In a firm manufacturing paving blocks, the blocks were moved along the line on wooden pallets. The pallets were propelled by a series of metal catches underneath the machine frame, which rose up to engage the pallet and to push it forward to the next stage of the process. At the end of the stage, the catches fell to a horizontal position and slid back along the line to the next pallet. They then rose to engage the new pallet to repeat the process.
A-weighted noise levels of over 100 dB were generated when the catches snapped back to the horizontal and fell onto the metal bar.
The solution was to replace the metal catches with similarly shaped components moulded from a tough polyurethane polymer. The new catches also proved to be almost as durable as the original steel components.
About £10 to £20 per catch. (1995)
Noise levels were reduced by about 5 dB. Impactive peaks were effectively removed.
Photographs courtesy of Redland Precast. Equipment supplied by Hallam Polymer Engineering Limited.