The principle of the engine rocker shaft is that when the blades of the camshaft raise the outer lever arm, the internal force will press on the valve rod, thus opening the action valve. When the outer arm is allowed to return due to the action of the camshaft, the inner arm rises, allowing the valve spring to compress and close the action valve.
The driving cam works by driving the camshaft. It can push the rocker arm to move up and down near the trunnion or rocker shaft. In this way, the roller follower of the cam can reduce the wear of the driving cam at the contact point with the valve rod.
At the same time, through the function of another cam roller follower, it is transmitted to the second rocker arm for similar movement. This rotates the rocker shaft and transmits the action to the poppet through the gear follower. In this case, open the air inlet valve and let the air rush to the cylinder head.