What are the four strokes of a four-stroke reciprocating engine?

What are the four strokes of a four-stroke reciprocating engine?

• A. Intake, compression, power, and exhaust.
• B. Compression, intake, exhaust, power.
• C. Intake, exhaust, compression, power.
• D. Power, intake, compression, exhaust.

Answer: (A)

The four-stroke engine operates in a specific, repeating order: intake, compression, power, and exhaust. During the intake stroke, the piston moves down and the intake valve opens to draw in air (or air-fuel mixture) filling the cylinder. Next comes the compression stroke, where the piston moves up with the valves closed, compressing the mixture to a high pressure. The power stroke follows, after ignition, as the combusted gases push the piston down and create usable work. Finally, the exhaust stroke pushes the burnt gases out through the exhaust valve as the piston moves up again. This sequence—intake, compression, power, exhaust—occurs with each cycle and is essential because you must first admit the mixture, then compress it, ignite and expand it to produce power, and only then expel the combustion products. Other sequences would require air or exhaust to occur out of order, which isn’t how the cycle functions.

The four-stroke engine operates in a specific, repeating order: intake, compression, power, and exhaust. During the intake stroke, the piston moves down and the intake valve opens to draw in air (or air-fuel mixture) filling the cylinder. Next comes the compression stroke, where the piston moves up with the valves closed, compressing the mixture to a high pressure. The power stroke follows, after ignition, as the combusted gases push the piston down and create usable work. Finally, the exhaust stroke pushes the burnt gases out through the exhaust valve as the piston moves up again. This sequence—intake, compression, power, exhaust—occurs with each cycle and is essential because you must first admit the mixture, then compress it, ignite and expand it to produce power, and only then expel the combustion products. Other sequences would require air or exhaust to occur out of order, which isn’t how the cycle functions.