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5 Facts About Pistons


WmHeffernan's Avatar
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Join Date: May 2004
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11-14-04, 01:43 AM   #1  
5 Facts About Pistons

My son is doing a project for school in which he has to choose 5 items to tell his class about. He is 8 years old and loves engines. He is doing his project on pistons. He has to give 1 fact about each of his 5 pistons. This part is easy as he will tell everyone what kind of a machine each piston came from. i.e. an edger, mower, leaf blower, etc. Secondly, he has to give 5 facts about pistons in general. We have a couple/few facts so far: 1. most pistons are made from aluminum (is this true?). 2. The piston is set in motion by the spark plug exploding the fuel. 3. Pistons are lubricated by oil. Anyone have any ideas for a couple more easy facts? What purpose does the piston ring serve? I think I know, but I'm not sure. I thought that answer would be an easy fact.

Thanks,
William

 
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fire-medic8104's Avatar
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11-14-04, 03:19 AM   #2  
fire-medic8104
The piston ring ensures a seal against the piston wall since the piston is smaller than the bore. The piston ring also scrapes oil down, so a minimal amount is burned during the combustion cycle.

Also how about, explain the combustion cycle: intake, combustion, power, exhaust.

Explain about the indentions in the piston are for the valves. Just a few suggestions.

 
davo's Avatar
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11-14-04, 05:05 AM   #3  
Yes pistons are made of aluminum and are either cast by melting aluminum into a mold or forged by taking powdered aluminum and compressing it under extreme pressure.Forged pistons are stronger by the way.Pistons also have to have a pin to float(pivot)on so they can go up and down the cylinder without binding.4 cycle engines have 2 types of rings on the piston compression rings and an oil ring.2 cycle engines only have compression rings because the lubricating oil is in the fuel mixture not the crankase.Just to clear it up on 4 cycle engines the combustion cycle is intake,compression,power and exhaust I'm sure that's what fire-medic meant.

 
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11-14-04, 05:15 AM   #4  
The Piston is not "round". It is elliptical shaped, this makes it tight in the bore when cold and expands to "round" when it warms up.

This is to lessen piston slap when cold.

 
WmHeffernan's Avatar
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11-14-04, 08:42 AM   #5  
Thank you all for your replies. I knew this was/is a great place to go to get some answers/suggestions.

William

 
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