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Your choice of filter is determined by several criterion. "When selecting filters, it's important to consider how clean the fluid needs to be (ISO cleanliness requirements), how well the filter cleans (Beta rating) and the capacity of the filter," says Zumbusch. "Vehicle manufacturers work closely with their hydraulic component manufacturers to determine the proper filter selection for a particular application."

The goal is to capture particle sizes that could damage the system. "The particle-blocking size and efficiency of installed filters must be matched to the target cleanliness level," says Casey. "Generally speaking, the finer the filtration, the better the achieved cleanliness and the longer the transmission service life - all other things being equal. Ten micron, Beta 200 would be the minimum level of filtration for most hydrostatic applications, down to 6 micron, Beta 200."

Wickenhauser adds, "A charge filter can provide higher performance than a suction filter. Charge filter ratings of 4 micron or better are best to maintain ISO levels of 18-15."

In addition to fluid cleanliness, radiators also need attention. "The radiator and cooling packages need to be cleaned on a periodic basis, and more frequently when operating in very dusty conditions," says Wickenhauser. Filters also need to be replaced immediately if the bypass warning system is on, and the machine should be shut down if the temperature warning comes on.

Cavitation is the enemy of pumps
"Cavitation happens when a pump or a motor tries to compress air in the hydraulic system fluid," says Cahalan. "When that air is compressed rapidly, it actually explodes and removes little bits of metal from the pump or motor internal parts (creating contamination)."