Several industrial rotor systems utilize hydraulic cylinders for adjustable support structures. Such systems are, for example, conveyer belts and paper winders. These rotors systems can experience vibrations due to asymmetries in the rotating bodies themselves or unsteady loads generated by moving materials. Typically, hydraulic cylinders are of lower dynamic stiffness compared to the mechanical structures, which makes then susceptible to vibrations. This makes increasing the dynamic stiffness of hydraulic cylinders beneficial for the operation of several rotor systems. If an accumulator is in direct connection with a hydraulic cylinder chamber via an open fluid line, a hydraulic equivalent of a mass-spring system with a damper is created. This system will be referred as hydraulic resonator in this paper. Resonator has a direct effect on the dynamic stiffness of the hydraulic cylinder, depending on oscillation frequency, fluid line length, accumulator throat dimensions, accumulator volume, and accumulator charge pressure. By modifying the aforementioned attributes, the hydraulic cylinder’s dynamic stiffness in response to a specific frequency vibration can be lowered or increased. In this research, experimental hydraulic passive resonator is simulated and constructed. Its effect on hydraulic cylinders dynamic stiffness characteristics is measured and compared to baseline values. Depending on cylinder chamber volume and excitation frequency, resonator increases the dynamic stiffness by a factor of 4–10 times that of baseline stiffness. Outside optimal frequencies, dynamic stiffness is lowered compared to baseline.