A Marsh Mellow spring is a fabric reinforced rubber cylinder. A main advantage of a Marsh Mellow spring over an air spring in isolation applications is a Marsh Mellow spring does not require air.
Marsh Mellow is a trade name of the rubber and fabric spring developed by Firestone Industrial Products in the early 1970's. Rubber springs have long time been a subject of interest in the vehicular suspension and industrial application fields because of their reliability, corrosion resistance, low cost, and basic simplicity. The concept has been tried with varying degrees of success over the years. The major obstacle to solid rubber springs has been that to obtain the load requirements for many applications, solid rubber springs were either physically too large, or became unstable laterally when they were made long enough to provide good isolation. The concept of "stacking" rubber springs answered the latter problem, but introduced the need for complicated mechanical guide systems to control the lateral movement.