rubber air spring
Though, its major role is to manage loading shock and a component of constant loading, using air pressure in conjunction with the rubber bellows. Other tech features include a spring with variable rate, depending on air pressure, and self-leveling capability to compensate for changes in load or road conditions. This is why it has become the standard for heavy vehicles such as railway coaches, or industrial machinery and even at suspension systems of some cars in highest technology segment, providing a much better and stable ride.