In the four-stroke power cycle, the downward movement of the piston is known as:

In a four-stroke power cycle, the downward movement of the piston during the intake phase is specifically referred to as the intake stroke. This phase occurs after the piston has completed the previous compression stroke and goes down to create a vacuum in the cylinder. As the piston moves down, the intake valve opens, allowing a mixture of air and fuel to enter the combustion chamber.

Understanding this phase is crucial because it sets up the engine for the power generation that occurs in the subsequent strokes of the cycle. The intake stroke is characterized by the engine drawing in fresh air-fuel mixture, which is essential for the subsequent combustion that drives the piston back up in the next phase of the cycle, ultimately producing power.

The other phases, such as power stroke, compression stroke, and exhaust stroke, follow in the correct order. Each has its specific role in the four-stroke cycle, but the downward movement that specifically allows the intake of the air-fuel mixture is defined as the intake stroke.