🔍 Key Concepts

• Study how a two-stroke diesel uses exhaust ports in the cylinder liner near the bottom of the stroke. • Follow the crank position and piston height from Fig. 1 through Fig. 6 to see the sequence of events. • Focus on when the piston first starts to clear the rectangular ports in the liner wall, allowing exhaust to escape.

💭 Think About

• In which figure is the piston moving downward and just about to reach bottom dead center (BDC), with the top edge of the piston just starting to expose the ports? • Compare the ports’ visibility in each figure: in which earlier figure are they still fully covered, and in which later figure are they already well open? The answer must be the first figure between those two. • Look at the flow arrows around the ports: where do you first see an exhaust flow path from the cylinder into the exhaust passage through those side ports?

✅ Before You Answer

• Verify which side openings in the liner are the exhaust ports (not the scavenge air inlets). • Check that in your chosen figure the ports are only just beginning to show above the piston crown—not still fully covered and not already widely open. • Confirm the sequence order of Figs. 1–6 by watching crank rotation and valve movement, then choose the earliest figure in that order where any part of the exhaust port is uncovered.