The rocker arm in a car is actually a two-armed lever that reoriates the force from the push rod and acts on the end of the valve rod to push open the valve. The ratio of arm lengths on both sides of the rocker arm is called the rocker arm ratio, which is about 1.2~1.8. One end of the long arm is used to push the valve. The working surface of the rocker arm head is generally made of cylindrical shape. When the rocker arm swings, it can roll along the end face of the valve rod, so that the force between the two can act along the valve axis as far as possible. The rocker arm is also drilled with lubricating oil and oil holes. An adjustment screw for adjusting valve clearance is inserted into the threaded hole at the short arm end of the rocker arm. The head ball of the screw is in contact with the concave tee at the top of the push rod.
The rocker arm is empty set on the rocker arm shaft through the rocker arm bushing, and the latter is supported on the rocker arm shaft seat, and the rocker arm is drilled with oil holes.
The rocker arm changes the direction of the force from the push rod and opens the valve.
