How the engine rocker shaft works: The rotating leaf of the camshaft causes one end to rise or fall (either directly or by the gear driven (lift rod) and pushrod), while the other end will act on the stem. When the blade of the camshaft raises the outside arm, the force generated internally will be pressed against the stem, opening the action valve.
When the outside arm lever is allowed to return due to the action of the camshaft, the inner arm bar rises, allowing the valve spring to compress and close the action valve. The drive cam operates by the camshaft. It can push the rocker arm up and down near the gun ear shaft or the rocker shaft. This allows the drive cam to wear less at points in contact with the stem through the action of the cam's roller driven. At the same time, the action of another cam roller disactor is passed to the second rocker arm to do similar movement. This rotates the rocker shaft and passes the action on the lift valve through the gear driven. In this case, open the intake valve and cause the gas to rush towards the cylinder head.