Engine Parts 101: Valve Train Components

In an OHV engine, the valve train process starts when the camshaft begins to rotate. At the highest point on the lobe of the camshaft, the lifter is lifted upward, which causes the pushrod to move upward as well. As the lifter raises the pushrod, the pushrod applies pressure to the underside of the rocker arm. The rocker arm is balanced between the pushrod and the valve spring. When the pushrod applies pressure to the underside of the rocker arm, the rocker arm pivots downward and compresses the valve spring. The compression of the valve spring opens up the exhaust valve and releases the exhaust. When the highest point of the camshaft lobe moves back to it’s original position, then the valve spring relaxes. This causes the valve to close and returns all the other valve train components back to their original position, too. The OHV engine, as well as the OHC engine, is synchronized with the rest of the engine cycle by the timing set.