At Exxaro Resources’ New Clydesdale Colliery in Mpumalanga, South Africa, a conveyor experienced repeated premature bearing damage on the tail pulleys. Spherical roller bearings mounted in traditional split-block housed units were failing after no more than eight weeks of service. Issues included fractured housings and failed seals.
The mine operators urged their bearing distributor to find a solution, and the distributor asked international bearing and power transmission solution provider Timken for a recommendation. After reviewing the situation with the distributor and the maintenance team at New Clydesdale, it was clear that bearing contamination and housing strength were the primary issues. Timken recommended its spherical roller bearing solid-block housed units, which were a change from the more traditional, split-block units in use.
Further, Timken recommended changing the housing specification from cast iron to cast steel. Other recommendations included reviewing the mounting and replacement methods to reduce their complexity. To prevent corrosion, the company recommended powder coating the housing and coating the mounting components and additional shields with black oxide. Using the same bolt hole and envelope dimensions, the solid-block housed units would be an easy, “drop in” installation without the need for modification to existing infrastructure.
After installing two Timken spherical roller bearing solid-block housed units at the tail pulley positions, New Clydesdale decided to install more units at several locations in its conveyor system. “We were getting eight weeks’ maximum bearing life with our previous solution. From fractured housings to seal failure and higher-than-normal maintenance cycles, the issues ran the gamut,” said Frans Botha, mechanical foreman at New Clydesdale.
“Timken presented the spherical roller bearing solid-block housed unit as a potential solution and we gave it a try. We saw benefits right from the start. It took us approximately 30 minutes to install each unit, compared to an hour and a half normally required to reinstall the previous split-block units. Nearly a year later, the original units were still running and our maintenance cycles have been reduced significantly.”
The solid-block housed unit design includes high performance spherical roller bearings that have high dynamic load ratings and internal misalignment capability. Powder and black oxide coatings are standard on the housed unit, as is the solid steel housing material. The units supplied include premium grease, as well as primary and secondary seals that promote grease retention and significantly reduce the entry of contaminants. In addition, the units are designed with fully machined feet for one time alignment of the tail pulley at installation, eliminating concerns about excessive bearing misalignment or unusual housing distortion. In summary, the Timken spherical roller bearing solid-block housed unit offers powerful combinations of features to improve conveyor uptime whilst lowering maintenance spend.
Timken engineers, manufactures and markets bearings, transmissions, gearboxes, chain and related products, and offers powertrain rebuild and repair services. As a specialist on tapered roller bearings, Timken applies its knowledge of metallurgy, tribology and mechanical power transmission across a variety of bearings and related systems to improve reliability and efficiency of machinery and equipment all around the world.
Australian Timken is the local distributor for tapered roller bearings, cylindrical roller bearings and spherical roller bearings and is based in Melbourne.
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Source: Australian Timken