The valve control cam is formed in a way that the maximum acceleration (A1) of the opening valve is smaller than the maximum acceleration of the closing valve. The maximum opening acceleration can be between 60 and 90 percent of the maximum closing acceleration. The cam can also be formed in a way that the maximum acceleration of the opening valve is smaller than the operating limitations given by the mechanical design. The cam increases the opening acceleration between the point when the cam starts to open the valve until about 20 degrees before the dead centre position of the crankshaft's rotation cycle. NB: The diagram shows acceleration against crank angle.
