What is the main working principle of the rocker arm?

The working principle of the rocker arm is: when the engine is running, the camshaft rotates with the CAM, and the camshaft presses the rocker arm. In this process, the rocker arm is partially rotated around the pin shaft, usually using the shaft as the other end to generate a pivot force. One end of the rocker arm is pushed down, the valve opens, and the other end returns to its original position, causing the valve spring to close the valve.