An estimated three-quarters of hydraulic system failures are caused by contaminants in the hydraulic fluid. These may be contaminations by dirt, bugs, cigarette butts, or similar items, or by air or water getting into the system.
Hydraulic systems are often components of heavy-duty machines: log splitters and car brakes, dump trucks and bulldozers, garage jacks and backhoes. These machines use fluid (usually some type of oil) under high pressure to create and control power. And they often operate in environments rife with potential contaminants, such as building sites and industrial enterprises.
In the best case, filters will keep out contaminants at every step of the hydraulic process: before the pump, after the pump, before the reservoir, and in the reservoir. However, money and space constraints usually make this level of filtration impracticable. A reasoned choice has to be made which considers how clean the components have to be and what kind of contaminants they are likely to encounter, along with other factors.
There are a variety of filter types available for hydraulic systems, including Donaldson hydraulic filters, and some of them give such good benefits for the cost that they should be considered for every hydraulic system whenever practical.
Fairly expensive, and used in high-performance applications, high-pressure filters clean the fluid after it leaves the pump. This means that if something goes wrong with your pump, the results won’t end up damaging other parts “downstream.” These filters operate using high pressure so tend to be heavy, and, generally, when maintenance is needed, the whole system has to be shut down.
Off-line filters (also called “kidney loops”) do a thorough job of cleaning the fluid in the reservoir. One advantage is that they can do their work even when the main system is shut down. Also, they are easy to get to in order to service, and the hydraulic system can continue running during servicing.
Air naturally will enter the hydraulic reservoir as the level of fluid drops during use or as it cools. A breather filter prevents the entrance of particles bigger than 3 microns. These filters can cost less than lunch and are well worth the investment. Some breather filters let you add a desiccant to remove water from the air as it enters the reservoir.
Keeping contaminants out of hydraulic fluid does not have to be costly. The inexpensive solutions do an impressive job, and even the more expensive options are likely to pay for themselves many times over by preventing damage to much more expensive components.