Abstract: The invention refers to a step adjustable monoaxial vibrator intended to be used on the vibrating rollers or similar machines.In order to adjust the peak value of the excitation at various levels, it has three rotary balls (rollers) rolling along the pendular frame rolling path while being driven by a dynamic balanced fork as a rotor.Across the rotor axle there is an obturating rod in order to locate the central ball either in the same compartment or in the opposite one versus the remaining two balls.This allows the steady frequency excitation to be set up either at the maximum peak value or at a value three times lower. By removing the central ball, a medium size excitation is obtained.