An extensive user of vibrating screen equipment has overcome chronic problems of metal spring fatigue and breakage.
TJ Bryant of Cowra, whose quarry and gravel washing plant delivers sand and metal throughout south-eastern NSW, was faced with breakdowns nearly every month, until the introduction of Marsh Mellow springs.
The springs are solid rubber fabric-reinforced bias ply springs designed to isolate vibrating equipment and, where desired, for better excitation of screens. They also eliminate downtime caused by broken coil springs.
The cylindrical springs are made of a solid rubber core with a hollow centre with several plies of fabric-reinforced rubber as an outer cover. The plies provide the springs with stability as well as a consistent cylindrical shape.
According to quarry owner Tom Bryant, the screen causing us problems was about five metres long by a bit under two metres wide, which was sitting on eight steel springs.
“We used to break springs on it about once a month,” Bryant says.
“They are very expensive and I made a lot of inquiries about replacing them with something more reliable.”
Bryant approached Air Springs Supply who recommended the Marsh Mellows, which have now given two-years trouble free operation. Bryant has not needed to replace any springs in this time.
“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,” Bryant says.
According to Air Springs Supply, one of the advantages of Marsh Mellows over steel springs is they only suffer a maximum of 7% compression set over the life of the part, as opposed to up to 27% for steel springs.
The company says 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.
The springs are said to 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. The low natural frequencies of the springs mean they provide isolation of forced frequencies in the range of 800-1200 cycles per minute (13-20Hz) for medium stroke applications.
Made by Firestone, the springs range from the 0216 model with an unloaded height of 44 mm and outside diameter of 41mm, through to the 0243 with an unloaded height of 203mm and an outside diameter of 279mm.
They are maintenance-free, have no moving parts and require no lubrication. Their rubber and fabric-reinforced construction is corrosion-resistant for a durable, long life.