What Do Engines Do? Part 3: Turn the Key

What Do Engines Do? Part 3: Turn the Key


You step into the car and turn the key.  Nothing happens.  Which is when you realize that your headlights were on all night and your battery is drained.  Now your car will never start!  But wait… why do you need the battery to start the car anyway?


The Key to the Engine


After all, a car engine is mostly self-sustaining.  The crankshaft turns because of the power provided by spark plugs igniting fuel and driving down pistons.  There’s no electricity in any of that.  But here’s the thing – you need to “turn it over” before the engine can start moving itself.  So the process when you turn the key is simple.


A Bit of Battery


The key turning sends a signal to the Starter Solenoid.  This pulls energy from your battery to the starter motor.  On the starter motor, a small gear spits out and turns quickly, making the large flywheel rotate.  The flywheel is connected to the crankshaft, which is connected to the pistons.  As the flywheel turns and the crankshaft rotates, pistons are pulled downward which makes the cylinders take in air.  The air is combined with gas, compressed, sparked and exploded, the pistons are shoved down, and there you go, your engine is up and running!


Power Down


When you turn the engine off, it disengages the spark plugs.  No more spark means no more explosions, no more explosions mean no more power, and no more power means your car can stop.


There you have it, the basics of turning cars off and on, and how your engine runs.  Also, the importance of your car battery – if you don’t have a battery, your flywheel is going nowhere.  But that’s not all there is to an engine – things go wrong.  What happens when they do?  We’ll be back with more on that next time.



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