Automobile Engineering in ME
It is necessary to maintain the valve clearances as they

Allow for lengthening of the valves owing to the heat of combustion
Increase the speed at which the valves move up and down
Make the crankshaft turn smoothly
Reduce the resistance to sliding that occurs between the cam and the tappet

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Automobile Engineering in ME
The function of a first compression ring (top ring) is that it

Creates swirl
Increases the combustion temperature
Maintains a seal and prevents escape of burned gases and loss of pressure in the combustion chamber
Maintains a seal and prevents the fuel leakage

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