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VALVES In IC ENGINES

 Valves are used for closing and opening passage of the cylinder. There are two valves in an engine   cylinder namely the inlet and exhaust valves. Fresh air - fuel mixture or air alone enters into the cylinder   through inlet valve. Exhaust gases are forced out through the exhaust valves. Valves are operated by cam   and rocker arm mechanisms. 




There are three types of valves : 

* Sleeve Valve 

* Rotary Valve 

* Tappet Valve

Tappet Valves are more commonly used. 

Normally, valves contains head (angular face ground 30* to 45*),   face , stem and spring retainer lock groove. The head of the inlet valve is the heat of the exhaust valve. Inlet valve is made of plain - nickel, nickel- chromium or chromium - molybdenum. The exhaust valve is rejected to more heat. Hence, it should be made of high heat resistance material like silicon-chrome steel, high speed steel, cobalt - chrome steel and tungsten steel. 


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