Poppet Valve

Poppet valves are used to control the inlet and exhaust openings of the cylinders in an IC engines.  Poppet Valves have a long stem which ends in a flat plug.  The plug sits on a seat in the cylinder block.

The valve is operated by the pushrods which are driven by the camshaft.  When the valve is seated in the seat, the opening is closed and the valve is considered closed.  When the valve is pushed out of the seat by the pushrod, it is open.