The article identifies some of the forces acting on hydraulic valves used in the civil and military vehicles. Particular attention was paid to the single-stage electrically controlled “on/off” hydraulic directional control valve. Special attention was focused on vibrations of hydraulic directional valve four ways, three positions (4/3) controlled by typical solenoids. Military vehicles can be a source of vibrations in low and high range of frequency. The spectrum of vibrations frequency is wide in this case. The value of the natural frequency of vibrations of the hydraulic directional control valve spool, whose body was affected by mechanical vibrations, was estimated. The paper shows that the natural vibrations of the directional control valve spool can coincide with the frequency of external vibrations acting on the valve from the ground. The mathematical description takes into account that when the spool is overdriven, the oscillating movement of the directional control valve spool is described by a model that takes into account the nonlinearity resulting from the fact that the spool is in the extreme position—it is a poor nonlinear mechanical system. The results of theoretical considerations were confronted with the results of experimental research. In addition, the presented modified model was used to assess the impact of the capacitance change on the value of the amplitude of pressure pulsations caused by the vibrations of the directional control valve spool.