News Releases

June 2004

Silent and maintenance-free Marsh Mellows® eliminate vibrating screen problems

Vibrating screens are among the hardest-working industrial plant. They are expected to function reliably day after day in some of the toughest and grimiest situations encountered on building supply sites, quarries, mines and manufacturing process plants.

One extensive user of vibrating screen equipment who has overcome chronic problems of metal spring fatigue and breakage is T.J. Bryant of Cowra, whose quarry and gravel washing plant delivers sand and metal to builders, farmers and others needing such building materials throughout South-Eastern NSW.

Faced with breakdowns nearly every month, Mr Bryant introduced Marsh Mellow® springs, which are solid rubber fabric-reinforced bias ply springs designed to achieve superior isolation of vibrating equipment and, where this is desired, better excitation of screens. They also eliminate problems of broken coil springs causing downtime in equipment such as vibrating screens, as well as preventing fragment damage to stamping and metal forming equipment, where Marsh Mellows® are also used.

The cylindrical Marsh Mellow® springs are constructed of a solid rubber core with a hollow centre and several plies of fabric-reinforced rubber as an outer cover.

The plies provide the springs with stability as well as a consistent cylindrical shape.

Marsh Mellow® Springs, manufactured by Firestone, the world's biggest producer of air springs for actuation and isolation tasks, complement the broader pneumatic air spring family distributed throughout Australia by Air Springs Supply Pty for the quiet isolation of machinery vibration and for actuation and isolation throughout industry. Depending on the application, either solid springs or pneumatic springs are recommended.

'The screen that was causing us problems was a substantial piece of equipment, about sixteen feet long by six feet wide (or a bit over 5 m long by a bit under 2 m wide) which was sitting on eight steel springs,' said Mr Bryant.

'We used to break springs on it about once a month. They are very expensive and I made a lot of inquiries about replacing them with something more reliable. I finally got on to the Air Springs Supply people and received detailed and useful advice from their Simon Agar in Sydney.'

'Given our problem, and drawing on his experience with mining, quarrying and manufacturing equipment he recommended the Marsh Mellows®, which we subsequently bought, put them on, and have had no trouble for more nearly two years. You start up the machine and it runs perfectly.'

Mr Bryant has not needed to replace any Marsh Mellows® since he installed them. 'Previously, when one of the steel springs on the screens broke, not only were they expensive to replace, but also we had to get a crane in to lift the screen to replace the springs. It was just an expensive operation, and you had down time, but it's been perfect with the new springs. I am more than happy with them.'

Simon Agar says Marsh Mellow® springs, unique construction is the secret of their flexibility, with the spring's components being combined to meet specific load and performance requirements.

'One of the big advantages of Marsh Mellows® over steel springs is that they only suffer a maximum of 7 per cent compression set over the life of the part, as opposed to up to 27 per cent for steel springs.

'Suffering high compression set is a bit like having a worn shock absorber on one side of your car. That side droops and the car is not as dynamically stable.

The same problem arises with mixing old and new steel springs on a vibrating screen. Using Marsh Mellows® means you can change out one spring without affecting the screen's performance.'

Marsh Mellows® give consistent performance regardless of changing loads, while offering high lateral stability and compact size.

Uses include vibrating screens, die springs, and shock absorption applications in cranes, hammers, bumpers and similar applications requiring the cushioning of a blow (such as conveyor stops in industries as diverse as packaging and logging).

The low natural frequencies of Marsh Mellow® springs mean they provide excellent isolation of forced frequencies in the range of 800-1200 cycles per minute (13-20 Hz) for medium stroke applications.

Marsh Mellow® springs are maintenance-free. They have no moving parts and require no lubrication. Their rubber and fabric-reinforced construction is corrosion-resistant for a durable, long life.

Springs available from Air Springs Supply's Marsh Mellow® catalogue range in size from the 0216 model with an unloaded height of 44 mm and outside diameter of 41 mm, through to models such as the 0243 with an unloaded height of 203 mm and an outside diameter of 279 mm.

Free Technical Information

Would you like to learn more about the technology discussed in this application? Readers can receive more information by contacting Air Springs Supply Pty Ltd, PO Box 215 West Ryde, 2114, Phone (02) 9807 4077, fax (02) 9807 6979.

Mr Tom Bryant, trading as T.J. Bryant, can be contacted at P.O. Box 156, COWRA, NSW 2794 Phone: (02) 6341 1288.