🔍 Key Concepts

• Cross flow scavenging in two-stroke diesel engines • How ports differ from valves in opening/closing the cylinder to the exhaust or intake • The piston’s movement in relation to the port openings in the cylinder liner

💭 Think About

• Is a port usually opened by a separate mechanical valve gear, or simply uncovered by something moving past it? • In cross flow scavenged engines, what part of the engine actually passes across the exhaust ports during the stroke? • Which of the choices mentions a motion that is directly linked to uncovering and covering ports cut in the cylinder liner?

✅ Before You Answer

• Identify whether ports typically have valve stems and springs, or are just openings in the cylinder wall • Decide which answer choice describes the device that physically uncovers and covers the ports during the engine cycle • Eliminate any options that clearly relate to valve gear rather than simple liner ports