Lesson 2/Learning Event 2
FIGURE 49. EXHAUST STROKE.
About halfway down on the power stroke, the exhaust valves open and some of the gases rush out through the
open valves. The piston continues down until the inlet ports are uncovered. The air blower then forces clean
air in, clearing the rest of the exhaust gases from the cylinder. The piston then starts back up first covering the
intake ports and, then, as the exhaust valves close, starts the compression once again. As you can see, all four
events--intake, compression, power, and exhaust--take place during two strokes of the piston and one turn of
the crankshaft in this engine.
In this lesson, you learned there are two types of compression-ignition engines. They are the straight diesel and
the multifuel types. You were also instructed on their operation and basic parts.
Now review the lesson once more; then take the practice exercise and grade yourself. If you have any problem
on the exercise, reread the lesson.
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