The decision followed trials on conveyors in the sand production area of the quarry, where bearings were failing up to three times a year, and the gearboxes lasted only 12 months. In some cases, a bearing failure also meant changing the gearbox, as it had to be removed by force, sustaining damage in the process. In these cases, the material costs were dwarfed by the day?s downtime needed for the repair.
Corcoran Concrete discussed the problem with local power transmission distributor Central Bearing Supplies, which suggested replacing the Plummer block bearings of the original conveyor equipment with Dodge ISN components. The main feature of interest was the ISN bearing?s combined triple-lip and flinger sealing system, which is effective against contaminants like sand and stone dust. A further advantage of the bearing is its provision as a shaft-ready bearing with an adapter mounting system that allows installation in 15 minutes.
As bearing failures occurred in the sand production and washing plant, Corcoran Concrete replaced them with ISN types, and saw reliability increase three-fold. When a gearbox also went down, Central Bearing Supplies suggested a Dodge Torque-Arm II shaft-mounted speed reducer, primarily because of its tapered bushing system, which makes disassembly and reassembly a quick, predictable task.
Reliability improved. So when Corcoran Concrete decided to invest in a new 300 tonnes per hour plant for stone chip production, it specified that the conveyors must come fitted with Dodge ISN bearings and Torque-Arm II speed reducers. The new plant uses Trio aggregate machinery, which is integrated together with custom structures and conveyor sections designed and manufactured by Gortavoy Plant.
?This is a competitive business and reliability of production is critical to make sure our clients? construction projects run smoothly,? said Ian Duffy, Corcoran Concrete?s maintenance manager. ?The sealing integrity built into these Dodge parts has made a significant difference for us. And when parts do eventually fail, we have the fallback position of predictable repair times through designed for maintainability features.?
A further spin-off benefit for Corcoran Concrete is the Torque-Arm II speed reducer?s use of two-stage helical gearing. This provides outstanding energy efficiency in the 96 per cent range, minimizing energy consumption. The difference became clear when Mr Duffy decided to make a comparison between old and new conveyors using an ammeter. Drives on the older conveyor systems tend to draw currents of around 70 to 75A. The new conveyors in the stone chip area with their Dodge helical gearboxes draw around 40A.
Although this evaluation exercise was not performed under closely controlled conditions, the obvious efficiency of the new automation made it clear that the energy savings would give a fast return on investment. These benefits are further amplified for Corcoran Concrete because they already draw almost the maximum capacity of the electricity supply to the quarry, and extending this would incur a substantial charge to improve the infrastructure.
?Dodge bearings and gearboxes have a formidable durability record on the most aggressive processes,? said Mike McGrath of Central Bearing Supplies. ?Compared with the components often fitted on quarry conveyors, they can often increase operating lifetimes substantially as this quarry application demonstrates.?
The handling automation for the new stone processing area was designed by Gortavoy Plant, a Northern Ireland company specialising in application-specific automation solutions for quarries. To aid the reliability and maintainability of the 17-section conveyor system, it produced for Corcoran Concrete just two sizes of Dodge gearbox and two sizes of ISN bearing have been used throughout the conveyor system, by allowing for good margins of performance above the nominal ratings. This feature aids the robustness of the system, and additionally allows Corcoran Concrete to maintain a spares holding on the site to deal quickly with any unforeseeable problems.
Source: Baldor Australia