Rubber springs have long 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.
The Marsh Mellow® fabric and rubber spring solves this basic problem and provides a new and unique way to make use of the many advantages of rubber as an isolator. The basic construction of the Marsh Mellow® spring includes a solid rubber core with a hollow center, and fabric reinforced body. The controllable variables of this construction are the keys to the extreme design flexibility that the spring offers.
Constant Vibration Isolation with Changing Loads
The variable spring rate allows for a nearly constant natural frequency with changing loads. This results in consistent vibration isolation with variable loading.
High Load Carrying Capacity
Due to the Marsh Mellow® spring’s greater deflection capabilities and load carrying influences of the fabric reinforcement, it can carry a greater load when compared to an all rubber part of the same modulus and dimensions.
Excellent Vibration Isolation
Low natural frequencies provide excellent isolation of forced frequencies in the range of 800-1200 cycles per minute (13-20Hz).
Lateral Vibration Isolation
The lateral spring rate of a Marsh Mellow® spring can be less than the vertical spring rate, resulting in a lower lateral natural frequency. Marsh Mellow springs provide better vibration isolation in all degrees of freedom.
Compact Overall Size
The ability to support greater loads and maintain a cylindrical shape results in a smaller overall size of the Marsh Mellow spring compared to an all rubber spring with identical load capacity. This is important when considering an application with a small design envelope.
Corrosion Resistant for a Durable, Long Life
Due to its rubber and fabric reinforced construction, the Marsh Mellow spring has been proven in the damp and corrosive environments of mines and mills where a standard coil spring will fail.
Does Not Bottom-Out
Due to the rubber construction, Marsh Mellow springs do not bottom-out like coil springs. Bottoming-out under overload or surge load sends a large amount of stress to all of the machine’s components.
Eliminates Downtime and Potential Damage to Machinery
When a coil spring fails, it will often crack allowing fragments of the coil to damage equipment. This problem is eliminated with the rubber construction of Marsh Mellow springs. Additionally, Marsh Mellow springs exhibit exceptionally high overload characteristics and usually do not fail catastrophically, offering some support even during failure.
Increased Stability at Higher Percentages of Compression
Rubber is an incompressible fluid which will flow to the path of least resistance. In a Marsh Mellow, as the height compresses, the fabric reinforced rubber plies pantograph and the diameter grows. This supports the rubber core laterally even at 30-40% compression.
Effective Noise Reduction
Marsh Mellow springs reduce structurally transmitted noise caused by vibration. Marsh Mellow springs are quiet, unlike steel springs which often suffer coil chatter and readily transmit high frequency structural noise.
The Marsh Mellow spring’s high load capability means fewer springs may be needed in an application, resulting in less overall cost.
Marsh Mellow springs have no moving parts.
No maintenance or lubrication is required.