Contamination Control in Earthmoving Machines -Hybrid Filter Elements Versus By-Pass Filters -Influence of Biodegradable Oil on Filter Life

By-pass filtering may achieve significant contamination control,but it has many disadvantages in terms of cost, maintenance and the need for a complete new system including a by-pass filter case and the lines and fittings. In contrast, a hybrid filtering system is constructed with a filter element that allows the filter paper media to share the filtration of oil with a high-efficiency media from the return line, assuring a high level of contamination control in a hydraulic system. Because the hybrid filter can be constructed in the same overall configuration as the existing filter elements, no further system change is required to make the conversion.

The author discusses the effects of hybrid and by-pass filters on contamination control in each and field tests. The adverse effects of biodegradable hydraulic oil on filter strength and life and how to counter these problems will also be addressed.