This apparatus is used to explain torsion of rods and torsional vibration experiments. This apparatus allow the student to demonstrate and to perform experiments foreseen as well as to calculate the results. The main unit of this apparatus is metal torsion bars. With the aid of chucks, mass discs of varying inertia can be attached to the bars. In this way it is possible to assemble torsional vibrator systems with up to three masses. Vibrations can be induced on the system using a servo motorized exciter and the control unit. An adjustable damper can be used to influence the vibrations. Shaft encoders on the chucks provide the amplitude of vibration as an electrical signal. The control unit conditions these signals and makes them available, e.g., for display on the data acquisition software or on an oscilloscope (optional).