The four steps are like this:
1) The piston starts at the top, the intake valve opens, and the piston moves down to let the engine take in a cylinder-full of air and gasoline. This is the intake stroke. Only the tiniest drop of gasoline needs to be mixed into the air for this to work. (Part 1 of the figure)
2) Then the piston moves back up to compress this fuel/air mixture. Compression makes the explosion more powerful. (Part 2 of the figure)
3) When the piston reaches the top of its stroke, the spark plug emits a spark to ignite the gasoline. The gasoline charge in the cylinder explodes, driving the piston down. (Part 3 of the figure)
4) Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder to go out the tailpipe. (Part 4 of the figure)
My questions:
1) What opens the intake valve? What moves the piston down?
2) What moves the piston back up?
3) Now I see that the piston moves down because of the explosion.
4) What moves the piston back up? And what opens the out valve?
1) The piston starts at the top, the intake valve opens, and the piston moves down to let the engine take in a cylinder-full of air and gasoline. This is the intake stroke. Only the tiniest drop of gasoline needs to be mixed into the air for this to work. (Part 1 of the figure)
2) Then the piston moves back up to compress this fuel/air mixture. Compression makes the explosion more powerful. (Part 2 of the figure)
3) When the piston reaches the top of its stroke, the spark plug emits a spark to ignite the gasoline. The gasoline charge in the cylinder explodes, driving the piston down. (Part 3 of the figure)
4) Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder to go out the tailpipe. (Part 4 of the figure)
My questions:
1) What opens the intake valve? What moves the piston down?
2) What moves the piston back up?
3) Now I see that the piston moves down because of the explosion.
4) What moves the piston back up? And what opens the out valve?