Question 115Motor Plants - Assistant Engineer

The correct answer is C) against the crosshead during the power and compression strokes. In a large slow-speed propulsion diesel engine, the force applied to the piston is directed against the crosshead during both the power stroke and the compression stroke. This is because the piston is connected to the crosshead through the connecting rod, and the force exerted by the expanding gases during the power stroke is transmitted to the crosshead, pushing it downward. Similarly, during the compression stroke, the force required to compress the air-fuel mixture is also directed against the crosshead. The other options are incorrect because they do not accurately describe the direction of the force applied to the crosshead during the power and compression strokes.