Fig. 21. Decibel amplitude-frequency-phase characteristics of the vehicle model expressing relative inertial force of the driver’s seat with the driver as a dynamical excitation function acting upon the driver’s seat in the direction of axle for free vibrations The analysis of the derived graphs indicates that the maximal vibrations amplitude in the form of the inertial force of the driver’s seat with the driver vibrations reaches the value of 320 [N]. The maximal vibrations amplitude in the form of linear acceleration reaches the value of 3.4 The maximal vibrations amplitude in the form of velocity of the centre of the driver’s seat with the driver mass for linear velocity is 0.012