Strength in Numbers

Whayne Supply Co.
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Four years of field use and analysis of vehicle maintenance histories reveal that the addition of high-strength magnets to hydraulic filtration systems can reduce service expenses up to 80%.

As a Caterpillar equipment dealer, we know that reducing maintenance costs and increasing uptime of our rental equipment are essential to the success of our business. Of course, this mission is never-ending, and we wouldn’t last very long if we ever decided we’ve done all we can.

More than four years ago we began testing the concept that removing the sub-micronic shards of ferrous metal typically found in hydraulic and lubrication systems would extend the life of critical components and reduce machine maintenance costs and downtime. We also felt that removing these damaging contaminants would improve equipment productivity beyond the already high levels expected of these machines.

Initial results from the field indicated that high-strength magnet technology from Magnom Inc., Warwick, England, holds promise of dramatically reducing premature failure of critical components. In particular, we used Magnom CP20 in-line magnetic filter elements in the high-pressure hydraulic line of fan drives on Caterpillar D-11 dozers.

We found the fan-drive circuits operated four times longer than drives without the Magnom filters. The results were less frequent component replacement, lower maintenance-labor costs, and less downtime of the machines. As a result, many of our customers now incorporate Magnom magnetic filters in their machines (for more details about the technology behind the filters, see "Like Magnets on Steroids").

Results from the tests quickly led to a cross-section of our customers to incorporate the Magnom filters into their machines. These Dozer operators have a keen sense to keep all their equipment operating efficiently, which led to the use of Magnom filters in a wide variety of equipment.

Today, with three to four years of maintenance cost data for the hydraulic systems from a study group of Cat Dozers, the Whayne Technology Division is able to quantify a significant reduction in hydraulic system maintenance expenses. Efficiently removing the very small particles of hard metal with Magnom filters has now been confirmed as a cost-effective way to reduce maintenance expenses by greatly reducing the instances of unscheduled system repairs or servicing.

Summary of tests

A group of D-6 and D-8 Cat dozers, used extensively in landfills, was selected for study. Magnom filters were added to the existing filter systems on some of the machines, while others—the control group—used only standard filters. The wide variation of loads, uneven terrain, dirty environment, and range of ambient temperatures make landfills a demanding application for this equipment. The annual maintenance costs for each machine’s hydraulic system was collected for a three-year period and analyzed.

All machines in the study group operated approximately 2,000 hr/yr and were provided with a standard schedule of preventive maintenance procedures, such as fluid analysis, spin-on filter change-outs, etc. Hydraulic system savings will vary based on hours of operation, operating environment, level of maintenance, and operator skill.

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Results showed the average annual hydraulic system maintenance and repair costs for equipment fitted with Magnom magnetic filters was 79.3% lower than the same costs for those machines in the control group. We also confirmed that the machines using the Magnom filters encountered less downtime from unscheduled repairs. The increased productivity of those machines was an added benefit on top of significantly reduced repair expenses.

A Caterpillar D-8 dozer is shown working at a landfill, a demanding application used for testing an unconventional magnetic filter component in equipment’s hydraulic system.

A Caterpillar D-8 dozer is shown working at a landfill, a demanding application used for testing an unconventional magnetic filter component in equipment’s hydraulic system.


This Magnom magnetic core is shown with particles collected from a machine’s hydraulic system. Most individual particles are sub-micron in size, so they could only be seen through a powerful microscope.


Magnom in-line magnetic filters are shown installed on the hydraulic fan drive circuit of a Caterpillar D-11 dozer. The motor’s supply line is at right, and the return line is at left.