How many revolutions does the crankshaft make for each complete cycle in a four-stroke Diesel engine?

How many revolutions does the crankshaft make for each complete cycle in a four-stroke Diesel engine?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

In a four-stroke Diesel engine, the crankshaft makes two revolutions for each complete cycle of operation. A complete cycle in this context includes four distinct strokes: intake, compression, power, and exhaust. During the first revolution of the crankshaft, the intake and compression strokes occur. The intake stroke draws in air, while the compression stroke compresses that air. The second revolution involves the power stroke, where the compressed air is ignited by diesel fuel, resulting in combustion that drives the piston down. Following this, the exhaust stroke expels the burnt gases from the cylinder, completing the cycle. This two-revolution process per cycle is fundamental to the functioning of a four-stroke engine, distinguishing it from two-stroke engines, where one revolution of the crankshaft corresponds to one complete cycle. Understanding this mechanism is essential for analyzing engine performance and efficiency.

In a four-stroke Diesel engine, the crankshaft makes two revolutions for each complete cycle of operation. A complete cycle in this context includes four distinct strokes: intake, compression, power, and exhaust.

During the first revolution of the crankshaft, the intake and compression strokes occur. The intake stroke draws in air, while the compression stroke compresses that air. The second revolution involves the power stroke, where the compressed air is ignited by diesel fuel, resulting in combustion that drives the piston down. Following this, the exhaust stroke expels the burnt gases from the cylinder, completing the cycle.

This two-revolution process per cycle is fundamental to the functioning of a four-stroke engine, distinguishing it from two-stroke engines, where one revolution of the crankshaft corresponds to one complete cycle. Understanding this mechanism is essential for analyzing engine performance and efficiency.