulic filter is used in hydraulic systems to clean the hydraulic fluid. None of these are responsible for filtering the air, which makes the air filter the correct choice for this function.