What Is The Valve Rocker Arm of Forklift Engine: The valve rocker arm of the forklift engine controls the opening and closing of the intake and exhaust valves. The valve rocker arm is pushed by the camshaft to open and close the valve. The opening and closing of the valve is completed by the action of the tappet and the rocker arm. The rocker arm is installed on the rocker arm seat through the rocker shaft. The function is to control the opening and closing of the valve.