a force limiting device for a motor vehicle , which features at least two parts controlled relative to each other with a frequency - based , defined movement , wherein the parts moving relative to each other have mutually engaging gearings and the frequency - controlled movement takes place in such a way that at least one of the parts performs a wave - like advancing motion with respect to another part , in which the gearing is alternately engaged and disengaged , wherein one or a plurality of individual masses are provided , which can be coupled to or decoupled from the part performing the wave - shaped advancing movement thereby changing the force limiting characteristics of the system .