208 front wheel hub bearing failures prevented with OEI Magnetic Filter Plugs saving a South African mine site $14 Million USD in under 2 years.

Fewer failures leads to minimized touch points – safety risk at the mine site has been significantly reduced with less human : machine interface.

ROI per Haul Truck: $185 USD one-time-purchase of 2 magnetic filter plugs… $156k savings in under 2 years.


The mine site was experiencing premature outer taper roller bearing failures on the front wheel hubs of their Komatsu 860 E and 960 E haul trucks.

The site operates 92 haul trucks, and the expected operating life of front wheel hubs is 20 000 hours; the site however, was experiencing 1-3 failures per week at a cost of 1 million South African Rand per failure.

The mine started investigating in May of 2015. Oil analysis determined that during operation, contamination was wearing heavily on the outer taper roller bearings which was, in turn, causing premature wheel hub failure.

Frequency of Failures 1-3 Weeks
Cost / Failure – South African Rand $1,000,000
Cost / Failure – Canadian Dollar $90,000
Cost / Failure – US Dollar $68,000


In November 2016, the minesite reliability team decided to run a trial on OEI magnetic filter elements to test their ability to improve haul truck front wheel hub reliability. The team replaced all the OEM plugs that were installed on the roller bearing covers with OEI magnetic filter elements.

10 Week Trial Results
Over the 10 weeks that the haul trucks operated with OEI filters, there were no front wheel hub failures. Based on the mine’s estimation that they were previously experiencing between 1-3 failures per week, the savings were significant.



Left-hand-side wheel hub



Right-hand-side wheel hub

The photos show contamination collected on the OEI magnetic filter elements from the left and right-hand-side wheel hubs of one haul truck after only 500 hours of operation.

Note that the most damaging wear particles to a bearing are between 1 and 4 microns, and the human eye can only see particles down to ~ 30 microns (the size of cigarette smoke particles). The contamination particles shown in the pictures below are large enough to cause significant bearing damage and consequent failure.

Fine foreign material in the bearing can cause excessive abrasive wear. Sand, fine metal from grinding or machining, and fine metal or carbides from gears wear or lap the rolling elements and races. In tapered bearings, the roller ends and cone rib wear to a greater degree than the races. This wear causes increased endplay or internal clearance, which can reduce fatigue life and create misalignment in the bearing. Abrasive wear also can affect other parts of the machine in which the bearings are used. The foreign particles may get in through badly worn or defective seals. Improper initial cleaning of housings and parts, ineffective filtration or improper filter maintenance can allow abrasive particles to accumulate.



For more information on bearing wear, tolerances and proper lubrication management, read this guide by Timken – “Timken Bearing Damage Analysis with Lubrication Reference Guide”

10 Week Trial Cost Savings

Wheel Hub Failures 0
Cost Savings – South African Rand $2,000,000
Cost Savings – Canadian Dollar $180,000
Cost Savings – US Dollar $136,000

Next Steps

Based on the success of the 10 week trial, the international mining organization decided to use this minesite to run a pilot program for OEI filtration. The minesite outfitted all of their haul truck front wheel motor hubs with OEI magnetic filter elements. They have since been recording their findings to determine the value of deploying OEI filtration on other critical equipment systems.

Pilot Program Results

The following results are the calculated savings for the operation of 92 haul trucks deploying OEI magnetic filter elements on their front wheel hubs for 2 years (104 weeks). The calculations are based on the prevention of 1-3 wheel hub failures per week, where each haul truck operates for 15 hours per day.


The pilot program success has identified OEI magnetic filtration as an integral tool in the mining organization’s reliability program. Using the magnetic filter elements as predictive maintenance tools, as well as high-efficiency filters, saved the minesite over $14 million USD in under 2 years.

These results have propelled the mine site to deploy OEI filtration on all critical haul truck systems: engines, hydraulics, coolant systems and lube oil systems. Further, there has been discussion regarding distribution of OEI filtration for equipment across all the mining organization’s international mine sites.


click here for more on OEI Magnetic Filter Plugs