What are pistons in a car used for?

MaggieG 5

This site explains fairly simply, but in too much detail to produce here, how the internal combustion engine works. The pistons are an important part of that. http://www.familycar.com/engine.htm Mar 20 05, 3:29 PM

McGruff

Here's another site than explains how engines work. http://auto.howstuffworks.com/engine.htm Mar 20 05, 3:32 PM

Baloo55th

They go up and down (or side to side in a Beetle, cos the engine's on its side in those). What causes them to go down is the burning of a mixture of fuel and air above them, which expands rapidly and forces the piston down. They come back up cos they're attached to a shaft which goes round and round. In a normal four stroke engine, first stroke is down with no spark, pulling mixture in. Second stroke is up, which squashes things up (and increases the heat as a result - diesel engines use that heat instead of sparks). Third stroke is the power one. Fourth stroke is back up, pushing the burnt mixture out. (There's an arrangement of valves that open and shut to sort all this out.) Obviously, the first two strokes have to be powered from outside when starting up. With four cylinders, each revolution has one of each stroke in it, one per cylinder. How five cylinder engines do it, I don't know. The piston fills up most of the bore of the cylinder (that's the hole), but there are rings round the piston that fill up the last bit of gap, and adjust to wear. When the rings get worn, you tend to get lower power and blue smoke as you will be burning oil that doesn't get pushed back down by the rings. Mar 20 05, 3:32 PM

RickF

They could also be used - in the appropriate hydraulic systems - to operate the brake and clutch. Mar 21 05, 9:19 AM

Baloo55th

Trying to remember when I last saw a hydraulic clutch! Mar 21 05, 11:59 AM