Method for providing high vertical damping to pneumatic isolators during large amplitude disturbances of isolated payload

A vibration isolator with a flange that extends from a piston. The piston may be coupled to a housing by a diaphragm. The diaphragm and flange define a balancing chamber that is in fluid communication with a leveling port. The flange is separated from the housing by a gap that provides fluid communication between the balance chamber and an inner chamber within which the piston moves relative to the housing. The piston is coupled to a support plate that is attached to a payload. The leveling port may be coupled to a leveling valve that varies the pressure within the balancing chamber and inner chamber to compensate for a disturbance applied to the isolator. The flange will provide a force that is opposite to the movement of the piston. The counteracting force minimizes oscillations in the isolator caused by releveling the support plate.