Question 383Motor Plants - Assistant Engineer

The correct answer is B) 3 and 4. The air scavenging of the cylinder shown in the illustration begins between figures 3 and 4. This is because the piston is moving downwards in figure 3, drawing in a fresh air charge, and then in figure 4 the piston is moving upwards, expelling the exhaust gases and allowing fresh air to enter the cylinder. The other answer choices are incorrect because: A) Air scavenging does not begin between figures 2 and 3, as the piston is still moving downwards in figure 2. C) Air scavenging does not begin between figures 4 and 5, as the piston is already in the upward stroke in figure 4. D) Air scavenging does not begin between figures 5 and 6, as the piston is already in the downward stroke in figure 5.