VALVE MECHANISMS USED IN ENGINES

The Valves are actuated by cams mounted on a cam shaft. Different types of valve operating mechanisms are

i) Side valve Mechanism

ii) Over head valve Mechanism

iii) Over head inlet and side exhaust valve mechanisms.

* Side Valve Mechanism

The cam mounted on the camshaft operates the valves tappet during its rotation. The valve tappet is pushed up. The valve tappet pushes the valves from its sheet against the spring force. Thus, the valve is opened. When the cam is not in action, the valve returns back to its seat by the valve spring and spring retainer.

* Over head Valve Mechanism

Here, the valves are located in the cylinder head. When the cam rotates, the valve lifter will push the push rod upwards. Push rod moves the rocker arm. Since, the rocker arm is pivoted at its Centre , it pushes the valves off its seat against the spring force. Thus, the valve is opened. When the cam is not in action, The valve returns back to its seat by the valve spring and spring retainer.

* Overhead Inlet and Side exhaust Valve Mechanism

In this system, inlet valve is located in the cylinder head whereas the exhaust valve is located in the cylinder block. The inlet valve is actuated by overhead valve mechanism. The exhaust valve is actuated by side valve mechanism.

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Mechinopedia For Mechanical Engineers

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