Longer bearing life and a separable structure allows for re-use of bearings after reconditioning, helping to reduce maintenance costs and cut CO? emissions    Suited for dump trucks, crushers, and other equipment commonly used under harsh conditions Long life and a separable structure allow for reconditioning and cost savings  High load capacity and up to 2x longer life realized by NSK’s exclusive Micro-UT? method for highly accurate life prediction A detachable rim (inner ring small rib) allows for detailed inspections of internal components 　

NSK Ltd. (NSK; Headquarters: Tokyo, Japan; President and CEO: Akitoshi Ichii) has developed the mining industry's first1 large-size tapered roller bearings that can be reconditioned and put back into service. 　

Reconditionable bearings must offer long life and a design structure that supports long-term use over the course of repairs and equipment maintenance. These newly developed reconditionable TRBs have up to twice the life of conventional products, thanks to NSK's exclusive Micro-UT? ultrasonic material testing method and highly accurate life prediction2. 　

In typical bearings, the inner ring and cage are non-separable, making it difficult to detect and address issues during inspections, but these reconditionable TRBs have a rim (small rib) that can be removed, allowing for detailed inspection of all bearing components. With fewer replacements, mining sites can benefit from bearing reconditioning with reduced maintenance costs and lower CO? emissions. 　

Plans to provide samples to mining equipment manufacturers are underway, with aims to expand offerings to cement manufacturers and other industries in targeting annual sales of 2 billion yen by 2030. 

 1 Per February 2025 NSK survey of tapered roller bearings for mining equipment. 

 2 Micro-UT provides detailed statistics on the size and quantity of non-metallic inclusions in bearing steel, facilitating highly accurate  predictions of fatigue life for rolling bearings (patent pending).

Development Background 　With increased urbanization and strong demand for resources such as iron ore and coal around the world, mining sites face growing pressure to take action towards carbon neutrality in energy-intensive operations. Efforts are underway to improve operating efficiency and electrify equipment, and the reuse of equipment components is a particularly important initiative to save energy and cut CO2 emissions. 　Dump trucks and crushers used at mine sites operate 24 hours a day under harsh conditions with low-speed rotation, heavy loads, and strong vibration, so large tapered roller bearings are generally used for their long life and high reliability. 　During equipment maintenance, components such as shafts and gears are reconditioned and put back into service; however, conventional bearings cannot be readily reconditioned, so they must be scrapped and replaced regularly. Therefore, there is a growing need for reconditionable bearings in the market. 　

Reconditioning requires parts to have long life and a separable structure so that maintenance tasks can be performed easily and accurately. Mining equipment can be used for decades or more, so all components must stand up to years of use across long maintenance intervals. Even if conventional bearings were repaired, their low load capacity makes bearing life too short for the life of the equipment, so they would still need replacement shortly after. Therefore, longer bearing life is essential for long-term bearing use. In addition, reconditioning requires in-depth inspections of bearing internals at the maintenance site, but conventional bearings use an non-separable structure that makes this difficult.