Gas spring bellows also enable a level control of the vehicle body with increasing load. The static spring compression is balanced by the additional pumping of gas. Hence the theoretical spring length hth remains constant. The feature of a gas spring bellow with pneumatic regulation is hence given by:
Gas volume = const.
As a result, for the spring stiffness of a gas spring bellow is determined as shown. In this case, the spring stiffness is directly proportional to the spring load. As a consequence, the natural frequency of the body oscillation does not change here with load (hth = const).