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One small movement.

January 14, 2011

It’s amazing how a few small steps can be the start of a series of complicated movements.  However, when we examine those movements more closely, we can understand how they work, and they can appear less complicated.

My original aim with this blog was to target those who know very little about auto-mechanics and what makes a car operate.  Now that I’m in school, I’d like to take it a little further and use this as a forum to examine my own ideas about the subject, as well as the automotive industry itself.

Let’s talk about pistons and the four-stroke engine.

The majority of cars these days rely on a four-stroke internal combustion engine.  Internal combustion means just what it sounds like; combustion occurs within the engine, which gives the engine power.

The “four strokes” refer to intake, compression, power and exhaust.  These four strokes is what it takes for the engine to complete a full cycle.

With the intake phase, the piston (located within a cylinder) moves downward, and the intake valve opens to allow an air and fuel mixture to enter.

This sounds kind of complicated if you’ve never read these terms before, but I encourage you to look it up, because it’s really quite interesting.

The next stroke is compression.  When the piston is pushed back up, the air and fuel mixture is compressed to prepare it for ignition.  Ignition occurs just before the piston gets to the very top of the cylinder.  A lot of pressure comes from the expanding gases, which then forces the piston down again.  This is the power stroke, which essentially makes the engine “do work.”  When it moves up again, this is the exhaust stroke; the exhaust valve opens and the waste, or burned gases, is forced out of the chamber and into the exhaust system of the vehicle.

Cool, huh?

If you’re sitting there with a bemused expression on your face, consider this illustration:

The picture shows us the fuel and air mixture entering the chamber on the left, and on the right we see the compression of the fuel and air.  Below is the crankshaft, which is linked to a connecting rod that changes the movement of the pistons into a rotary motion in order to move the wheels.

I think that’s enough technical stuff for this evening.  However, I will be sharing more about how the engine works in future entries.

For now, you can also click here to take a look at this page, which has an animation of the four strokes in action.

Towards the end of this month, I’ll be going to a car show here in the Village, and hopefully I’ll have some neat photos to post.  For now, I think I’ll sleep on it.

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