Agricultural Mechanics EOPA Practice Exam

A four-stroke cycle engine is characterized by completing its operational cycle in four distinct strokes of the piston: intake, compression, power, and exhaust. This design allows for efficient fuel combustion and engine operation.

During the intake stroke, the piston moves down, drawing in the air-fuel mixture. The compression stroke follows, where the piston moves up, compressing that mixture. The power stroke is initiated by igniting the compressed mixture, driving the piston down and creating the engine's power output. Finally, in the exhaust stroke, the piston moves back up to expel the combustion gases. This sequential process is what distinguishes four-stroke engines from others, particularly two-stroke engines, which complete a cycle in just two strokes.

Other options, such as operating on two strokes or being exclusively powered by diesel fuel, do not accurately depict the functioning of a four-stroke engine. The engines can actually run on various types of fuel, not limited to diesel, and they involve a more complex cycle compared to two-stroke engines. The four-stroke design is widely recognized for its efficiency and is commonly found in many automotive and agricultural applications.