This animation shows the working principle of a Normal and a Resonance Free vibratory hammer side by side. The first part of the video shows the 55NF during its start and stop creating resonant vibrations, and the second part of the video shows the 20RF resonance free hammer avoiding resonance by setting the variable moment of the eccentric weights to cancel-out vibrations in the sensitive frequency band. In the last shots the hammers are shown side-to-side to highlight the difference.